C4GEM, a Genome-Scale Metabolic Model to Study C4 Plant Metabolism1[W][OA

PubMed Central

de Oliveira Dal’Molin, Cristiana Gomes; Quek, Lake-Ee; Palfreyman, Robin William; Brumbley, Stevens Michael; Nielsen, Lars Keld

2010-01-01

Leaves of C4 grasses (such as maize [Zea mays], sugarcane [Saccharum officinarum], and sorghum [Sorghum bicolor]) form a classical Kranz leaf anatomy. Unlike C3 plants, where photosynthetic CO2 fixation proceeds in the mesophyll (M), the fixation process in C4 plants is distributed between two cell types, the M cell and the bundle sheath (BS) cell. Here, we develop a C4 genome-scale model (C4GEM) for the investigation of flux distribution in M and BS cells during C4 photosynthesis. C4GEM, to our knowledge, is the first large-scale metabolic model that encapsulates metabolic interactions between two different cell types. C4GEM is based on the Arabidopsis (Arabidopsis thaliana) model (AraGEM) but has been extended by adding reactions and transporters responsible to represent three different C4 subtypes (NADP-ME [for malic enzyme], NAD-ME, and phosphoenolpyruvate carboxykinase). C4GEM has been validated for its ability to synthesize 47 biomass components and consists of 1,588 unique reactions, 1,755 metabolites, 83 interorganelle transporters, and 29 external transporters (including transport through plasmodesmata). Reactions in the common C4 model have been associated with well-annotated C4 species (NADP-ME subtypes): 3,557 genes in sorghum, 11,623 genes in maize, and 3,881 genes in sugarcane. The number of essential reactions not assigned to genes is 131, 135, and 156 in sorghum, maize, and sugarcane, respectively. Flux balance analysis was used to assess the metabolic activity in M and BS cells during C4 photosynthesis. Our simulations were consistent with chloroplast proteomic studies, and C4GEM predicted the classical C4 photosynthesis pathway and its major effect in organelle function in M and BS. The model also highlights differences in metabolic activities around photosystem I and photosystem II for three different C4 subtypes. Effects of CO2 leakage were also explored. C4GEM is a viable framework for in silico analysis of cell cooperation between M and BS cells during photosynthesis and can be used to explore C4 plant metabolism. PMID:20974891

Unraveling the Plant-Soil Interactome

NASA Astrophysics Data System (ADS)

Lipton, M. S.; Hixson, K.; Ahkami, A. H.; HaHandkumbura, P. P.; Hess, N. J.; Fang, Y.; Fortin, D.; Stanfill, B.; Yabusaki, S.; Engbrecht, K. M.; Baker, E.; Renslow, R.; Jansson, C.

2017-12-01

Plant photosynthesis is the primary conduit of carbon fixation from the atmosphere to the terrestrial ecosystem. While more is known about plant physiology and biochemistry, the interplay between genetic and environmental factors that govern partitioning of carbon to above- and below ground plant biomass, to microbes, to the soil, and respired to the atmosphere is not well understood holistically. To address this knowledge gap there is a need to define, study, comprehend, and model the plant ecosystem as an integrated system of integrated biotic and abiotic processes and feedbacks. Local rhizosphere conditions are an important control on plant performance but are in turn affected by plant uptake and rhizodeposition processes. C3 and C4 plants have different CO2 fixation strategies and likely have differential metabolic profiles resulting in different carbon sources exuding to the rhizosphere. In this presentation, we report on an integrated capability to better understand plant-soil interactions, including modeling tools that address the spatiotemporal hydrobiogeochemistry in the rhizosphere. Comparing Brachypodium distachyon, (Brachypodium) as our C3 representative and Setaria viridis (Setaria) as our C4 representative, we designed, highly controlled single-plant experimental ecosystems based these model grasses to enable quantitative prediction of ecosystem traits and responses as a function of plant genotype and environmental variables. A metabolomics survey of 30 Brachypodium genotypes grown under control and drought conditions revealed specific metabolites that correlated with biomass production and drought tolerance. A comparison of Brachypodium and Setaria grown with control and a future predicted elevated CO2 level revealed changes in biomass accumulation and metabolite profiles between the C3 and C4 species in both leaves and roots. Finally, we are building an mechanistic modeling capability that will contribute to a better basis for modeling plant water and nutrient cycling in larger scale models.

C4 plants use fluctuating light less efficiently than do C3 plants: a study of growth, photosynthesis and carbon isotope discrimination.

PubMed

Kubásek, Jiří; Urban, Otmar; Šantrůček, Jiří

2013-12-01

Plants in the field are commonly exposed to fluctuating light intensity, caused by variable cloud cover, self-shading of leaves in the canopy and/or leaf movement due to turbulence. In contrast to C3 plant species, only little is known about the effects of dynamic light (DL) on photosynthesis and growth in C4 plants. Two C4 and two C3 monocot and eudicot species were grown under steady light or DL conditions with equal sum of daily incident photon flux. We measured leaf gas exchange, plant growth and dry matter carbon isotope discrimination to infer CO2 bundle sheath leakiness in C4 plants. The growth of all species was reduced by DL, despite only small changes in steady-state gas exchange characteristics, and this effect was more pronounced in C4 than C3 species due to lower assimilation at light transitions. This was partially attributed to increased bundle sheath leakiness in C4 plants under the simulated lightfleck conditions. We hypothesize that DL leads to imbalances in the coordination of C4 and C3 cycles and increasing leakiness, thereby decreasing the quantum efficiency of photosynthesis. In addition to their other constraints, the inability of C4 plants to efficiently utilize fluctuating light likely contributes to their absence in such environments as forest understoreys. © 2013 Scandinavian Plant Physiology Society.

Starch Accumulation in the Bundle Sheaths of C3 Plants: A Possible Pre-Condition for C4 Photosynthesis.

PubMed

Miyake, Hiroshi

2016-05-01

C4 plants have evolved >60 times from their C3 ancestors. C4 photosynthesis requires a set of closely co-ordinated anatomical and biochemical characteristics. However, it is now recognized that the evolution of C4 plants requires fewer changes than had ever been considered, because of the genetic, biochemical and anatomical pre-conditions of C3 ancestors that were recruited into C4 photosynthesis. Therefore, the pre-conditions in C3 plants are now being actively investigated to clarify the evolutionary trajectory from C3 to C4 plants and to engineer C4 traits efficiently into C3 crops. In the present mini review, the anatomical characteristics of C3 and C4 plants are briefly reviewed and the importance of the bundle sheath for the evolution of C4 photosynthesis is described. For example, while the bundle sheath of C3 rice plants accumulates large amounts of starch in the developing leaf blade and at the lamina joint of the mature leaf, the starch sheath function is also observed during leaf development in starch accumulator grasses regardless of photosynthetic type. The starch sheath function of C3 plants is therefore also implicated as a possible pre-condition for the evolution of C4 photosynthesis. The phylogenetic relationships between the types of storage carbohydrates and of photosynthesis need to be clarified in the future. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Timing and Nature of Appearance of C4 Plants in the Indian Subcontinent: Clue from Isotopic Ratios of Biomarker

NASA Astrophysics Data System (ADS)

Sanyal, P.

2014-12-01

Appearance and expansion of C4 plants during the late Miocene was first documented from Siwalik Group of sediments using carbon isotope ratio of soil carbonates. It was proposed that C4 plants appeared drastically in response to change in hydrological cycle. Subsequently, various workers documented evolution and expansion of C4 plants from different Siwalik sections of India, Nepal and Pakistan. Although evolution and expansion of C4 plants was documented in all these studies but nature and timing of expansion of C4 plants showed variations from section to sections. Even from same section, the results varied with change in proxies. The hydrological changes also differ regionally. One of the reasons of differences in results was lack of modern data set from the Indian subcontinent. For example, in many cases δ18O values of New Delhi rainwater has been considered as reference data set and applied to site of investigation with some corrections. The average δ13C values of C3 and C4 plants was considered as -27‰ and -12.5‰ respectively, but modern C3 plants in the Gangetic plain is almost 2.5‰ lower than the value used in those studies. Additional problem raised as preservation of pristine isotopic character of soil organic matter is also apprehensive. To resolve all these issues, the δ13C value of long chain alkane have been used to reconstruct C3-C4 plants after isotopic characterization of modern plants and their biomarker from the Gangetic plain which is equivalent to the past Siwalik flood plain. Additionally, δD values of long chain alkane were also measured. Variations of d13C values of long chain alkane with time show presence of C4 plants in Siwalik from 11 Ma ago and since then gradual increase in C4 plants till 6 Ma followed by a sharp increase. The statistically significant correlation between δD and δ13C values of long chain alkane show that positive impact of hydrological change on abundance of C3-C4 plants.

Glyphosate Resistance of C3 and C4 Weeds under Rising Atmospheric CO2.

PubMed

Fernando, Nimesha; Manalil, Sudheesh; Florentine, Singarayer K; Chauhan, Bhagirath S; Seneweera, Saman

2016-01-01

The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C3 and C4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C3 and C4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant's functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C3 weeds which have a simpler photosynthetic pathway, than for C4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of essential in managing weed control by herbicide use, and to thus ensure an increase in global food production in the event of increased atmospheric [CO2] levels.

Effects of climate and atmospheric CO2 partial pressure on the global distribution of C4 grasses: present, past, and future.

PubMed

Collatz, G James; Berry, Joseph A; Clark, James S

1998-05-01

C 4 photosynthetic physiologies exhibit fundamentally different responses to temperature and atmospheric CO 2 partial pressures (pCO 2 ) compared to the evolutionarily more primitive C 3 type. All else being equal, C 4 plants tend to be favored over C 3 plants in warm humid climates and, conversely, C 3 plants tend to be favored over C 4 plants in cool climates. Empirical observations supported by a photosynthesis model predict the existence of a climatological crossover temperature above which C 4 species have a carbon gain advantage and below which C 3 species are favored. Model calculations and analysis of current plant distribution suggest that this pCO 2 -dependent crossover temperature is approximated by a mean temperature of 22°C for the warmest month at the current pCO 2 (35 Pa). In addition to favorable temperatures, C 4 plants require sufficient precipitation during the warm growing season. C 4 plants which are predominantly graminoids of short stature can be competitively excluded by trees (nearly all C 3 plants) - regardless of the photosynthetic superiority of the C 4 pathway - in regions otherwise favorable for C 4 . To construct global maps of the distribution of C 4 grasses for current, past and future climate scenarios, we make use of climatological data sets which provide estimates of the mean monthly temperature to classify the globe into areas which should favor C 4 photosynthesis during at least 1 month of the year. This area is further screened by excluding areas where precipitation is <25 mm per month during the warm season and by selecting areas classified as grasslands (i.e., excluding areas dominated by woody vegetation) according to a global vegetation map. Using this approach, grasslands of the world are designated as C 3 , C 4 , and mixed under current climate and pCO 2 . Published floristic studies were used to test the accuracy of these predictions in many regions of the world, and agreement with observations was generally good. We then make use of this protocol to examine changes in the global abundance of C 4 grasses in the past and the future using plausible estimates for the climates and pCO 2 . When pCO 2 is lowered to pre-industrial levels, C 4 grasses expanded their range into large areas now classified as C 3 grasslands, especially in North America and Eurasia. During the last glacial maximum (∼18 ka BP) when the climate was cooler and pCO 2 was about 20 Pa, our analysis predicts substantial expansion of C 4 vegetation - particularly in Asia, despite cooler temperatures. Continued use of fossil fuels is expected to result in double the current pCO 2 by sometime in the next century, with some associated climate warming. Our analysis predicts a substantial reduction in the area of C 4 grasses under these conditions. These reductions from the past and into the future are based on greater stimulation of C 3 photosynthetic efficiency by higher pCO 2 than inhibition by higher temperatures. The predictions are testable through large-scale controlled growth studies and analysis of stable isotopes and other data from regions where large changes are predicted to have occurred.

Comparative cell-specific transcriptomics reveals differentiation of C4 photosynthesis pathways in switchgrass and other C4 lineages

PubMed Central

Rao, Xiaolan; Lu, Nan; Li, Guifen; Nakashima, Jin; Tang, Yuhong; Dixon, Richard A.

2016-01-01

Almost all C4 plants require the co-ordination of the adjacent and fully differentiated cell types, mesophyll (M) and bundle sheath (BS). The C4 photosynthetic pathway operates through two distinct subtypes based on how malate is decarboxylated in BS cells; through NAD-malic enzyme (NAD-ME) or NADP-malic enzyme (NADP-ME). The diverse or unique cell-specific molecular features of M and BS cells from separate C4 subtypes of independent lineages remain to be determined. We here provide an M/BS cell type-specific transcriptome data set from the monocot NAD-ME subtype switchgrass (Panicum virgatum). A comparative transcriptomics approach was then applied to compare the M/BS mRNA profiles of switchgrass, monocot NADP-ME subtype C4 plants maize and Setaria viridis, and dicot NAD-ME subtype Cleome gynandra. We evaluated the convergence in the transcript abundance of core components in C4 photosynthesis and transcription factors to establish Kranz anatomy, as well as gene distribution of biological functions, in these four independent C4 lineages. We also estimated the divergence between NAD-ME and NADP-ME subtypes of C4 photosynthesis in the two cell types within C4 species, including differences in genes encoding decarboxylating enzymes, aminotransferases, and metabolite transporters, and differences in the cell-specific functional enrichment of RNA regulation and protein biogenesis/homeostasis. We suggest that C4 plants of independent lineages in both monocots and dicots underwent convergent evolution to establish C4 photosynthesis, while distinct C4 subtypes also underwent divergent processes for the optimization of M and BS cell co-ordination. The comprehensive data sets in our study provide a basis for further research on evolution of C4 species. PMID:26896851

Changes in the C/N balance caused by increasing external ammonium concentrations are driven by carbon and energy availabilities during ammonium nutrition in pea plants: the key roles of asparagine synthetase and anaplerotic enzymes.

PubMed

Ariz, Idoia; Asensio, Aaron C; Zamarreño, Angel M; García-Mina, Jose M; Aparicio-Tejo, Pedro M; Moran, Jose F

2013-08-01

An understanding of the mechanisms underlying ammonium (NH(4)(+)) toxicity in plants requires prior knowledge of the metabolic uses for nitrogen (N) and carbon (C). We have recently shown that pea plants grown at high NH(4)(+) concentrations suffer an energy deficiency associated with a disruption of ionic homeostasis. Furthermore, these plants are unable to adequately regulate internal NH4(+) levels and the cell-charge balance associated with cation uptake. Herein we show a role for an extra-C application in the regulation of C-N metabolism in NH(4)(+) -fed plants. Thus, pea plants (Pisum sativum) were grown at a range of NH(4)(+) concentrations as sole N source, and two light intensities were applied to vary the C supply to the plants. Control plants grown at high NH(4)(+) concentration triggered a toxicity response with the characteristic pattern of C-starvation conditions. This toxicity response resulted in the redistribution of N from amino acids, mostly asparagine, and lower C/N ratios. The C/N imbalance at high NH(4)(+) concentration under control conditions induced a strong activation of root C metabolism and the upregulation of anaplerotic enzymes to provide C intermediates for the tricarboxylic acid cycle. A high light intensity partially reverted these C-starvation symptoms by providing higher C availability to the plants. The extra-C contributed to a lower C4/C5 amino acid ratio while maintaining the relative contents of some minor amino acids involved in key pathways regulating the C/N status of the plants unchanged. C availability can therefore be considered to be a determinant factor in the tolerance/sensitivity mechanisms to NH(4)(+) nutrition in plants. Copyright © Physiologia Plantarum 2012.

Climate-driven C4 plant distributions in China: divergence in C4 taxa

PubMed Central

Wang, Renzhong; Ma, Linna

2016-01-01

There have been debates on the driving factors of C4 plant expansion, such as PCO2 decline in the late Micocene and warmer climate and precipitation at large-scale modern ecosystems. These disputes are mainly due to the lack of direct evidence and extensive data analysis. Here we use mass flora data to explore the driving factors of C4 distribution and divergent patterns for different C4 taxa at continental scale in China. The results display that it is mean annual climate variables driving C4 distribution at present-day vegetation. Mean annual temperature is the critical restriction of total C4 plants and the precipitation gradients seem to have much less impact. Grass and sedge C4 plants are largely restricted to mean annual temperature and precipitation respectively, while Chenopod C4 plants are strongly restricted by aridity in China. Separate regression analysis can succeed to detect divergences of climate distribution patterns of C4 taxa at global scale. PMID:27302686

Evidence of shift in C4 species range in central Argentina during the late Holocene

USGS Publications Warehouse

Silva, L.C.R.; Giorgis, M.A.; Anand, M.; Enrico, L.; Perez-Harguindeguy, N.; Falczuk, V.; Tieszen, L.L.; Cabido, M.

2011-01-01

AimMillennial-scale biogeographic changes are well understood in many parts of the world, but little is known about long-term vegetation dynamics in subtropical regions. Here we investigate shifts in C3/C4 plant abundance occurred in central Argentina during the past few millenniaMethodsWe determined present day soil organic matter δ13C signatures of grasslands, shrublands and woodlands, containing different mixtures of C3 and C4 plants. We measured past changes in the relative cover of C3/C4 plants by comparing δ13C values in soil profiles with present day δ13C signatures. We analyzed 14C activity in soil depths that showed major changes in vegetation.ResultsPresent day relative cover of C3/C4 plants determines whole ecosystem δ13C signatures integrated as litter and superficial soil organic matter (R2 = 0.78; p < 0.01). Deeper soils show a consistent shift in δ13C, indicating a continuous replacement of C4 by C3 plants since 3,870 (±210) YBP. During this period, the relative abundance of C3 plants increased 32% (average across sites) with significant changes being observed in all studied ecosystems.ConclusionsOur results show that C4 species were more abundant in the past, but C3 species became dominant during the late Holocene. We identified increases in the relative C3/C4 cover in grasslands, shrublands and woodlands, suggesting a physiological basis for changes in vegetation. The replacement of C4 by C3 plants coincided with changes in climate towards colder and wetter conditions and could represent a climatically driven shift in the C4 species optimum range.

C-isotope composition of fossil sedges and grasses

NASA Astrophysics Data System (ADS)

Kurschner, Wolfram M.

2010-05-01

C4 plants differ from C3 plants regarding their anatomy and their C-isotope composition. Both features can be used in the geological record to determine the presence of C4 plants. Yet, the evolution of the C4 pathway in the fossil record is enigmatic as palaeobotanical and geological evidence for C4 plants is sparse. The oldest structural evidence for Kranz anatomy has been found in Late Miocene permineralized grass leaf remains. But studies on the C-isotope composition of sedimentary organic matter indicate that abundant C4 biomass was present in N-America and Asia throughout the Miocene in expanding savannahs and grasslands. The success of C4 plants appears to be related also to an increasing seasonal aridity in the tropical climate belts and the co-evolution of grazers. However, C- isotope composition of palaeosols or vertebrate teeth only allows to estimate the abundance of C4 plant biomass in the vegetation or in the diet without further taxonomical specification which plant groups would have had C4 metabolism. In this contribution the first extensive C-isotope analysis of fossil seeds of sedges and a few grasses are presented. The age of the carpological material ranges from Late Eocene to Pliocene and was collected from several central European brown coal deposits. The 52 different taxa studied include several species of Carex, Cladiocarya, Eriopherum, Eleocharis, Scirpus, Sparganium. Most of them representing herbaceous elements of a (sub)tropical vegetation growing near the edge of a lake. The C-isotope composition of the fossil seeds varies between -30 and -23 o/oo indicating C3 photosynthesis. This first systematic inventory shows that C4 plants were absent in the European (sub)tropical brown coal forming wetland vegetation during the Tertiary. These preliminary data are in agreement with phylogenetic studies which predict the origin of C4 plants outside the European realm.

Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology

Treesearch

Jeffrey F. Kelly

2000-01-01

Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers...

Photosynthetic diversity meets biodiversity: the C4 plant example.

PubMed

Sage, Rowan F; Stata, Matt

2015-01-01

Physiological diversification reflects adaptation for specific environmental challenges. As the major physiological process that provides plants with carbon and energy, photosynthesis is under strong evolutionary selection that gives rise to variability in nearly all parts of the photosynthetic apparatus. Here, we discuss how plants, notably those using C4 photosynthesis, diversified in response to environmental challenges imposed by declining atmospheric CO2 content in recent geological time. This reduction in atmospheric CO2 increases the rate of photorespiration and reduces photosynthetic efficiency. While plants have evolved numerous mechanisms to compensate for low CO2, the most effective are the carbon concentration mechanisms of C4, C2, and CAM photosynthesis; and the pumping of dissolved inorganic carbon, mainly by algae. C4 photosynthesis enables plants to dominate warm, dry and often salinized habitats, and to colonize areas that are too stressful for most plant groups. Because C4 lineages generally lack arborescence, they cannot form forests. Hence, where they predominate, C4 plants create a different landscape than would occur if C3 plants were to predominate. These landscapes (mostly grasslands and savannahs) present unique selection environments that promoted the diversification of animal guilds able to graze upon the C4 vegetation. Thus, the rise of C4 photosynthesis has made a significant contribution to the origin of numerous biomes in the modern biosphere. Copyright © 2014. Published by Elsevier GmbH.

Antisense and sense expression of cDNA coding for CYP73A15, a class II cinnamate 4-hydroxylase, leads to a delayed and reduced production of lignin in tobacco

NASA Technical Reports Server (NTRS)

Blee, K.; Choi, J. W.; O'Connell, A. P.; Jupe, S. C.; Schuch, W.; Lewis, N. G.; Bolwell, G. P.

2001-01-01

A number of plant species contain the class II of genes encoding the cytochrome P450, CYP73, the cognate protein of which cinnamic acid 4-hydroxylase, is the second enzyme of the phenylpropanoid pathway. In order to begin to determine possible functionality, tobacco has been transformed with a truncated French bean class II cinnamate hydroxylase (CYP73A15) in the sense and antisense orientations. Signals for C4H protein could be detected in vascular tissue from wild-type plants using heterologous probes. The transformed plants showed a normal phenotype, even though detectable C4H protein was much reduced in tissue prints. Young propagated transformants displayed a range of reduced C4H activities, as well as either reduced or no phloroglucinol-stainable lignin. However, all mature tobacco plants showed the accumulation of lignin, even though its deposition was apparently delayed. This was not due to induction of tyrosine ammonia-lyase activity, which was not detected, but instead it is presumed due to sufficient C4H residual activity. Analysis of the lignin content of the plants showed reductions of up to 30% with a slightly reduced syringyl to guaiacyl ratio as compared to wild type. This reduction level was favourable in comparison with some other targets in the lignification pathway that have been manipulated including that of class I cinnamate 4-hydroxylase. It is proposed that the class II cinnamate 4-hydroxylase might also function in lignification in a number of species including French bean and tobacco, based on these data.

Changing carbon isotope ratio of atmospheric carbon dioxide: implications for food authentication.

PubMed

Peck, William H; Tubman, Stephanie C

2010-02-24

Carbon isotopes are often used to detect the addition of foreign sugars to foods. This technique takes advantage of the natural difference in carbon isotope ratio between C(3) and C(4) plants. Many foods are derived from C(3) plants, but the low-cost sweeteners corn and sugar cane are C(4) plants. Most adulteration studies do not take into account the secular shift of the carbon isotope ratio of atmospheric carbon dioxide caused by fossil fuel burning, a shift also seen in plant tissues. As a result statistical tests and threshold values that evaluate authenticity of foods based on carbon isotope ratios may need to be corrected for changing atmospheric isotope values. Literature and new data show that the atmospheric trend in carbon isotopes is seen in a 36-year data set of maple syrup analyses (n = 246), demonstrating that published thresholds for cane or corn sugar adulteration in maple syrup (and other foods) have become progressively more lenient over time.

Coherent changes in relative C4 plant productivity and climate during the late Quaternary in the North American Great Plains

USGS Publications Warehouse

Nordt, L.; Von Fischer, J.; Tieszen, L.; Tubbs, J.

2008-01-01

Evolution of the mixed and shortgrass prairie of the North American Great Plains is poorly understood because of limited proxies available for environmental interpretations. Buried soils in the Great Plains provide a solution to the problem because they are widespread both spatially and temporally with their organic reservoirs serving as a link to the plants than once grew on them. Through stable carbon isotopic analysis of soil organic carbon (??13C), the percent carbon from C4 plants (%C4) can be ascertained. Because C4 plants are primarily warm season grasses responding positively to summer temperature, their representation has the added advantage of serving as a climate indicator. To better understand grassland and climate dynamics in the Great Plains during the last 12 ka (ka=1000 radiocarbon years) we developed an isotopic standardization technique by: determining the difference in buried soil ??13C and modern soil ??13C expected for that latitude (????13C), and transferring the ????13C to ??%C4 (% C4) using mass balance calculations. Our analysis reveals two isotopic stages in the mixed and shortgrass prairie of the Great Plains based on trends in ??%C4. In response to orbital forcing mechanisms, ??%C4 was persistently below modern in the Great Plains between 12 and 6.7 ka (isotopic stage II) evidently because of the cooling effect of the Laurentide ice sheet and proglacial lakes in northern latitudes, and glacial meltwater pulses cooling the Gulf of Mexico and North Atlantic Ocean. The ??%C4 after 6.7 ka (isotopic stage I) increased to modern levels as conditioned by the outflow of warm, moist air from the Gulf of Mexico and dry incursions from the west that produced periodic drought. At the millennial-scale, time series analysis demonstrates that ??%C4 oscillated with 0.6 and 1.8 ka periodicities, possibly governed by variations in solar irradiance. Our buried soil isotopic record correlates well with other environmental proxy from the Great Plains and surrounding regions. ?? 2008 Elsevier Ltd.

VpRFP1, a novel C4C4-type RING finger protein gene from Chinese wild Vitis pseudoreticulata, functions as a transcriptional activator in defence response of grapevine

PubMed Central

Yu, Yihe; Xu, Weirong; Wang, Shengyi; Xu, Yan; Li, Hui'e; Wang, Yuejin; Li, Shuxiu

2011-01-01

RING finger proteins comprise a large family and play important roles in regulation of growth and development, hormone signalling, and responses to biotic and abiotic stresses in plants. In this study, the identification and functional characterization of a C4C4-type RING finger protein gene from the Chinese wild grapevine Vitis pseudoreticulata (designated VpRFP1) are reported. VpRFP1 was initially identified as an expressed sequence tag (EST) from a cDNA library constructed from leaves of V. pseudoreticulata inoculated with the grapevine powdery mildew Uncinula necator. Sequence analysis of the deduced VpRFP1 protein based on the full-length cDNA revealed an N-terminal nuclear localization signal (NLS) and a C-terminal C4C4-type RING finger motif with the consensus sequence Cys-X2-Cys-X13-Cys-X1-Cys-X4-Cys-X2-Cys-X10-Cys-X2-Cys. Upon inoculation with U. necator, expression of VpRFP1 was rapidly induced to higher levels in mildew-resistant V. pseudoreticulata plants. In contrast, expression of VpRFP1 was down-regulated in mildew-susceptible V. vinifera plants. Western blotting using an antibody raised against VpRFP1 showed that VpRFP1 was also induced to higher levels in V. pseudoreticulata plants at 12–48 hours post-inoculation (hpi). However, there was only slight increase in VpRFP in V. vinifera plants in the same time frame, even though a more significant increase was observed at 96–144 hpi in these plants. Results from transactivation assays in yeast showed that the RING finger motif of VpRFP1 exhibited some activity of transcriptional activation; however, no activity was seen with the full-length VpRFP1. Overexpression of VpRFP1 in Arabidopsis plants was found to enhance resistance to Arabidopsis powdery mildew Golovinomyces cichoracearum, which seemed to be correlated with increased transcript levels of AtPR1 and AtPR2 in the pathogen-infected tissues. In addition, the Arabidopsis transgenic lines showed enhanced resistance to a virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000. Taken together, the results suggested that VpRFP1 may be a transcriptional activator of defence-related genes in grapevines. PMID:21862480

Molecular Physiology of Root System Architecture in Model Grasses

NASA Astrophysics Data System (ADS)

Hixson, K.; Ahkami, A. H.; Anderton, C.; Veličković, D.; Myers, G. L.; Chrisler, W.; Lindenmaier, R.; Fang, Y.; Yabusaki, S.; Rosnow, J. J.; Farris, Y.; Khan, N. E.; Bernstein, H. C.; Jansson, C.

2017-12-01

Unraveling the molecular and physiological mechanisms involved in responses of Root System Architecture (RSA) to abiotic stresses and shifts in microbiome structure is critical to understand and engineer plant-microbe-soil interactions in the rhizosphere. In this study, accessions of Brachypodium distachyon Bd21 (C3 model grass) and Setaria viridis A10.1 (C4 model grass) were grown in phytotron chambers under current and elevated CO2 levels. Detailed growth stage-based phenotypic analysis revealed different above- and below-ground morphological and physiological responses in C3 and C4 grasses to enhanced CO2 levels. Based on our preliminary results and by screening values of total biomass, water use efficiency, root to shoot ratio, RSA parameters and net assimilation rates, we postulated a three-phase physiological mechanism, i.e. RootPlus, BiomassPlus and YieldPlus phases, for grass growth under elevated CO2 conditions. Moreover, this comprehensive set of morphological and process-based observations are currently in use to develop, test, and calibrate biophysical whole-plant models and in particular to simulate leaf-level photosynthesis at various developmental stages of C3 and C4 using the model BioCro. To further link the observed phenotypic traits at the organismal level to tissue and molecular levels, and to spatially resolve the origin and fate of key metabolites involved in primary carbohydrate metabolism in different root sections, we complement root phenotypic observations with spatial metabolomics data using mass spectrometry imaging (MSI) methods. Focusing on plant-microbe interactions in the rhizosphere, six bacterial strains with plant growth promoting features are currently in use in both gel-based and soil systems to screen root growth and development in Brachypodium. Using confocal microscopy, GFP-tagged bacterial systems are utilized to study the initiation of different root types of RSA, including primary root (PR), coleoptile node axile root (CNR) and leaf node axile root (LNR) during developmental stages of root formation. The root exudates also will be quantified and preliminary data will be used to engineer our microbial consortium to improve plant growth.

Despite phylogenetic effects, C3-C4 lineages bridge the ecological gap to C4 photosynthesis.

PubMed

Lundgren, Marjorie R; Christin, Pascal-Antoine

2017-01-01

C 4 photosynthesis is a physiological innovation involving several anatomical and biochemical components that emerged recurrently in flowering plants. This complex trait evolved via a series of physiological intermediates, broadly termed 'C 3 -C 4 ', which have been widely studied to understand C 4 origins. While this research program has focused on biochemistry, physiology, and anatomy, the ecology of these intermediates remains largely unexplored. Here, we use global occurrence data and local habitat descriptions to characterize the niches of multiple C 3 -C 4 lineages, as well as their close C 3 and C 4 relatives. While C 3 -C 4 taxa tend to occur in warm climates, their abiotic niches are spread along other dimensions, making it impossible to define a universal C 3 -C 4 niche. Phylogeny-based comparisons suggest that, despite shifts associated with photosynthetic types, the precipitation component of the C 3 -C 4 niche is particularly lineage specific, being highly correlated with that of closely related C 3 and C 4 taxa. Our large-scale analyses suggest that C 3 -C 4 lineages converged toward warm habitats, which may have facilitated the transition to C 4 photosynthesis, effectively bridging the ecological gap between C 3 and C 4 plants. The intermediates retained some precipitation aspects of their C 3 ancestors' habitat, and likely transmitted them to their C 4 descendants, contributing to the diversity among C 4 lineages seen today. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Compound-specific stable carbon isotope composition as a fingerprint for sediment transport: Reproducibility, homogeneity and application in a catchment of the Swiss plateau.

NASA Astrophysics Data System (ADS)

Birkholz, Axel; Niemann, Helge; Alewell, Christine

2014-05-01

A new field for the applications of compound-specific isotope analyses (CSIA) has opened in the recent years. The isotopic signature in fatty acids (FA) can be used to track sediment transport pathways from erosional areas to river systems. In this approach distinct FA d13C values of even numbered saturated and/or unsaturated FAs from soils are traced in suspended river sediments, ie. the place of deposition. CSIA has been shown to be particularly useful in catchment areas with C4 plant crops because, compared to the regularly occurring C3-plants, they are (naturally) depleted in 13C. However, in theory, all plant species even among C3 plants should inherit significant differences in their d13C of FAs. Thus, we tried to differentiate between source areas for suspended sediments from three different land use types: forest (C3 plants), grassland (C3 plants) and arable land (mixture of C3 and C4 plants). Statistical geo software (eg. Isosource) can be used to additionally model the spatial and temporal variability of erosion. We present d13C values of FAs from 8 erosion areas from the Enziwigger catchment of the Swiss plateau (Canton of Lucerne). Each area was assessed through randomised triplicate sampling to test the spatial homogeneity of each one. The homogeneity of a single sample, as well as the reproducibility of our measurements was tested by extracting and analysing the same sample bag in triplicates. We compare compound-specific stable isotope (CSSI) fingerprints of source areas to d13C-values of FAs from suspended sediments of two high-flow events and one base flow period at 3 different sites of the Enziwiger river (upstream, midstream, downstream).

A Meta-analysis of Plant Photosynthetic Traits and Water-use efficiency Responses to Drought

NASA Astrophysics Data System (ADS)

Zhang, J.

2017-12-01

Drought is predicted to become more intense and frequent in many regions of the world in the context of climate change, especially in the semi-arid regions of the Northern Hemisphere. Understanding the plant photosynthetic traits (Pn, Gs and Tr) and water use efficiency (WUE) response to drought is very important with regard to plant growth and productivity, which could reflect the terrestrial primary productivity worldwide. We used a meta-analysis based on studies of a worldwide range and full plant species Pn, Gs, Tr and WUE under drought condition and aimed to determine the responses of Pn, Gs, Tr and WUE of different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Furthermore, reveal the differences from different plant groups (e.g. C3 and C4 plants; annual (A-herbs) and perennial (P-herbs) herbs; conifer, deciduous and evergreen trees) under the same drought intensities. Additionally, we analyzed the relationship between stomatal conductance (Gs) with Pn, Tr and WUE. Our results were as follows: 1) drought decreased the photosynthetic traits with the drought stress increasing, but increased the water use efficiency, and increased to the greatest extent in lianas, compared with herbs, shrubs and trees. 2) Furthermore, C4 plants had an advantage in photosynthesis compared to C3 plants under the same drought conditions. However, the WUE in C4 plants was not promoted as in C3 plants. The photosynthesis traits showed a more substantial decrease in P-herbs than in A-herbs. The drought promoted the WUE in P-herbs, but inhibited it in A-herbs. Compared with conifer and deciduous trees, the photosynthesis traits declined the most in evergreen tree. The WUE in deciduous trees showed a more obvious increase among the three leaf habits. 3) Finally, the Gs showed a close relationship with photosynthesis rate (Pn) and transpiration rate (Tr), which could explain 50% of the decrease in the Pn and 72% of the decline in Tr. Nevertheless, the Gs did not show a significant linear correlation with WUE, it's a more complex relationship between them .Our study provides comprehensive information about the changes in plant photosynthetic traits and water use efficiency under drought.

Glyphosate Resistance of C3 and C4 Weeds under Rising Atmospheric CO2

PubMed Central

Fernando, Nimesha; Manalil, Sudheesh; Florentine, Singarayer K.; Chauhan, Bhagirath S.; Seneweera, Saman

2016-01-01

The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C3 and C4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C3 and C4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant’s functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C3 weeds which have a simpler photosynthetic pathway, than for C4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of essential in managing weed control by herbicide use, and to thus ensure an increase in global food production in the event of increased atmospheric [CO2] levels. PMID:27446140

Expanding the Range of Plant Functional Diversity Represented in Global Vegetation Models: Towards Lineage-based Plant Functional Types

NASA Astrophysics Data System (ADS)

Still, C. J.; Griffith, D.; Edwards, E.; Forrestel, E.; Lehmann, C.; Anderson, M.; Craine, J.; Pau, S.; Osborne, C.

2014-12-01

Variation in plant species traits, such as photosynthetic and hydraulic properties, can indicate vulnerability or resilience to climate change, and feed back to broad-scale spatial and temporal patterns in biogeochemistry, demographics, and biogeography. Yet, predicting how vegetation will respond to future environmental changes is severely limited by the inability of our models to represent species-level trait variation in processes and properties, as current generation process-based models are mostly based on the generalized and abstracted concept of plant functional types (PFTs) which were originally developed for hydrological modeling. For example, there are close to 11,000 grass species, but most vegetation models have only a single C4 grass and one or two C3 grass PFTs. However, while species trait databases are expanding rapidly, they have been produced mostly from unstructured research, with a focus on easily researched traits that are not necessarily the most important for determining plant function. Additionally, implementing realistic species-level trait variation in models is challenging. Combining related and ecologically similar species in these models might ameliorate this limitation. Here we argue for an intermediate, lineage-based approach to PFTs, which draws upon recent advances in gene sequencing and phylogenetic modeling, and where trait complex variations and anatomical features are constrained by a shared evolutionary history. We provide an example of this approach with grass lineages that vary in photosynthetic pathway (C3 or C4) and other functional and structural traits. We use machine learning approaches and geospatial databases to infer the most important environmental controls and climate niche variation for the distribution of grass lineages, and utilize a rapidly expanding grass trait database to demonstrate examples of lineage-based grass PFTs. For example, grasses in the Andropogoneae are typically tall species that dominate wet and seasonally burned ecosystems, whereas Chloridoideae grasses are associated with semi-arid regions. These two C4 lineages are expected to respond quite differently to climate change, but are often modelled as a single PFT.

A meta-analysis of leaf gas exchange and water status responses to drought.

PubMed

Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping

2016-02-12

Drought is considered to be one of the most devastating natural hazards, and it is predicted to become increasingly frequent and severe in the future. Understanding the plant gas exchange and water status response to drought is very important with regard to future climate change. We conducted a meta-analysis based on studies of plants worldwide and aimed to determine the changes in gas exchange and water status under different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Our results were as follows: 1) drought negatively impacted gas exchange and water status, and stomatal conductance (gs) decreased more than other physiological traits and declined to the greatest extent in shrubs and C3 plants. Furthermore, C4 plants had an advantage compared to C3 plants under the same drought conditions. 2) The decrease in gs mainly reduced the transpiration rate (Tr), and gs could explain 55% of the decrease in the photosynthesis (A) and 74% of the decline in Tr. 3). Finally, gas exchange showed a close relationship with the leaf water status. Our study provides comprehensive information about the changes in plant gas exchange and water status under drought.

A meta-analysis of leaf gas exchange and water status responses to drought

PubMed Central

Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping

2016-01-01

Drought is considered to be one of the most devastating natural hazards, and it is predicted to become increasingly frequent and severe in the future. Understanding the plant gas exchange and water status response to drought is very important with regard to future climate change. We conducted a meta-analysis based on studies of plants worldwide and aimed to determine the changes in gas exchange and water status under different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Our results were as follows: 1) drought negatively impacted gas exchange and water status, and stomatal conductance (gs) decreased more than other physiological traits and declined to the greatest extent in shrubs and C3 plants. Furthermore, C4 plants had an advantage compared to C3 plants under the same drought conditions. 2) The decrease in gs mainly reduced the transpiration rate (Tr), and gs could explain 55% of the decrease in the photosynthesis (A) and 74% of the decline in Tr. 3). Finally, gas exchange showed a close relationship with the leaf water status. Our study provides comprehensive information about the changes in plant gas exchange and water status under drought. PMID:26868055

The use and misuse of V(c,max) in Earth System Models.

PubMed

Rogers, Alistair

2014-02-01

Earth System Models (ESMs) aim to project global change. Central to this aim is the need to accurately model global carbon fluxes. Photosynthetic carbon dioxide assimilation by the terrestrial biosphere is the largest of these fluxes, and in many ESMs is represented by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis. The maximum rate of carboxylation by the enzyme Rubisco, commonly termed V c,max, is a key parameter in the FvCB model. This study investigated the derivation of the values of V c,max used to represent different plant functional types (PFTs) in ESMs. Four methods for estimating V c,max were identified; (1) an empirical or (2) mechanistic relationship was used to relate V c,max to leaf N content, (3) V c,max was estimated using an approach based on the optimization of photosynthesis and respiration or (4) calibration of a user-defined V c,max to obtain a target model output. Despite representing the same PFTs, the land model components of ESMs were parameterized with a wide range of values for V c,max (-46 to +77% of the PFT mean). In many cases, parameterization was based on limited data sets and poorly defined coefficients that were used to adjust model parameters and set PFT-specific values for V c,max. Examination of the models that linked leaf N mechanistically to V c,max identified potential changes to fixed parameters that collectively would decrease V c,max by 31% in C3 plants and 11% in C4 plants. Plant trait data bases are now available that offer an excellent opportunity for models to update PFT-specific parameters used to estimate V c,max. However, data for parameterizing some PFTs, particularly those in the Tropics and the Arctic are either highly variable or largely absent.

Evolution of CAM and C4 carbon-concentrating mechanisms

USGS Publications Warehouse

Keeley, Jon E.; Rundel, Philip W.

2003-01-01

Mechanisms for concentrating carbon around the Rubisco enzyme, which drives the carbon-reducing steps in photosynthesis, are widespread in plants; in vascular plants they are known as crassulacean acid metabolism (CAM) and C4 photosynthesis. CAM is common in desert succulents, tropical epiphytes, and aquatic plants and is characterized by nighttime fixation of CO2. The proximal selective factor driving the evolution of this CO2-concentrating pathway is low daytime CO2, which results from the unusual reverse stomatal behavior of terrestrial CAM species or from patterns of ambient CO2 availability for aquatic CAM species. In terrestrials the ultimate selective factor is water stress that has selected for increased water use efficiency. In aquatics the ultimate selective factor is diel fluctuations in CO2 availability for palustrine species and extreme oligotrophic conditions for lacustrine species. C4 photosynthesis is based on similar biochemistry but carboxylation steps are spatially separated in the leaf rather than temporally as in CAM. This biochemical pathway is most commonly associated with a specialized leaf anatomy known as Kranz anatomy; however, there are exceptions. The ultimate selective factor driving the evolution of this pathway is excessively high photorespiration that inhibits normal C3 photosynthesis under high light and high temperature in both terrestrial and aquatic habitats. CAM is an ancient pathway that likely has been present since the Paleozoic era in aquatic species from shallow-water palustrine habitats. While atmospheric CO2 levels have undoubtedly affected the evolution of terrestrial plant carbon-concentrating mechanisms, there is reason to believe that past atmospheric changes have not played as important a selective role in the aquatic milieu since palustrine habitats today are not generally carbon sinks, and the selective factors driving aquatic CAM are autogenic. Terrestrial CAM, in contrast, is of increasing selective value under extreme water deficits, and undoubtedly, high Mesozoic CO2 levels reduced the amount of landscape perceived by plants as water limited. Late Tertiary and Quaternary reductions in atmospheric CO2, coupled with increasing seasonality, were probably times of substantial species radiation and ecological expansion for CAM plants. C4 photosynthesis occurs in only about half as many families as CAM, and three-fourths of C4 species are either grasses or sedges. Molecular phylogenies indicate C4 is a more recent innovation than CAM and that it originated in the mid-Tertiary, 20–30 Ma, although some data support an earlier origin. While the timing of the origin of C4 remains controversial, the nearly explosive increase in C4 species is clearly documented in the late Miocene, 4–7 Ma. Increasing seasonality has been widely suggested as an important climatic stimulus for this C4 expansion. Alternatively, based on models of photosynthetic quantum yield at different temperatures and CO2 concentration, it has been hypothesized that the late Miocene C4 expansion resulted from declining atmospheric CO2 levels. This model is most appropriate for explaining the transition from C3 grasslands to C4 grasslands but by itself may not be sufficient to explain the more likely scenario of a late Miocene transition from C3 woodland/ savanna to C4 grasslands. A largely unexplored hypothesis is that climatic changes in late Miocene altered disturbance regimes, in particular the incidence of fires, which today are often associated with maintenance of C4 grasslands. Oceanic charcoal sediments that appear to represent Aeolian deposits from continental wildfires follow a strikingly similar pattern of explosive increase in late Miocene. Climate, CO2, and disturbance are not mutually exclusive explanations and probably all acted in concert to promote the expansion of C4 grasslands. More recently, late Quaternary changes in CO2 may have been responsible for driving major changes in the landscape distribution of C4 species. The theory is sound; however, many of the studies cited in support of this model are open to alternative interpretations, and none has eliminated climatic factors as important selective agents. CAM and C4 evolution required coupling of biochemical pathways with structural changes in photosynthetic tissues, succulence in CAM and Kranz in C4. This was apparently accomplished by piecemeal evolution beginning with mechanisms for recapturing respiratory CO2, although this need not have been so in aquatic CAM species. It has been proposed that the extreme rarity of both pathways in the same plant results from biochemical and structural incompatibilities (Sage 2002). Equally important is the fact that the selective environments are quite different, with CAM evolution thriving on stressful sites inhospitable to C3 species whereas C4 evolution has selected for rapid growth capable of outcompeting associated C3 plants.

Climate controls on C3 vs. C4 productivity in North American grasslands from carbon isotope composition of soil organic matter

USGS Publications Warehouse

von Fischer, J.C.; Tieszen, L.L.; Schimel, D.S.

2008-01-01

We analyzed the ??13 C of soil organic matter (SOM) and fine roots from 55 native grassland sites widely distributed across the US and Canadian Great Plains to examine the relative production of C3 vs. C4 plants (hereafter %C4) at the continental scale. Our climate vs. %C4 results agreed well with North American field studies on %C4, but showed bias with respect to %C4 from a US vegetation database (statsgo) and weak agreement with a physiologically based prediction that depends on crossover temperature. Although monthly average temperatures have been used in many studies to predict %C4, our analysis shows that high temperatures are better predictors of %C4. In particular, we found that July climate (average of daily high temperature and month's total rainfall) predicted %C4 better than other months, seasons or annual averages, suggesting that the outcome of competition between C3 and C4 plants in North American grasslands was particularly sensitive to climate during this narrow window of time. Root ??13 C increased about 1??? between the A and B horizon, suggesting that C 4 roots become relatively more common than C3 roots with depth. These differences in depth distribution likely contribute to the isotopic enrichment with depth in SOM where both C3 and C4 grasses are present. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

A Pleistocene palaeovegetation record from plant wax biomarkers from the Nachukui Formation, West Turkana, Kenya

PubMed Central

Uno, Kevin T.; Polissar, Pratigya J.; Kahle, Emma; Feibel, Craig; Harmand, Sonia; Roche, Hélène; deMenocal, Peter B.

2016-01-01

Reconstructing vegetation at hominin fossil sites provides us critical information about hominin palaeoenvironments and the potential role of climate in their evolution. Here we reconstruct vegetation from carbon isotopes of plant wax biomarkers in sediments of the Nachukui Formation in the Turkana Basin. Plant wax biomarkers were extracted from samples from a wide range of lithologies that include fluvial–lacustrine sediments and palaeosols, and therefore provide a record of vegetation from diverse depositional environments. Carbon isotope ratios from biomarkers indicate a highly dynamic vegetation structure (ca 5–100% C4 vegetation) from 2.3 to 1.7 Ma, with an overall shift towards more C4 vegetation on the landscape after about 2.1 Ma. The biomarker isotope data indicate ca 25–30% more C4 vegetation on the landscape than carbon isotope data of pedogenic carbonates from the same sequence. Our data show that the environments of early Paranthropus and Homo in this part of the Turkana Basin were primarily mixed C3–C4 to C4-dominated ecosystems. The proportion of C4-based foods in the diet of Paranthropus increases through time, broadly paralleling the increase in C4 vegetation on the landscape, whereas the diet of Homo remains unchanged. Biomarker isotope data associated with the Kokiselei archaeological site complex, which includes the site where the oldest Acheulean stone tools to date were recovered, indicate 61–97% C4 vegetation on the landscape. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298466

[Effects of enhanced CO2 fertilization on phytoremediation of DEHP-polluted soil].

PubMed

Diao, Xiao-Jun; Wang, Shu-Guang; Mu, Nan

2013-03-01

Low efficiency of remediation is one of the key issues to be solved in phytoremediation technology. Based on the necessity of reducing CO2 emission in China and the significance of CO2 in plant photosynthesis, this paper studied the effects of enhanced CO2 fertilization on the phytoremediation of polluted soil, selecting the C3 plant mung bean (Vigna radiate) and the C4 plant maize (Zea mays) as test plants for phytoremediation and the DEHP as the target pollutant. DEHP pollution had negative effects on the growth and rhizosphere micro-environment of the two plants. After enhanced CO2 fertilization, the aboveground dry mass of the two plants and the alkaline phosphatase activity in the rhizosphere soils of the two plants increased, the COD activity in the leaves of the two plants decreased, the microbial community in the rhizosphere soils shifted, and the numbers of the microbes with DEHP-tolerance in the rhizosphere soils increased. These changes indicated that enhanced CO2 fertilization could promote the plant growth and the plant tolerance to DEHP stress, and improve the rhizosphere micro-environment. Enhanced CO2 fertilization also increased the DEHP uptake by the two plants, especially their underground parts. All these effects induced the residual DEHP concentration in the rhizospheres of the two plants, especially that of mung bean, decreased obviously, and the phytoremediation efficiency increased. Overall, enhanced CO2 fertilization produced greater effects on C3 plant than on C4 plant. It was suggested that enhanced CO2 fertilization could be a useful measure to enhance the efficiency of phytoremediation.

Record of C4 Photosynthesis Through the Late Neogene and Pleistocene

NASA Astrophysics Data System (ADS)

Cerling, T. E.

2016-12-01

C4 photosynthesis is an adaptation to the low atmospheric carbon dioxide concentrations experienced in the Neogene; it is found principally in tropical to sub-tropical/temperate regions where temperatures are high in the growing season. Although C4 photosynthesis makes up about 50% of Net Primary Productivity in tropical regions, its macroscopic fossil record is extremely sparse. Therefore, inferences to its significance in local ecosystems are based primarily on stable isotopes, with phytoliths become more important as phytolith morphology becomes better associated with plant structure and classification. Stable isotopes have been the principal recorder for understanding the history of C4 photosynthesis; however, different materials record different aspects of the C4 contribution to ecosystem structure and thus are telling different parts of the same story. With the fossil record so poorly known, we often assume similar ecosystem structures and functions as we observe in modern analogues. It is likely that large evolutionary changes have taken place within C4 plants as they went from < 1% tropical NPP to > 50% tropical NPP in the late Neogene.

Leaf gas exchange and oxidative stress in sorghum plants supplied with silicon and infected by Colletotrichum sublineolum.

PubMed

Resende, Renata Sousa; Rodrigues, Fabrício Ávila; Cavatte, Paulo Cezar; Martins, Samuel Cordeiro Vitor; Moreira, Wiler Ribas; Chaves, Agnaldo Rodrigues Melo; Damatta, Fábio Murilo

2012-09-01

Considering the economic importance of anthracnose, caused by Colletotrichum sublineolum, and silicon (Si) to enhance sorghum resistance against this disease, this study aimed to investigate the effect of this element on leaf gas exchange and also the antioxidative system when infected by C. sublineolum. Plants from sorghum line CMSXS142 (BR 009 [Tx623] - Texas), growing in hydroponic culture with (+Si, 2 mM) or without (-Si) Si, were inoculated with C. sublineolum. Disease severity was assessed at 2, 4, 6, 8, and 10 days after inoculation (dai) and data were used to calculate the area under anthracnose progress curve (AUAPC). Further, the net carbon assimilation rate (A), stomatal conductance to water vapor (g(s)), internal-to-ambient CO₂ concentration ratio (C(i)/C(a)), and transpiration rate (E); the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR); the electrolyte leakage (EL), and the concentrations of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were determined. The AUAPC was reduced by 86% for the +Si plants compared with the -Si plants. The values of A, g(s), and E were lower upon inoculation of -Si plants in contrast to inoculated +Si plants with decreases of 31 and 60% for A, 34 and 61% for g(s), and 27 and 57% for E, respectively, at 4 and 8 dai. For the noninoculated plants, there was no significant difference between the -Si and +Si treatments for the values of A, g(s), and E. The C(i)/C(a) ratio was similar between the -Si and +Si treatments, regardless of the pathogen inoculation. The activities of SOD, CAT, APX, and GR tended to be higher in the +Si plants compared with the -Si plants upon inoculation with C. sublineolum. The EL significantly increased for -Si plants compared with +Si plants. The MDA concentration significantly increased by 31 and 38% at 4 and 8 dai, respectively, for the -Si plants compared with the +Si plants. Based on these results, Si may have a positive effect on sorghum physiology when infected by C. sublineolum through the maintenance of carbon fixation and also by enhancing the antioxidant system, which resulted in an increase in reactive oxygen species scavenging and, ultimately, reduced damage to the cell membranes.

C/sub 4/ photosynthesis in Euphorbia degeneri and E. remyi: a comparison of photosynthetic carbon metabolism in leaves, callus cultures and regenerated plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruzin, S.E.

1984-04-01

Based on analysis of /sup 14/CO/sub 2/ fixation kinetics and assays of enzymes related to C/sub 4/ metabolism (NAD-ME, NADP-ME, NAD-MDH, NADP-MDH, AST, ALT), leaves and regenerated plants of Euphorbia degeneri exhibit a modified NADP-ME-type photosynthesis. Apparently, both aspartate and malate are used for transport of CO/sub 2/ to bundle sheath cells. Callus grown on either non-shoot-forming or shoot-forming media fixes CO/sub 2/ into RPP-cycle intermediates and sucrose, as well as malate and aspartate. /sup 14/CO/sub 2/ pulse/chase kinetics show no significant loss of label from C/sub 4/ acids throughout a one minute chase. Analysis of PEPCase revealed the presencemore » of 2 isoenzymes in both leaf and regenerated plant tissues (K/sub m/ (PEP) = 0.080 and 0.550) but only one isoenzyme in callus (K/sub m/ = 0.100). It appears that C/sub 4/ photosynthesis does not occur in callus derived from this C/sub 4/ dicot but is regenerated concomitant with shoot regeneration, and ..beta..-carboxylation of PEP in callus, mediated by the low K/sub m/ isoenzyme of PEPCase, produces C/sub 4/ acids that are not involved in the CO/sub 2/ shuttle mechanism characteristic of C/sub 4/ photosynthesis. 161 references, 19 figures, 12 tables.« less

Spatial variability in plant species composition and peatland carbon exchange

NASA Astrophysics Data System (ADS)

Goud, E.; Moore, T. R.; Roulet, N. T.

2015-12-01

Plant species shifts in response to global change will have significant impacts on ecosystem carbon (C) exchange and storage arising from changes in hydrology. Spatial variation in peatland C fluxes have largely been attributed to the spatial distribution of microhabitats that arise from variation in surface topography and water table depth, but little is known about how plant species composition impacts peatland C cycling or how these impacts will be influenced by changing environmental conditions. We quantified the effect of species composition and environmental variables on carbon dioxide (CO2) and methane (CH4) fluxes over 2 years in a temperate peatland for four plant communities situated along a water table gradient from ombrotrophic bog to beaver pond. We hypothesized that (i) spatial heterogeneity in species composition would drive predictable spatial heterogeneity in C fluxes due to variation in plant traits and ecological tolerances, and (ii) increases in peat temperature would increase C fluxes. Species had different effects on C fluxes primarily due to differences in leaf traits. Differences in ecological tolerances among communities resulted in different rates of CO2 exchange in response to changes in water table depth. There was an overall reduction in ecosystem respiration (ER), gross primary productivity (GPP) and CH4 flux in response to colder peat temperatures in the second year, and the additive effects of a deeper water table in the bog margin and pond sites further reduced flux rates in these areas. These results demonstrate that different plant species can increase or decrease the flux of C into and out of peatlands based on differences in leaf traits and ecological tolerances, and that CO2 and CH4 fluxes are sensitive to changes in soil temperature, especially when coupled with changes in moisture availability.

Engineering C4 photosynthesis into C3 chassis in the synthetic biology age.

PubMed

Schuler, Mara L; Mantegazza, Otho; Weber, Andreas P M

2016-07-01

C4 photosynthetic plants outperform C3 plants in hot and arid climates. By concentrating carbon dioxide around Rubisco C4 plants drastically reduce photorespiration. The frequency with which plants evolved C4 photosynthesis independently challenges researchers to unravel the genetic mechanisms underlying this convergent evolutionary switch. The conversion of C3 crops, such as rice, towards C4 photosynthesis is a long-standing goal. Nevertheless, at the present time, in the age of synthetic biology, this still remains a monumental task, partially because the C4 carbon-concentrating biochemical cycle spans two cell types and thus requires specialized anatomy. Here we review the advances in understanding the molecular basis and the evolution of the C4 trait, advances in the last decades that were driven by systems biology methods. In this review we emphasise essential genetic engineering tools needed to translate our theoretical knowledge into engineering approaches. With our current molecular understanding of the biochemical C4 pathway, we propose a simplified rational engineering model exclusively built with known C4 metabolic components. Moreover, we discuss an alternative approach to the progressing international engineering attempts that would combine targeted mutagenesis and directed evolution. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

New evidence for grain specific C4 photosynthesis in wheat

PubMed Central

Rangan, Parimalan; Furtado, Agnelo; Henry, Robert J

2016-01-01

The C4 photosynthetic pathway evolved to allow efficient CO2 capture by plants where effective carbon supply may be limiting as in hot or dry environments, explaining the high growth rates of C4 plants such as maize. Important crops such as wheat and rice are C3 plants resulting in efforts to engineer them to use the C4 pathway. Here we show the presence of a C4 photosynthetic pathway in the developing wheat grain that is absent in the leaves. Genes specific for C4 photosynthesis were identified in the wheat genome and found to be preferentially expressed in the photosynthetic pericarp tissue (cross- and tube-cell layers) of the wheat caryopsis. The chloroplasts exhibit dimorphism that corresponds to chloroplasts of mesophyll- and bundle sheath-cells in leaves of classical C4 plants. Breeding to optimize the relative contributions of C3 and C4 photosynthesis may adapt wheat to climate change, contributing to wheat food security. PMID:27530078

CO2 availability influences hydraulic function of C3 and C4 grass leaves

PubMed Central

Blackman, Chris J

2018-01-01

Abstract Atmospheric CO2 (ca) has increased since the last glacial period, increasing photosynthetic water use efficiency and improving plant productivity. Evolution of C4 photosynthesis at low ca led to decreased stomatal conductance (gs), which provided an advantage over C3 plants that may be reduced by rising ca. Using controlled environments, we determined how increasing ca affects C4 water use relative to C3 plants. Leaf gas exchange and mass per area (LMA) were measured for four C3 and four C4 annual, crop-related grasses at glacial (200 µmol mol−1), ambient (400 µmol mol−1), and super-ambient (640 µmol mol−1) ca. C4 plants had lower gs, which resulted in a water use efficiency advantage at all ca and was broadly consistent with slower stomatal responses to shade, indicating less pressure on leaf water status. At glacial ca, net CO2 assimilation and LMA were lower for C3 than for C4 leaves, and C3 and C4 grasses decreased leaf hydraulic conductance (Kleaf) similarly, but only C4 leaves decreased osmotic potential at turgor loss. Greater carbon availability in C4 leaves at glacial ca generated a different hydraulic adjustment relative to C3 plants. At current and future ca, C4 grasses have advantages over C3 grasses due to lower gs, lower stomatal sensitivity, and higher absolute water use efficiency. PMID:29538702

Identifying Chloris Species from Cuban Citrus Orchards and Determining Their Glyphosate-Resistance Status

PubMed Central

Bracamonte, Enzo R.; Fernández-Moreno, Pablo T.; Bastida, Fernando; Osuna, María D.; Alcántara-de la Cruz, Ricardo; Cruz-Hipolito, Hugo E.; De Prado, Rafael

2017-01-01

The Chloris genus is a C4 photosynthetic species mainly distributed in tropical and subtropical regions. Populations of three Chloris species occurring in citrus orchards from central Cuba, under long history glyphosate-based weed management, were studied for glyphosate-resistant status by characterizing their herbicide resistance/tolerance mechanisms. Morphological and molecular analyses allowed these species to be identified as C. ciliata Sw., Chloris elata Desv., and Chloris barbata Sw. Based on the glyphosate rate that causes 50% mortality of the treated plants, glyphosate resistance (R) was confirmed only in C. elata, The R population was 6.1-fold more resistant compared to the susceptible (S) population. In addition, R plants of C. elata accumulated 4.6-fold less shikimate after glyphosate application than S plants. Meanwhile, populations of C. barbata and C. ciliata with or without glyphosate application histories showed similar LD50 values and shikimic acid accumulation rates, demonstrating that resistance to glyphosate have not evolved in these species. Plants of R and S populations of C. elata differed in 14C-glyphosate absorption and translocation. The R population exhibited 27.3-fold greater 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) activity than the S population due to a target site mutation corresponding to a Pro-106-Ser substitution found in the EPSPS gene. These reports show the innate tolerance to glyphosate of C. barbata and C. ciliata, and confirm the resistance of C. elata to this herbicide, showing that both non-target site and target-site mechanisms are involved in its resistance to glyphosate. This is the first case of herbicide resistance in Cuba. PMID:29187862

A rapid screening method to detect specific inhibitors of pyruvate orthophosphate dikinase as leads for C4 plant-selective herbicides.

PubMed

Doyle, Jason R; Burnell, James N; Haines, Dianne S; Llewellyn, Lyndon E; Motti, Cherie A; Tapiolas, Dianne M

2005-02-01

Plants using the C(4) photosynthetic pathway are highly represented among the world's worst weeds, with only 4 C(4) species being agriculturally productive (maize, sorghum, millet, and sugar cane). With the C(4) acid cycle operating as a biochemical appendage of C(3) photosynthesis, the additional enzymes involved in C(4) photosynthesis represent an attractive target for the development of weed-specific herbicides. The rate-limiting enzyme of this metabolic pathway is pyruvate orthophosphate dikinase (PPDK). PPDK, coupled with phosphoenolpyruvate carboxylase and nicotinamide adenine dinucleotide-malate dehydrogenase, was used to develop a microplate-based assay to detect inhibitors of enzymes of the C(4) acid cycle. The resulting assay had a Z' factor of 0.61, making it a high-quality assay able to reliably identify active test samples. Organic extracts of 6679 marine macroscopic organisms were tested within the assay, and 343 were identified that inhibited the 3 enzyme-coupled reaction. A high confirmation rate was achieved, with 95% of these hit extracts proving active again upon retesting. Sequential addition of phosphoenolpyruvate and oxaloacetate to the assay facilitated identification of 83 extracts that specifically inhibited PPDK.

Isolation and characterization of isochorismate synthase and cinnamate 4-hydroxylase during salinity stress, wounding, and salicylic acid treatment in Carthamus tinctorius

PubMed Central

Sadeghi, Mahnaz; Dehghan, Sara; Fischer, Rainer; Wenzel, Uwe; Vilcinskas, Andreas; Kavousi, Hamid Reza; Rahnamaeian, Mohammad

2013-01-01

Salicylic acid (SA) is a prominent signaling molecule during biotic and abiotic stresses in plants biosynthesized via cinnamate and isochorismate pathways. Cinnamate 4-hydroxylase (C4H) and isochorismate synthase (ICS) are the main enzymes in phenylpropanoid and isochorismate pathways, respectively. To investigate the actual roles of these genes in resistance mechanism to environmental stresses, here, the coding sequences of these enzymes in safflower (Carthamus tinctorius), as an oilseed industrial medicinal plant, were partially isolated and their expression profiles during salinity stress, wounding, and salicylic acid treatment were monitored. As a result, safflower ICS (CtICS) and C4H (CtC4H) were induced in early time points after wounding (3–6 h). Upon salinity stress, CtICS and CtC4H were highly expressed for the periods of 6–24 h and 3–6 h after treatment, respectively. It seems evident that ICS expression level is SA concentration dependent as if safflower treatment with 1 mM SA could induce ICS much stronger than that with 0.1 mM, while C4H is less likely to be so. Based on phylogenetic analysis, safflower ICS has maximum similarity to its ortholog in Vitis vinifera up to 69%, while C4H shows the highest similarity to its ortholog in Echinacea angustifolia up to 96%. Overall, the isolated genes of CtICS and CtC4H in safflower could be considered in plant breeding programs for salinity tolerance as well as for pathogen resistance. PMID:24309561

Pulse-drought atop press-drought: unexpected plant responses and implications for dryland ecosystems.

PubMed

Hoover, David L; Duniway, Michael C; Belnap, Jayne

2015-12-01

In drylands, climate change is predicted to cause chronic reductions in water availability (press-droughts) through reduced precipitation and increased temperatures as well as increase the frequency and intensity of short-term extreme droughts (pulse-droughts). These changes in precipitation patterns may have profound ecosystem effects, depending on the sensitivities of the dominant plant functional types (PFTs). Here we present the responses of four Colorado Plateau PFTs to an experimentally imposed, 4-year, press-drought during which a natural pulse-drought occurred. Our objectives were to (1) identify the drought sensitivities of the PFTs, (2) assess the additive effects of the press- and pulse-drought, and (3) examine the interactive effects of soils and drought. Our results revealed that the C3 grasses were the most sensitive PFT to drought, the C3 shrubs were the most resistant, and the C4 grasses and shrubs had intermediate drought sensitivities. Although we expected the C3 grasses would have the greatest response to drought, the higher resistance of C3 shrubs relative to the C4 shrubs was contrary to our predictions based on the higher water use efficiency of C4 photosynthesis. Also, the additive effects of press- and pulse-droughts caused high morality in C3 grasses, which has large ecological and economic ramifications for this region. Furthermore, despite predictions based on the inverse texture hypothesis, we observed no interactive effects of soils with the drought treatment on cover or mortality. These results suggest that plant responses to droughts in drylands may differ from expectations and have large ecological effects if press- and pulse-droughts push species beyond physiological and mortality thresholds.

Pulse-drought atop press-drought: unexpected plant responses and implications for dryland ecosystems

USGS Publications Warehouse

Hoover, David L.; Duniway, Michael C.; Belnap, Jayne

2015-01-01

In drylands, climate change is predicted to cause chronic reductions in water availability (press-droughts) through reduced precipitation and increased temperatures as well as increase the frequency and intensity of short-term extreme droughts (pulse-droughts). These changes in precipitation patterns may have profound ecosystem effects, depending on the sensitivities of the dominant plant functional types (PFTs). Here we present the responses of four Colorado Plateau PFTs to an experimentally imposed, 4-year, press-drought during which a natural pulse-drought occurred. Our objectives were to (1) identify the drought sensitivities of the PFTs, (2) assess the additive effects of the press- and pulse-drought, and (3) examine the interactive effects of soils and drought. Our results revealed that the C3 grasses were the most sensitive PFT to drought, the C3shrubs were the most resistant, and the C4 grasses and shrubs had intermediate drought sensitivities. Although we expected the C3 grasses would have the greatest response to drought, the higher resistance of C3 shrubs relative to the C4 shrubs was contrary to our predictions based on the higher water use efficiency of C4 photosynthesis. Also, the additive effects of press- and pulse-droughts caused high morality in C3 grasses, which has large ecological and economic ramifications for this region. Furthermore, despite predictions based on the inverse texture hypothesis, we observed no interactive effects of soils with the drought treatment on cover or mortality. These results suggest that plant responses to droughts in drylands may differ from expectations and have large ecological effects if press- and pulse-droughts push species beyond physiological and mortality thresholds.

Plant rhizosphere species-specific stoichiometry and regulation of extracellular enzyme and microbial community structure

NASA Astrophysics Data System (ADS)

Bell, C. W.; Calderon, F.; Pendall, E.; Wallenstein, M. D.

2012-12-01

Plant communities affect the activity and composition of soil microbial communities through alteration of the soil environment during root growth; substrate availability through root exudation; nutrient availability through plant uptake; and moisture regimes through transpiration. As a result, positive feedbacks in soil properties can result from alterations in microbial community composition and function in the rhizosphere zone. At the ecosystem-scale, many properties of soil microbial communities can vary between forest stands dominated by different species, including community composition and stoichiometry. However, the influence of smaller individual plants on grassland soils and microbial communities is less well documented. There is evidence to suggest that some plants can modify their soil environment in a manner that favors their persistence. For example, when Bromus tectorum plants invade, soil microbial communities tend to have higher N mineralization rates (in the rhizosphere zone) relative to native plants. If tight linkages between individual plant species and microbial communities inhabiting the rhizosphere exist, we hypothesized that any differences among plant species specific rhizosphere zones could be observed by shifts in: 1) soil -rhizosphere microbial community structure, 2) enzymatic C:N:P acquisition activities, 3) alterations in the soil C chemistry composition in the rhizosphere, and 4) plant - soil - microbial C:N:P elemental stoichiometry. We selected and grew 4 different C3 grasses species including three species native to the Shortgrass Steppe region (Pascopyrum smithii, Koeleria macrantha, and Vulpia octoflora) and one exotic invasive plant species (B. tectorum) in root-boxes that are designed to allow for easy access to the rhizosphere. The field soil was homogenized using a 4mm sieve and mixed 1:1 with sterile sand and seeded as monocultures (24 replicate root - boxes for each species). Plant and soil samples (along with no - plant control soil samples) were collected on day 28, 78, and 148 (N = 4 /sample period/species). Microbial community structure was quantified using the barcoded pyrosequencing protocols. We measured the potential activity of seven hydrolytic soil enzymes to represent the degradation of C, N, and P-rich substrates. Soil microbial C:N biomass responses to specific plant rhizospheres (MBC and MBN) were measured using the chloroform fumigation extraction method followed by DOC & N analysis. Fourier Transform Infrared Spectroscopy was used to assess differences in plant and soil C chemistry. We found that species specific rhizospheres are characteristic of very different soil chemical, edaphic, and microbial properties. These plant species act as gateways that introduce variability into soil C, N, and P ecosystem functional dynamics directly facilitated by rhizosphere - microbe associations. Our results suggest that nutrient stoichiometry within plant species' rhizospheres is a useful tool for identifying intra-ecosystem functional patterns. By identifying what and how specific species rhizospheres differ among the overall plant community, we can better predict how below-ground microbial community function and subsequent ecosystem processes can be influenced by alterations in plant community shifts based on the rhizosphere effects.

The palaeoecological context of the Oldowan-Acheulean in southern Africa.

PubMed

Ecker, Michaela; Brink, James S; Rossouw, Lloyd; Chazan, Michael; Horwitz, Liora K; Lee-Thorp, Julia A

2018-05-21

The influence of climatic and environmental change on human evolution in the Pleistocene epoch is understood largely from extensive East African stable isotope records. These records show increasing proportions of C 4 plants in the Early Pleistocene. We know far less about the expansion of C 4 grasses at higher latitudes, which were also occupied by early Homo but are more marginal for C 4 plants. Here we show that both C 3 and C 4 grasses and prolonged wetlands remained major components of Early Pleistocene environments in the central interior of southern Africa, based on enamel stable carbon and oxygen isotope data and associated faunal abundance and phytolith evidence from the site of Wonderwerk Cave. Vegetation contexts associated with Oldowan and early Acheulean lithic industries, in which climate is driven by an interplay of regional rainfall seasonality together with global CO 2 levels, develop along a regional distinct trajectory compared to eastern South Africa and East Africa.

Impact of plant photosystems in the remediation of benzo[a]pyrene and pyrene spiked soils.

PubMed

Sivaram, Anithadevi Kenday; Logeshwaran, Panneerselvan; Lockington, Robin; Naidu, Ravi; Megharaj, Mallavarapu

2018-02-01

The phytoremediation potential of 14 different plant species belonging to C3 and C4 carbon fixation pathway for soils spiked with polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P) and pyrene (PYR) was investigated. A glasshouse experiment was conducted to measure the changes in morphological, physiological, biochemical parameters and the bioaccumulation and biodegradation ability of the plants in soils spiked with 48 and 194 mg kg -1 of B[a]P and PYR, respectively. The per cent removal efficacy of B[a]P and PYR by the tested plant species over a period of 50 days was from 6 to 26% and 14 to 40% respectively. The maximum removal of both B[a]P and PYR was observed in Sudan grass (C4), vetiver (C4), maize (C4), and sunflower (C3). In terms of accumulation in root and shoot, the concentration of PYR was higher in both C3 and C4 plant species when compared to B[a]P. Overall the results indicated that C4 plants were more efficient than their C3 counterparts in terms of morphological, physiological, biochemical and degradation ability of PAHs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Leaf and plant water use efficiency of C{sub 4} species grown at glacial to elevated CO{sub 2} concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polley, H.W.; Johnson, H.B.; Mayeux, H.S.

1996-03-01

Leaf gas exchange was measured on C{sub 4} plants grown from near glacial to current CO{sub 2} concentrations (200-350 {mu}mol mol{sup -1}) and from the current concentration to possible future levels (near 700 and 1000 {mu}mol mol{sup -1}) to test the prediction that intrinsic water use efficiency (CO{sub 2} assimilation [A]/stomatal conductance to water [g]) would rise by a similar relative amount as CO{sub 2} concentration. Studied were species differing in growth form or life history, the perennial grass Schizachyrium scoparium (little bluestem), perennial shrub Atriplex canescens (four-wing saltbush), and annual grass Schizachyrium scoparium (little bluestem), leaf A/g of themore » C{sub 4} species examined was stimulated proportionally more by a given relative increase in CO{sub 2} over subambient than by elevated concentrations. The ratio of the relative increase in A/g to that in CO{sub 2} exceeded unity in S, scoparium and A. canescens as CO{sub 2} rose from 700 to 1000 {mu}mol mol{sup -1}. At higher CO{sub 2} concentrations, A/g of the C{sub 4} perennials was similar to that expected for C{sub 3} plants. Since much of the potential response of C{sub 4} plants to CO{sub 4} perennials was similar to that expected for C{sub 3} plants. Since much of the potential response of C{sub 4} plants to CO{sub 2} often derives from higher water use efficiency (WUE), these results indicated that potential productivity of some C{sub 4} plants increased relatively more since glaciation than it will in the future. There also were large (>100%) differences in A/g and plant WUE (production/transpiration) at a given CO{sub 2} level among the plants examined that could influence the relative productivities of C{sub 4} species or growth forms and their interactions with C{sub 3} plants. 34 refs., 3 figs., 3 tabs.« less

Late Pleistocene-Holocene paleoclimate in southwestern Brazilian Amazonia with basis on floristic changes interpreted from isotope data

NASA Astrophysics Data System (ADS)

Rossetti, D. F.; Cohen, M. C. L.; Pessenda, L. C. R.

2015-12-01

Previous late Quaternary paleoclimatic interpretations in Amazonia have considered fluctuating dry to wet episodes with changes from savanna to forest, a view that concurs with other proposals of undisturbed rainforest despite global oscillations. Most of this debate is based on pollen data, but such elements are scarce in Amazonian sedimentary records. This work interprets vegetation in the Late Pleistocene and Holocene in a southwestern Amazonia lowland using δ13C, δ15N, C/N integrated with geomorphology, sedimentology and radiocarbon dating. The goal was to reconstruct vegetation changes through time and analyze their relation to climate and sedimentary dynamics. Fluvial channel and floodplain deposits with phytoplankton, as well as C3 and C4 land plants, were recorded. Between 42,033-43,168 cal yr BP and 34,804-35,584 cal yr BP, C4 land plants increased as a result of a climate drier than todaýs. However, wet climate prevailed from this time-frame until the onset of the Last Glaciation Maximum. In the Pleistocene/Holocene transition, there was an increased contribution of C4 land plants potentially related to dry episodes. However, the increased contribution of this type of land plant is not synchronous with Holocene dry episodes previously documented for the Amazonian lowland. On the other hand, it is remarkable that the record of this plant type was verified only in sites with modern grassland confined to fluvial paleo-landforms. Thus, rather than due to a dry climatic episode, the recorded grassland expansion and its maintenance up to the present time in the studied sites is more likely associated with the evolution of depositional environments, being coincidental with the progressive abandonment of fluvial systems. An important conclusion derived from the present work is that great care must be placed when reconstructing late Quaternary paleoclimate in Amazonia based on changes in floristic patterns, as they may be also a response to sedimentary dynamics.

Induction of kranz anatomy and C4-like biochemical characteristics in a submerged amphibious plant by abscisic acid

PubMed Central

Ueno, O

1998-01-01

The amphibious leafless sedge Eleocharis vivipara develops C4-like traits as well as Kranz anatomy under terrestrial conditions, but it develops C3-like traits without Kranz anatomy under submerged conditions. When submerged plants are exposed to aerial conditions, they rapidly produce new photosynthetic tissues with C4-like traits. In this study, experiments were performed to determine whether abscisic acid (ABA), a plant stress hormone, could induce the formation of photosynthetic tissues with Kranz anatomy and C4-like biochemical traits under water in the submerged form. When the submerged plants were grown in water containing 5 &mgr;M ABA, they developed new photosynthetic tissues with Kranz anatomy, forming well-developed Kranz (bundle sheath) cells that contained many organelles. The ABA-induced tissues accumulated large amounts of phosphoenolpyruvate carboxylase, pyruvate orthophosphate dikinase, and NAD-malic enzyme at the appropriate cellular sites. The tissues had 3.4 to 3.8 times more C4 enzyme activity than did tissues of the untreated submerged plants. Carbon-14 pulse and carbon-12 chase experiments revealed that the ABA-induced tissues fixed higher amounts of carbon-14 into C4 compounds and lower amounts of carbon-14 into C3 compounds as initial products than did the submerged plants and that they exhibited a C4-like pattern of carbon fixation under aqueous conditions of low carbon, indicating enhanced C4 capacity in the tissues. This report provides an example of the hormonal control of the differentiation of the structural and functional traits required for the C4 pathway. PMID:9548983

From sunlight to phytomass: on the potential efficiency of converting solar radiation to phyto-energy.

PubMed

Amthor, Jeffrey S

2010-12-01

The relationship between solar radiation capture and potential plant growth is of theoretical and practical importance. The key processes constraining the transduction of solar radiation into phyto-energy (i.e. free energy in phytomass) were reviewed to estimate potential solar-energy-use efficiency. Specifically, the out-put:input stoichiometries of photosynthesis and photorespiration in C(3) and C(4) systems, mobilization and translocation of photosynthate, and biosynthesis of major plant biochemical constituents were evaluated. The maintenance requirement, an area of important uncertainty, was also considered. For a hypothetical C(3) grain crop with a full canopy at 30°C and 350 ppm atmospheric [CO(2) ], theoretically potential efficiencies (based on extant plant metabolic reactions and pathways) were estimated at c. 0.041 J J(-1) incident total solar radiation, and c. 0.092 J J(-1) absorbed photosynthetically active radiation (PAR). At 20°C, the calculated potential efficiencies increased to 0.053 and 0.118 J J(-1) (incident total radiation and absorbed PAR, respectively). Estimates for a hypothetical C(4) cereal were c. 0.051 and c. 0.114 J J(-1), respectively. These values, which cannot be considered as precise, are less than some previous estimates, and the reasons for the differences are considered. Field-based data indicate that exceptional crops may attain a significant fraction of potential efficiency. © The Author (2010). Journal compilation © New Phytologist Trust (2010).

Pepper pathogenesis-related protein 4c is a plasma membrane-localized cysteine protease inhibitor that is required for plant cell death and defense signaling.

PubMed

Kim, Nak Hyun; Hwang, Byung Kook

2015-01-01

Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis-related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT-triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease-inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H2 O2 and significant induction of some defense-response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT-triggered resistance responses, and enabled Xcv proliferation in infected leaves. H2 O2 accumulation, cell-death induction, and defense-response gene expression were distinctly reduced in CaPR4c-silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Differential positioning of C(4) mesophyll and bundle sheath chloroplasts: recovery of chloroplast positioning requires the actomyosin system.

PubMed

Kobayashi, Hiroaki; Yamada, Masahiro; Taniguchi, Mitsutaka; Kawasaki, Michio; Sugiyama, Tatsuo; Miyake, Hiroshi

2009-01-01

In C(4) plants, bundle sheath (BS) chloroplasts are arranged in the centripetal position or in the centrifugal position, although mesophyll (M) chloroplasts are evenly distributed along cell membranes. To examine the molecular mechanism for the intracellular disposition of these chloroplasts, we observed the distribution of actin filaments in BS and M cells of the C(4) plants finger millet (Eleusine coracana) and maize (Zea mays) using immunofluorescence. Fine actin filaments encircled chloroplasts in both cell types, and an actin network was observed adjacent to plasma membranes. The intracellular disposition of both chloroplasts in finger millet was disrupted by centrifugal force but recovered within 2 h in the dark. Actin filaments remained associated with chloroplasts during recovery. We also examined the effects of inhibitors on the rearrangement of chloroplasts. Inhibitors of actin polymerization, myosin-based activities and cytosolic protein synthesis blocked migration of chloroplasts. In contrast, a microtubule-depolymerizing drug had no effect. These results show that C(4) plants possess a mechanism for keeping chloroplasts in the home position which is dependent on the actomyosin system and cytosolic protein synthesis but not tubulin or light.

Phylogeny in Defining Model Plants for Lignocellulosic Ethanol Production: A Comparative Study of Brachypodium distachyon, Wheat, Maize, and Miscanthus x giganteus Leaf and Stem Biomass

PubMed Central

Meineke, Till; Manisseri, Chithra; Voigt, Christian A.

2014-01-01

The production of ethanol from pretreated plant biomass during fermentation is a strategy to mitigate climate change by substituting fossil fuels. However, biomass conversion is mainly limited by the recalcitrant nature of the plant cell wall. To overcome recalcitrance, the optimization of the plant cell wall for subsequent processing is a promising approach. Based on their phylogenetic proximity to existing and emerging energy crops, model plants have been proposed to study bioenergy-related cell wall biochemistry. One example is Brachypodium distachyon, which has been considered as a general model plant for cell wall analysis in grasses. To test whether relative phylogenetic proximity would be sufficient to qualify as a model plant not only for cell wall composition but also for the complete process leading to bioethanol production, we compared the processing of leaf and stem biomass from the C3 grasses B. distachyon and Triticum aestivum (wheat) with the C4 grasses Zea mays (maize) and Miscanthus x giganteus, a perennial energy crop. Lambda scanning with a confocal laser-scanning microscope allowed a rapid qualitative analysis of biomass saccharification. A maximum of 108–117 mg ethanol·g−1 dry biomass was yielded from thermo-chemically and enzymatically pretreated stem biomass of the tested plant species. Principal component analysis revealed that a relatively strong correlation between similarities in lignocellulosic ethanol production and phylogenetic relation was only given for stem and leaf biomass of the two tested C4 grasses. Our results suggest that suitability of B. distachyon as a model plant for biomass conversion of energy crops has to be specifically tested based on applied processing parameters and biomass tissue type. PMID:25133818

Stable C &N isotopes in 2100 Year-B.P. human bone collagen indicate rare dietary dominance of C4 plants in NE-Italy.

PubMed

Laffranchi, Zita; Huertas, Antonio Delgado; Jiménez Brobeil, Sylvia A; Torres, Arsenio Granados; Riquelme Cantal, Jose A

2016-12-09

C 4 plants (e.g. maize, millet), part of our current diet, are only endemic of reduced areas in South-Europe due to their need of warm climates. Since the first vestiges of agriculture in Europe remains of C 4 plants were recorded but their overall proportion in the human diet remains unknown. Therefore, isotopic (δ 13 C and δ 15 N) composition of bone collagen from the skeletal remains (human and animals) of a Celtic population, Cenomani Gauls, from Verona (3 rd to 1 st century BC) in the NE Italy provide a new perspective on this matter. The δ 13 C collagen values of 90 human skeletal individuals range between -20.2‰ and -9.7‰ (V-PDB) with a mean value of -15.3‰. As present day C 4 plants have δ 13 C values around -11‰, which is equivalent to -9.5‰ for samples of preindustrial age, the less negative δ 13 C values in these individuals indicate a diet dominated by C 4 plants. This palaeodietary study indicates that some European populations predominantly consumed cultivated C 4 plants 2100 year B.P. This is supported by the paleobotanical records and ancient Roman sources (e.g. Pliny the Elder), which indicate that millet was a staple food in South-Europe.

Stable C & N isotopes in 2100 Year-B.P. human bone collagen indicate rare dietary dominance of C4 plants in NE-Italy

NASA Astrophysics Data System (ADS)

Laffranchi, Zita; Huertas, Antonio Delgado; Jiménez Brobeil, Sylvia A.; Torres, Arsenio Granados; Riquelme Cantal, Jose A.

2016-12-01

C4 plants (e.g. maize, millet), part of our current diet, are only endemic of reduced areas in South-Europe due to their need of warm climates. Since the first vestiges of agriculture in Europe remains of C4 plants were recorded but their overall proportion in the human diet remains unknown. Therefore, isotopic (δ13C and δ15N) composition of bone collagen from the skeletal remains (human and animals) of a Celtic population, Cenomani Gauls, from Verona (3rd to 1st century BC) in the NE Italy provide a new perspective on this matter. The δ13C collagen values of 90 human skeletal individuals range between -20.2‰ and -9.7‰ (V-PDB) with a mean value of -15.3‰. As present day C4 plants have δ13C values around -11‰, which is equivalent to -9.5‰ for samples of preindustrial age, the less negative δ13C values in these individuals indicate a diet dominated by C4 plants. This palaeodietary study indicates that some European populations predominantly consumed cultivated C4 plants 2100 year B.P. This is supported by the paleobotanical records and ancient Roman sources (e.g. Pliny the Elder), which indicate that millet was a staple food in South-Europe.

Failure and Degradation Modes of PV modules in a Hot Dry Climate: Results after 4 and 12 years of field exposure

NASA Astrophysics Data System (ADS)

Mallineni, Jaya krishna

This study evaluates two photovoltaic (PV) power plants based on electrical performance measurements, diode checks, visual inspections and infrared scanning. The purpose of this study is to measure degradation rates of performance parameters (Pmax, Isc, Voc, Vmax, Imax and FF) and to identify the failure modes in a "hot-dry desert" climatic condition along with quantitative determination of safety failure rates and reliability failure rates. The data obtained from this study can be used by module manufacturers in determining the warranty limits of their modules and also by banks, investors, project developers and users in determining appropriate financing or decommissioning models. In addition, the data obtained in this study will be helpful in selecting appropriate accelerated stress tests which would replicate the field failures for the new modules and would predict the lifetime for new PV modules. The study was conducted at two, single axis tracking monocrystalline silicon (c-Si) power plants, Site 3 and Site 4c of Salt River Project (SRP). The Site 3 power plant is located in Glendale, Arizona and the Site 4c power plant is located in Mesa, Arizona both considered a "hot-dry" field condition. The Site 3 power plant has 2,352 modules (named as Model-G) which was rated at 250 kW DC output. The mean and median degradation of these 12 years old modules are 0.95%/year and 0.96%/year, respectively. The major cause of degradation found in Site 3 is due to high series resistance (potentially due to solder-bond thermo-mechanical fatigue) and the failure mode is ribbon-ribbon solder bond failure/breakage. The Site 4c power plant has 1,280 modules (named as Model-H) which provide 243 kW DC output. The mean and median degradation of these 4 years old modules are 0.96%/year and 1%/year, respectively. At Site 4c, practically, none of the module failures are observed. The average soiling loss is 6.9% in Site 3 and 5.5% in Site 4c. The difference in soiling level is attributed to the rural and urban surroundings of these two power plants.

Growth and phenolic compounds of Lactuca sativa L. grown in a closed-type plant production system with UV-A, -B, or -C lamp.

PubMed

Lee, Min-Jeong; Son, Jung Eek; Oh, Myung-Min

2014-01-30

The production of high-quality crops based on phytochemicals is a strategy for accelerating the practical use of plant factories. Previous studies have demonstrated that ultraviolet (UV) light is effective in improving phytochemical production. This study aimed to determine the effect of various UV wavelengths on growth and phenolic compound accumulation in lettuce (Lactuca sativa L.) grown in a closed-type plant production system. Seven days, 1 day and 0.25 day were determined as the upper limit of the irradiation periods for UV-A, -B, and -C, respectively, in the lettuce based on physiological disorders and the fluorescence parameter F(v)/F(m). Continuous UV-A treatment significantly induced the accumulation of phenolic compounds and antioxidants until 4 days of treatment without growth inhibition, consistent with an increase in phenylalanine ammonia lyase (PAL) gene expression and PAL activity. Repeated or gradual UV-B exposure yielded approximately 1.4-3.6 times more total phenolics and antioxidants, respectively, than the controls did 2 days after the treatments, although both treatments inhibited lettuce growth. Repeated UV-C exposure increased phenolics but severely inhibited the growth of lettuce plants. Our data suggest that UV irradiation can improve the accumulation of phenolic compounds with antioxidant properties in lettuce cultivated in plant factories. © 2013 Society of Chemical Industry.

A meta-analysis of context-dependency in plant response to inoculation with mycorrhizal fungi.

PubMed

Hoeksema, Jason D; Chaudhary, V Bala; Gehring, Catherine A; Johnson, Nancy Collins; Karst, Justine; Koide, Roger T; Pringle, Anne; Zabinski, Catherine; Bever, James D; Moore, John C; Wilson, Gail W T; Klironomos, John N; Umbanhowar, James

2010-03-01

Ecology Letters (2010) 13: 394-407 Abstract Mycorrhizal fungi influence plant growth, local biodiversity and ecosystem function. Effects of the symbiosis on plants span the continuum from mutualism to parasitism. We sought to understand this variation in symbiotic function using meta-analysis with information theory-based model selection to assess the relative importance of factors in five categories: (1) identity of the host plant and its functional characteristics, (2) identity and type of mycorrhizal fungi (arbuscular mycorrhizal vs. ectomycorrhizal), (3) soil fertility, (4) biotic complexity of the soil and (5) experimental location (laboratory vs. field). Across most subsets of the data, host plant functional group and N-fertilization were surprisingly much more important in predicting plant responses to mycorrhizal inoculation ('plant response') than other factors. Non-N-fixing forbs and woody plants and C(4) grasses responded more positively to mycorrhizal inoculation than plants with N-fixing bacterial symbionts and C(3) grasses. In laboratory studies of the arbuscular mycorrhizal symbiosis, plant response was more positive when the soil community was more complex. Univariate analyses supported the hypothesis that plant response is most positive when plants are P-limited rather than N-limited. These results emphasize that mycorrhizal function depends on both abiotic and biotic context, and have implications for plant community theory and restoration ecology.

Molecular adaptation in Rubisco: Discriminating between convergent evolution and positive selection using mechanistic and classical codon models.

PubMed

Parto, Sahar; Lartillot, Nicolas

2018-01-01

Rubisco (Ribulose-1, 5-biphosphate carboxylase/oxygenase) is the most important enzyme on earth, catalyzing the first step of photosynthetic CO2 fixation. So, without it, there would be no storing of the sun's energy in plants. Molecular adaptation of Rubisco to C4 photosynthetic pathway has attracted a lot of attention. C4 plants, which comprise less than 5% of land plants, have evolved more efficient photosynthesis compared to C3 plants. Interestingly, a large number of independent transitions from C3 to C4 phenotype have occurred. Each time, the Rubisco enzyme has been subject to similar changes in selective pressure, thus providing an excellent model for convergent evolution at the molecular level. Molecular adaptation is often identified with positive selection and is typically characterized by an elevated ratio of non-synonymous to synonymous substitution rate (dN/dS). However, convergent adaptation is expected to leave a different molecular signature, taking the form of repeated transitions toward identical or similar amino acids. Here, we used a previously introduced codon-based differential-selection model to detect and quantify consistent patterns of convergent adaptation in Rubisco in eudicots. We further contrasted our results with those obtained by classical codon models based on the estimation of dN/dS. We found that the two classes of models tend to select distinct, although overlapping, sets of positions. This discrepancy in the results illustrates the conceptual difference between these models while emphasizing the need to better discriminate between qualitatively different selective regimes, by using a broader class of codon models than those currently considered in molecular evolutionary studies.

Dietary analysis of Late Cenozoic Mexican equids from three different geographic/geologic settings using stable carbon isotopes: Coincidences, differences and paleobiologic significance

NASA Astrophysics Data System (ADS)

Pérez-Crespo, Víctor Adrian; Ferrusquía-Villafranca, Ismael; Bravo-Cuevas, Víctor Manuel; Morales-Puente, Pedro; Ruiz-González, José E.

2016-03-01

The development of Vertebrate Paleontology in Mexico is uneven, so that there is a strong bias in favor of Neogene/Quaternary mammals largely collected in the Trans-Mexican Volcanic Belt (TMVB hereafter) and Central Plateau (CeP hereafter) Morphotectonic Provinces [MP hereafter]; however, the time is ripe for pursuing research in other than taxonomic areas. Here we investigate C3/C4 plant consumption in the equid lineage in three such provinces, which provide different geographic/geologic and paleoecologic scenarios during the Barstovian, Hemphillian and Rancholabrean times. Our results show that the Barstovian equids from Oaxaca, Sierra Madre del Sur MP Cormohipparion aff. C. quinni, Merychippus cf. M. sejunctus and Pliohippus sp. largely fed on C3 plants, which were the chief food stuff of horses in Mexico, particularly in the Southeast. On the other hand, the Hemphillian equid from Guanajuato, CeP Astrohippus stocki, was an unbalanced C3/C4 mixed feeders in favor of C4 plants, a fact that indicates a profound plant diversification due to the inception and rapid diversification of C4 plants that occurred there at this time, as it occurred in temperate North America, resulting in the differential consumption of C4 plants over that of C3 plants. Such trend prevailed until the Rancholabrean, as born out by the inferred diet for Equus conversidens and Equus sp. from Hidalgo, TMVB. Clearly then, the coeval diet change observed in Mexico and temperate North America implies a correlative vegetation change resulting in the appearance and rapid diversification of C4 plants, which largely formed the preferred food stuff of equids since the Hemphillian, although some C3 plant consumption was maintained till the Rancholabrean. It should be noted that the development of hypsodonty in equids and many artiodactyls, has long been interpreted as the adaptive mammalian response to the new feeding conditions.

A critical review on the improvement of photosynthetic carbon assimilation in C3 plants using genetic engineering.

PubMed

Ruan, Cheng-Jiang; Shao, Hong-Bo; Teixeira da Silva, Jaime A

2012-03-01

Global warming is one of the most serious challenges facing us today. It may be linked to the increase in atmospheric CO2 and other greenhouse gases (GHGs), leading to a rise in sea level, notable shifts in ecosystems, and in the frequency and intensity of wild fires. There is a strong interest in stabilizing the atmospheric concentration of CO2 and other GHGs by decreasing carbon emission and/or increasing carbon sequestration. Biotic sequestration is an important and effective strategy to mitigate the effects of rising atmospheric CO2 concentrations by increasing carbon sequestration and storage capacity of ecosystems using plant photosynthesis and by decreasing carbon emission using biofuel rather than fossil fuel. Improvement of photosynthetic carbon assimilation, using transgenic engineering, potentially provides a set of available and effective tools for enhancing plant carbon sequestration. In this review, firstly different biological methods of CO2 assimilation in C3, C4 and CAM plants are introduced and three types of C4 pathways which have high photosynthetic performance and have evolved as CO2 pumps are briefly summarized. Then (i) the improvement of photosynthetic carbon assimilation of C3 plants by transgenic engineering using non-C4 genes, and (ii) the overexpression of individual or multiple C4 cycle photosynthetic genes (PEPC, PPDK, PCK, NADP-ME and NADP-MDH) in transgenic C3 plants (e.g. tobacco, potato, rice and Arabidopsis) are highlighted. Some transgenic C3 plants (e.g. tobacco, rice and Arabidopsis) overexpressing the FBP/SBPase, ictB and cytochrome c6 genes showed positive effects on photosynthetic efficiency and growth characteristics. However, over the last 28 years, efforts to overexpress individual, double or multiple C4 enzymes in C3 plants like tobacco, potato, rice, and Arabidopsis have produced mixed results that do not confirm or eliminate the possibility of improving photosynthesis of C3 plants by this approach. Finally, a prospect is provided on the challenges of enhancing carbon assimilation of C3 plants using transgenic engineering in the face of global warming, and the trends of the most promising approaches to improving the photosynthetic performance of C3 plants.

Metabolism of agrochemicals and related environmental chemicals based on cytochrome P450s in mammals and plants.

PubMed

Ohkawa, Hideo; Inui, Hideyuki

2015-06-01

A yeast gene expression system originally established for mammalian cytochrome P450 monooxygenase cDNAs was applied to functional analysis of a number of mammalian and plant P450 species, including 11 human P450 species (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1 and CYP3A4). The human P450 species CYP1A1, CYP1A2, CYP2B6, CYP2C18 and CYP2C19 were identified as P450 species metabolising various agrochemicals and environmental chemicals. CYP2C9 and CYP2E1 specifically metabolised sulfonylurea herbicides and halogenated hydrocarbons respectively. Plant P450 species metabolising phenylurea and sulfonylurea herbicides were also identified mainly as the CYP71 family, although CYP76B1, CYP81B1 and CYP81B2 metabolised phenylurea herbicides. The transgenic plants expressing these mammalian and plant P450 species were applied to herbicide tolerance as well as phytoremediation of agrochemical and environmental chemical residues. The combined use of CYP1A1, CYP2B6 and CYP2C19 belonging to two families and three subfamilies covered a wide variety of herbicide tolerance and phytoremediation of these residues. The use of 2,4-D-and bromoxynil-induced CYP71AH11 in tobacco seemed to enhance herbicide tolerance and selectivity. © 2014 Society of Chemical Industry.

Toward Development of an Oral, Plant-Based Vaccine Against Escherichia coli O157:H7

DTIC Science & Technology

2004-01-01

Mason, H. S., Haq, T. A., Clements, J. D., and Arntzen, C. J. (1998). Edible vaccine protects mice against Escherichia coli heat-labile enterotoxin (LT...based Vaccine Against Escherichia coli O157:H7.” beyond brief excerpts is with the permission of the copyright owner, and will save and hold...4. TITLE AND SUBTITLE Toward Development of an Oral, Plant-based Vaccine Against Escherichia coli O157:H7 5a. CONTRACT NUMBER 5b. GRANT

Carbon isotope compositions of terrestrial C3 plants as indicators of (paleo)ecology and (paleo)climate.

PubMed

Kohn, Matthew J

2010-11-16

A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ(13)C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ(13)C of atmospheric CO(2), these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7-8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward dry ecosystems, although wet ecosystems are also represented. Unambiguous isotopic evidence for C4 plants is lacking prior to 7-8 Ma, and hominid ecosystems at 4.4 Ma show no isotopic evidence for dense forests. Consideration of global plant biomass indicates that average δ(13)C of C3 plants is commonly overestimated by approximately 2‰.

Temperature Responses of C4 Photosynthesis: Biochemical Analysis of Rubisco, Phosphoenolpyruvate Carboxylase, and Carbonic Anhydrase in Setaria viridis.

PubMed

Boyd, Ryan A; Gandin, Anthony; Cousins, Asaph B

2015-11-01

The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are currently no published temperature responses of both Rubisco carboxylation and oxygenation kinetics from a C4 plant, nor are there known measurements of the temperature dependency of the PEPc Michaelis-Menten constant for its substrate HCO3 (-), and there is little information on the temperature response of plant CA activity. Here, we used membrane inlet mass spectrometry to measure the temperature responses of Rubisco carboxylation and oxygenation kinetics, PEPc carboxylation kinetics, and the activity and first-order rate constant for the CA hydration reaction from 10°C to 40°C using crude leaf extracts from the C4 plant Setaria viridis. The temperature dependencies of Rubisco, PEPc, and CA kinetic parameters are provided. These findings describe a new method for the investigation of PEPc kinetics, suggest an HCO3 (-) limitation imposed by CA, and show similarities between the Rubisco temperature responses of previously measured C3 species and the C4 plant S. viridis. © 2015 American Society of Plant Biologists. All Rights Reserved.

Stable C & N isotopes in 2100 Year-B.P. human bone collagen indicate rare dietary dominance of C4 plants in NE-Italy

PubMed Central

Laffranchi, Zita; Huertas, Antonio Delgado; Jiménez Brobeil, Sylvia A.; Torres, Arsenio Granados; Riquelme Cantal, Jose A.

2016-01-01

C4 plants (e.g. maize, millet), part of our current diet, are only endemic of reduced areas in South-Europe due to their need of warm climates. Since the first vestiges of agriculture in Europe remains of C4 plants were recorded but their overall proportion in the human diet remains unknown. Therefore, isotopic (δ13C and δ15N) composition of bone collagen from the skeletal remains (human and animals) of a Celtic population, Cenomani Gauls, from Verona (3rd to 1st century BC) in the NE Italy provide a new perspective on this matter. The δ13C collagen values of 90 human skeletal individuals range between −20.2‰ and −9.7‰ (V-PDB) with a mean value of −15.3‰. As present day C4 plants have δ13C values around −11‰, which is equivalent to −9.5‰ for samples of preindustrial age, the less negative δ13C values in these individuals indicate a diet dominated by C4 plants. This palaeodietary study indicates that some European populations predominantly consumed cultivated C4 plants 2100 year B.P. This is supported by the paleobotanical records and ancient Roman sources (e.g. Pliny the Elder), which indicate that millet was a staple food in South-Europe. PMID:27934943

Characterizing isotopic variability of primary production and consumers in Great Plains ecosystems during protracted regional drought

NASA Astrophysics Data System (ADS)

Haveles, A. W.; Fox-Dobbs, K.; Talmadge, K. A.; Fetrow, A.; Fox, D. L.

2012-12-01

Over the last few years (2010-2012), the Great Plains of the central USA experienced protracted drought conditions, including historically severe drought during Summer, 2011. Drought severity in the region generally decreases with increasing latitude, but episodic drought is a fundamental trait of grassland ecosystems. Documenting above ground energy and nutrient flow with current drought is critical to understanding responses of grassland ecosystems in the region to predicted increased episodicity of rainfall and recurrence of drought due to anthropogenic climate change. Characterization of biogeochemical variability of modern ecosystems at the microhabitat, local landscape, and regional scales is also necessary to interpret biogeochemical records of ancient grasslands based on paleosols and fossil mammals. Here, we characterize three grassland ecosystems that span the drought gradient in the Great Plains (sites in the Texas panhandle, southwest Kansas, and northwest Nebraska). We measured δ13C and δ15N values of plants and consumers to characterize the biogeochemical variability within each ecosystem. Vegetation at each site is a mix of trees, shrubs, herbs, and cool- and warm-growing season grasses (C3 and C4, respectively). Thus, consumers have access to isotopically distinct sources of forage that vary in abundance with microhabitat (e.g., open grassland, shrub thicket, riparian woodland). Observations indicate herbivorous arthropod (grasshoppers and crickets) abundance follows drought severity, with high abundance of many species in Texas, and low abundance of few species in Nebraska. Small mammal (rodents) abundance follows the inverse pattern with 0.8%, 3.2% and 17.2% capture success in Texas, Kansas and Nebraska, respectively. The inverse abundance patterns of consumer groups may result from greater sensitivity of small mammal consumers with high metabolic needs to lower local net primary productivity and forage quality under drought conditions. As a result, ecological interactions among consumer groups likely change as available energy sources decrease. In Kansas, neither C3 nor C4 plants have δ13C values that vary in relation to microhabitat. Most abundant arthropod taxa mainly utilize C3 plant resources. Small mammals have mixed diets derived from both C3 and C4 plant resources. Diets include general herbivory, or consumption of both plants and arthropods. Although C4 resources are available in all study areas, C3 resources are the dominant energy source for all consumers in Kansas, and rodents in Nebraska. Plant δ15N values for C3 and C4 plants, and all consumer species in Kansas were variable. High variability in plant δ15N values (hence consumers) complicates our ability to estimate trophic levels of consumers using δ15N values. Differences in δ15N values of consumers among microhabitats are evident in Kansas and Nebraska, which may result from differences in plant communities or foraging habits. Large isotopic variations within plants, arthropods, and mammals illustrate the need to monitor grassland ecosystems seasonally, and at varying spatial scales to characterize patterns of energy flow and trophic dynamics. Identifying how grassland consumers record local and regional environmental variance will help predict future responses of Great Plains ecosystems to anthropogenic climate change.

Investigate the plant biomass response to climate warming in permafrost ecosystem using matrix-based data assimilation

NASA Astrophysics Data System (ADS)

Lu, X.; Du, Z.; Schuur, E.; Luo, Y.

2017-12-01

Permafrost is one of the most vulnerable regions on the earth with over 40% world soil C represented in this region. Future climate warming potentially has a great impact on this region. On one hand, rising temperature accelerates permafrost soil thaw and release more C from land. On the other hand, warming may also increase the plant growing season length and therefore negatively feedback to climate change by increasing annual land C uptake. However, whether permafrost vegetation biomass change in response to warming can sequester more C has not been well understood. Manipulated air warming experiments reported that air warming has very limited impacts on grass land productivity and biomass growth in permafrost region [Mauritz et al., 2017]. It is hard to reveal the mechanisms behind the limited air warming response directly from experiment data. We employ a vegetation C cycle matrix model based on Community land model 4.5 (CLM4.5) and data assimilation technique to investigate how much do phenology and physiology processes contribute to the response respectively. Our results indicate phenology contributes the most in response to warming. The shift of vegetation parameter distributions after 2012 indicate vegetation acclimation may explain the modest response in plant biomass to air warming. The results suggest future model development need to take vegetation acclimation more seriously. The novel matrix-based model allows data assimilation to be conducted more efficiently. It provides more functional understanding of the models as well as the mechanism behind experiment data.

Inter-annual changes in detritus-based food chains can enhance plant growth response to elevated atmospheric CO2.

PubMed

Hines, Jes; Eisenhauer, Nico; Drake, Bert G

2015-12-01

Elevated atmospheric CO2 generally enhances plant growth, but the magnitude of the effects depend, in part, on nutrient availability and plant photosynthetic pathway. Due to their pivotal role in nutrient cycling, changes in abundance of detritivores could influence the effects of elevated atmospheric CO2 on essential ecosystem processes, such as decomposition and primary production. We conducted a field survey and a microcosm experiment to test the influence of changes in detritus-based food chains on litter mass loss and plant growth response to elevated atmospheric CO2 using two wetland plants: a C3 sedge (Scirpus olneyi) and a C4 grass (Spartina patens). Our field study revealed that organism's sensitivity to climate increased with trophic level resulting in strong inter-annual variation in detritus-based food chain length. Our microcosm experiment demonstrated that increased detritivore abundance could not only enhance decomposition rates, but also enhance plant growth of S. olneyi in elevated atmospheric CO2 conditions. In contrast, we found no evidence that changes in the detritus-based food chains influenced the growth of S. patens. Considered together, these results emphasize the importance of approaches that unite traditionally subdivided food web compartments and plant physiological processes to understand inter-annual variation in plant production response to elevated atmospheric CO2. © 2015 John Wiley & Sons Ltd.

Coal gasification systems engineering and analysis. Appendix C: Alternate product facility designs

NASA Technical Reports Server (NTRS)

1980-01-01

The study of the production of methane, methanol, gasoline, and hydrogen by an add-on facility to a Koppers-Totzek based MBG plant is presented. Applications to a Texaco facility are inferred by evaluation of delta effects from the K-T cases. The production of methane from an add-on facility to a Lurgi based MBG plant and the co-production of methane and methanol from a Lurgi based system is studied. Studies are included of the production of methane from up to 50 percent of the MBG produced in an integrated K-T based plant and the production of methane from up to 50 percent of the MBG produced from an integrated plant in which module 1 is based on K-T technology and modules 2, 3, and 4 are based on Texaco technology.

Little Cross-Feeding of the Mycorrhizal Networks Shared Between C3-Panicum bisulcatum and C4-Panicum maximum Under Different Temperature Regimes

PubMed Central

Řezáčová, Veronika; Zemková, Lenka; Beskid, Olena; Püschel, David; Konvalinková, Tereza; Hujslová, Martina; Slavíková, Renata; Jansa, Jan

2018-01-01

Common mycorrhizal networks (CMNs) formed by arbuscular mycorrhizal fungi (AMF) interconnect plants of the same and/or different species, redistributing nutrients and draining carbon (C) from the different plant partners at different rates. Here, we conducted a plant co-existence (intercropping) experiment testing the role of AMF in resource sharing and exploitation by simplified plant communities composed of two congeneric grass species (Panicum spp.) with different photosynthetic metabolism types (C3 or C4). The grasses had spatially separated rooting zones, conjoined through a root-free (but AMF-accessible) zone added with 15N-labeled plant (clover) residues. The plants were grown under two different temperature regimes: high temperature (36/32°C day/night) or ambient temperature (25/21°C day/night) applied over 49 days after an initial period of 26 days at ambient temperature. We made use of the distinct C-isotopic composition of the two plant species sharing the same CMN (composed of a synthetic AMF community of five fungal genera) to estimate if the CMN was or was not fed preferentially under the specific environmental conditions by one or the other plant species. Using the C-isotopic composition of AMF-specific fatty acid (C16:1ω5) in roots and in the potting substrate harboring the extraradical AMF hyphae, we found that the C3-Panicum continued feeding the CMN at both temperatures with a significant and invariable share of C resources. This was surprising because the growth of the C3 plants was more susceptible to high temperature than that of the C4 plants and the C3-Panicum alone suppressed abundance of the AMF (particularly Funneliformis sp.) in its roots due to the elevated temperature. Moreover, elevated temperature induced a shift in competition for nitrogen between the two plant species in favor of the C4-Panicum, as demonstrated by significantly lower 15N yields of the C3-Panicum but higher 15N yields of the C4-Panicum at elevated as compared to ambient temperature. Although the development of CMN (particularly of the dominant Rhizophagus and Funneliformis spp.) was somewhat reduced under high temperature, plant P uptake benefits due to AMF inoculation remained well visible under both temperature regimes, though without imminent impact on plant biomass production that actually decreased due to inoculation with AMF. PMID:29681914

Comparison of carbon balance in Mediterranean pilot constructed wetlands vegetated with different C4 plant species.

PubMed

Barbera, Antonio C; Borin, Maurizio; Cirelli, Giuseppe L; Toscano, Attilio; Maucieri, Carmelo

2015-02-01

This study investigates carbon dioxide (CO2) and methane (CH4) emissions and carbon (C) budgets in a horizontal subsurface flow pilot-plant constructed wetland (CW) with beds vegetated with Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty, and Mischantus × giganteus Greef et Deu in the Mediterranean basin (Sicily) during the 1st year of plant growing season. At the end of the vegetative season, M. giganteus showed the higher biomass accumulation (7.4 kg m(-2)) followed by C. zizanioides (5.3 kg m(-2)) and C. papyrus (1.8 kg m(-2)). Significantly higher emissions of CO2 were detected in the summer, while CH4 emissions were maximum during spring. Cumulative CO2 emissions by C. papyrus and C. zizanioides during the monitoring period showed similar trends with final values of about 775 and 1,074 g m(-2), respectively, whereas M. giganteus emitted 3,395 g m(-2). Cumulative CH4 bed emission showed different trends for the three C4 plant species in which total gas release during the study period was for C. papyrus 12.0 g m(-2) and ten times higher for M. giganteus, while C. zizanioides bed showed the greatest CH4 cumulative emission with 240.3 g m(-2). The wastewater organic carbon abatement determined different C flux in the atmosphere. Gas fluxes were influenced both by plant species and monitored months with an average C-emitted-to-C-removed ratio for C. zizanioides, C. papyrus, and M. giganteus of 0.3, 0.5, and 0.9, respectively. The growing season C balances were positive for all vegetated beds with the highest C sequestered in the bed with M. giganteus (4.26 kg m(-2)) followed by C. zizanioides (3.78 kg m(-2)) and C. papyrus (1.89 kg m(-2)). To our knowledge, this is the first paper that presents preliminary results on CO2 and CH4 emissions from CWs vegetated with C4 plant species in Mediterranean basin during vegetative growth.

Long-term dietary replacement of fishmeal and fish oil in diets for rainbow trout (Oncorhynchus mykiss): Effects on growth, whole body fatty acids and intestinal and hepatic gene expression

PubMed Central

Lazzarotto, Viviana; Larroquet, Laurence; Corraze, Geneviève

2018-01-01

The effects of replacing fishmeal and fish oil with a plant-based diet were studied in juvenile (10g) and ongrowing (250-350g) rainbow trout from first-feeding. Feed-related differences in the intestinal and hepatic transcriptome were examined in juveniles after 7 months of feeding at 7°C. Based on microarray results obtained for juveniles, the expression of selected genes related to lipid, cholesterol and energy metabolisms, was assessed by RT-qPCR in ongrowing trout after 6 additional months of feeding at 17°C. Plasma glucose and cholesterol, lipid content and fatty acid profile of whole body were analyzed at both stages. After 7 months at 7°C, all juveniles reached the same body weight (10g), while at 13 months ongrowing fish fed the totally plant-based diet exhibited lower body weight (234 vs 330-337g). Body lipid content was higher in juveniles fed the totally plant-based diet (13.2 vs 9.4–9.9%), and plasma cholesterol was about 2-times lower in trout fed the plant-based diets at both stages. Fatty acid profile mirrored that of the respective diet, with low proportions of long-chain n-3 polyunsaturated fatty acids in fish fed plant-based diets. Genes involved in protein catabolism, carbohydrate metabolism and trafficking were down-regulated in the intestines of juveniles fed the plant-based diets. This was not true for ongrowing fish. Genes involved in lipid and cholesterol metabolisms were up-regulated in the livers of fish fed plant-based diets for both stages. In this study, feeding trout a totally plant-based diet from first-feeding affect a relatively low proportion of metabolism-related genes. In the longer term, when fish were reared at a higher temperature, only some of these changes were maintained (i.e. up-regulation of lipid/cholesterol metabolism). Although the plant-based diets tested in this study had no major deficiencies, small adjustments in the feed-formula are needed to further optimize growth performance while sparing marine resources. PMID:29364933

Interaction between C 4 barnyard grass and C 3 upland rice under elevated CO 2: Impact of mycorrhizae

NASA Astrophysics Data System (ADS)

Tang, Jianjun; Xu, Liming; Chen, Xin; Hu, Shuijin

2009-03-01

Atmospheric CO 2 enrichment may impact arbuscular mycorrhizae (AM) development and function, which could have subsequent effects on host plant species interactions by differentially affecting plant nutrient acquisition. However, direct evidence illustrating this scenario is limited. We examined how elevated CO 2 affects plant growth and whether mycorrhizae mediate interactions between C 4 barnyard grass ( Echinochloa crusgalli (L.) Beauv.) and C 3 upland rice ( Oryza sativa L.) in a low nutrient soil. The monocultures and combinations with or without mycorrhizal inoculation were grown at ambient (400 ± 20 μmol mol -1) and elevated CO 2 (700 ± 20 μmol mol -1) levels. The 15N isotope tracer was introduced to quantify the mycorrhizally mediated N acquisition of plants. Elevated CO 2 stimulated the growth of C 3 upland rice but not that of C 4 barnyard grass under monoculture. Elevated CO 2 also increased mycorrhizal colonization of C 4 barnyard grass but did not affect mycorrhizal colonization of C 3 upland rice. Mycorrhizal inoculation increased the shoot biomass ratio of C 4 barnyard grass to C 3 upland rice under both CO 2 concentrations but had a greater impact under the elevated than ambient CO 2 level. Mycorrhizae decreased relative interaction index (RII) of C 3 plants under both ambient and elevated CO 2, but mycorrhizae increased RII of C 4 plants only under elevated CO 2. Elevated CO 2 and mycorrhizal inoculation enhanced 15N and total N and P uptake of C 4 barnyard grass in mixture but had no effects on N and P acquisition of C 3 upland rice, thus altering the distribution of N and P between the species in mixture. These results implied that CO 2 stimulation of mycorrhizae and their nutrient acquisition may impact competitive interaction of C 4 barnyard grass and C 3 upland rice under future CO 2 scenarios.

Genome-scale modeling of the evolutionary path to C4 photosynthesis

NASA Astrophysics Data System (ADS)

Myers, Christopher R.; Bogart, Eli

In C4 photosynthesis, plants maintain a high carbon dioxide level in specialized bundle sheath cells surrounding leaf veins and restrict CO2 assimilation to those cells, favoring CO2 over O2 in competition for Rubisco active sites. In C3 plants, which do not possess such a carbon concentrating mechanism, CO2 fixation is reduced due to this competition. Despite the complexity of the C4 system, it has evolved convergently from more than 60 independent origins in diverse families of plants around the world over the last 30 million years. We study the evolution of the C4 system in a genome-scale model of plant metabolism that describes interacting mesophyll and bundle sheath cells and enforces key nonlinear kinetic relationships. Adapting the zero-temperature string method for simulating transition paths in physics and chemistry, we find the highest-fitness paths connecting C3 and C4 positions in the model's high-dimensional parameter space, and show that they reproduce known aspects of the C3-C4 transition while making additional predictions about metabolic changes along the path. We explore the relationship between evolutionary history and C4 biochemical subtype, and the effects of atmospheric carbon dioxide levels.

PROGRESS IN DESIGN OF THE INSTRUMENTATION AND CONTROL OF THE TOKAMAK COOLING WATER SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korsah, Kofi; DeVan, Bill; Ashburn, David

This paper discusses progress in the design of the control, interlock and safety systems of the Tokamak Cooling Water System (TCWS) for the ITER fusion reactor. The TCWS instrumentation and control (I&C) is one of approximately 200 separate plant I&C systems (e.g., vacuum system I&C, magnets system I&C) that interface to a common central I&C system through standardized networks. Several aspects of the I&C are similar to the I&C of fission-based power plants. However, some of the unique features of the ITER fusion reactor and the TCWS (e.g., high quasi-static magnetic field, need for baking and drying as well asmore » cooling operations), also demand some unique safety and qualification considerations. The paper compares the design strategy/guidelines of the TCWS I&C and the I&C of conventional nuclear power plants. Issues such as safety classifications, independence between control and safety systems, sensor sharing, redundancy, voting schemes, and qualification methodologies are discussed. It is concluded that independence and separation requirements are similar in both designs. However, the voting schemes for safety systems in nuclear power plants typically use 2oo4 (i.e., 4 divisions of safety I&C, any 2 of which is sufficient to trigger a safety action), while 2oo3 voting logic - within each of 2 independent trains - is used in the TCWS I&C. It is also noted that 2oo3 voting is also acceptable in nuclear power plants if adequate risk assessment and reliability is demonstrated. Finally, while qualification requirements provide similar guidance [e.g., both IEC 60780 (invoked in ITER-space), and IEEE 323 (invoked in fission power plant space) provide similar guidance], an important qualification consideration is the susceptibility of I&C to the magnetic fields of ITER. Also, the radiation environments are different. In the case of magnetic fields the paper discusses some options that are being considered.« less

Effects of different elevated CO2 concentrations on chlorophyll contents, gas exchange, water use efficiency, and PSII activity on C3 and C4 cereal crops in a closed artificial ecosystem.

PubMed

Wang, Minjuan; Xie, Beizhen; Fu, Yuming; Dong, Chen; Hui, Liu; Guanghui, Liu; Liu, Hong

2015-12-01

Although terrestrial CO2 concentrations [CO2] are not expected to reach 1000 μmol mol(-1) (or ppm) for many decades, CO2 levels in closed systems such as growth chambers and greenhouses can easily exceed this concentration. CO2 levels in life support systems (LSS) in space can exceed 10,000 ppm (1 %). In order to understand how photosynthesis in C4 plants may respond to elevated CO2, it is necessary to determine if leaves of closed artificial ecosystem grown plants have a fully developed C4 photosynthetic apparatus, and whether or not photosynthesis in these leaves is more responsive to elevated [CO2] than leaves of C3 plants. To address this issue, we evaluated the response of gas exchange, water use efficiency, and photosynthetic efficiency of PSII by soybean (Glycine max (L.) Merr., 'Heihe35') of a typical C3 plant and maize (Zea mays L., 'Susheng') of C4 plant under four CO2 concentrations (500, 1000, 3000, and 5000 ppm), which were grown under controlled environmental conditions of Lunar Palace 1. The results showed that photosynthetic pigment by the C3 plants of soybean was more sensitive to elevated [CO2] below 3000 ppm than the C4 plants of maize. Elevated [CO2] to 1000 ppm induced a higher initial photosynthetic rate, while super-elevated [CO2] appeared to negate such initial growth promotion for C3 plants. The C4 plant had the highest ETR, φPSII, and qP under 500-3000 ppm [CO2], but then decreased substantially at 5000 ppm [CO2] for both species. Therefore, photosynthetic down-regulation and a decrease in photosynthetic electron transport occurred by both species in response to super-elevated [CO2] at 3000 and 5000 ppm. Accordingly, plants can be selected for and adapt to the efficient use of elevated CO2 concentration in LSS.

Bundle-sheath thylakoids from NADP-malic enzyme-type C4 plants require an exogenous electron donor for enzyme light activation.

PubMed

Lavergne, D; Droux, M; Jacquot, J P; Miginiac-Maslow, M; Champigny, M L; Gadal, P

1985-10-01

Light activation of either NADP-malate dehydrogenase (EC 1.1.1.82) or fructose-1,6-bisphosphate phosphatase (EC 3.1.3.11) was assayed in a reconstituted chloroplastic, system comprising the isolated proteins of the ferredoxin-thioredoxin light-activation system and thylakoids from either mesophyll or bundle-sheath tissues of different C4 plants. While C4-plant thylakoids functionned almost equally well with C3-or C4-plant proteins, the photosyntem-II-deficient bundle-sheath thylakoids from the NADP-malic enzyme type, were unable to perform enzyme photoactivation unless supplemented with an electron donor to photosystem I. Bundle-sheath thylakoids isolated from plants showing no photosystem-II deficiency did not require such an addition. The results are discussed with respect to a possible requirement for a physiological reductant of ferredoxin for enzyme light activation in bundle-sheath, tissues.

Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

2014-05-01

The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66-80%, 16-24%, and 0-13%. For corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), the values vary respectively as 56-64%, 18-20%, and 16-26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite-HCO3--aragonite equilibrium.

Terrestrial biome distribution in the Late Neogene inferred from a black carbon record in the northeastern equatorial Pacific

NASA Astrophysics Data System (ADS)

Kim, Donghyun; Lee, Yong Il; Hyeong, Kiseong; Yoo, Chan Min

2016-09-01

The appearance and expansion of C4 plants in the Late Cenozoic was a dramatic example of terrestrial ecological change. The fire hypothesis, which suggests fire as a major cause of C4 grassland is gaining support, yet a more detailed relationship between fire and vegetation-type change remains unresolved. We report the content and stable carbon isotope record of black carbon (BC) in a sediment core retrieved from the northeastern equatorial Pacific that covers the past 14.3 million years. The content record of BC suggests the development process of a flammable ecosystem. The stable carbon isotope record of BC reveals the existence of the Late Miocene C4 expansion, the ‘C4 maximum period of burned biomass’ during the Pliocene to Early Pleistocene, and the collapse of the C4 in the Late Pleistocene. Records showing the initial expansion of C4 plants after large fire support the role of fire as a destructive agent of C3-dominated forest, yet the weak relationships between fire and vegetation after initial expansion suggest that environmental advantages for C4 plants were necessary to maintain the development of C4 plants during the late Neogene. Among the various environmental factors, aridity is likely most influential in C4 expansion.

13C NMR and isotopic (δ13C) investigations on modern vegetation samples: a tool to understand the soil organic matter degradation dynamics and preferences

NASA Astrophysics Data System (ADS)

Rakshit, Subhadeep; Sanyal, Prasanta; Vardhan Gaur, Harsh

2015-04-01

Soil organic carbon, one of the largest reservoirs of carbon, is a heterogeneous mixture of organic compounds with dominant contribution derived from decomposition of plants in various stages. Although general ideas about the processes and mechanisms of soil organic matter (SOM) degradation have been developed, a very few study has linked the SOM with its parent material. In this study we aim to generate reference data set of functional groups from modern vegetation samples (C3 and C4plants) to better understand the degradation dynamics and preferences. The carbon functional groups from modern vegetation samples (eight C3 and nine C4 plants collected from Mohanpur, Nadia, West Bengal, India) were examined by solid state 13C CPMAS NMR spectroscopy. Additionally, isotopic investigations (δ13C) has also been carried out on the modern vegetation samples to understand the relationship of bulk isotopic values to the concentration of functional groups. The major functional groups (alkyl C, O-alkyl C, aromatic C, carbonyl C and aldehyde/ketone) of modern vegetation samples form 16%, 65%, 5%, 14% and 1% respectively in C3 plants. Considerable differences has been observed for C4 plants with average values of alkyl C, O-alkyl C, aromatic C, carbonyl C and aldehyde/ketone are 8%, 83%, 3%, 5% and 1% respectively. The concentration of functional groups from the modern vegetational samples can be considered as reference scale to compare with the 13C NMR data derived from the different soil horizons to understand the SOM degradation dynamics. The δ13CV PDB values of modern vegetation samples plotted against the individual concentration of functional groups shows significant correlation in C4 plants, whereas a lack in correlation has been observed for C3 plants. We assume this difference in relationship of δ13CV PDB values with functional groups of C3 and C4plants can be due to the differences in photosynthesis pathways, the fractionation of CO2 and accumulation of the products during various stages of photosynthesis. A more detailed investigation is warranted to understand the governing mechanism behind this observation.

Experimental Evidence for a Hydride Transfer Mechanism in Plant Glycolate Oxidase Catalysis*

PubMed Central

Dellero, Younès; Mauve, Caroline; Boex-Fontvieille, Edouard; Flesch, Valérie; Jossier, Mathieu; Tcherkez, Guillaume; Hodges, Michael

2015-01-01

In plants, glycolate oxidase is involved in the photorespiratory cycle, one of the major fluxes at the global scale. To clarify both the nature of the mechanism and possible differences in glycolate oxidase enzyme chemistry from C3 and C4 plant species, we analyzed kinetic parameters of purified recombinant C3 (Arabidopsis thaliana) and C4 (Zea mays) plant enzymes and compared isotope effects using natural and deuterated glycolate in either natural or deuterated solvent. The 12C/13C isotope effect was also investigated for each plant glycolate oxidase protein by measuring the 13C natural abundance in glycolate using natural or deuterated glycolate as a substrate. Our results suggest that several elemental steps were associated with an hydrogen/deuterium isotope effect and that glycolate α-deprotonation itself was only partially rate-limiting. Calculations of commitment factors from observed kinetic isotope effect values support a hydride transfer mechanism. No significant differences were seen between C3 and C4 enzymes. PMID:25416784

Snohomish Estuary Wetlands Study Volume III. Classification and Mapping

DTIC Science & Technology

1978-07-01

Marine plant communities form the basis for some of the most complex i food webs known to man. Because of their complexity any destruction of these plant... NCV ) Ř fv;1 4 CV r% . coI * ".444 Ř m- 0mf n4 ~ ’ oC- . -4c C4 C CJL t o% P o I-""C4enc n S qw qt "* *n *nL P o% 0zwk oU a "C-4 2 C" Iv3gMNIV~ I.z -I

Mid-Miocene C4 expansion on the Chinese Loess Plateau under an enhanced Asian summer monsoon

NASA Astrophysics Data System (ADS)

Dong, Jibao; Liu, Zhonghui; An, Zhisheng; Liu, Weiguo; Zhou, Weijian; Qiang, Xiaoke; Lu, Fengyan

2018-06-01

Atmospheric CO2 starvation, aridity, fire and warm season precipitation have all been proposed as major contributors to C4 plant expansion during the Late Miocene. However, the driving factors responsible for the distribution of C4 plants in the early and mid-Miocene still remain enigmatic. Here we report pedogenic carbon and oxygen isotope data (δ13Cpedo, δ18Opedo), along with magnetic susceptibility (MS) results, from the Zhuang Lang drilling core on the Chinese Loess Plateau (CLP). Elevated δ13Cpedo values (>-5‰) signal a prominent C4 expansion and substantially increased δ18Opedo and MS values indicate enhanced Asian summer monsoon (ASM) precipitation. Both of these conditions are observed during the Mid-Miocene Climatic Optimum (MMCO), 14.5-17 million years ago. The marked increase in C4 plants, associated with warm temperatures and increased precipitation, strongly suggests the control of an enhanced ASM on C4 expansion on the CLP during the MMCO. This finding contrasts with the late-Miocene C4 expansion associated with cooling and drying conditions observed in low latitudes and argues for regionally specific control of C4 plant distribution/expansion.

[Determination of longistylin A and longistylin C in Cajanus cajan].

PubMed

Wang, Dawu; Xiao, Minxun; Li, Yirong; Shen, Xiaoling; Lu, Yuanyuan; Liu, Kanglun; Li, Zhenghong; Hu, Yingjie

2011-10-01

To establish quality control criteria for medicinal herb Cajanus cajan based on the determination of longistylin A and longistylin C, two bioactive and specific stilbenes of the plant. Longistylin A and longistylin C were obtained from the leaves of C. cajan by silica gel column chromatography and identified as marker compounds of this plant by spectroscopic analysis. A RP-HPLC method was established to determine the two compounds. Longistylin A and longistylin C were well separated on a Thermo BDS Hypersil C18 column (4.6 mm x 250 mm, 5 microm) with a mobile phase methanol-water (8:2), and showed good linearity in the range of 0.00288 - 0.0576 microg and 0.0112 - 0.224 microg, respectively. The average recoveries were 98.9% and 97.2% with RSD of 2.4% and 2.2% for these two compounds, respectively. The established analysis method is simple and accurate, whicn can be used for quality control of C. cajan.

Significant accumulation of C(4)-specific pyruvate, orthophosphate dikinase in a C(3) plant, rice.

PubMed

Fukayama, H; Tsuchida, H; Agarie, S; Nomura, M; Onodera, H; Ono, K; Lee, B H; Hirose, S; Toki, S; Ku, M S; Makino, A; Matsuoka, M; Miyao, M

2001-11-01

The C(4)-Pdk gene encoding the C(4) enzyme pyruvate, orthophosphate dikinase (PPDK) of maize (Zea mays cv Golden Cross Bantam) was introduced into the C(3) plant, rice (Oryza sativa cv Kitaake). When the intact maize C(4)-Pdk gene, containing its own promoter and terminator sequences and exon/intron structure, was introduced, the PPDK activity in the leaves of some transgenic lines was greatly increased, in one line reaching 40-fold over that of wild-type plants. In a homozygous line, the PPDK protein accounted for 35% of total leaf-soluble protein or 16% of total leaf nitrogen. In contrast, introduction of a chimeric gene containing the full-length cDNA of the maize PPDK fused to the maize C(4)-Pdk promoter or the rice Cab promoter only increased PPDK activity and protein level slightly. These observations suggest that the intron(s) or the terminator sequence of the maize gene, or a combination of both, is necessary for high-level expression. In maize and transgenic rice plants carrying the intact maize gene, the level of transcript in the leaves per copy of the maize C(4)-Pdk gene was comparable, and the maize gene was expressed in a similar organ-specific manner. These results suggest that the maize C(4)-Pdk gene behaves in a quantitatively and qualitatively similar way in maize and transgenic rice plants. The activity of the maize PPDK protein expressed in rice leaves was light/dark regulated as it is in maize. This is the first reported evidence for the presence of an endogenous PPDK regulatory protein in a C(3) plant.

Carbon isotope compositions of terrestrial C3 plants as indicators of (paleo)ecology and (paleo)climate

PubMed Central

Kohn, Matthew J.

2010-01-01

A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ13C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ13C of atmospheric CO2, these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7–8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward dry ecosystems, although wet ecosystems are also represented. Unambiguous isotopic evidence for C4 plants is lacking prior to 7–8 Ma, and hominid ecosystems at 4.4 Ma show no isotopic evidence for dense forests. Consideration of global plant biomass indicates that average δ13C of C3 plants is commonly overestimated by approximately 2‰. PMID:21041671

Identification and Genetic Characterization of Ralstonia solanacearum Species Complex Isolates from Cucurbita maxima in China

PubMed Central

She, Xiaoman; Yu, Lin; Lan, Guobing; Tang, Yafei; He, Zifu

2017-01-01

Ralstonia solanacearum species complex is a devastating phytopathogen with an unusually wide host range, and new host plants are continuously being discovered. In June 2016, a new bacterial wilt on Cucurbita maxima was observed in Guangdong province, China. Initially, in the adult plant stage, several leaves of each plant withered suddenly and drooped; the plant then wilted completely, and the color of their vasculature changed to dark brown, ultimately causing the entire plant to die. Creamy-whitish bacterial masses were observed to ooze from crosscut stems of these diseased plants. To develop control strategies for C. maxima bacterial wilt, the causative pathogenic isolates were identified and characterized. Twenty-four bacterial isolates were obtained from diseased C. maxima plants, and 16S rRNA gene sequencing and pathogenicity analysis results indicated that the pathogen of C. maxima bacterial wilt was Ralstonia solanacearum. The results from DNA-based analysis, host range determination and bacteriological identification confirmed that the 24 isolates belonged to R. solanacearum phylotype I, race 1, and eight of these isolates belonged to biovar 3, while 16 belonged to biovar 4. Based on the results of partial egl gene sequence analysis, the 24 isolates clustered into three egl- sequence type groups, sequevars 17, 45, and 56. Sequevar 56 is a new sequevar which is described for the first time in this paper. An assessment of the resistance of 21 pumpkin cultivars revealed that C. moschata cv. Xiangyu1 is resistant to strain RS378, C. moschata cv. Xiangmi is moderately resistant to strain RS378, and 19 other pumpkin cultivars, including four C. maxima cultivars and 15 C. moschata cultivars, are susceptible to strain RS378. To the best of our knowledge, this is the first report of C. maxima bacterial wilt caused by R. solanacearum race 1 in the world. Our results provide valuable information for the further development of control strategies for C. maxima wilt disease. PMID:29093727

Identification and Genetic Characterization of Ralstonia solanacearum Species Complex Isolates from Cucurbita maxima in China.

PubMed

She, Xiaoman; Yu, Lin; Lan, Guobing; Tang, Yafei; He, Zifu

2017-01-01

Ralstonia solanacearum species complex is a devastating phytopathogen with an unusually wide host range, and new host plants are continuously being discovered. In June 2016, a new bacterial wilt on Cucurbita maxima was observed in Guangdong province, China. Initially, in the adult plant stage, several leaves of each plant withered suddenly and drooped; the plant then wilted completely, and the color of their vasculature changed to dark brown, ultimately causing the entire plant to die. Creamy-whitish bacterial masses were observed to ooze from crosscut stems of these diseased plants. To develop control strategies for C. maxima bacterial wilt, the causative pathogenic isolates were identified and characterized. Twenty-four bacterial isolates were obtained from diseased C. maxima plants, and 16S rRNA gene sequencing and pathogenicity analysis results indicated that the pathogen of C. maxima bacterial wilt was Ralstonia solanacearum . The results from DNA-based analysis, host range determination and bacteriological identification confirmed that the 24 isolates belonged to R. solanacearum phylotype I, race 1, and eight of these isolates belonged to biovar 3, while 16 belonged to biovar 4. Based on the results of partial egl gene sequence analysis, the 24 isolates clustered into three egl- sequence type groups, sequevars 17, 45, and 56. Sequevar 56 is a new sequevar which is described for the first time in this paper. An assessment of the resistance of 21 pumpkin cultivars revealed that C. moschata cv. Xiangyu1 is resistant to strain RS378, C. moschata cv. Xiangmi is moderately resistant to strain RS378, and 19 other pumpkin cultivars, including four C. maxima cultivars and 15 C. moschata cultivars, are susceptible to strain RS378. To the best of our knowledge, this is the first report of C. maxima bacterial wilt caused by R. solanacearum race 1 in the world. Our results provide valuable information for the further development of control strategies for C. maxima wilt disease.

The soil microbial community composition and soil microbial carbon uptake are more affected by soil type than by different vegetation types (C3 and C4 plants) and seasonal changes

NASA Astrophysics Data System (ADS)

Griselle Mellado Vazquez, Perla; Lange, Markus; Gleixner, Gerd

2016-04-01

This study investigates the influence of different vegetation types (C3 and C4 plants), soil type and seasonal changes on the soil microbial biomass, soil microbial community composition and soil microbial carbon (C) uptake. We collected soil samples in winter (non-growing season) and summer (growing season) in 2012 from an experimental site cropping C3 and C4 plants for 6 years on two different soil types (sandy and clayey). The amount of phospholipid fatty acids (PLFAs) and their compound-specific δ13C values were used to determined microbial biomass and the flow of C from plants to soil microorganisms, respectively. Higher microbial biomass was found in the growing season. The microbial community composition was mainly explained by soil type. Higher amounts of SOC were driving the predominance of G+ bacteria, actinobacteria and cyclic G- bacteria in sandy soils, whereas root biomass was significantly related to the increased proportions of G- bacteria in clayey soils. Plant-derived C in G- bacteria increased significantly in clayey soils in the growing season. This increase was positively and significantly driven by root biomass. Moreover, changes in plant-derived C among microbial groups pointed to specific capabilities of different microbial groups to decompose distinct sources of C. We concluded that soil texture and favorable growth conditions driven by rhizosphere interactions are the most important factors controlling the soil microbial community. Our results demonstrate that a change of C3 plants vs. C4 plants has only a minor effect on the soil microbial community. Thus, such experiments are well suited to investigate soil organic matter dynamics as they allow to trace the C flow from plants into the soil microbial community without changing the community abundance and composition.

A sorghum (Sorghum bicolor) mutant with altered carbon isotope ratio.

PubMed

Rizal, Govinda; Karki, Shanta; Thakur, Vivek; Wanchana, Samart; Alonso-Cantabrana, Hugo; Dionora, Jacque; Sheehy, John E; Furbank, Robert; von Caemmerer, Susanne; Quick, William Paul

2017-01-01

Recent efforts to engineer C4 photosynthetic traits into C3 plants such as rice demand an understanding of the genetic elements that enable C4 plants to outperform C3 plants. As a part of the C4 Rice Consortium's efforts to identify genes needed to support C4 photosynthesis, EMS mutagenized sorghum populations were generated and screened to identify genes that cause a loss of C4 function. Stable carbon isotope ratio (δ13C) of leaf dry matter has been used to distinguishspecies with C3 and C4 photosynthetic pathways. Here, we report the identification of a sorghum (Sorghum bicolor) mutant with a low δ13C characteristic. A mutant (named Mut33) with a pale phenotype and stunted growth was identified from an EMS treated sorghum M2 population. The stable carbon isotope analysis of the mutants showed a decrease of 13C uptake capacity. The noise of random mutation was reduced by crossing the mutant and its wildtype (WT). The back-cross (BC1F1) progenies were like the WT parent in terms of 13C values and plant phenotypes. All the BC1F2 plants with low δ13C died before they produced their 6th leaf. Gas exchange measurements of the low δ13C sorghum mutants showed a higher CO2 compensation point (25.24 μmol CO2.mol-1air) and the maximum rate of photosynthesis was less than 5μmol.m-2.s-1. To identify the genetic determinant of this trait, four DNA pools were isolated; two each from normal and low δ13C BC1F2 mutant plants. These were sequenced using an Illumina platform. Comparison of allele frequency of the single nucleotide polymorphisms (SNPs) between the pools with contrasting phenotype showed that a locus in Chromosome 10 between 57,941,104 and 59,985,708 bps had an allele frequency of 1. There were 211 mutations and 37 genes in the locus, out of which mutations in 9 genes showed non-synonymous changes. This finding is expected to contribute to future research on the identification of the causal factor differentiating C4 from C3 species that can be used in the transformation of C3 to C4 plants.

A sorghum (Sorghum bicolor) mutant with altered carbon isotope ratio

PubMed Central

Karki, Shanta; Thakur, Vivek; Wanchana, Samart; Alonso-Cantabrana, Hugo; Dionora, Jacque; Sheehy, John E.; Furbank, Robert; von Caemmerer, Susanne; Quick, William Paul

2017-01-01

Recent efforts to engineer C4 photosynthetic traits into C3 plants such as rice demand an understanding of the genetic elements that enable C4 plants to outperform C3 plants. As a part of the C4 Rice Consortium’s efforts to identify genes needed to support C4 photosynthesis, EMS mutagenized sorghum populations were generated and screened to identify genes that cause a loss of C4 function. Stable carbon isotope ratio (δ13C) of leaf dry matter has been used to distinguishspecies with C3 and C4 photosynthetic pathways. Here, we report the identification of a sorghum (Sorghum bicolor) mutant with a low δ13C characteristic. A mutant (named Mut33) with a pale phenotype and stunted growth was identified from an EMS treated sorghum M2 population. The stable carbon isotope analysis of the mutants showed a decrease of 13C uptake capacity. The noise of random mutation was reduced by crossing the mutant and its wildtype (WT). The back-cross (BC1F1) progenies were like the WT parent in terms of 13C values and plant phenotypes. All the BC1F2 plants with low δ13C died before they produced their 6th leaf. Gas exchange measurements of the low δ13C sorghum mutants showed a higher CO2 compensation point (25.24 μmol CO2.mol-1air) and the maximum rate of photosynthesis was less than 5μmol.m-2.s-1. To identify the genetic determinant of this trait, four DNA pools were isolated; two each from normal and low δ13C BC1F2 mutant plants. These were sequenced using an Illumina platform. Comparison of allele frequency of the single nucleotide polymorphisms (SNPs) between the pools with contrasting phenotype showed that a locus in Chromosome 10 between 57,941,104 and 59,985,708 bps had an allele frequency of 1. There were 211 mutations and 37 genes in the locus, out of which mutations in 9 genes showed non-synonymous changes. This finding is expected to contribute to future research on the identification of the causal factor differentiating C4 from C3 species that can be used in the transformation of C3 to C4 plants. PMID:28640841

Heavy and light beer: a carbon isotope approach to detect C(4) carbon in beers of different origins, styles, and prices.

PubMed

Brooks, J Renée; Buchmann, Nina; Phillips, Sue; Ehleringer, Bruce; Evans, R David; Lott, Mike; Martinelli, Luiz A; Pockman, William T; Sandquist, Darren; Sparks, Jed P; Sperry, Lynda; Williams, Dave; Ehleringer, James R

2002-10-23

The carbon isotope ratios (delta(13)C) of 160 beers from around the world ranged from -27.3 to -14.9 per thousand, primarily due to variation in the percentage of C(3) or C(4) plant carbon in the final product. Thirty-one percent of beers had a carbon signature of C(3) plants (barley, rice, etc.), whereas the remaining 69% contained some C(3)-C(4) mixture (mean of mixtures, 39 +/- 11% C(4) carbon). Use of C(4) carbon (corn, cane sugar, etc.) was not confined to beers from any particular region (Pacific Rim, Mexico, Brazil, Europe, Canada, and the United States). However, the delta(13)C of European beers indicated mostly C(3) plant carbon. In contrast, U.S. and Canadian beers contained either only C(3) or C(3)-C(4) mixtures; Brazilian, Mexican, and Pacific Rim beers were mostly C(3)-C(4) mixtures. Among different lagers, U.S.-style lagers generally contained more C(4) carbon than did imported pilsners. Among different ales, those brewed by large high-production breweries contained significant proportions of C(4) carbon, while C(4) carbon was not detected in microbrewery or home-brew ales. Furthermore, inexpensive beers generally contained more C(4) carbon than expensive beers.

[Trends of the grass ecological evolution].

PubMed

Sheremet'ev, S N; Gamaleĭ, Iu V

2009-01-01

The results of an analytic research show that the evolution of leaf structure and water balance are completely coincident with the global changes of the planet climate and hydrology. Taxic diversity of herbs and herbaceous biomes is a function of the paleoclimate variability and the plant adaptations to it. The correlation between the plant organization and climate changes allow to reconstruct both the climate changes chronicle and the geological ages of plant taxa based on the structure and function of the plant species. Two global trends of ecological evolution can be recognized differing mutually by the composition of herbaceous adaptive types: (a) the evolutionary line of herbs of chilling plains with domination of the plant species with C3 apoplastic syndrome formed under cold climate condition, and (b) the evolutionary line of herbs of hot plains with domination of plant species with C4 apoplastic syndrome. Both trends include the monocots and dicots, and both are the results of climate changes in the Cenozoic. C3 herbs of chilling plains and the steppe and meadow phytocoenoses formed by them arose as an answer to the temperature decrease in the significant areas of high latitudes. The apoplastic syndrome (transfer from symplastic transport of assimilates suppressed by cold to their apoplastic transport) is a diagnostic feature for this group of herbs. The C4 herbs of hot plains and the savannas, deserts and the saline land plant vegetation are an adaptive answer to iridizations of low latitude areas. The C4 syndrome (compensation of stomata closure by the mechanism of CO2 concentration in the leaf tissues) is a special character of this group of herbs. Both types of herbaceous biomes come to change forest biomes which were strongly decreased in both areas at low and high latitudes. This tendency is continued in parallel with the climate tendency to the continent dessication and cooling.

Solanesol Biosynthesis in Plants.

PubMed

Yan, Ning; Liu, Yanhua; Zhang, Hongbo; Du, Yongmei; Liu, Xinmin; Zhang, Zhongfeng

2017-03-23

Solanesol is a non-cyclic terpene alcohol composed of nine isoprene units that mainly accumulates in solanaceous plants. Solanesol plays an important role in the interactions between plants and environmental factors such as pathogen infections and moderate-to-high temperatures. Additionally, it is a key intermediate for the pharmaceutical synthesis of ubiquinone-based drugs such as coenzyme Q10 and vitamin K2, and anti-cancer agent synergizers such as N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl) ethylenediamine (SDB). In plants, solanesol is formed by the 2- C -methyl-d-erythritol 4-phosphate (MEP) pathway within plastids. Solanesol's biosynthetic pathway involves the generation of C5 precursors, followed by the generation of direct precursors, and then the biosynthesis and modification of terpenoids; the first two stages of this pathway are well understood. Based on the current understanding of solanesol biosynthesis, we here review the key enzymes involved, including 1-deoxy-d-xylulose 5-phosphate synthase (DXS), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), isopentenyl diphosphate isomerase (IPI), geranyl geranyl diphosphate synthase (GGPPS), and solanesyl diphosphate synthase (SPS), as well as their biological functions. Notably, studies on microbial heterologous expression and overexpression of key enzymatic genes in tobacco solanesol biosynthesis are of significant importance for medical uses of tobacco.

Modification of Monolignol Biosynthetic Pathway in Jute: Different Gene, Different Consequence

PubMed Central

Shafrin, Farhana; Ferdous, Ahlan Sabah; Sarkar, Suprovath Kumar; Ahmed, Rajib; Amin, Al-; Hossain, Kawsar; Sarker, Mrinmoy; Rencoret, Jorge; Gutiérrez, Ana; del Rio, Jose C.; Sanan-Mishra, Neeti; Khan, Haseena

2017-01-01

Lignin, a cross-linked macromolecule of hydrophobic aromatic structure, provides additional rigidity to a plant cell wall. Although it is an integral part of the plant cell, presence of lignin considerably reduces the quality of the fiber of fiber-yielding plants. Decreasing lignin in such plants holds significant commercial and environmental potential. This study aimed at reducing the lignin content in jute-a fiber crop, by introducing hpRNA-based vectors for downregulation of two monolignoid biosynthetic genes- cinnamate 4-hydroxylase (C4H) and caffeic acid O-methyltransferase (COMT). Transgenic generations, analyzed through Southern, RT-PCR and northern assays showed downregulation of the selected genes. Transgenic lines exhibited reduced level of gene expression with ~ 16–25% reduction in acid insoluble lignin for the whole stem and ~13–14% reduction in fiber lignin content compared to the control lines. Among the two transgenic plant types one exhibited an increase in cellulose content and concomitant improvement of glucose release. Composition of the lignin building blocks was found to alter and this alteration resulted in a pattern, different from other plants where the same genes were manipulated. It is expected that successful COMT-hpRNA and C4H-hpRNA transgenesis in jute will have far-reaching commercial implications leading to product diversification and value addition. PMID:28051165

Enhancement of growth, photosynthetic performance and yield by exclusion of ambient UV components in C3 and C4 plants.

PubMed

Kataria, Sunita; Guruprasad, K N; Ahuja, Sumedha; Singh, Bupinder

2013-10-05

A field experiment was conducted under tropical climate for assessing the effect of ambient UV-B and UV-A by exclusion of UV components on the growth, photosynthetic performance and yield of C3 (cotton, wheat) and C4 (amaranthus, sorghum) plants. The plants were grown in specially designed UV exclusion chambers, wrapped with filters that excluded UV-B (<315nm), UV-A+B (<400nm), transmitted all the UV (280-400nm) or without filters. All the four plant species responded to UV exclusion by a significant increase in plant height, leaf area, leaf biomass, total biomass accumulation and yield. Measurements of the chlorophyll, chlorophyll fluorescence parameters, gas exchange parameters and the activity of Ribulose-1,5-bisphosphate carboxylase (Rubisco) by fixation of (14)CO2 indicated a direct relationship between enhanced rate of photosynthesis and yield of the plants. Quantum yield of electron transport was enhanced by the exclusion of UV indicating better utilization of PAR assimilation and enhancement in reducing power in all the four plant species. Exclusion of UV-B in particular significantly enhanced the net photosynthetic rate, stomatal conductance and activity of Rubisco. Additional fixation of carbon due to exclusion of ambient UV-B was channeled towards yield as there was a decrease in the level of UV-B absorbing substances and an increase in soluble proteins in all the four plant species. The magnitude of the promotion in all the parameters studied was higher in dicots (cotton, amaranthus) compared to monocots (wheat, sorghum) after UV exclusion. The results indicated a suppressive action of ambient UV-B on growth and photosynthesis; dicots were more sensitive than monocots in this suppression while no great difference in sensitivity was found between C3 and C4 plants. Experiments indicated the suppressive action of ambient UV on carbon fixation and yield of C3 and C4 plants. Exclusion of solar UV-B will have agricultural benefits in both C3 and C4 plants under tropical climate. Copyright © 2013 Elsevier B.V. All rights reserved.

Drought sensitivities of dominant plant functional types in the Colorado Plateau

NASA Astrophysics Data System (ADS)

Hoover, D. L.; Duniway, M.; Belnap, J.

2014-12-01

Drylands of the Southwestern US are predicted to experience greater water limitations with climate change due to changes in precipitation and increased warming. Certain plants may be living at or near their tolerance thresholds in these ecosystems and thus subtle changes in water availability may have dramatic effects on their performances. We imposed a four-year experiment in the Colorado Plateau to assess the vulnerability of this dryland ecosystem to chronic, but subtle drought using 40 sites varying in plant communities, parent materials and soil textures. Within a site, two plots were selected with matching cover of target species, which were randomly assigned to either control (ambient precipitation) or drought (35% reduction) treatments. Drought treatments were imposed year-round from 2011 through 2014. Over the course of the experiment, we examined plant cover changes and mortality of four dominant plant functional types (PFT's): C3 grasses, C4 grasses, C3 shrubs and C4 shrubs. We hypothesized that overall, grasses would be more sensitive to drought than shrubs, and that within these two groups, plants with C3 photosynthesis would be more sensitive than plants with C4 photosynthesis. During three of the four years, precipitation inputs were either near average (50th percentile, control) or dry (25th percentile, drought). However in 2012, both treatments experienced extremely dry growing season precipitation with the control and drought below the 5th and 1st percentiles, respectively. We observed three general responses to drought in this experiment: 1. change in cover with mortality (C3 grasses), 2. change in cover without mortality (C4 grasses and C4 shrubs) and 3. no change in cover or mortality (C3 shrubs). The dramatic responses of the C3 grasses suggest that this PFT is very sensitive to drought and it is living at or near its tolerance threshold in this region. While the C4 grasses also experienced cover changes, they did not experience widespread mortality and thus have higher tolerance to drought than the C3 grasses. Finally, contrary to our hypothesis, C3 shrubs were more drought tolerant than C4 shrubs. These results suggest that subtle changes in water availability may differentially impact key plant functional types and potentially alter the structure and function of this ecosystem.

Metabolite Profiling of adh1 Mutant Response to Cold Stress in Arabidopsis

PubMed Central

Song, Yuan; Liu, Lijun; Wei, Yunzhu; Li, Gaopeng; Yue, Xiule; An, Lizhe

2017-01-01

As a result of global warming, vegetation suffers from repeated freeze-thaw cycles caused by more frequent short-term low temperatures induced by hail, snow, or night frost. Therefore, short-term freezing stress of plants should be investigated particularly in light of the current climatic conditions. Alcohol dehydrogenase (ADH) plays a central role in the metabolism of alcohols and aldehydes and it is a key enzyme in anaerobic fermentation. ADH1 responds to plant growth and environmental stress; however, the function of ADH1 in the response to short-term freezing stress remains unknown. Using real-time quantitative fluorescence PCR, the expression level of ADH1 was analyzed at low temperature (4°C). The lethal temperature was calculated based on the electrolyte leakage tests for both ADH1 deletion mutants (adh1) and wild type (WT) plants. To further investigate the relationship between ADH1 and cold tolerance in plants, low-Mr polar metabolite analyses of Arabidopsis adh1 and WT were performed at cold temperatures using gas chromatography-mass spectrometry. This investigation focused on freezing treatments (cold acclimation group: −6°C for 2 h with prior 4°C for 7 d, cold shock group: −6°C for 2 h without cold acclimation) and recovery (23°C for 24 h) with respect to seedling growth at optimum temperature. The experimental results revealed a significant increase in ADH1 expression during low temperature treatment (4°C) and at a higher lethal temperature in adh1 compared to that in the WT. Retention time indices and specific mass fragments were used to monitor 263 variables and annotate 78 identified metabolites. From these analyses, differences in the degree of metabolite accumulation between adh1 and WT were detected, including soluble sugars (e.g., sucrose) and amino acids (e.g., asparagine). In addition, the correlation-based network analysis highlighted some metabolites, e.g., melibiose, fumaric acid, succinic acid, glycolic acid, and xylose, which enhanced connectedness in adh1 network under cold chock. When considered collectively, the results showed that adh1 possessed a metabolic response to freezing stress and ADH1 played an important role in the cold stress response of a plant. These results expands our understanding of the short-term freeze response of ADH1 in plants. PMID:28123394

Quantification of greenhouse gas (GHG) emissions from wastewater treatment plants using a ground-based remote sensing approach

NASA Astrophysics Data System (ADS)

Delre, Antonio; Mønster, Jacob; Scheutz, Charlotte

2016-04-01

The direct release of nitrous oxide (N2O) and methane (CH4) from wastewater treatment plants (WWTP) is important because it contributes to the global greenhouse gases (GHGs) release and strongly effects the WWTP carbon footprint. Biological nitrogen removal technologies could increase the direct emission of N2O (IPCC, 2006), while CH4 losses are of environmental, economic and safety concern. Currently, reporting of N2O and CH4 emissions from WWTPs are performed mainly using methods suggested by IPCC which are not site specific (IPCC, 2006). The dynamic tracer dispersion method (TDM), a ground based remote sensing approach implemented at DTU Environment, was demonstrated to be a novel and successful tool for full-scale CH4 and N2O quantification from WWTPs. The method combines a controlled release of tracer gas from the facility with concentration measurements downwind of the plant (Mønster et al., 2014; Yoshida et al., 2014). TDM in general is based on the assumption that a tracer gas released at an emission source, in this case a WWTP, disperses into the atmosphere in the same way as the GHG emitted from process units. Since the ratio of their concentrations remains constant along their atmospheric dispersion, the GHG emission rate can be calculated using the following expression when the tracer gas release rate is known: EGHG=Qtr*(CGHG/Ctr)*(MWGHG/MWtr) EGHG is the GHG emission in mass per time, Qtr is the tracer release in mass per time, CGHG and Ctr are the concentrations measured downwind in parts per billion subtracted of their background values and integrated over the whole plume, and MWGHG and MWtr are the molar weights of GHG and tracer gas respectively (Mønster et al. 2014). In this study, acetylene (C2H2) was used as tracer. Downwind plume concentrations were measured driving along transects with two cavity ring down spectrometers (Yoshida et al., 2014). TDM was successfully applied in different seasons at several Scandinavian WWTPs characterized by different capacity, process unit technologies and locations. The method was applied at plants with different combination of nitrogen removal technologies and sewage sludge treatment. According to the plant capacity and technologies, quantified emissions ranged in the following intervals: from 0.7 to 3.4 kg N2O/h and from 1.1 to 17.6 kg CH4/h. In addition to quantifying the whole emission from the facilities, main sources in the plants were identified. While CH4 was generally emitted from sludge treatment areas, N2O was detected from nitrogen removal technologies both in the main stream and in the side treatment. Process units like biosolids storage and aeration tanks were the only units releasing both GHGs, although in different magnitude. References IPCC, 2006. Guidelines for National Greenhouse Gas Inventories, Volume 5 - Waste. Mønster, J., Samuelsson, J., Kjeldsen, P., Rella, C.W., Scheutz, C., 2014. Quantifying methane emission from fugitive sources by combining tracer release and downwind measurements - a sensitivity analysis based on multiple field surveys. Waste Manag. 34, 1416-28. doi:10.1016/j.wasman.2014.03.025 Yoshida, H., Mønster, J., Scheutz, C., 2014. Plant-integrated measurement of greenhouse gas emissions from a municipal wastewater treatment plant. Water Res. 1, 108-118. doi:10.1016/j.watres.2014.05.014

Review Guidelines for Software Languages for use in Nuclear Power Plant Safety Systems

DTIC Science & Technology

1997-10-01

desirable to segregate base classes from derived classes. Review is facilitated and safety is enhanced if project-specific guidance is provided on the... Segregate base from derived classes. In C++, it is desirable to segregate base classes from derived classes. 4.4.1.8 Minimizing Use of Literals...memory utilization. At the lowest level are base attributes, i.e., attributes xv NUREG/CR-6463 Rev. 1 sufficiently specific to define guidelines. An

Historic Properties Report. Sunflower Army Ammunition Plant, Desoto, Kansas.

DTIC Science & Technology

1984-08-01

the plant produced amonium nitrate liquor for two years before entering "standby" status. The SFAAP was rehabilitated and reactivated in 1951 for... D -A175 882 HISTORIC PROPERTIES REPORT SUNFLOWER RMY AMUNITION ±,𔃻 PLANT DESOTO KANSAS(U) BUILDING TECHNOLOGY INC SILVER UNCR7SIFEDSPRING ND R...33.6 I..11111 120 11111 II L - i.E ~L.. 111111.25 flfflI4 fl 16 t’Ca.. .5 ’C ’C ’C ’C a. ’a ’I B-J 4 S ’a 4 N t C,. ’C di. ’aI. .5 a .* d

4. Credit PSR. View east at west and south facades ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. Credit PSR. View east at west and south facades of Unicon Portable Hangar with immediate ancillary structures. Building 4307 (Supply & Equipment Warehouse) appears at left, Building 4303 (Air Compressor Plant) in middle foreground, and Building 4306 (Boiler House) at the southwest corner of the hangar. - Edwards Air Force Base, North Base, Unicon Portable Hangar, First & C Streets, Boron, Kern County, CA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goni, M.A.; Hedges, J.I.

An extensive suite of C{sub 14}-C{sub 18} hydroxylated fatty acids of cutin origin was identified among the nonlignin CuO reaction products from tissues of 67 different plant species. These mid-chain and {omega}-hydroxylated cutin acids together accounted for 0.5 to 4% of the organic carbon (OC) in these nonwoody vascular plant tissues and were produced in characteristically different yields by the various plant types. Nonvascular plants, including bulk phytoplankton, kelps, mosses, and liverworts, did not yield measurable amounts of cutin acids, except for trace levels of {omega}-hydroxytetradecanoic acid detected in kelps. Most of the lower vascular plants, such as clubmosses andmore » ferns, produced simple cutin acid suites composed mainly of {omega}-hydroxy C{sub 14} and C{sub 16} acids. Gymnosperm needles yielded cutin acid suites dominated by C{sub 16} acids, in which 9,16- and 10,16-dihydroxyhexadecanoic acids were characteristically abundant. Relatively high yields of C{sub 18} acids were obtained from angiosperm tissues, among which dicotyledons exhibited a predominance of 9,10,18-trihydroxyoctadecanoic acid over all the other C{sub 18} acids. The chromatographic peak corresponding to dihydroxyhexadecanoic acid was a mixture of the positional isomers 8,16-, 9,16-, and 10,16-dihydroxyhexadecanoic acids, whose relative abundances uniquely characterized monocotyledon tissues and distinguished among different types of gymnosperm tissues. Based on the cutin acid yields obtained from the different plant types, several geochemical parameters were developed to distinguish up to six different cutin-bearing plant groups as possible components of sedimentary mixtures.« less

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3–CAM intermediate plant Mesembryanthemum crystallinum

PubMed Central

Kuźniak, Elżbieta; Kornas, Andrzej; Kaźmierczak, Andrzej; Rozpądek, Piotr; Nosek, Michał; Kocurek, Maciej; Zellnig, Günther; Müller, Maria; Miszalski, Zbigniew

2016-01-01

Background and Aims Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis. Recent studies demonstrate that enzymes required for C4 photosynthesis are also active in the veins of C3 plants, and their vascular system contains photosynthetically competent parenchyma cells. However, our understanding of photosynthesis in veins of C3 and CAM plants still remains insufficient. Here spatial analysis of photosynthesis-related properties were applied to the midrib and the interveinal lamina cells in leaves of Mesembryanthemum crystallinum, a C3–CAM intermediate plant. Methods The midrib anatomy as well as chloroplast structure and chlorophyll fluorescence, diurnal gas exchange profiles, the immunoblot patterns of PEPC (phosphoenolpyruvate carboxylase) and RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), H2O2 localization and antioxidant enzyme activities were compared in the midrib and in the interveinal mesophyll cells in leaves of C3 and CAM plants. Key Results Leaf midribs were structurally competent to perform photosynthesis in C3 and CAM plants. The midrib chloroplasts resembled those in the bundle sheath cells of C4 plants and were characterized by limited photosynthetic activity. Conclusions The metabolic roles of midrib chloroplasts differ in C3 and CAM plants. It is suggested that in leaves of C3 plants the midrib chloroplasts could be involved in the supply of CO2 for carboxylation, and in CAM plants they could provide malate to different metabolic processes and mediate H2O2 signalling. PMID:27091507

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3-CAM intermediate plant Mesembryanthemum crystallinum.

PubMed

Kuźniak, Elżbieta; Kornas, Andrzej; Kaźmierczak, Andrzej; Rozpądek, Piotr; Nosek, Michał; Kocurek, Maciej; Zellnig, Günther; Müller, Maria; Miszalski, Zbigniew

2016-06-01

Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis. Recent studies demonstrate that enzymes required for C4 photosynthesis are also active in the veins of C3 plants, and their vascular system contains photosynthetically competent parenchyma cells. However, our understanding of photosynthesis in veins of C3 and CAM plants still remains insufficient. Here spatial analysis of photosynthesis-related properties were applied to the midrib and the interveinal lamina cells in leaves of Mesembryanthemum crystallinum, a C3-CAM intermediate plant. The midrib anatomy as well as chloroplast structure and chlorophyll fluorescence, diurnal gas exchange profiles, the immunoblot patterns of PEPC (phosphoenolpyruvate carboxylase) and RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), H2O2 localization and antioxidant enzyme activities were compared in the midrib and in the interveinal mesophyll cells in leaves of C3 and CAM plants. Leaf midribs were structurally competent to perform photosynthesis in C3 and CAM plants. The midrib chloroplasts resembled those in the bundle sheath cells of C4 plants and were characterized by limited photosynthetic activity. The metabolic roles of midrib chloroplasts differ in C3 and CAM plants. It is suggested that in leaves of C3 plants the midrib chloroplasts could be involved in the supply of CO2 for carboxylation, and in CAM plants they could provide malate to different metabolic processes and mediate H2O2 signalling. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Reconciling functions and evolution of isoprene emission in higher plants.

PubMed

Loreto, Francesco; Fineschi, Silvia

2015-04-01

Compilation and analysis of existing inventories reveal that isoprene is emitted by c. 20% of the perennial vegetation of tropical and temperate regions of the world. Isoprene emitters are found across different plant families without any clear phylogenetic thread. However, by critically appraising information in inventories, several ecological patterns of isoprene emission can be highlighted, including absence of emission from C4 and annual plants, and widespread emission from perennial and deciduous plants of temperate environments. Based on this analysis, and on available information on biochemistry, ecology and functional roles of isoprene, it is suggested that isoprene may not have evolved to help plants face heavy or prolonged stresses, but rather assists C3 plants to run efficient photosynthesis and to overcome transient and mild stresses, especially during periods of active plant growth in warm seasons. When the stress status persists, or when evergreen leaves cope with multiple and repeated stresses, isoprene biosynthesis is replaced by the synthesis of less volatile secondary compounds, in part produced by the same biochemical pathway, thus indicating causal determinism in the evolution of isoprene-emitting plants in response to the environment. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Maize Benefits the Predatory Beetle, Propylea japonica (Thunberg), to Provide Potential to Enhance Biological Control for Aphids in Cotton

PubMed Central

Ouyang, Fang; Men, Xingyuan; Yang, Bing; Su, Jianwei; Zhang, Yongsheng; Zhao, Zihua; Ge, Feng

2012-01-01

Background Biological control provided by natural enemies play an important role in integrated pest management. Generalist insect predators provide an important biological service in the regulation of agricultural insect pests. Our goal is to understand the explicit process of oviposition preference, habitat selection and feeding behavior of predators in farmland ecosystem consisting of multiple crops, which is central to devising and delivering an integrated pest management program. Methodology The hypotheses was that maize can serve as habitat for natural enemies and benefits predators to provide potential to enhance biological control for pest insects in cotton. This explicit process of a predatory beetle, Propylea japonica, in agricultural ecosystem composed of cotton and maize were examined by field investigation and stable carbon isotope analysis during 2008–2010. Principal Finding Field investigation showed that P. japonica adults will search host plants for high prey abundance before laying eggs, indicating indirectly that P. japonica adults prefer to inhabit maize plants and travel to cotton plants to actively prey on aphids. The δ13C values of adult P. japonica in a dietary shift experiment found that individual beetles were shifting from a C3- to a C4-based diet of aphids reared on maize or cotton, respectively, and began to reflect the isotope ratio of their new C4 resources within one week. Approximately 80–100% of the diet of P. japonica adults in maize originated from a C3-based resource in June, July and August, while approximately 80% of the diet originated from a C4-based resource in September. Conclusion/Significance Results suggest that maize can serve as a habitat or refuge source for the predatory beetle, P. japonica, and benefits predators to provide potential to enhance biological control for insect pests in cotton. PMID:22984499

Influence of water stress on the carbon isotopic composition of modern plants: Implications for C4 plant appearance in Indian subcontinent

NASA Astrophysics Data System (ADS)

Basu, S.; Ghosh, S.; Sanyal, P.

2016-12-01

The carbon isotopic composition (d13C) of modern terrestrial plants (C3 and C4) provides the baseline to understand past vegetation composition, paleodietary changes and animal migration etc. Accuracy of past environment reconstruction is dependent on the end-member d13C values of plants which found to vary in regional scale. For instance, the d13C values of Indian C3 plants (d13CC3) are 1 to 2‰ more negative compared to global mean. As observed, most of the previous database is devoid of samples from tropical monsoon realm (like India) and the difference between global and regional mean may introduce errors in vegetation reconstruction. To constrain end-member d13CC3 value, published and newly generated results from wide range of mean annual precipitation (MAP: 1-11,700 mm) are compiled which is ca. 1.5 higher in sample size (n=2440) compared to previous database. Using logarithmic function, new relationship between d13C value and MAP (d13CC3 (‰) =20.1585(0.3061)-1.1276(0.0489)ln(MAP+700)) is proposed. The modeled mean d13CC3 value (-28.9‰) is close to average d13CC3 value for Indian plants (-29.1‰) and suggests the importance of vegetation from low-latitudinal tropical region in global compilation. It was observed that C3 plants, on a global scale, are less sensitive to wet climate relative to dry condition. This inference is in agreement with the paleoclimatic data from Indian subcontinent for the late Quaternary period. Despite well established correlation between d13CC3 value and MAP, previous investigation from Indian subcontinent used fixed end-member values to reconstruct past vegetation and total change in the d13C value of proxies was attributed to changes in relative abundance of C3 and C4 plants. Using region-specific mean d13C value of plants, after correcting for changing MAP and error propagation, existence of C4 before ca. 11 Ma plant is observed; earlier to previous reported timing.

Photosynthetic characteristics of an amphibious plant, Eleocharis vivipara: Expression of C4 and C3 modes in contrasting environments

PubMed Central

Ueno, Osamu; Samejima, Muneaki; Muto, Shoshi; Miyachi, Shigetoh

1988-01-01

Eleocharis vivipara Link, a freshwater amphibious leafless plant belonging to the Cyperaceae can grow in both terrestrial and submersed aquatic conditions. Two forms of E. vivipara obtained from these contrasting environments were examined for the characteristics associated with C4 and C3 photosynthesis. In the terrestrial form (δ 13C values = -13.5 to -15.4‰, where ‰ is parts per thousand), the culms, which are photosynthetic organs, possess a Kranz-type anatomy typical of C4 plants, and well-developed bundle-sheath cells contain numerous large chloroplasts. In the submersed form (δ 13C value = -25.9‰), the culms possess anatomical features characteristic of submersed aquatic plants, and the reduced bundle-sheath cells contain only a few small chloroplasts. 14C pulse-12C chase experiments showed that the terrestrial form and the submersed form fix carbon by way of the C4 pathway, with aspartate (40%) and malate (35%) as the main primary products, and by way of the C3 pathway, with 3-phosphoglyceric acid (53%) and sugar phosphates (14%) as the main primary products, respectively. The terrestrial form showed photosynthetic enzyme activities typical of the NAD-malic enzyme-C4 subtype, whereas the submersed form showed decreased activities of key C4 enzymes and an increased ribulose 1,5-bisphosphate carboxylase (EC 4.1.1.39) activity. These data suggest that this species can differentiate into the C4 mode under terrestrial conditions and into the C3 mode under submersed conditions. Images PMID:16593980

Risk analysis of heat recovery steam generator with semi quantitative risk based inspection API 581

NASA Astrophysics Data System (ADS)

Prayogo, Galang Sandy; Haryadi, Gunawan Dwi; Ismail, Rifky; Kim, Seon Jin

2016-04-01

Corrosion is a major problem that most often occurs in the power plant. Heat recovery steam generator (HRSG) is an equipment that has a high risk to the power plant. The impact of corrosion damage causing HRSG power plant stops operating. Furthermore, it could be threaten the safety of employees. The Risk Based Inspection (RBI) guidelines by the American Petroleum Institute (API) 58 has been used to risk analysis in the HRSG 1. By using this methodology, the risk that caused by unexpected failure as a function of the probability and consequence of failure can be estimated. This paper presented a case study relating to the risk analysis in the HRSG, starting with a summary of the basic principles and procedures of risk assessment and applying corrosion RBI for process industries. The risk level of each HRSG equipment were analyzed: HP superheater has a medium high risk (4C), HP evaporator has a medium-high risk (4C), and the HP economizer has a medium risk (3C). The results of the risk assessment using semi-quantitative method of standard API 581 based on the existing equipment at medium risk. In the fact, there is no critical problem in the equipment components. Damage mechanisms were prominent throughout the equipment is thinning mechanism. The evaluation of the risk approach was done with the aim of reducing risk by optimizing the risk assessment activities.

Comparing the Performance of Three Land Models in Global C Cycle Simulations: A Detailed Structural Analysis: Structural Analysis of Land Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafique, Rashid; Xia, Jianyang; Hararuk, Oleksandra

Land models are valuable tools to understand the dynamics of global carbon (C) cycle. Various models have been developed and used for predictions of future C dynamics but uncertainties still exist. Diagnosing the models’ behaviors in terms of structures can help to narrow down the uncertainties in prediction of C dynamics. In this study three widely used land surface models, namely CSIRO’s Atmosphere Biosphere Land Exchange (CABLE) with 9 C pools, Community Land Model (version 3.5) combined with Carnegie-Ames-Stanford Approach (CLM-CASA) with 12 C pools and Community Land Model (version 4) (CLM4) with 26 C pools were driven by themore » observed meteorological forcing. The simulated C storage and residence time were used for analysis. The C storage and residence time were computed globally for all individual soil and plant pools, as well as net primary productivity (NPP) and its allocation to different plant components’ based on these models. Remotely sensed NPP and statistically derived HWSD, and GLC2000 datasets were used as a reference to evaluate the performance of these models. Results showed that CABLE exhibited better agreement with referenced C storage and residence time for plant and soil pools, as compared with CLM-CASA and CLM4. CABLE had longer bulk residence time for soil C pools and stored more C in roots, whereas, CLM-CASA and CLM4 stored more C in woody pools due to differential NPP allocation. Overall, these results indicate that the differences in C storage and residence times in three models are largely due to the differences in their fundamental structures (number of C pools), NPP allocation and C transfer rates. Our results have implications in model development and provide a general framework to explain the bias/uncertainties in simulation of C storage and residence times from the perspectives of model structures.« less

The bacterial type III-secreted protein AvrRps4 is a bipartite effector

PubMed Central

Spears, Benjamin J.; Garner, Christopher M.; Rogan, Conner J.; Su, Jianbin; Bhattacharjee, Saikat

2018-01-01

Bacterial effector proteins secreted into host plant cells manipulate those cells to the benefit of the pathogen, but effector-triggered immunity (ETI) occurs when effectors are recognized by host resistance proteins. The RPS4/RRS1 pair recognizes the Pseudomonas syringae pv. pisi effector AvrRps4. AvrRps4 is processed in planta into AvrRps4N (133 amino acids), homologous to the N-termini of other effectors including the native P. syringae pv. tomato strain DC3000 effector HopK1, and AvrRps4C (88 amino acids). Previous data suggested that AvrRps4C alone is necessary and sufficient for resistance when overexpressed in heterologous systems. We show that delivering AvrRps4C from DC3000, but not from a DC3000 hopK1- strain, triggers resistance in the Arabidopsis accession Col-0. Delivering AvrRps4C in tandem with AvrRps4N, or as a chimera with HopK1N, fully complements AvrRps4-triggered immunity. AvrRps4N in the absence of AvrRps4C enhances virulence in Col-0. In addition, AvrRps4N triggers a hypersensitive response in lettuce that is attenuated by coexpression of AvrRps4C, further supporting the role of AvrRps4N as a bona fide effector domain. Based on these results we propose that evolutionarily, fusion of AvrRps4C to AvrRps4N may have counteracted recognition of AvrRps4N, and that the plant RPS4/RRS1 resistance gene pair was selected as a countermeasure. We conclude that AvrRps4 represents an unusual chimeric effector, with recognition in Arabidopsis by RPS4/RRS1 requiring the presence of both processed effector moieties. PMID:29601603

The bacterial type III-secreted protein AvrRps4 is a bipartite effector.

PubMed

Halane, Morgan K; Kim, Sang Hee; Spears, Benjamin J; Garner, Christopher M; Rogan, Conner J; Okafor, Elizabeth C; Su, Jianbin; Bhattacharjee, Saikat; Gassmann, Walter

2018-03-01

Bacterial effector proteins secreted into host plant cells manipulate those cells to the benefit of the pathogen, but effector-triggered immunity (ETI) occurs when effectors are recognized by host resistance proteins. The RPS4/RRS1 pair recognizes the Pseudomonas syringae pv. pisi effector AvrRps4. AvrRps4 is processed in planta into AvrRps4N (133 amino acids), homologous to the N-termini of other effectors including the native P. syringae pv. tomato strain DC3000 effector HopK1, and AvrRps4C (88 amino acids). Previous data suggested that AvrRps4C alone is necessary and sufficient for resistance when overexpressed in heterologous systems. We show that delivering AvrRps4C from DC3000, but not from a DC3000 hopK1- strain, triggers resistance in the Arabidopsis accession Col-0. Delivering AvrRps4C in tandem with AvrRps4N, or as a chimera with HopK1N, fully complements AvrRps4-triggered immunity. AvrRps4N in the absence of AvrRps4C enhances virulence in Col-0. In addition, AvrRps4N triggers a hypersensitive response in lettuce that is attenuated by coexpression of AvrRps4C, further supporting the role of AvrRps4N as a bona fide effector domain. Based on these results we propose that evolutionarily, fusion of AvrRps4C to AvrRps4N may have counteracted recognition of AvrRps4N, and that the plant RPS4/RRS1 resistance gene pair was selected as a countermeasure. We conclude that AvrRps4 represents an unusual chimeric effector, with recognition in Arabidopsis by RPS4/RRS1 requiring the presence of both processed effector moieties.

Potential applications of cutin-derived CuO reaction products for discriminating vascular plant sources in natural environments

NASA Astrophysics Data System (ADS)

Goñi, Miguel A.; Hedges, John I.

1990-11-01

An extensive suite of C 14-C 18 hydroxylated fatty acids of cutin origin was identified among the nonlignin CuO reaction products from tissues of 67 different plant species. These mid-chain and ω-hydroxylated cutin acids together accounted for 0.5 to 4% of the organic carbon (OC) in these nonwoody vascular plant tissues and were produced in characteristically different yields by the various plant types. Nonvascular plants, including bulk phytoplankton, kelps, mosses, and liverworts, did not yield measurable amounts of cutin acids, except for trace levels of ω-hydroxytetradecanoic acid detected in kelps. Most of the "lower" vascular plants, such as clubmosses and ferns, produced simple cutin acid suites composed mainly of ω-hydroxy C 14 and C 16 acids. Gymnosperm needles yielded cutin acid suites dominated by C 16 acids, in which 9,16- and 10,16-dihydroxyhexadecanoic acids were characteristically abundant. Relatively high yields of C 18 acids were obtained from angiosperm tissues, among which dicotyledons exhibited a predominance of 9,10,18-trihydroxyoctadecanoic acid over all the other C 18 acids. The Chromatographie peak corresponding to dihydroxyhexadecanoic acid was a mixture of the positional isomers 8,16-, 9, 16-, and 10,16-dihydroxyhexadecanoic acids, whose relative abundances uniquely characterized monocotyledon tissues and distinguished among different types of gymnosperm tissues. Based on the cutin acid yields obtained from the different plant types, several geochemical parameters were developed to distinguish up to six different cutin-bearing plant groups as possible components of sedimentary mixtures.

Leaf Respiratory Acclimation: Magnitude of Acclimation to the Long-term Warming in Tallgrass Prairie

NASA Astrophysics Data System (ADS)

Jung, C. G.; Peng, F.; Luo, Y.

2016-12-01

Plant respiration has a positive response with temperature; hence, the plant under warmer climate makes plant releases more CO2. However, plant leaf can acclimate to the warmer climate so that plant leaf respiratory acclimation contributes less positive feedback between climate warming and ecosystem CO2 release. In order to examine the feedback between ecosystem and evolution of carbon dioxide due to global warming, we conducted the experiment of warming and clipping as mimicking grazing effect in a tall grass prairie in central Oklahoma, US since November 1999. The warming plot's air and soil temperature show 1.1 °C and 2.3 °C higher than ambient, respectively. Since our experiment has been over 16 years, the plot's species compositions and plant richness have changed so far. Most species composition events occurred at the clipping plot; therefore, we selected the plants within unclipped plots to see whether plants that exposed long-term warming, play a role of thermal acclimation and how those major plant species across experimental site possess difference magnitude of acclimation. We have investigated five species, one legume, one forb, and three of C4 grass: Illinois bundle (Desmanthus illinoensis, C3), stiff goldenrod (Solidago rigida, C3), King Ranch bluestem (Bothriochloa ischaemum, C4), Indian grass (Sorghastrum nutans, C4), and Little bluestem (Schizachyrium scoparium, C4). Data has collected from May as the first month of growing season in our field site in 2016. In our results, measurements in +2 °C warming show strong acclimation across the species (185% ±41% s.e.m. among species). The strongest acclimation occurred by stiff goldenrod (309%). The lowest acclimation rate is 51% in Illinois bundle, as well as the partial acclimation. The other three C4 grass species have 188% acclimation rate (±37% s.e.m. among species). Whether different plant species have a different capability of acclimation or respond through different way as shown various magnitudes, our results provide strong evidence for plant leaf thermal acclimation and its actual degree in the experimental warmed tall grass prairie. Further analysis will distinguish the plant species into the different type of acclimation; furthermore, our results can contribute a precise prediction of terrestrial feedback.

The pepper Bs4C proteins are localized to the endoplasmic reticulum (ER) membrane and confer disease resistance to bacterial blight in transgenic rice.

PubMed

Wang, Jun; Zeng, Xuan; Tian, Dongsheng; Yang, Xiaobei; Wang, Lanlan; Yin, Zhongchao

2018-03-30

Transcription activator-like effector (TALE)-dependent dominant disease resistance (R) genes in plants, also referred to as executor R genes, are induced on infection by phytopathogenic bacteria of the genus Xanthomonas harbouring the corresponding TALE genes. Unlike the traditional R proteins, the executor R proteins do not determine the resistance specificity and may function broadly in different plant species. The executor R gene Bs4C-R in the resistant genotype PI 235047 of the pepper species Capsicum pubescens (CpBs4C-R) confers disease resistance to Xanthomonas campestris pv. vesicatoria (Xcv) harbouring the TALE genes avrBsP/avrBs4. In this study, the synthetic genes of CpBs4C-R and two other Bs4C-like genes, the susceptible allele in the genotype PI585270 of C. pubescens (CpBs4C-S) and the CaBs4C-R homologue gene in the cultivar 'CM334' of Capsicum annum (CaBs4C), were characterized in tobacco (Nicotiana benthamiana) and rice (Oryza sativa). The Bs4C genes induced cell death in N. benthamiana. The functional Bs4C-eCFP fusion proteins were localized to the endoplasmic reticulum (ER) membrane in the leaf epidermal cells of N. benthamiana. The Xa10 promoter-Bs4C fusion genes in transgenic rice conferred strain-specific disease resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight in rice, and were specifically induced by the Xa10-incompatible Xoo strain PXO99 A (pHM1avrXa10). The results indicate that the Bs4C proteins from pepper species function broadly in rice and the Bs4C protein-mediated cell death from the ER is conserved between dicotyledonous and monocotyledonous plants, which can be utilized to engineer novel and enhanced disease resistance in heterologous plants. © 2018 TEMASEK LIFE SCIENCES LABORATORY. MOLECULAR PLANT PATHOLOGY © 2018 JOHN WILEY & SONS LTD.

Aquatic modules for bioregenerative life support systems based on the C.E.B.A.S. biotechnology

NASA Astrophysics Data System (ADS)

Bluem, Volker; Paris, Frank

2001-03-01

Most concepts for bioregenerative life support systems are based on edible higher land plants which create some problems with growth and seed generation under space conditions. Animal protein production is mostly neglected because of the tremendous waste management problems with tetrapods under reduced weightlessness. Therefore, the "Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) was developed which represents an artificial aquatic ecosystem containing aquatic organisms which are adpated at all to "near weightlessness conditions" (fishes Xiphophorus helleri, water snails Biomphalaria glabrata, ammonia oxidizing bacteria and the rootless non-gravitropic edible water plant Ceratophyllum demersum). Basically the C.E.B.A.S. consists of 4 subsystems: a ZOOLOGICASL COMPONENT (animal aquarium), a BOTANICAL COMPONENT (aquatic plant bioreactor), a MICROBIAL COMPONENT (bacteria filter) and an ELECTRONICAL COMPONENT (data acquisition and control unit). Superficially, the function principle appears simple: the plants convert light energy into chemical energy via photosynthesis thus producing biomass and oxygen. The animals and microorganisms use the oxygen for respiration and produce the carbon dioxide which is essential for plant photosynthesis. The ammonia ions excreted by the animals are converted by the bacteria to nitrite and then to nitrate ions which serve as a nitrogen source for the plants. Other essential ions derive from biological degradation of animal waste products and dead organic matter. The C.E.B.A.S. exists in 2 basic versions: the original C.E.B.A.S. with a volume of 150 liters and a self-sustaining standing time of more than 13 month and the so-called C.E.B.A.S. MINI MODULE with a volume of about 8.5 liters. In the latter there is no closed food loop by reasons of available space so that animal food has to be provided via an automated feeder. This device was flown already successfully on the STS-89 and STS-90 spaceshuttle missions and the working hypothesis was verified that aquatic organisms are nearly not affected at all by space conditions, i . e. that the plants exhibited biomass production rates identical to the ground controls and that as well the reproductive, and the immune system as the the embryonic and ontogenic development of the animals remained undisturbed. Currently the C.E.B.A.S. MINI MODLULE is prepared for a third spaceshuttle fligt (STS-107) in spring 2001. Based on the results of the space experiments a series of prototypes of aquatic food production modules for the implementation into BLSS were developed. This paper describes the scientific disposition of the STS-107 experiments and of open and closed aquaculture systems based on another aquatic plant species, the Lemnacean Wolffia arrhiza which is cultured as a vegetable in Southeastern Asia. This plant can be grown in suspension culture and several special bioreactors were developed for this purpose. W. arrhiza reproduces mainly vegetatively by buds but also sexually from time to time and is therefore especially suitable for genetic engineering, too. Therefore it was used, in addition, to optimize the C.E.B.A.S. MINI MODULE to allow experiments with a duration of 4 month in the International Space Station the basic principle of which will be explained. In the context of aquaculture systems for BLSS the continuous replacement of removed fish biomass is an essential demand. Although fish reproduction seems not to be affected in the short-term space experiments with the C.E.B.A.S. MIMI MODULE a functional and reliable hatchery for the production of siblings under reduced weightlessness is connected with some serious problems. Therefore an automated "reproduction module" for the herbivorous fish Tilapia rendalli was developed as a laboratory prototype. It is concluded that aquatic modules of different degrees of complexity can optimize the productivity of BLSS based on higher land plants and that they offer an unique opportunity for the production of animal protein in lunar or planetary bases.

Coordination between leaf and stem traits related to leaf carbon gain and hydraulics across 32 drought-tolerant angiosperms.

PubMed

Ishida, Atsushi; Nakano, Takashi; Yazaki, Kenichi; Matsuki, Sawako; Koike, Nobuya; Lauenstein, Diego L; Shimizu, Michiru; Yamashita, Naoko

2008-05-01

We examined 15 traits in leaves and stems related to leaf C economy and water use for 32 co-existing angiosperms at ridge sites with shallow soil in the Bonin Islands. Across species, stem density was positively correlated to leaf mass per area (LMA), leaf lifespan (LLS), and total phenolics and condensed tannins per unit leaf N (N-based), and negatively correlated to leaf osmotic potential and saturated water content in leaves. LMA and LLS were negatively correlated to photosynthetic parameters, such as area-, mass-, and N-based assimilation rates. Although stem density and leaf osmotic potential were not associated with photosynthetic parameters, they were associated with some parameters of the leaf C economy, such as LMA and LLS. In the principal component (PCA) analysis, the first three axes accounted for 74.4% of total variation. Axis 1, which explained 41.8% of the total variation, was well associated with parameters for leaf C and N economy. Similarly, axis 2, which explained 22.3% of the total variation, was associated with parameters for water use. Axis 3, which explained 10.3% of the total variation, was associated with chemical defense within leaves. Axes 1 and 2 separated functional types relatively well, i.e., creeping trees, ruderal trees, other woody plants, C(3) shrubs and forbs, palms, and CAM plants, indicating that plant functional types were characterized by similar attributes of traits related to leaf C and N economy and water use. In addition, when the plot was extended by two unrelated traits, leaf mass-based assimilation rates and stem density, it also separated these functional types. These data indicate that differences in the functional types with contrasting plant strategies can be attributed to functional integration among leaf C economy, hydraulics, and leaf longevity, and that both leaf mass-based assimilation rates and stem density are key factors reflecting the different functions of plant species.

Photosynthetic strategies of two Mojave Desert shrubs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinkopf, G.E.; Hartsock, T.L.; Wallace, A.

1980-01-01

Photosynthetic production of two Mojave Desert shrubs was measured under natural growing conditions. Measurements of photosynthesis, transpiration, resistances to water vapor flux, soil moisture potential, and tissue water potential were made. Atriplex canescens (Pursh) Nutt., a member of the C/sub 4/ biochemical carbon dioxide fixation group was highly competitive in growth rate and production during conditions of adequate soil moisture. As soil moisture conditions declined to minus 40 bars, the net photosynthetic rate of Atriplex decreased to zero. However, the C/sub 3/ shrub species Larrea tridentata (Sesse and Moc. ex DC.) Cov. was able to maintain positive net photosynthetic productionmore » during conditions of high temperature and extreme low soil moisture through the major part of the season. The comparative advantages of the C/sub 4/ versus the C/sub 3/ pathway of carbon fixation was lost between these two species as the soil moisture potential declined to minus 40 bars. Desert plants have diffferent strategies for survival, one of the strategies being the C/sub 4/ biochemical carbon fixation pathway. However, many of the plants are members of the C/sub 3/ group. In this instance, the C/sub 4/ fixation pathway does not confer an added advantage to the productivity of the species in the Mojave Desert. Species distribution based on comparative photosynthetic production is discussed« less

4. Credit PEM. Interior of Martinsburg Plant; on right showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. Credit PEM. Interior of Martinsburg Plant; on right showing Taylor 150 hp steam engine belt-connected to a Warren 150 KW, 2200 Volt a.c. generator. On left, a Fisher 400 hp steam engine belt-connected to a Warren 200 KW, 2200 Volt a.c. generator. In center, also belt-connected to Fisher 400 hp engine is a Bail 120 light, arc-light generator. Photo c. 1905. - Dam No. 4 Hydroelectric Plant, Potomac River, Martinsburg, Berkeley County, WV

C3 and C4 plant responses to increased temperatures and altered monsoonal precipitation in a cool desert on the Colorado Plateau, USA

USGS Publications Warehouse

Wertin, Timothy M.; Reed, Sasha C.; Belnap, Jayne

2015-01-01

Dryland ecosystems represent >40 % of the terrestrial landscape and support over two billion people; consequently, it is vital to understand how drylands will respond to climatic change. However, while arid and semiarid ecosystems commonly experience extremely hot and dry conditions, our understanding of how further temperature increases or altered precipitation will affect dryland plant communities remains poor. To address this question, we assessed plant physiology and growth at a long-term (7-year) climate experiment on the Colorado Plateau, USA, where the community is a mix of shallow-rooted C3 and C4 grasses and deep-rooted C4 shrubs. The experiment maintained elevated-temperature treatments (+2 or +4 °C) in combination with altered summer monsoonal precipitation (+small frequent precipitation events or +large infrequent events). Increased temperature negatively affected photosynthesis and growth of the C3 and C4 grasses, but effects varied in their timing: +4 °C treatments negatively affected the C3 grass early in the growing season of both years, while the negative effects of temperature on the C4 grass were seen in the +2 and +4 °C treatments, but only during the late growing season of the drier year. Increased summer precipitation did not affect photosynthesis or biomass for any species, either in the year the precipitation was applied or the following year. Although previous research suggests dryland plants, and C4 grasses in particular, may respond positively to elevated temperature, our findings from a cool desert show marked declines in C3 and C4 photosynthesis and growth, with temperature effects dependent on the degree of warming and growing-season precipitation.

Heat inactivation of leaf phosphoenolpyruvate carboxylase: Protection by aspartate and malate in C4 plants.

PubMed

Rathnam, C K

1978-01-01

The activity of phosphoenolpyruvate (PEP) carboxylase EC 4.1.1.31 in leaf extracts of Eleusine indica L. Gaertn., a C4 plant, exhibited a temperature optimum of 35-37° C with a complete loss of activity at 50° C. However, the enzyme was protected effectively from heat inactivation up to 55° C by L-aspartate. Activation energies (Ea) for the enzyme in the presence of aspartate were 2.5 times lower than that of the control enzyme. Arrhenius plots of PEP carboxylase activity (±aspartate) showed a break in the slope around 17-20° C with a 3-fold increase in the Ea below the break. The discontinuity in the slopes was abolished by treating the enzyme extracts with Triton X-100, suggesting that PEP carboxylase in C4 plants is associated with lipid and may be a membrane bound enzyme. Depending upon the species, the major C4 acid formed during photosynthesis (malate or aspartate) was found to be more protective than the minor C4 acid against the heat inactivation of their PEP carboxylase. Oxaloacetate, the reaction product, was less effective compared to malate or aspartate. Several allosteric inhibitors of PEP carboxylase were found to be moderately to highly effective in protecting the C4 enzyme while its activators showed no significant effect. PEP carboxylase from C3 species was not protected from thermal inactivation by the C4 acids. The physiological significance of these results is discussed in relation to the high temperature tolerance of C4 plants.

Plant phenology and composition controls of carbon fluxes in a boreal peatland

NASA Astrophysics Data System (ADS)

Peichl, Matthias; Gažovič, Michal; Vermeij, Ilse; De Goede, Eefje; Sonnentag, Oliver; Limpens, Juul; Nilsson, Mats B.

2016-04-01

Vegetation drives the peatland carbon (C) cycle via the processes of photosynthesis, plant respiration and decomposition as well as by providing substrate for methane (CH4) and dissolved organic carbon production. However, due to the lack of comprehensive vegetation data, variations in the peatland C fluxes are commonly related to temperature and other more easily measured abiotic (i.e. weather and soil) variables. Due to the temporal co-linearity between plant development and abiotic variables, these relationships may describe the variations in C fluxes reasonably well, however, without representing the true mechanistic processes driving the peatland C cycle. As a consequence, current process-based models are poorly parameterized and unable to adequately predict the responses of the peatland C cycle to climate change, extreme events and anthropogenic impacts. To fill this knowledge gap, we explored vegetation phenology and composition effects on the peatland C cycle at the Degerö peatland located in northern Sweden. We used a greenness index derived from digital repeat photography to quantitatively describe plant canopy development with high temporal (i.e. daily) and spatial (plot to ecosystem) resolution. In addition, eddy covariance and static chamber measurements of carbon dioxide (CO2) and CH4 fluxes over an array of vegetation manipulation plots were conducted over multiple years. Our results suggest that vascular plant phenology controls the onset and pattern of eddy covariance-derived gross primary production (GPP) during the spring period, while abiotic conditions modify GPP during the summer period when plant canopy cover is fully developed. Inter-annual variations in the spring onset and patterns of plant canopy development were best explained by differences in the preceding growing degree day sum. We also observed strong correlations of canopy greenness with the net ecosystem CO2 exchange and ecosystem respiration. On average, vascular plant and moss production accounted for ~60 and 40% of GPP, respectively. However, while the seasonal variation of vascular plant productivity was driven by plant phenology, water table level was the strongest control of moss productivity. Across vegetation manipulation plots, highest chamber-derived GPP and net CO2 uptake occurred when both vascular and moss species were present. Furthermore, CH4 fluxes increased with the amount of sedge species leaf area; however, their seasonal flux patterns were more closely related to water table level than to plant phenology. Overall these findings highlight the need for better understanding the separate controls of biotic and abiotic drivers of the peatland C fluxes to improve predictions of ecosystem processes and the peatland C sink strength in response to future climate change and management impacts.

Walking the C4 pathway: past, present, and future.

PubMed

Furbank, Robert T

2017-01-01

The year 2016 marks 50 years since the publication of the seminal paper by Hatch and Slack describing the biochemical pathway we now know as C 4 photosynthesis. This review provides insight into the initial discovery of this pathway, the clues which led Hatch and Slack and others to these definitive experiments, some of the intrigue which surrounds the international activities which led up to the discovery, and personal insights into the future of this research field. While the biochemical understanding of the basic pathways came quickly, the role of the bundle sheath intermediate CO 2 pool was not understood for a number of years, and the nature of C 4 as a biochemical CO 2 pump then linked the unique Kranz anatomy of C 4 plants to their biochemical specialization. Decades of "grind and find biochemistry" and leaf physiology fleshed out the regulation of the pathway and the differences in physiological response to the environment between C 3 and C 4 plants. The more recent advent of plant transformation then high-throughput RNA and DNA sequencing and synthetic biology has allowed us both to carry out biochemical experiments and test hypotheses in planta and to better understand the evolution-driven molecular and genetic changes which occurred in the genomes of plants in the transition from C 3 to C 4 Now we are using this knowledge in attempts to engineer C 4 rice and improve the C 4 engine itself for enhanced food security and to provide novel biofuel feedstocks. The next 50 years of photosynthesis will no doubt be challenging, stimulating, and a drawcard for the best young minds in plant biology. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Walking the C4 pathway: past, present, and future.

PubMed

Furbank, Robert T

2016-07-01

The year 2016 marks 50 years since the publication of the seminal paper by Hatch and Slack describing the biochemical pathway we now know as C4 photosynthesis. This review provides insight into the initial discovery of this pathway, the clues which led Hatch and Slack and others to these definitive experiments, some of the intrigue which surrounds the international activities which led up to the discovery, and personal insights into the future of this research field. While the biochemical understanding of the basic pathways came quickly, the role of the bundle sheath intermediate CO2 pool was not understood for a number of years, and the nature of C4 as a biochemical CO2 pump then linked the unique Kranz anatomy of C4 plants to their biochemical specialization. Decades of "grind and find biochemistry" and leaf physiology fleshed out the regulation of the pathway and the differences in physiological response to the environment between C3 and C4 plants. The more recent advent of plant transformation then high-throughput RNA and DNA sequencing and synthetic biology has allowed us both to carry out biochemical experiments and test hypotheses in planta and to better understand the evolution-driven molecular and genetic changes which occurred in the genomes of plants in the transition from C3 to C4 Now we are using this knowledge in attempts to engineer C4 rice and improve the C4 engine itself for enhanced food security and to provide novel biofuel feedstocks. The next 50 years of photosynthesis will no doubt be challenging, stimulating, and a drawcard for the best young minds in plant biology. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Metabolism of 2,4-dichlorophenol in tobacco engineered with bacterial degradative genes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perkins, E.J.; Sekine, M.; Gordon, M.P.

1990-05-01

The potential use of plants in toxic waste remediation has been overlooked. While chlorophenols are relatively slowly metabolized in Nicotiana tabacum var. Xanthi leaf extracts, chlorocatechols are rapidly metabolized, presumably by polyphenol oxidases. Our initial focus has been the fate of 2,4-dichlorophenol (2,4DCP) in var. Xanthi plants which express a bacterial 2,4DCP hydroxylase, which converts 2,4DCP to 3,5-dichlorocatechol. The roots of wild type and 2,4DCP hydroxylase transgenic plants growing in hydroponics were exposed to {sup 14}C-2,4DCP. Approximately 95% of {sup 14}C-2,4DCP metabolites remained in the roots when exposed to 2,4DCP. Upon extraction of root tissue, three major metabolites were foundmore » in untransformed plants and four major metabolites in transformed plants. Upon digestion with beta-D-glucosidase, these metabolites disappeared concomitant with the appearance of free 2,4DCP in wild type plants and 2,4DCP and 3,5-dichlorocatechol in transgenic plants. It is apparent that the chlorophenols are not readily available substrates for polyphenol oxidases in whole plants.« less

Wetland plant waxes from Olduvai Gorge, Tanzania

NASA Astrophysics Data System (ADS)

Tamalavage, A.; Magill, C. R.; Barboni, D.; Ashley, G. M.; Freeman, K. H.

2013-12-01

Olduvai Gorge, northern Tanzania, exposes a Plio-Pleistocene sedimentary record that includes lake and lake-margin sediments and fossil remains of ancient plants and early humans. There are rich paleontological and cultural records at Olduvai Gorge that include thousands of vertebrate fossils and stone tools. Previous studies of plant biomarkers in lake sediments from Olduvai Gorge reveal repeated, abrupt changes in landscape dominance by woodland or grassland vegetation during the early Pleistocene, about 1.8 million years ago. However, the reconstruction of wetland vegetation in the past is limited by a dearth of published lipid signatures for modern wetland species. Here, we present lipid and isotopic data for leaf tissues from eight modern plants (i.e., sedge and Typha species) living in wetlands near Olduvai Gorge. Trends in values for molecular and leaf δ13C and average chain length (ACL) of n-alkanes in plant tissues are similar to values for underlying soils. Compound-specific δ13C values for n-alkanes C25 to C33 range between -36.4 to -23.1‰ for C3 plants and -22.3 to -19.5‰ for C4 plants. Fractionation factors between leaf and lipids, ɛ29 and ɛ33, fall within the range reported in the literature, but they differ more widely within a single plant. For C3 plants, the average difference between ɛ29 and ɛ33 is 6.5 ‰, and the difference between ɛ29 and ɛ33 for C4 plants is less than 2‰. Both plant types show a parabolic relationship between chain length and δ13C values, in which C29 typically has the most depleted value, and typically shift by 3-5‰ between alkane homologs. This pattern has not been previously reported, and could be unique for sedge lipids. If so, these data help constrain the application of plant wax biomarkers from sedges for paleo-vegetation reconstruction in paleoclimate studies and at archaeological sites.

Response of biofilms-leaves of two submerged macrophytes to high ammonium.

PubMed

Gong, Lixue; Zhang, Songhe; Chen, Deqiang; Liu, Kaihui; Lu, Jian

2018-02-01

Submerged macrophytes can provide attached surface for biofilms (known as periphyton) growth. In the present study, the alterations in biofilms formation, and chemical compositions and physiological responses were investigated on leaves of Vallisneria asiatica and Hydrilla verticillata exposed to 0.1 mg L -1 (control) or with 10 mg L -1 NH 4 + -N for 13 days. Results from physiological and biochemical indices (content of H 2 O 2 , malondialdehyde, total chlorophyll and activity of superoxide dismutase, catalase and peroxidase) showed that high ammonium caused oxidative damage to leaves of two species of plant. Multifractal analysis (based on scanning electron microscope images) showed that for the same plant, the values of width △α (△α = α max -α min ) of the f(α) and Δf (Δf = f(α min )-f(α max )) were smaller on leaves surface of two species of plant treated with 10 mg L -1 NH 4 + -N for 13 days than their controls, suggesting high ammonium treatments reduced morphological heterogeneity of leaf surface and enhanced area of the colony-like biofilms. X-ray photoelectron spectroscopy analysis showed that C, O, N and P were dominant elements on leaves surface of two species of plant and ammonium application increased the percentage of C but decreased that of O. High ammonium increased C1 (C-C or C-H) percentage but decreased C2 (C-O) and C3 (O-C-O or C=O) percentage on leaves surface of two species of plant, indicating that ammonium stress changed the surface chemical states and thus might reduce the capacity of leaves to adsorb nutrients from water column. Our results provided useful information to understand ammonium induced toxicity to submerged macrophytes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contemporaneous and recent radiations of the world's major succulent plant lineages

PubMed Central

Arakaki, Mónica; Christin, Pascal-Antoine; Nyffeler, Reto; Lendel, Anita; Eggli, Urs; Ogburn, R. Matthew; Spriggs, Elizabeth; Moore, Michael J.; Edwards, Erika J.

2011-01-01

The cacti are one of the most celebrated radiations of succulent plants. There has been much speculation about their age, but progress in dating cactus origins has been hindered by the lack of fossil data for cacti or their close relatives. Using a hybrid phylogenomic approach, we estimated that the cactus lineage diverged from its closest relatives ≈35 million years ago (Ma). However, major diversification events in cacti were more recent, with most species-rich clades originating in the late Miocene, ≈10–5 Ma. Diversification rates of several cactus lineages rival other estimates of extremely rapid speciation in plants. Major cactus radiations were contemporaneous with those of South African ice plants and North American agaves, revealing a simultaneous diversification of several of the world's major succulent plant lineages across multiple continents. This short geological time period also harbored the majority of origins of C4 photosynthesis and the global rise of C4 grasslands. A global expansion of arid environments during this time could have provided new ecological opportunity for both succulent and C4 plant syndromes. Alternatively, recent work has identified a substantial decline in atmospheric CO2 ≈15–8 Ma, which would have strongly favored C4 evolution and expansion of C4-dominated grasslands. Lowered atmospheric CO2 would also substantially exacerbate plant water stress in marginally arid environments, providing preadapted succulent plants with a sharp advantage in a broader set of ecological conditions and promoting their rapid diversification across the landscape. PMID:21536881

[Study on flavonoids from stem bark of Pongamia pinnata].

PubMed

Yin, Hao; Zhang, Si; Wu, Jun

2004-07-01

Seven flavonoids, pongaflavone (1), karanjin (2), pongapin (3), pongachromene (4), 3,7-Dimethoxy-3', 4'-methylenedioxyflavone (5), millettocalyxin C( 6), 3,3',4', 7-tetramethoxyflavone (7), were isolated from 50% EtOH syrup of the bark of Pongamia pinnata and structureal elucidated on the base of spectral data. Compound 6 was isolated for first time from the plant of the genus Pongamia.

Effects of Substrate Addition on Soil Respiratory Carbon Release Under Long-Term Warming and Clipping in a Tallgrass Prairie

PubMed Central

Jia, Xiaohong; Zhou, Xuhui; Luo, Yiqi; Xue, Kai; Xue, Xian; Xu, Xia; Yang, Yuanhe; Wu, Liyou; Zhou, Jizhong

2014-01-01

Regulatory mechanisms of soil respiratory carbon (C) release induced by substrates (i.e., plant derived substrates) are critical for predicting ecosystem responses to climate change, but the mechanisms are not well understood. In this study, we sampled soils from a long-term field manipulative experiment and conducted a laboratory incubation to explore the role of substrate supply in regulating the differences in soil C release among the experimental treatments, including control, warming, clipping, and warming plus clipping. Three types of substrates (glucose, C3 and C4 plant materials) were added with an amount equal to 1% of soil dry weight under the four treatments. We found that the addition of all three substrates significantly stimulated soil respiratory C release in all four warming and clipping treatments. In soils without substrate addition, warming significantly stimulated soil C release but clipping decreased it. However, additions of glucose and C3 plant materials (C3 addition) offset the warming effects, whereas C4 addition still showed the warming-induced stimulation of soil C release. Our results suggest that long-term warming may inhibit microbial capacity for decomposition of C3 litter but may enhance it for decomposition of C4 litter. Such warming-induced adaptation of microbial communities may weaken the positive C-cycle feedback to warming due to increased proportion of C4 species in plant community and decreased litter quality. In contrast, clipping may weaken microbial capacity for warming-induced decomposition of C4 litter but may enhance it for C3 litter. Warming- and clipping-induced shifts in microbial metabolic capacity may be strongly associated with changes in plant species composition and could substantially influence soil C dynamics in response to global change. PMID:25490701

Effects of substrate addition on soil respiratory carbon release under long-term warming and clipping in a tallgrass prairie.

PubMed

Jia, Xiaohong; Zhou, Xuhui; Luo, Yiqi; Xue, Kai; Xue, Xian; Xu, Xia; Yang, Yuanhe; Wu, Liyou; Zhou, Jizhong

2014-01-01

Regulatory mechanisms of soil respiratory carbon (C) release induced by substrates (i.e., plant derived substrates) are critical for predicting ecosystem responses to climate change, but the mechanisms are not well understood. In this study, we sampled soils from a long-term field manipulative experiment and conducted a laboratory incubation to explore the role of substrate supply in regulating the differences in soil C release among the experimental treatments, including control, warming, clipping, and warming plus clipping. Three types of substrates (glucose, C3 and C4 plant materials) were added with an amount equal to 1% of soil dry weight under the four treatments. We found that the addition of all three substrates significantly stimulated soil respiratory C release in all four warming and clipping treatments. In soils without substrate addition, warming significantly stimulated soil C release but clipping decreased it. However, additions of glucose and C3 plant materials (C3 addition) offset the warming effects, whereas C4 addition still showed the warming-induced stimulation of soil C release. Our results suggest that long-term warming may inhibit microbial capacity for decomposition of C3 litter but may enhance it for decomposition of C4 litter. Such warming-induced adaptation of microbial communities may weaken the positive C-cycle feedback to warming due to increased proportion of C4 species in plant community and decreased litter quality. In contrast, clipping may weaken microbial capacity for warming-induced decomposition of C4 litter but may enhance it for C3 litter. Warming- and clipping-induced shifts in microbial metabolic capacity may be strongly associated with changes in plant species composition and could substantially influence soil C dynamics in response to global change.

Mitigative effects of spermidine on photosynthesis and carbon-nitrogen balance of cucumber seedlings under Ca(NO3)2 stress.

PubMed

Du, Jing; Shu, Sheng; Shao, Qiaosai; An, Yahong; Zhou, Heng; Guo, Shirong; Sun, Jin

2016-01-01

Ca(NO3)2 stress is one of the most serious constraints to plants production and limits the plants growth and development. Application of polyamines is a convenient and effective approach for enhancing plant salinity tolerance. The present investigation aimed to discover the photosynthetic carbon-nitrogen (C-N) mechanism underlying Ca(NO3)2 stress tolerance by spermidine (Spd) of cucumber (Cucumis sativus L. cv. Jinyou No. 4). Seedling growth and photosynthetic capacity [including net photosynthetic rate (P N), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr)] were significantly inhibited by Ca(NO3)2 stress (80 mM). However, a leaf-applied Spd (1 mM) treatment alleviated the reduction in growth and photosynthesis in cucumber caused by Ca(NO3)2 stress. Furthermore, the application of exogenous Spd significantly decreased the accumulation of NO3 (-) and NH4 (+) caused by Ca(NO3)2 stress and remarkably increased the activities of N metabolism enzymes simultaneously. In addition, photosynthesis N-use efficiency (PNUE) and free amino acids were significantly enhanced by exogenous Spd in response to Ca(NO3)2 stress, thus promoting the biosynthesis of N containing compounds and soluble protein. Also, the amounts of several carbohydrates (including sucrose, fructose and glucose), total C content and the C/N radio increased significantly in the presence of Spd. Based on our results, we suggest that exogenous Spd could effectively accelerate nitrate transformation into amino acids and improve cucumber plant photosynthesis and C assimilation, thereby enhancing the ability of the plants to maintain their C/N balance, and eventually promote the growth of cucumber plants under Ca(NO3)2 stress.

Landscape object-based analysis of wetland plant functional types: the effects of spatial scale, vegetation classes and classifier methods

NASA Astrophysics Data System (ADS)

Dronova, I.; Gong, P.; Wang, L.; Clinton, N.; Fu, W.; Qi, S.

2011-12-01

Remote sensing-based vegetation classifications representing plant function such as photosynthesis and productivity are challenging in wetlands with complex cover and difficult field access. Recent advances in object-based image analysis (OBIA) and machine-learning algorithms offer new classification tools; however, few comparisons of different algorithms and spatial scales have been discussed to date. We applied OBIA to delineate wetland plant functional types (PFTs) for Poyang Lake, the largest freshwater lake in China and Ramsar wetland conservation site, from 30-m Landsat TM scene at the peak of spring growing season. We targeted major PFTs (C3 grasses, C3 forbs and different types of C4 grasses and aquatic vegetation) that are both key players in system's biogeochemical cycles and critical providers of waterbird habitat. Classification results were compared among: a) several object segmentation scales (with average object sizes 900-9000 m2); b) several families of statistical classifiers (including Bayesian, Logistic, Neural Network, Decision Trees and Support Vector Machines) and c) two hierarchical levels of vegetation classification, a generalized 3-class set and more detailed 6-class set. We found that classification benefited from object-based approach which allowed including object shape, texture and context descriptors in classification. While a number of classifiers achieved high accuracy at the finest pixel-equivalent segmentation scale, the highest accuracies and best agreement among algorithms occurred at coarser object scales. No single classifier was consistently superior across all scales, although selected algorithms of Neural Network, Logistic and K-Nearest Neighbors families frequently provided the best discrimination of classes at different scales. The choice of vegetation categories also affected classification accuracy. The 6-class set allowed for higher individual class accuracies but lower overall accuracies than the 3-class set because individual classes differed in scales at which they were best discriminated from others. Main classification challenges included a) presence of C3 grasses in C4-grass areas, particularly following harvesting of C4 reeds and b) mixtures of emergent, floating and submerged aquatic plants at sub-object and sub-pixel scales. We conclude that OBIA with advanced statistical classifiers offers useful instruments for landscape vegetation analyses, and that spatial scale considerations are critical in mapping PFTs, while multi-scale comparisons can be used to guide class selection. Future work will further apply fuzzy classification and field-collected spectral data for PFT analysis and compare results with MODIS PFT products.

NDH-Mediated Cyclic Electron Flow Around Photosystem I is Crucial for C4 Photosynthesis.

PubMed

Ishikawa, Noriko; Takabayashi, Atsushi; Noguchi, Ko; Tazoe, Youshi; Yamamoto, Hiroshi; von Caemmerer, Susanne; Sato, Fumihiko; Endo, Tsuyoshi

2016-10-01

C 4 photosynthesis exhibits efficient CO 2 assimilation in ambient air by concentrating CO 2 around ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) through a metabolic pathway called the C 4 cycle. It has been suggested that cyclic electron flow (CEF) around PSI mediated by chloroplast NADH dehydrogenase-like complex (NDH), an alternative pathway of photosynthetic electron transport (PET), plays a crucial role in C 4 photosynthesis, although the contribution of NDH-mediated CEF is small in C 3 photosynthesis. Here, we generated NDH-suppressed transformants of a C 4 plant, Flaveria bidentis, and showed that the NDH-suppressed plants grow poorly, especially under low-light conditions. CO 2 assimilation rates were consistently decreased in the NDH-suppressed plants under low and medium light intensities. Measurements of non-photochemical quenching (NPQ) of Chl fluorescence, the oxidation state of the reaction center of PSI (P700) and the electrochromic shift (ECS) of pigment absorbance indicated that proton translocation across the thylakoid membrane is impaired in the NDH-suppressed plants. Since proton translocation across the thylakoid membrane induces ATP production, these results suggest that NDH-mediated CEF plays a role in the supply of ATP which is required for C 4 photosynthesis. Such a role is more crucial when the light that is available for photosynthesis is limited and the energy production by PET becomes rate-determining for C 4 photosynthesis. Our results demonstrate that the physiological contribution of NDH-mediated CEF is greater in C 4 photosynthesis than in C 3 photosynthesis, suggesting that the mechanism of PET in C 4 photosynthesis has changed from that in C 3 photosynthesis accompanying the changes in the mechanism of CO 2 assimilation. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Plant nitrogen dynamics and nitrogen-use strategies under altered nitrogen seasonality and competition.

PubMed

Yuan, Zhiyou; Liu, Weixing; Niu, Shuli; Wan, Shiqiang

2007-10-01

Numerous studies have examined the effects of climatic factors on the distribution of C(3) and C(4) grasses in various regions throughout the world, but the role of seasonal fluctuations in temperature, precipitation and soil N availability in regulating growth and competition of these two functional types is still not well understood. This report is about the effects of seasonality of soil N availability and competition on plant N dynamics and N-use strategies of one C(3) (Leymus chinensis) and one C(4) (Chloris virgata) grass species. Leymus chinensis and C. virgata, two grass species native to the temperate steppe in northern China, were planted in a monoculture and a mixture under three different N seasonal availabilities: an average model (AM) with N evenly distributed over the growing season; a one-peak model (OM) with more N in summer than in spring and autumn; and a two-peak model (TM) with more N in spring and autumn than in summer. The results showed that the altered N seasonality changed plant N concentration, with the highest value of L. chinensis under the OM treatment and C. virgata under the TM treatment, respectively. N seasonality also affected plant N content, N productivity and N-resorption efficiency and proficiency in both the C(3) and C(4) species. Interspecific competition influenced N-use and resorption efficiency in both the C(3) and C(4) species, with higher N-use and resorption efficiency in the mixture than in monoculture. The C(4) grass had higher N-use efficiency than the C(3) grass due to its higher N productivity, irrespective of the N treatment or competition. The observations suggest that N-use strategies in the C(3) and C(4) species used in the study were closely related to seasonal dynamics of N supply and competition. N seasonality might be involved in the growth and temporal niche separation between C(3) and C(4) species observed in the natural ecosystems.

In silico analysis of decomposed reflectances of C3 and C4 plants aiming at the effective assessment of crop needs

NASA Astrophysics Data System (ADS)

Baranoski, Gladimir V. G.; Van Leeuwen, Spencer; Chen, Tenn F.

2017-04-01

By separating the surface and subsurface components of foliar hyperspectral signatures using polarization optics, it is possible to enhance the remote discrimination of different plant species and optimize the assessment of different factors associated with their health status. These initiatives, in turn, can lead to higher crop yield and lower environmental impact. It is important to consider, however, that the main varieties of crops, represented by C3 (e.g., soy) and C4 (e.g., maize) plants, have markedly distinct morphological characteristics. Accordingly, the influence of these characteristics on their interactions with impinging light may affect the selection of optimal probe wavelengths for specific applications making use of combined hyperspectral and polarization measurements. In this paper, we compare the sensitivity of the total (including surface and subsurface components) and subsurface reflectance responses of C3 and C4 plants to different spectral and geometrical light incidence conditions. This investigation is supported by measured biophysical data and predictive light transport simulations. The results of our comparisons indicate that the total and subsurface reflectance responses of C3 and C4 plants depict well-defined patterns of sensitivity for varying illumination conditions. We believe that these patterns should be considered in the design of high-fidelity crop discrimination and monitoring procedures.

Down-regulation of p-coumaroyl quinate/shikimate 3'-hydroxylase (C3'H) and cinnamate 4-hydroxylase (C4H) genes in the lignin biosynthetic pathway of Eucalyptus urophylla x E. grandis leads to improved sugar release

DOE PAGES

Sykes, Robert W.; Gjersing, Erica L.; Foutz, Kirk; ...

2015-08-27

In this study, lignocellulosic materials provide an attractive replacement for food-based crops used to produce ethanol. Understanding the interactions within the cell wall is vital to overcome the highly recalcitrant nature of biomass. One factor imparting plant cell wall recalcitrance is lignin, which can be manipulated by making changes in the lignin biosynthetic pathway. In this study, eucalyptus down-regulated in expression of cinnamate 4-hydroxylase (C4H, EC 1.14.13.11) or p-coumaroyl quinate/shikimate 3'-hydroxylase (C3'H, EC 1.14.13.36) were evaluated for cell wall composition and reduced recalcitrance.

Mesophyll Chloroplast Investment in C3, C4 and C2 Species of the Genus Flaveria.

PubMed

Stata, Matt; Sage, Tammy L; Hoffmann, Natalie; Covshoff, Sarah; Ka-Shu Wong, Gane; Sage, Rowan F

2016-05-01

The mesophyll (M) cells of C4 plants contain fewer chloroplasts than observed in related C3 plants; however, it is uncertain where along the evolutionary transition from C3 to C4 that the reduction in M chloroplast number occurs. Using 18 species in the genus Flaveria, which contains C3, C4 and a range of C3-C4 intermediate species, we examined changes in chloroplast number and size per M cell, and positioning of chloroplasts relative to the M cell periphery. Chloroplast number and coverage of the M cell periphery declined in proportion to increasing strength of C4 metabolism in Flaveria, while chloroplast size increased with increasing C4 cycle strength. These changes increase cytosolic exposure to the cell periphery which could enhance diffusion of inorganic carbon to phosphenolpyruvate carboxylase (PEPC), a cytosolic enzyme. Analysis of the transcriptome from juvenile leaves of nine Flaveria species showed that the transcript abundance of four genes involved in plastid biogenesis-FtsZ1, FtsZ2, DRP5B and PARC6-was negatively correlated with variation in C4 cycle strength and positively correlated with M chloroplast number per planar cell area. Chloroplast size was negatively correlated with abundance of FtsZ1, FtsZ2 and PARC6 transcripts. These results indicate that natural selection targeted the proteins of the contractile ring assembly to effect the reduction in chloroplast numbers in the M cells of C4 Flaveria species. If so, efforts to engineer the C4 pathway into C3 plants might evaluate whether inducing transcriptome changes similar to those observed in Flaveria could reduce M chloroplast numbers, and thus introduce a trait that appears essential for efficient C4 function. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Soil properties determine the elevational patterns of base cations and micronutrients in the plant-soil system up to the upper limits of trees and shrubs

NASA Astrophysics Data System (ADS)

Wang, Ruzhen; Wang, Xue; Jiang, Yong; Cerdà, Artemi; Yin, Jinfei; Liu, Heyong; Feng, Xue; Shi, Zhan; Dijkstra, Feike A.; Li, Mai-He

2018-03-01

To understand whether base cations and micronutrients in the plant-soil system change with elevation, we investigated the patterns of base cations and micronutrients in both soils and plant tissues along three elevational gradients in three climate zones in China. Base cations (Ca, Mg, and K) and micronutrients (Fe, Mn, and Zn) were determined in soils, trees, and shrubs growing at lower and middle elevations as well as at their upper limits on Balang (subtropical, SW China), Qilian (dry temperate, NW China), and Changbai (wet temperate, NE China) mountains. No consistent elevational patterns were found for base cation and micronutrient concentrations in both soils and plant tissues (leaves, roots, shoots, and stem sapwood). Soil pH, soil organic carbon (SOC), total soil nitrogen (TN), the SOC to TN ratio (C : N), and soil extractable nitrogen (NO3- and NH4+) determined the elevational patterns of soil exchangeable Ca and Mg and available Fe, Mn, and Zn. However, the controlling role of soil pH and SOC was not universal as revealed by their weak correlations with soil base cations under tree canopies at the wet temperate mountain and with micronutrients under both tree and shrub canopies at the dry temperate mountain. In most cases, soil base cation and micronutrient availabilities played fundamental roles in determining the base cation and micronutrient concentrations in plant tissues. An exception existed for the decoupling of leaf K and Fe with their availabilities in the soil. Our results highlight the importance of soil physicochemical properties (mainly SOC, C : N, and pH) rather than elevation (i.e., canopy cover and environmental factors, especially temperature), in determining base cation and micronutrient availabilities in soils and subsequently their concentrations in plant tissues.

The effect of a plant-based low-carbohydrate ("Eco-Atkins") diet on body weight and blood lipid concentrations in hyperlipidemic subjects.

PubMed

Jenkins, David J A; Wong, Julia M W; Kendall, Cyril W C; Esfahani, Amin; Ng, Vivian W Y; Leong, Tracy C K; Faulkner, Dorothea A; Vidgen, Ed; Greaves, Kathryn A; Paul, Gregory; Singer, William

2009-06-08

Low-carbohydrate, high-animal protein diets, which are advocated for weight loss, may not promote the desired reduction in low-density lipoprotein cholesterol (LDL-C) concentration. The effect of exchanging the animal proteins and fats for those of vegetable origin has not been tested. Our objective was to determine the effect on weight loss and LDL-C concentration of a low-carbohydrate diet high in vegetable proteins from gluten, soy, nuts, fruits, vegetables, cereals, and vegetable oils compared with a high-carbohydrate diet based on low-fat dairy and whole grain products. A total of 47 overweight hyperlipidemic men and women consumed either (1) a low-carbohydrate (26% of total calories), high-vegetable protein (31% from gluten, soy, nuts, fruit, vegetables, and cereals), and vegetable oil (43%) plant-based diet or (2) a high-carbohydrate lacto-ovo vegetarian diet (58% carbohydrate, 16% protein, and 25% fat) for 4 weeks each in a parallel study design. The study food was provided at 60% of calorie requirements. Of the 47 subjects, 44 (94%) (test, n = 22 [92%]; control, n = 22 [96%]) completed the study. Weight loss was similar for both diets (approximately 4.0 kg). However, reductions in LDL-C concentration and total cholesterol-HDL-C and apolipoprotein B-apolipoprotein AI ratios were greater for the low-carbohydrate compared with the high-carbohydrate diet (-8.1% [P = .002], -8.7% [P = .004], and -9.6% [P = .001], respectively). Reductions in systolic and diastolic blood pressure were also seen (-1.9% [P = .052] and -2.4% [P = .02], respectively). A low-carbohydrate plant-based diet has lipid-lowering advantages over a high-carbohydrate, low-fat weight-loss diet in improving heart disease risk factors not seen with conventional low-fat diets with animal products.

Expression of the C3-C 4 intermediate character in somatic hybrids between Brassica napus and the C3-C 4 species Moricandia arvensis.

PubMed

O'Neill, C M; Murata, T; Morgan, C L; Mathias, R J

1996-12-01

The wild crucifer Moricandia arvensis is a potential source of alien genes for the genetic improvement of related Brassica crops. In particular M. arvensis has a C3-C4 intermediate photosynthetic mechanism which results in enhanced recapture of photorespired CO2 and may increase plant water-use efficiency. In order to transfer this trait into Brassica napus, somatic hybridisations were made between leaf mesophyll protoplasts from cultured M. arvensis shoot tips and hypocotyl protoplasts from three Brassica napus cultivars, 'Ariana', 'Cobra' and 'Westar'. A total of 23 plants were recovered from fusion experiments and established in the greenhouse. A wide range of chromosome numbers were observed among the regenerated plants, including some apparent mixoploids. Thirteen of the regenerated plants were identified as nuclear hybrids between B. napus and M. arvensis on the basis of isozyme analysis. The phenotypes of these hybrids were typically rather B. napus-like, but much variability was observed, including variation in flower colour, leaf shape and colour, leaf waxiness, fertility and plant vigour. CO2 compensation point measurements on the regenerated plants demonstrated that 3 of the hybrids express the M. arvensis C3-C4 intermediate character at the physiological level. Semi-thin sections through leaf tissues of these 3 plants revealed the presence of a Kranz-like leaf anatomy characteristic of M. arvensis but not found in B. napus. This is the first report of the expression of this potentially important agronomic trait, transferred from Moricandia, in M. arvensis x B. napus hybrids.

The boron transporter BnaC4.BOR1;1c is critical for inflorescence development and fertility under boron limitation in Brassica napus.

PubMed

Zhang, Quan; Chen, Haifei; He, Mingliang; Zhao, Zhuqing; Cai, Hongmei; Ding, Guangda; Shi, Lei; Xu, Fangsen

2017-09-01

Boron (B) is an essential micronutrient for plants, but the molecular mechanisms underlying the uptake and distribution of B in allotetraploid rapeseed (Brassica napus) are unclear. Here, we identified a B transporter of rapeseed, BnaC4.BOR1;1c, which is expressed in shoot nodes and involved in distributing B to the reproductive organs. Transgenic Arabidopsis plants containing a BnaC4.BOR1;1c promoter-driven GUS reporter gene showed strong GUS activity in roots, nodal regions of the shoots and immature floral buds. Overexpressing BnaC4.BOR1;1c in Arabidopsis wild type or in bor1-1 mutants promoted wild-type growth and rescued the bor1-1 mutant phenotype. Conversely, knockdown of BnaC4.BOR1;1c in a B-efficient rapeseed line reduced B accumulation in flower organs, eventually resulting in severe sterility and seed yield loss. BnaC4.BOR1;1c RNAi plants exhibited large amounts of disintegrated stigma papilla cells with thickened cell walls accompanied by abnormal proliferation of lignification under low-B conditions, indicating that the sterility may be a result of altered cell wall properties in flower organs. Taken together, our results demonstrate that BnaC4.BOR1;1c is a AtBOR1-homologous B transporter gene expressing in both roots and shoot nodes that is essential for the developing inflorescence tissues, which highlights its diverse functions in allotetraploid rapeseed compared with diploid model plant Arabidopsis. © 2017 John Wiley & Sons Ltd.

Phenotypic landscape inference reveals multiple evolutionary paths to C4 photosynthesis

PubMed Central

Williams, Ben P; Johnston, Iain G; Covshoff, Sarah; Hibberd, Julian M

2013-01-01

C4 photosynthesis has independently evolved from the ancestral C3 pathway in at least 60 plant lineages, but, as with other complex traits, how it evolved is unclear. Here we show that the polyphyletic appearance of C4 photosynthesis is associated with diverse and flexible evolutionary paths that group into four major trajectories. We conducted a meta-analysis of 18 lineages containing species that use C3, C4, or intermediate C3–C4 forms of photosynthesis to parameterise a 16-dimensional phenotypic landscape. We then developed and experimentally verified a novel Bayesian approach based on a hidden Markov model that predicts how the C4 phenotype evolved. The alternative evolutionary histories underlying the appearance of C4 photosynthesis were determined by ancestral lineage and initial phenotypic alterations unrelated to photosynthesis. We conclude that the order of C4 trait acquisition is flexible and driven by non-photosynthetic drivers. This flexibility will have facilitated the convergent evolution of this complex trait. DOI: http://dx.doi.org/10.7554/eLife.00961.001 PMID:24082995

Bioremediation of pesticide wastes in soil using two plant species, Kochia Scoparia and Brassica Napus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, E.L.; Anderson, T.A.; Coats, J.R.

1995-12-31

Radiotracer studies were conducted to determine the fate of atrazine and metolachlor, applied as a mixture, in soils taken from pesticide-contaminated sites. Samples taken from nonvegetated areas and from the rhizosphere of Kochia scoparia were treated with {sup 14}C-atrazine and unlabeled metolachlor (50 {mu}g/g each) and incubated for 30, 60 or 135 d. A mass balance of the {sup 14}C applied revealed significant differences between the two soil types in soil bound residues, {sup 14}CO{sub 2}, and the extractable organic fraction (p<0.05). After 135-d incubation, 28% of the applied {sup 14}C was mineralized in Kochia rhizosphere soil, compared to 4%more » in soil taken from a nonvegetated area. A greater amount of {sup 14}C was extractable from the nonvegetated soil compared to the rhizosphere soil (64% and 22%, respectively). The half-life of atrazine based on extractable {sup 14}C-atrazine was 193 d in nonvegetated soil and 50 d in Kochia rhizosphere soil. Additional subsamples of nonvegetated soils treated with a mixture of {sup 14}C-atrazine and metolachlor were allowed to age for 135 d, and then were either planted with Brassica napus, Kochia scoparia, or left unvegetated. Incubations were carried out in enclosed chambers under controlled conditions. After 30 additional days, a subset of samples was extracted and analyzed using thin-layer chromatography, soil and plant combustion, and liquid scintillation spectroscopy. The percent of applied {sup 14}C-atrazine remaining as atrazine in soil which was nonvegetated, or planted with Brassica napus or Kochia scoparia was 9.3, 6.5, and 4.2%, respectively. Combustion of plants revealed that 11% of the applied radioactivity was taken up in Kochia scoparia, while less than 1% was taken up in Brassica napus plants. The potential for vegetation to aid in bioremediating pesticide wastes in soil is promising.« less

C₃ and C₄ plant responses to increased temperatures and altered monsoonal precipitation in a cool desert on the Colorado Plateau, USA.

PubMed

Wertin, Timothy M; Reed, Sasha C; Belnap, Jayne

2015-04-01

Dryland ecosystems represent >40% of the terrestrial landscape and support over two billion people; consequently, it is vital to understand how drylands will respond to climatic change. However, while arid and semiarid ecosystems commonly experience extremely hot and dry conditions, our understanding of how further temperature increases or altered precipitation will affect dryland plant communities remains poor. To address this question, we assessed plant physiology and growth at a long-term (7-year) climate experiment on the Colorado Plateau, USA, where the community is a mix of shallow-rooted C3 and C4 grasses and deep-rooted C4 shrubs. The experiment maintained elevated-temperature treatments (+2 or +4 °C) in combination with altered summer monsoonal precipitation (+small frequent precipitation events or +large infrequent events). Increased temperature negatively affected photosynthesis and growth of the C3 and C4 grasses, but effects varied in their timing: +4 °C treatments negatively affected the C3 grass early in the growing season of both years, while the negative effects of temperature on the C4 grass were seen in the +2 and +4 °C treatments, but only during the late growing season of the drier year. Increased summer precipitation did not affect photosynthesis or biomass for any species, either in the year the precipitation was applied or the following year. Although previous research suggests dryland plants, and C4 grasses in particular, may respond positively to elevated temperature, our findings from a cool desert show marked declines in C3 and C4 photosynthesis and growth, with temperature effects dependent on the degree of warming and growing-season precipitation.

Carbon sequestration by mangrove forest: One approach for managing carbon dioxide emission from coal-based power plant

NASA Astrophysics Data System (ADS)

Ray, Raghab; Jana, Tapan Kumar

2017-12-01

Mangroves are known as natural carbon sinks, taking CO2 out of the atmosphere and store it in their biomass for many years. This study aimed to investigate the capacity of world's largest mangrove, the Sundarbans (Indian part) to sequester anthropogenic CO2 emitted from the proximate coal-based thermal power plant in Kolaghat (∼100 km away from mangrove site). Study also includes Kolkata, one of the largest metropolises of India (∼150 km away from mangrove site) for comparing micrometeorological parameters, biosphere-atmosphere CO2 exchange fluxes and atmospheric pollutants between three distinct environments: mangrove-power plant-metropolis. Hourly sampling of atmospheric CO2 in all three sites (late December 2011 and early January 2012) revealed that CO2 concentrations and emission fluxes were maximum around the power plant (360-621 ppmv, 5.6-56.7 mg m-2s-1 respectively) followed by the metropolis (383-459 ppmv, 3.8-20.4 mg m-2s-1 respectively) and mangroves (277-408 ppmv, -8.9-11.4 mg m-2s-1, respectively). Monthly coal consumption rates (41-57, in 104 ton month-1) were converted to CO2 suggesting that 2.83 Tg C was added to the atmosphere in 2011 for the generation of 7469732 MW energy from the power plant. Indian Sundarbans (4264 km2) sequestered total of 2.79 Tg C which was 0.64% of the annual fossil fuel emission from India in the same time period. Based on these data from 2010 to 2011, it is calculated that about 4328 km2 mangrove forest coverage is needed to sequester all CO2 emitted from the Kolaghat power plant.

Effects of climate on deer bone δ15N and δ13C: Lack of precipitation effects on δ15N for animals consuming low amounts of C 4 plants

NASA Astrophysics Data System (ADS)

Cormie, A. B.; Schwarcz, H. P.

1996-11-01

We have examined the relationship of bone collagen δ15N and δ13C to climatic variables, humidity, temperature, and amount of precipitation using fifty-nine specimens of North American white-tailed deer ( Odocoileus virginianus) from forty-six different locations. In previous studies of African mammals there was a significant correlation between bone collagen δ15N and local amount of precipitation. Results presented here similarly show an increase in δ15N with decreasing amount of precipitation but only for 25% of the animals, namely those consuming more than 10% C 4 plants. These animals also exhibited a significant correlation between δ13C and temperature which mirrors previous observations for grasses suggesting that these deer consume grasses during times of population and nutrient stress. In contrast, even in dry areas containing high proportions of C 4 grasses, the majority of the deer had consumed low amounts of C 4 plants and these deer did not have δ15N which correlate with amount of precipitation. Only when deer deviated from their normal feeding pattern by consuming C 4 plants or grasses did their δ15N correlate with amount of rainfall. For these animals, consumption of C 4 plants or grasses may signal conditions of water and nutrient stress. An increase in δ15N of bone collagen may result from combined effects from excretion of concentrated urine (to conserve water) and increased internal recycling of nitrogen (to conserve nitrogen).

Last millennium environmental changes and climate inferences in the Southeastern Atlantic forest, Brazil.

PubMed

Pessenda, Luiz C R; Saia, Soraya E M G; Gouveia, Susy E M; Ledru, Marie-Pierre; Sifeddine, Abdelfettah; Amaral, Paula G C; Bendassolli, José A

2010-09-01

This study presents paleoenvironmental data based on pollen, elemental and isotopic compositions of organic matter (TOC, N, δ(13)C and δ(15)N) and (14)C dating of 170 cm lake sediment record. Samplings have been made in Lagoa Grande at Parque Estadual Turístico do Alto Ribeira - PETAR, Southern São Paulo State, Southeastern Brazil. The variations in relative frequencies (in percentage) of arboreal pollen along the core range between 40 and 80%. The δ(13)C values ranged from -23% to -30% and C/N of ~10 to 15, indicating the contribution of terrestrial C(3) plants and algae in the sediment organic matter. The δ(15)N results presented values from 3 to 4.5%, also suggesting a mixture of algae and terrestrial C(3) plants. The (14)C dating indicates modern age for the shallow horizons to ~1030 BP at the base of the core. A probable wetter climate in the period of ~370 BP to ~340 BP was inferred from the data set, which corresponds to a part of the period covered by the Little Ice Age (LIA).

Particulate Organic Carbon (POC) and Particulate N (PN) behaviors in Response to Storm Events in the Clear Creek, IA Site of the Intensively Managed Landscape - Critical Zone Observatory (IML-CZO)

NASA Astrophysics Data System (ADS)

Blair, N. E.; Ward, A. S.; Bettis, E. A., III; Zhou, N.; Kazmierczak, B. M.

2017-12-01

A goal of the NSF-sponsored IML-CZO (EAR-1331906) is to understand how the Critical Zone of the agricultural Midwest of North America will respond to the pressures of increased land use and climate change. As a step towards that goal, the landscape response to storm events of one of the IML-CZO field sites, the Clear Creek watershed in Iowa, was studied to determine the sources and quantities of suspended load POC and PN to the creek. The Clear Creek watershed is 270 km2 and is dominated by corn-soybean agriculture. Water samples were collected prior to, during and after 6 storm events during the 2014-2016 period at up to three stations on the creek. The suspended particulate load was isolated via filtration and characterized by C, N elemental and stable isotope analyses. Sediment concentration - discharge relationships vary considerably between storm events. POC δ13C values exhibit pronounced yet consistent changes within events as a function of discharge. In general, δ13C values are reflective of C3 plant sources ( -30‰) at base flow and trend towards an asymptotic value of -22‰ with increasing discharge. The most positive δ13C values also correlate with higher C/N ratios. The 13C-enrichment of the suspended load thus seems to be the result of the inclusion of C4 plant debris, principally corn, from surface soils. Bank erosion with mobilization of in-channel production likely dominate the POC sources at base flow. Top soil erosion incorporating corn (and C3 plant) residue dominate stream inputs at Q >3000 l/s. The C4 plant signal is more prevalent at upstream stations, which is consistent with land use patterns. The presence of corn in the system provides an in situ particle tracer for POC and PN that can be followed downstream and used to investigate exchanges of material between the landscape and stream.

Environmental Assessment (EA): Proposed Construction of a Munitions Flight Maintenance Facility, Hill Air Force Base, Utah

DTIC Science & Technology

2008-07-01

1997) Ozone(031 /·-c.,.. ?i Ogden C.ty Ma1 tenance Area (Redes~gnated 2001) er ~~.., Sa Laice Oty Ma1 enance Alea (RedeSIQreled 1999) Pr...disposal. 3.4 Vegetation Hill AFB is located in a geographic region that would typically support a mountain -brush type native plant community. Dominant

A dual resistance gene system prevents infection by three distinct pathogens.

PubMed

Narusaka, Mari; Kubo, Yasuyuki; Shiraishi, Tomonori; Iwabuchi, Masaki; Narusaka, Yoshihiro

2009-10-01

Colletotrichum higginsianum causes typical anthracnose lesions on the leaves, petioles, and stems of cruciferous plants. Inoculation of Arabidopsis thaliana ecotype Columbia leaves with C. higginsianum results in fungal growth and disease symptoms reminiscent of those induced in other cruciferous plants. We performed map-based cloning and natural variation analysis of 19 A. thaliana ecotypes to identify a dominant resistance locus against C. higginsianum. We found that the A. thaliana RCH2 (for recognition of C. higginsianum) locus encodes two NB-LRR proteins, both of which are required for resistance to C. higginsianum in the A. thaliana ecotype Ws-0. Both proteins are well-characterized R proteins involved in resistance against bacterial pathogens; RRS1 (resistance to Ralstonia solanacearum 1) confers resistance to strain Rs1000 of R. solanacearum and RPS4 to Pseudomonas syringae pv. tomato strain DC3000 expressing avrRps4 (Pst-avrRps4). Furthermore, we found that both RRS1-Ws and RPS4-Ws genes are required for resistance to Pst-avrRps4 and to Rs1002 R. solanacearum. We therefore demonstrate that a pair of neighboring genes, RRS1-Ws and RPS4-Ws, function cooperatively as a dual R-gene system against at least three distinct pathogens.

Stability-activity tradeoffs constrain the adaptive evolution of RubisCO.

PubMed

Studer, Romain A; Christin, Pascal-Antoine; Williams, Mark A; Orengo, Christine A

2014-02-11

A well-known case of evolutionary adaptation is that of ribulose-1,5-bisphosphate carboxylase (RubisCO), the enzyme responsible for fixation of CO2 during photosynthesis. Although the majority of plants use the ancestral C3 photosynthetic pathway, many flowering plants have evolved a derived pathway named C4 photosynthesis. The latter concentrates CO2, and C4 RubisCOs consequently have lower specificity for, and faster turnover of, CO2. The C4 forms result from convergent evolution in multiple clades, with substitutions at a small number of sites under positive selection. To understand the physical constraints on these evolutionary changes, we reconstructed in silico ancestral sequences and 3D structures of RubisCO from a large group of related C3 and C4 species. We were able to precisely track their past evolutionary trajectories, identify mutations on each branch of the phylogeny, and evaluate their stability effect. We show that RubisCO evolution has been constrained by stability-activity tradeoffs similar in character to those previously identified in laboratory-based experiments. The C4 properties require a subset of several ancestral destabilizing mutations, which from their location in the structure are inferred to mainly be involved in enhancing conformational flexibility of the open-closed transition in the catalytic cycle. These mutations are near, but not in, the active site or at intersubunit interfaces. The C3 to C4 transition is preceded by a sustained period in which stability of the enzyme is increased, creating the capacity to accept the functionally necessary destabilizing mutations, and is immediately followed by compensatory mutations that restore global stability.

Root hairs increase root exudation and rhizosphere extension

NASA Astrophysics Data System (ADS)

Holz, Maire; Zarebandanadkouki, Mohsen; Kuzyakov, Yakov; Carmintati, Andrea

2017-04-01

Plant roots employ various mechanisms to increase their access to limited soil resources. An example of such strategies is the production of root hairs. Root hairs extend the root surface and therefore increase the access to nutrients. Additionally, carbon release from root hairs might facilitate nutrient uptake by spreading of carbon in the rhizosphere and enhancing microbial activity. The aim of this study was to test: i) how root hairs change the allocation of carbon in the soil-plant system; ii) whether root hairs exude carbon into the soil and iii) how differences in C release between plants with and without root hairs affect rhizosphere extension. We grew barley plants with and without root hairs (wild type: WT, bald root barley: brb) in rhizoboxes filled with a sandy soil. Root elongation was monitored over time. After 4 weeks of growth, plants were labelled with 14CO2. A filter paper was placed on the soil surface before labelling and was removed after 36 h. 14C imaging of the soil surface and of the filter paper was used to quantify the allocation of 14C into the roots and the exudation of 14C, respectively. Plants were sampled destructively one day after labeling to quantify 14C in the plant-soil system. 14CO2 release from soil over time (17 d) was quantified by trapping CO2 in NaOH with an additional subset of plants. WT and brb plants had a similar aboveground biomass and allocated similar amounts of 14C into shoots (170 KBq for WT; 152 KBq for brb) and roots one day after labelling. Biomass of root, rhizosphere soil as well as root elongation were lower for brb compared to the wild type. WT plants transported more C from the shoots to the roots (22.8% for WT; 13.8% for brb) and from the root into the rhizosphere (8.8% for WT 3.5% for brb). Yet lower amounts of 14CO2 were released from soil over time for WT. Radial and longitudinal rhizosphere extension was increased for WT compared to brb (4.7 vs. 2.6 mm; 5.6 vs. 3.1 cm). The total exudation which was estimated based on the grey values of the filter paper images was 1.6 times higher for WT compared to brb. After one month, brb plants performed as good as WT plants, presumably because nutrients and water were not limiting for young plants. Under nutrient limiting conditions higher C release as well as increased longitudinal and radial rhizosphere extension for WT may maintain higher nutrient accessibility compared to root hair free plants.

Transcriptome comparisons shed light on the pre-condition and potential barrier for C4 photosynthesis evolution in eudicots.

PubMed

Tao, Yimin; Lyu, Ming-Ju Amy; Zhu, Xin-Guang

2016-05-01

C4 photosynthesis evolved independently from C3 photosynthesis in more than 60 lineages. Most of the C4 lineages are clustered together in the order Poales and the order Caryophyllales while many other angiosperm orders do not have C4 species, suggesting the existence of biological pre-conditions in the ancestral C3 species that facilitate the evolution of C4 photosynthesis in these lineages. To explore pre-adaptations for C4 photosynthesis evolution, we classified C4 lineages into the C4-poor and the C4-rich groups based on the percentage of C4 species in different genera and conducted a comprehensive comparison on the transcriptomic changes between the non-C4 species from the C4-poor and the C4-rich groups. Results show that species in the C4-rich group showed higher expression of genes related to oxidoreductase activity, light reaction components, terpene synthesis, secondary cell synthesis, C4 cycle related genes and genes related to nucleotide metabolism and senescence. In contrast, C4-poor group showed up-regulation of a PEP/Pi translocator, genes related to signaling pathway, stress response, defense response and plant hormone metabolism (ethylene and brassinosteroid). The implications of these transcriptomic differences between the C4-rich and C4-poor groups to C4 evolution are discussed.

Relative contribution of C3 and C4 type terrestrial organic matter in the Mahanadi offshore (Bay of Bengal) sediments and climatic implication.

NASA Astrophysics Data System (ADS)

da Silva, Rheane; Mazumdar, Aninda; Naik, Bg

2017-04-01

C3 and C4 are dominant vegetation in terrestrial environment. The primary product of photosynthesis of C3 plants is a 3 carbon bearing compound called phosphoglycerate (PGA). In contrast, CO2 is transferred to bundle sheath cells via 4 carbon bearing compound oxaloacetate/mallate and fixed by RuBiSCO in C4 plants. This marked variation in CO2 diffusion across stomata and enzymatic pathways lead to differences in stable carbon isotope ratios. Factors that control relative abundance of these vegetation types are concentration of p-CO2, temperature and humidity. Low p-CO2, air temperature below cross over temperature and aridity are the climatic parameters favoring expansion of C4 type vegetation, whereas higher extreme conditions promote greater C3 type production (Ehleringer, J. R, 2005). In marine sediment n-alkane (lipid fraction) distribution and compound specific isotope ratios are ideal markers to characterize nature of terrestrial organic flux owing to high diagenetic stability and near 100% extraction efficiency. We report here the relative abundance of C3-C4 vegetation over 8 marine isotope stages covering 300kyr. A 39.08 m long core (MD 161-19) was collected onboard ORV Marion Dufresne, at a water depth of 1480 m (Lat: 18 59.1092N Long: 85 41.1669E) (Mazumdar., et. al. 2014) for the study of sediment physico chemical properties and their link to paleoclimatic variation. The carbon isotope ratios of C-27 n-alkane range from -35.3‰ to -23.6‰ VPDB. 13C enrichment trends indicate a greater contribution from C4 vegetation type and 13C depletion trends are attributed to greater flux of C3 type vegetation. Mass balance calculation to reconstruct the temporal variation in C3/ C4 ratios is carried out using the end member values of -34.5‰ and -19.8‰ respectively (Collister.,et. al. 1994). The calculated C3/C4 ratio is 27:73 at LGM and shifts to 71:29 around 6 kyr BP. Based on results, we observe that colder isotope substages characterized by lower pCO2 saw relative expansion of C4 vegetation while warmer, high pCO2 periods supported C3 expansion. A high resolution work is being carried out to get better understanding on actual limiting factors across the last 300 ky responsible for changes in C3 vs C4 expansion. Our data may help in understanding how vegetation may respond to future global warming and climate change including pCO2 build up, change in air temperature and monsoonal rainfall. References: • Collister, James W., et al. "Compound-specific δ 13C analyses of leaf lipids from plants with differing carbon dioxide metabolisms." Organic Geochemistry 21.6-7 (1994): 619-627. • Ehleringer, J. R. The influence of atmospheric CO2, temperature, and water on the abundance of C3/C4 taxa. In A history of atmospheric CO2 and its effects on plants, animals, and ecosystems Springer New York 214-231 (2005). • Mazumdar, A., et al. "Pore-water chemistry of sediment cores off Mahanadi Basin, Bay of Bengal: Possible link to deep seated methane hydrate deposit." Marine and Petroleum Geology 49 (2014): 162-175.

C3 and C4 biomass allocation responses to elevated CO2 and nitrogen: contrasting resource capture strategies

USGS Publications Warehouse

White, K.P.; Langley, J.A.; Cahoon, D.R.; Megonigal, J.P.

2012-01-01

Plants alter biomass allocation to optimize resource capture. Plant strategy for resource capture may have important implications in intertidal marshes, where soil nitrogen (N) levels and atmospheric carbon dioxide (CO2) are changing. We conducted a factorial manipulation of atmospheric CO2 (ambient and ambient + 340 ppm) and soil N (ambient and ambient + 25 g m-2 year-1) in an intertidal marsh composed of common North Atlantic C3 and C4 species. Estimation of C3 stem turnover was used to adjust aboveground C3 productivity, and fine root productivity was partitioned into C3-C4 functional groups by isotopic analysis. The results suggest that the plants follow resource capture theory. The C3 species increased aboveground productivity under the added N and elevated CO2 treatment (P 2 alone. C3 fine root production decreased with added N (P 2 (P = 0.0481). The C4 species increased growth under high N availability both above- and belowground, but that stimulation was diminished under elevated CO2. The results suggest that the marsh vegetation allocates biomass according to resource capture at the individual plant level rather than for optimal ecosystem viability in regards to biomass influence over the processes that maintain soil surface elevation in equilibrium with sea level.

Risk analysis of heat recovery steam generator with semi quantitative risk based inspection API 581

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prayogo, Galang Sandy, E-mail: gasandylang@live.com; Haryadi, Gunawan Dwi; Ismail, Rifky

Corrosion is a major problem that most often occurs in the power plant. Heat recovery steam generator (HRSG) is an equipment that has a high risk to the power plant. The impact of corrosion damage causing HRSG power plant stops operating. Furthermore, it could be threaten the safety of employees. The Risk Based Inspection (RBI) guidelines by the American Petroleum Institute (API) 58 has been used to risk analysis in the HRSG 1. By using this methodology, the risk that caused by unexpected failure as a function of the probability and consequence of failure can be estimated. This paper presentedmore » a case study relating to the risk analysis in the HRSG, starting with a summary of the basic principles and procedures of risk assessment and applying corrosion RBI for process industries. The risk level of each HRSG equipment were analyzed: HP superheater has a medium high risk (4C), HP evaporator has a medium-high risk (4C), and the HP economizer has a medium risk (3C). The results of the risk assessment using semi-quantitative method of standard API 581 based on the existing equipment at medium risk. In the fact, there is no critical problem in the equipment components. Damage mechanisms were prominent throughout the equipment is thinning mechanism. The evaluation of the risk approach was done with the aim of reducing risk by optimizing the risk assessment activities.« less

matK-QR classifier: a patterns based approach for plant species identification.

PubMed

More, Ravi Prabhakar; Mane, Rupali Chandrashekhar; Purohit, Hemant J

2016-01-01

DNA barcoding is widely used and most efficient approach that facilitates rapid and accurate identification of plant species based on the short standardized segment of the genome. The nucleotide sequences of maturaseK ( matK ) and ribulose-1, 5-bisphosphate carboxylase ( rbcL ) marker loci are commonly used in plant species identification. Here, we present a new and highly efficient approach for identifying a unique set of discriminating nucleotide patterns to generate a signature (i.e. regular expression) for plant species identification. In order to generate molecular signatures, we used matK and rbcL loci datasets, which encompass 125 plant species in 52 genera reported by the CBOL plant working group. Initially, we performed Multiple Sequence Alignment (MSA) of all species followed by Position Specific Scoring Matrix (PSSM) for both loci to achieve a percentage of discrimination among species. Further, we detected Discriminating Patterns (DP) at genus and species level using PSSM for the matK dataset. Combining DP and consecutive pattern distances, we generated molecular signatures for each species. Finally, we performed a comparative assessment of these signatures with the existing methods including BLASTn, Support Vector Machines (SVM), Jrip-RIPPER, J48 (C4.5 algorithm), and the Naïve Bayes (NB) methods against NCBI-GenBank matK dataset. Due to the higher discrimination success obtained with the matK as compared to the rbcL , we selected matK gene for signature generation. We generated signatures for 60 species based on identified discriminating patterns at genus and species level. Our comparative assessment results suggest that a total of 46 out of 60 species could be correctly identified using generated signatures, followed by BLASTn (34 species), SVM (18 species), C4.5 (7 species), NB (4 species) and RIPPER (3 species) methods As a final outcome of this study, we converted signatures into QR codes and developed a software matK -QR Classifier (http://www.neeri.res.in/matk_classifier/index.htm), which search signatures in the query matK gene sequences and predict corresponding plant species. This novel approach of employing pattern-based signatures opens new avenues for the classification of species. In addition to existing methods, we believe that matK -QR Classifier would be a valuable tool for molecular taxonomists enabling precise identification of plant species.

On the contributions of photorespiration and compartmentation to the contrasting intramolecular 2H profiles of C3 and C4 plant sugars

Treesearch

Youping Zhou; Benli Zhang; Hilary Stuart-Williams; Kliti Grice; Charles H. Hocart; Arthur Gessler; Zachary E. Kayler; Graham D. Farquhar

2018-01-01

Compartmentation of C4 photosynthetic biochemistry into bundle sheath (BS) and mesophyll (M) cells, and photorespiration in C3 plants is predicted to have hydrogen isotopic consequences for metabolites at both molecular and site-specific levels. Molecular-level evidence was recently reported (Zhou et al., 2016), but...

Photosynthetic pathway diversity in a seasonal pool community

USGS Publications Warehouse

Keeley, Jon E.

1999-01-01

1. Photosynthetic pathway diversity was evaluated for the dominant species in a seasonally aquatic community in the south-western USA using 14C pulse-chase techniques.2. Under submerged conditions, only about half of the species were clearly C3, three of the 15 dominants were CAM, one species was C4 and three were potentially assimilating carbon with both C3 and C4 fixation.3. During the brief terrestrial stage in the life history of these amphibious plants, both the CAM and the C3 + C4 species switched to C3, whereas the C4 species did not switch.4. Numerous variations were apparent; for example, the C4 species, while exhibiting a biochemical pathway indistinguishable from terrestrial C4 plants, lacked Kranz anatomy in the aquatic foliage. Also, despite well-developed CAM in several species, others exhibited low-level diel changes in acidity, apparently not indicative of CAM.5. Species with C4 or CAM CO2 concentrating mechanisms lacked the capacity for bicarbonate uptake, an alternative CO2 concentrating mechanism found in certain C3 species in this community.6. Rubisco/PEPC in aquatic foliage was higher in C3 species than in C4, CAM or putative C3 + C4species. In the terrestrial phase, as expected, the switch from CAM or C3 + C4 to strictly C3assimilation was associated with a substantial increase in Rubisco/PEPC. Quite unexpected, however, was the substantial increase in this ratio in terrestrial C3 foliage. It is hypothesized that submerged C3 plants utilize PEPC for recycling of respiratory CO2 and/or C4 phototrophism under field conditions of limited CO2 and O2 saturation, and this is lost in the terrestrial foliage.

Tomato leaf curl Yunnan virus-encoded C4 induces cell division through enhancing stability of Cyclin D 1.1 via impairing NbSKη -mediated phosphorylation in Nicotiana benthamiana

PubMed Central

Mei, Yuzhen; Yang, Xiuling; Huang, Changjun

2018-01-01

The whitefly-transmitted geminiviruses induce severe developmental abnormalities in plants. Geminivirus-encoded C4 protein functions as one of viral symptom determinants that could induce abnormal cell division. However, the molecular mechanism by which C4 contributes to cell division induction remains unclear. Here we report that tomato leaf curl Yunnan virus (TLCYnV) C4 interacts with a glycogen synthase kinase 3 (GSK3)/SHAGGY-like kinase, designed NbSKη, in Nicotiana benthamiana. Pro32, Asn34 and Thr35 of TLCYnV C4 are critical for its interaction with NbSKη and required for C4-induced typical symptoms. Interestingly, TLCYnV C4 directs NbSKη to the membrane and reduces the nuclear-accumulation of NbSKη. The relocalization of NbSKη impairs phosphorylation dependent degradation on its substrate-Cyclin D1.1 (NbCycD1;1), thereby increasing the accumulation level of NbCycD1;1 and inducing the cell division. Moreover, NbSKη-RNAi, 35S::NbCycD1;1 transgenic N. benthamiana plants have the similar phenotype as 35S::C4 transgenic N. benthamiana plants on callus-like tissue formation resulted from abnormal cell division induction. Thus, this study provides new insights into mechanism of how a viral protein hijacks NbSKη to induce abnormal cell division in plants. PMID:29293689

[Separation and identification of endophytic fungi from desert plant Cynanchum komarovii].

PubMed

Duan, Hai-Jing; Han, Ting; Wu, Xiu-Li; Li, Na; Chen, Jing; Qin, Lu-Ping

2013-02-01

The research aimed to investigate the entophytic fungal community of Cynanchum Komarrovii, including the biodiversity in different organs and the correlations with ecological environment. Endophytic fungi with patent bioactivity were also rapidly screened. PDA medium was used to isolate and purify the endophytic fungi from C. komarovii living in Shaanxi and Ningxia district, respectively. The strains were identified based on the morphological characteristics of the fungi and similarity of 5.8S gene and internal transcribed spacer (ITS) sequence. Pyriculaia oryzae model was applied to preliminarily screen the active fungi. Ninety-four strains of endophytic fungi were isolated and identified to 9 species, 13 genera, 9 families and 6 orders, among them, 47 strains were from the plants living in Ningxia. And then, 5 of them were isolated from roots, 14 from branches, and 28 from leaves. They were identified belonging to 8 species, 9 genera, 5 families and 4 orders. Additionally, 47 strains were from the plants living in Shaanxi. 16 were isolated from the roots, 18 from branches, 13 from leaves. They were identified belonging to 5 species, 8 genera, 6 families and 4 orders. By preliminary screening, 18 strains of endophytes completely inhibited the germination of conidium, which showed a potential bioactivity for these fungi. Both N4 and S17 strains had stronger growth inhibition effect. Endophytic fungi from desert plant C. komarovii have the feature of diversity. Different geographical environment and type of organizations lead to the significant difference on the quantity and the species composition. Most of fungi in Ningxia C. komarovii distribute in leaves. However, most of those in Shaanxi C. komarovii distribute in stems and leaves. It also indicated that endophytes from C. komarovii had a strong antifungal activity.

Late Pleistocene C4 plant dominance and summer rainfall in the southwestern United States from isotopic study of herbivore teeth

USGS Publications Warehouse

Connin, S.L.; Betancourt, J.; Quade, Jay

1998-01-01

Patterns of climate and C4 plant abundance in the southwestern United States during the last glaciation were evaluated from isotopic study of herbivore tooth enamel. Enamel ??13C values revealed a substantial eastward increase in C4 plant consumption for Mammuthus spp., Bison spp., Equus spp., and Camelops spp. The ??13C values were greatest in Bison spp. (-6.9 to + 1.7???) and Mammuthus spp. (-9.0 to +0.3???), and in some locales indicated C4-dominated grazing. The ??13C values of Antilocaprids were lowest among taxa (-12.5 to -7.9???) and indicated C3 feeding at all sites. On the basis of modern correlations between climate and C4 grass abundance, the enamel data imply significant summer rain in parts of southern Arizona and New Mexico throughout the last glaciation. Enamel ??18O values range from +19.0 to +31.0??? and generally increase to the east. This pattern could point to a tropical or subtropical source of summer rainfall. At a synoptic scale, the isotope data indicate that interactions of seasonal moisture, temperature, and lowered atmospheric pCO2 determined glacial-age C4 abundance patterns.

Evolution of C4 plants: a new hypothesis for an interaction of CO2 and water relations mediated by plant hydraulics.

PubMed

Osborne, Colin P; Sack, Lawren

2012-02-19

C(4) photosynthesis has evolved more than 60 times as a carbon-concentrating mechanism to augment the ancestral C(3) photosynthetic pathway. The rate and the efficiency of photosynthesis are greater in the C(4) than C(3) type under atmospheric CO(2) depletion, high light and temperature, suggesting these factors as important selective agents. This hypothesis is consistent with comparative analyses of grasses, which indicate repeated evolutionary transitions from shaded forest to open habitats. However, such environmental transitions also impact strongly on plant-water relations. We hypothesize that excessive demand for water transport associated with low CO(2), high light and temperature would have selected for C(4) photosynthesis not only to increase the efficiency and rate of photosynthesis, but also as a water-conserving mechanism. Our proposal is supported by evidence from the literature and physiological models. The C(4) pathway allows high rates of photosynthesis at low stomatal conductance, even given low atmospheric CO(2). The resultant decrease in transpiration protects the hydraulic system, allowing stomata to remain open and photosynthesis to be sustained for longer under drying atmospheric and soil conditions. The evolution of C(4) photosynthesis therefore simultaneously improved plant carbon and water relations, conferring strong benefits as atmospheric CO(2) declined and ecological demand for water rose.

Aquatic modules for bioregenerative life support systems based on the C.E.B.A.S. biotechnology [correction of biotechnilogy].

PubMed

Bluem, V; Paris, F

2001-01-01

Most concepts for bioregenerative life support systems are based on edible higher land plants which create some problems with growth and seed generation under space conditions. Animal protein production is mostly neglected because of the tremendous waste management problems with tetrapods under reduced weightlessness. Therefore, the "Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) was developed which represents an artificial aquatic ecosystem containing aquatic organisms which are adapted at all to "near weightlessness conditions" (fishes Xiphophorus helleri, water snails Biomphalaria glabrata, ammonia oxidizing bacteria and the rootless non-gravitropic edible water plant Ceratophyllum demersum). Basically the C.E.B.A.S. consists of 4 subsystems: a ZOOLOGICAL (correction of ZOOLOGICASL) COMPONENT (animal aquarium), a BOTANICAL COMPONENT (aquatic plant bioreactor), a MICROBIAL COMPONENT (bacteria filter) and an ELECTRONICAL COMPONENT (data acquisition and control unit). Superficially, the function principle appears simple: the plants convert light energy into chemical energy via photosynthesis thus producing biomass and oxygen. The animals and microorganisms use the oxygen for respiration and produce the carbon dioxide which is essential for plant photosynthesis. The ammonia ions excreted by the animals are converted by the bacteria to nitrite and then to nitrate ions which serve as a nitrogen source for the plants. Other essential ions derive from biological degradation of animal waste products and dead organic matter. The C.E.B.A.S. exists in 2 basic versions: the original C.E.B.A.S. with a volume of 150 liters and a self-sustaining standing time of more than 13 month and the so-called C.E.B.A.S. MINI MODULE with a volume of about 8.5 liters. In the latter there is no closed food loop by reasons of available space so that animal food has to be provided via an automated feeder. This device was flown already successfully on the STS-89 and STS-90 spaceshuttle missions and the working hypothesis was verified that aquatic organisms are nearly not affected at all by space conditions, i.e. that the plants exhibited biomass production rates identical to the sound controls and that as well the reproductive, and the immune system as the embryonic and ontogenic development of the animals remained undisturbed. Currently the C.E.B.A.S. MINI MODLULE is prepared for a third spaceshuttle flight (STS-107) in spring 2001. Based on the results of the space experiments a series of prototypes of aquatic food production modules for the implementation into BLSS were developed. This paper describes the scientific disposition of the STS-107 experiment and of open and closed aquaculture systems based on another aquatic plant species, the Lemnacean Wolffia arrhiza which is cultured as a vegetable in Southeastern Asia. This plant can be grown in suspension culture and several special bioreactors were developed for this purpose. W. arrhiza reproduces mainly vegetatively by buds but also sexually from time to time and is therefore especially suitable for genetic engineering, too. Therefore it was used, in addition, to optimize the C.E.B.A.S. MINI MODULE to allow experiments with a duration of 4 month in the International Space Station the basic principle of which will be explained. In the context of aquaculture systems for BLSS the continuous replacement of removed fish biomass is an essential demand. Although fish reproduction seems not to be affected in the shortterm space experiments with the C.E.B.A.S. MINI MODULE a functional and reliable hatchery for the production of siblings under reduced weightlessness is connected with some serious problems. Therefore an automated "reproduction module" for the herbivorous fish Tilapia rendalli was developed as a laboratory prototype. It is concluded that aquatic modules of different degrees of complexity can optimize the productivity of BLSS based on higher land plants and that they offer an unique opportunity for the production of animal protein in lunar or planetary bases. c2001 Elsevier Science Ltd. All rights reserved.

Production and postharvest characteristics of Rosa hybrida L. Meijikatar'' grown in pots under carbon dioxide enrichment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, D.G.; Kelly, J.W.; Rajapakse, N.C.

1993-09-01

The effects of carbon dioxide enrichment on growth, photosynthesis, and postharvest characteristics of Meijikatar'' potted roses were determined. Plants were grown in 350, 700, or 1,050 [mu]l CO[sub 2]/liter until they reached 50% flower bud coloration and then were placed into dark storage for 5 days at 4 or 16C. Plants grown in 700 or 1,050 [mu]l CO[sub 2]/liter reached the harvest stage earlier and were taller at harvest than plants produced in 350 [mu]l CO[sub 2]/liter, but there were no differences in the number of flowers and flower buds per plant among CO[sub 2] treatments. Plants grown in earlymore » spring were taller and had more flowers and flower buds than plants grown in late winter. shoot and root growth of plants grown in 700 or 1,050 [mu]l CO[sub 2]/liter were higher than in plants produced in 350 [mu]l CO[sub 2]/liter, with plants grown in early spring showing greater increases than plants grown in late winter. Immediately after storage, plants grown in 350 [mu]l CO[sub 2]/liter and stored at 4C had the fewest etiolated shoots, while plants grown in 1,050 [mu]l CO[sub 2]/liter and stored at 16C had the most. Five days after removal from storage, chlorophyll concentration of upper and lower leaves had been reduced by [approximately]50% from the day of harvest. Carbon dioxide enrichment had no effect on postharvest leaf chlorosis, but plants grown in early spring and stored at 16C had the most leaf chlorosis while plants grown in late winter and stored at 4C had the least leaf chlorosis.« less

Identifying the role of plant-microbial interactions in driving Arctic carbon cycle changes using a 13C isotope tracer

NASA Astrophysics Data System (ADS)

Hough, M.; Tfaily, M. M.; Blazewicz, S.; Dorrepaal, E.; Crill, P. M.; Rich, V. I.; Saleska, S. R.

2017-12-01

Thawing arctic permafrost (which contains 30-50% of global soil carbon) is expected to drive substantial alterations to carbon (C) cycling that will accelerate climate change. As permafrost thaws, old C may decompose more rapidly and be released as methane (CH4) and carbon dioxide (CO2), but thawing soil can also increase plant productivity as perennial shrub communities transition to faster growing annual wetland plants. The effect of plant community changes on the C cycle is not yet well understood. It could mitigate C loss if C input rates are high enough, or it could increase contributions to CH4 emission (a more potent greenhouse gas than CO2) if it decomposes anaerobically. To investigate the influence of fresh plant litter inputs on peat organic material, microbial communities, and greenhouse gas emissions we traced 13C-enriched plant material from Eriophorum and Sphagnum plants added to arctic peat decomposition incubations into each of these components. High resolution FT-ICR mass spectrometry showed changes in the types of enriched compounds over time indicative of microbial processing. Density fractionation of microbial DNA showed enrichment of the microbial community indicating uptake of 13C-enriched compounds from the plant litter. CO2 and CH4 fluxes were highly 13C enriched and showed three distinct phases of flux after litter addition which were not seen in incubations with no litter added. Together, these lines of evidence indicate that fresh litter inputs may play an important role in structuring microbial decomposition. Future work will explore this influence through closer examination of organic matter and microbial community changes during decomposition.

Nature based solutions to mitigate soil sealing in urban areas: Results from a 4-year study comparing permeable, porous, and impermeable pavements.

PubMed

Fini, A; Frangi, P; Mori, J; Donzelli, D; Ferrini, F

2017-07-01

Soil sealing is one of the most pervasive forms of soil degradation that follows urbanization and, despite innovative pavements (i.e. pervious) are being installed in urban areas to mitigate it, there is little research on the effects of pervious pavements on soil water and carbon cycle and on the physiology of urban trees. The aim of this 4-year experiment was to assess the effects of three pavements, differing in permeability to water and gases, on some soil physical parameters, and on growth and physiology of newly planted Celtis australis and Fraxinus ornus. Treatments were: 1) impermeable pavement (asphalt on concrete sub-base); 2) permeable pavement (pavers on crushed rock sub-base); 3) porous design (porous pavement on crushed rock sub-base); 4) control (unpaved soil, kept free of weed by chemical control). Soil (temperature, moisture, oxygen content and CO 2 efflux) and plant (above- and below-ground growth, leaf gas exchange, chlorophyll fluorescence, water relations) parameters were measured. All types of pavements altered the water cycle compared to unpaved soil plots, but this disturbance was less intense in porous pavements than in other soil cover types. Porous pavements allowed both higher infiltration and evaporation of water than both pavers and asphalt. Reduction of evaporative cooling from soil paved with permeable and impermeable pavements contributed to significant soil warming: at 20cm depth, soils under concrete pavers and asphalt were 4 and 5°C warmer than soil covered by porous pavements and unpaved soils, respectively. Thus, enhancing evaporation from paved soil by the use of porous pavements may contribute to mitigating urban heat islands. CO 2 greatly accumulated under impermeable and permeable pavements, but not under porous pavements, which showed CO 2 efflux rates similar to control. Soil oxygen slightly decreased only beneath asphalt. Growth of newly planted C. australis and F. ornus was little affected by pavement type. Tree transpiration rapidly depleted soil moisture compared to the not-planted scenario, but soil moisture did not fall below wilting point (particularly in the deeper soil layers, i.e. 40-50cm) in any treatment. While C. australis showed similar leaf gas exchange and water relations in all treatments, F. ornus showed a depression in CO 2 assimilation and slight signs of stress of the photosynthetic apparatus when planted in soil covered with impermeable pavement. The effects of soil cover with different materials on tree growth and physiology were little, because newly planted trees have most of their roots still confined in the unpaved planting pit. Still, the reduction of soil sealing around the planting pit triggered the establishment of sensitive species such as ash. Further research is needed to assess the effects of different pavement types on established, larger trees. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of physiological and anatomical changes of C3 (Oryza sativa [L.]) and C4 (Echinochloa crusgalli [L.]) leaves in response to drought stress

NASA Astrophysics Data System (ADS)

Hamim, Hamim; Banon, Sri; Dorly, Dorly

2016-01-01

The experiment aimed to analyse the different response of C3 (Oryza sativa L.) and C4 (Echinochloa crusgalli L.) species to drought stress based on physiological and anatomical properties. Seeds of rice (Oryza sativa) and Echinochloa (Echinochloa crusgalli) were grown in 15 cm (D) pot for 6 weeks under well-watered conditions. After 6 weeks the plants were divided into two groups, (1) well-watered which were watered daily, and (2) drought stress which were withheld from watering for 6 days. After 6 days of drought, the plants were then re-watered to analyse plant recovery. During drought period, the plants were analysed for growth, leaf relative water content (RWC), photosynthesis, and leaf anatomy. Drought stress significantly reduced leaf RWC of both species, but the reduction was bigger in rice than in Echinochloa. The maximum efficiency of photosynthesis (Fv/Fm) was decrease significantly in response to drought stress by about 48.04% in rice, while it was only 34.40% in Echinochloa. Anatomical analysis showed drought treatment tended to reduce leaf thickness in the area of bulliform cell, major- as well as intervein and xylem diameter, more in Echinochloa than in rice, suggesting that the decrease of vein and xylem diameter is among the anatomical parameters that is important to overcome from drought stress in Echinochloa. The number of chloroplast in the mesophyll cell and bundle sheath cell (BSC) was different between these two species, where in Echinochloa chloroplast was found in both mesophyll as well as BSC, while in rice it was only found in mesophyll cell, confirmed that Echinochloa is a C4 and rice is a C3 species. Interestingly, in Echinochloa, the number of chloroplast was significantly increased due to drought stress in BSC, but not in mesophyll cell. The number of starch granules also dramatically increased in response to drought in the mesophyll cells of rice and Echinochloa, and in the bundle sheath cell of Echinochloa which indicate that C3 cycle may be occurred in C4 species, at least in Echinochloa, especially during drought stress.

CO2 enrichment inhibits shoot nitrate assimilation in C3 but not C4 plants and slows growth under nitrate in C3 plants.

PubMed

Bloom, Arnold J; Asensio, Jose Salvador Rubaio; Randall, Lesley; Rachmilevitch, Shimon; Cousins, Asaph B; Carlisle, Eli A

2012-02-01

The CO2 concentration in Earth's atmosphere may double during this century. Plant responses to such an increase depend strongly on their nitrogen status, but the reasons have been uncertain. Here, we assessed shoot nitrate assimilation into amino acids via the shift in shoot CO2 and O2 fluxes when plants received nitrate instead of ammonium as a nitrogen source (deltaAQ). Shoot nitrate assimilation became negligible with increasing CO2 in a taxonomically diverse group of eight C3 plant species, was relatively insensitive to CO2 in three C4 species, and showed an intermediate sensitivity in two C3-C4 intermediate species. We then examined the influence of CO2 level and ammonium vs. nitrate nutrition on growth, assessed in terms of changes in fresh mass, of several C3 species and a Crassulacean acid metabolism (CAM) species. Elevated CO2 (720 micromol CO2/mol of all gases present) stimulated growth or had no effect in the five C3 species tested when they received ammonium as a nitrogen source but inhibited growth or had no effect if they received nitrate. Under nitrate, two C3 species grew faster at sub-ambient (approximately 310 micromol/mol) than elevated CO2. A CAM species grew faster at ambient than elevated or sub-ambient CO2 under either ammonium or nitrate nutrition. This study establishes that CO2 enrichment inhibits shoot nitrate assimilation in a wide variety of C3 plants and that this phenomenon can have a profound effect on their growth. This indicates that shoot nitrate assimilation provides an important contribution to the nitrate assimilation of an entire C3 plant. Thus, rising CO2 and its effects on shoot nitrate assimilation may influence the distribution of C3 plant species.

Evolution of the Phosphoenolpyruvate Carboxylase Protein Kinase Family in C3 and C4 Flaveria spp.1[W][OPEN

PubMed Central

Aldous, Sophia H.; Weise, Sean E.; Sharkey, Thomas D.; Waldera-Lupa, Daniel M.; Stühler, Kai; Mallmann, Julia; Groth, Georg; Gowik, Udo; Westhoff, Peter; Arsova, Borjana

2014-01-01

The key enzyme for C4 photosynthesis, Phosphoenolpyruvate Carboxylase (PEPC), evolved from nonphotosynthetic PEPC found in C3 ancestors. In all plants, PEPC is phosphorylated by Phosphoenolpyruvate Carboxylase Protein Kinase (PPCK). However, differences in the phosphorylation pattern exist among plants with these photosynthetic types, and it is still not clear if they are due to interspecies differences or depend on photosynthetic type. The genus Flaveria contains closely related C3, C3-C4 intermediate, and C4 species, which are evolutionarily young and thus well suited for comparative analysis. To characterize the evolutionary differences in PPCK between plants with C3 and C4 photosynthesis, transcriptome libraries from nine Flaveria spp. were used, and a two-member PPCK family (PPCKA and PPCKB) was identified. Sequence analysis identified a number of C3- and C4-specific residues with various occurrences in the intermediates. Quantitative analysis of transcriptome data revealed that PPCKA and PPCKB exhibit inverse diel expression patterns and that C3 and C4 Flaveria spp. differ in the expression levels of these genes. PPCKA has maximal expression levels during the day, whereas PPCKB has maximal expression during the night. Phosphorylation patterns of PEPC varied among C3 and C4 Flaveria spp. too, with PEPC from the C4 species being predominantly phosphorylated throughout the day, while in the C3 species the phosphorylation level was maintained during the entire 24 h. Since C4 Flaveria spp. evolved from C3 ancestors, this work links the evolutionary changes in sequence, PPCK expression, and phosphorylation pattern to an evolutionary phase shift of kinase activity from a C3 to a C4 mode. PMID:24850859

Changes of paddy rice planting areas in Northeastern Asia from 1986 to 2014 based on Landsat data

NASA Astrophysics Data System (ADS)

Dong, J.; Xiao, X.; Kou, W.; Qin, Y.; Wang, J.; Zhang, G.; Jin, C.; Zhou, Y.; Menarguez, M. A.; Moore, B., III

2014-12-01

Paddy rice is an important cereal crop and main grain source for more than half of the global human population. However, knowledge about its area and spatial pattern is still limited due to large changes in agriculture in different regions; for example, higher latitude areas underwent increase (e.g., northeastern China) and decrease (e.g., South Korea) of paddy rice planting areas due to climatic warming, urbanization and other drivers. It is necessary to track paddy rice planting area changes in these regions in the past decades. We developed a pixel- and phenology-based image analysis system, Landsat-RICE, to map the paddy rice by using Landsat imagery. The algorithm was based on the unique physical and spectral characteristics of paddy rice fields during the flooding and transplanting phases. First, Landsat images are preprocessed and time series vegetation indices (NDVI, EVI, and LSWI) are generated. Second, MODIS Land Surface Temperature (LST) data were used to define thermal plant growing season (0 oC, 5 oC and 10 oC), which provides a guide for selection of Landsat images within the period of flooding and transplanting. Third, several non-cropland land cover maps (e.g., permanent water bodies, built-up and barren lands, sparsely vegetated lands, and evergreen vegetation) are produced through analysis of Landsat-based vegetation indices within the plant growing season and combined as a mask. Fourthly, vegetation index data within the time window of flooded and rice transplanting were analyzed to identify flood/transplanting signals. Finally, the maps of paddy rice planting areas were generated through overlying the results from Step 3 and 4. Paddy rice planting area changes were investigated in some hotspots of Northeastern Asia from 1986 to 2014 at 30-m spatial resolution and 5-year interval. This study has demonstrated that our newly developed Landsat-Rice system is robust and effective for tracking paddy rice changes in cold temperate and temperate zones.

Plant Nitrogen Dynamics and Nitrogen-use Strategies under Altered Nitrogen Seasonality and Competition

PubMed Central

Yuan, Zhiyou; Liu, Weixing; Niu, Shuli; Wan, Shiqiang

2007-01-01

Background and Aims Numerous studies have examined the effects of climatic factors on the distribution of C3 and C4 grasses in various regions throughout the world, but the role of seasonal fluctuations in temperature, precipitation and soil N availability in regulating growth and competition of these two functional types is still not well understood. This report is about the effects of seasonality of soil N availability and competition on plant N dynamics and N-use strategies of one C3 (Leymus chinensis) and one C4 (Chloris virgata) grass species. Methods Leymus chinensis and C. virgata, two grass species native to the temperate steppe in northern China, were planted in a monoculture and a mixture under three different N seasonal availabilities: an average model (AM) with N evenly distributed over the growing season; a one-peak model (OM) with more N in summer than in spring and autumn; and a two-peak model (TM) with more N in spring and autumn than in summer. Key Results The results showed that the altered N seasonality changed plant N concentration, with the highest value of L. chinensis under the OM treatment and C. virgata under the TM treatment, respectively. N seasonality also affected plant N content, N productivity and N-resorption efficiency and proficiency in both the C3 and C4 species. Interspecific competition influenced N-use and resorption efficiency in both the C3 and C4 species, with higher N-use and resorption efficiency in the mixture than in monoculture. The C4 grass had higher N-use efficiency than the C3 grass due to its higher N productivity, irrespective of the N treatment or competition. Conclusions The observations suggest that N-use strategies in the C3 and C4 species used in the study were closely related to seasonal dynamics of N supply and competition. N seasonality might be involved in the growth and temporal niche separation between C3 and C4 species observed in the natural ecosystems. PMID:17704500

The Effect of Copper And Zinc Nanoparticles on the Growth Parameters, Contents of Ascorbic Acid, and Qualitative Composition of Amino Acids and Acylcarnitines in Pistia stratiotes L. (Araceae)

NASA Astrophysics Data System (ADS)

Olkhovych, Olga; Volkogon, Mykola; Taran, Nataliya; Batsmanova, Lyudmyla; Kravchenko, Inna

2016-04-01

The paper covers the research of copper and zinc nanoparticle effect on the content of ascorbic acid, and quantitative and qualitative composition of amino acids and acylcarnitines in Pistia stratiotes L. plants. Plant exposition to copper nanoparticles led to the decrease in (1) the amount of ascorbic acid, (2) the total content of amino acids (by 25 %), and (3) the amount of all studied amino acids except for the glycine amino acid. At this, the amount of 5-oxoproline, arginine, leucine, ornithine, phenylalanine, proline, serine, and tyrosine was two times lower than in control plants. The reduction of the contents of 8 out of 12 investigated acylcarnitines (namely C0, C2, C3, C5, C6, C8, C16, C18:1) was observed in plants under the influence of copper nanoparticles. The result of plants incubation with zinc nanoparticles was the decrease in (1) the amount of ascorbic acid, (2) the total content of amino acids (by 15 %), (3) the content of leucine, methionine, phenylalanine, proline, and tyrosine (more than twice), and (4) the content of 10 acylcarnitines (C0, C2, C3, C4, C5, C10, C16, C18, C18:1, C18:2). The observed reduction in amino acid contents may negatively affect plants adaptive reactions associated with de novo synthesis of stress proteins. At the same time, the decrease in the content of acylcarnitines, responsible for fatty acid transportation, may lead to the changes in the activity and direction of lipid metabolism in plants and reduce plant's ability to use free fatty acids as the oxidation substrate for cell reparation.

The Ditylenchus destructor genome provides new insights into the evolution of plant parasitic nematodes

PubMed Central

Zheng, Jinshui; Peng, Donghai; Chen, Ling; Liu, Hualin; Chen, Feng; Xu, Mengci; Ju, Shouyong; Ruan, Lifang

2016-01-01

Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor. We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plant-parasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants. PMID:27466450

Expression of Nudix hydrolase genes in barley under UV irradiation

NASA Astrophysics Data System (ADS)

Tanaka, Sayuri; Sugimoto, Manabu; Kihara, Makoto

Seed storage and cultivation should be necessary to self-supply foods when astronauts would stay and investigate during long-term space travel and habitation in the bases on the Moon and Mars. Thought the sunlight is the most importance to plants, both as the ultimate energy source and as an environmental signal regulating growth and development, UV presenting the sunlight can damage many aspects of plant processes at the physiological and DNA level. Especially UV-C, which is eliminated by the stratospheric ozone layer, is suspected to be extremely harmful and give a deadly injury to plants in space. However, the defense mechanism against UV-C irradiation damage in plant cells has not been clear. In this study, we investigated the expression of Nudix hydrolases, which defense plants from biotic / abiotic stress, in barley under UV irradiation. The genes encoding the amino acid sequences, which show homology to those of 28 kinds of Nudix hydrolases in Arabidopsis thaliana, were identified in the barley full-length cDNA library. BLAST analysis showed 14 kinds of barley genes (HvNUDX1-14), which encode the Nudix motif sequence. A phylogenetic tree showed that HvNUDX1, HvNUDX7, HvNUDX9 and HvNUDX11 belonged to the ADP-ribose pyrophosphohydrolase, ADP-sugar pyrophosphohydrolase, NAD(P)H pyrophosphohydrolase and FAD pyrophosphohydrolase subfamilies, respectively, HvNUDX3, HvNUDX6, and HvNUDX8 belonged to the Ap _{n}A pyrophosphohydrolase subfamilies, HvNUDX5 and HvNUDX14 belonged to the coenzyme A pyrophosphohydrolase subfamilies, HvNUDX12 and HvNUDX13 belonged to the Ap _{4}A pyrophosphohydrolase subfamilies. Induction of HvNUDX genes by UV-A (340nm), UV-B (312nm), and UV-C (260nm) were analyzed by quantitative RT-PCR. The results showed that HvNUDX4 was induced by UV-A and UV-B, HvNUDX6 was induced by UV-B and UV-C, and HvNUDX7 and HvNUDX14 were induced by UV-C, significantly. Our results suggest that the response of HvNUDXs to UV irradiation is different by UV wavelength, and UV-C induced 4 genes of HvNUDX.

Continuous Measurements of Canopy-level Solar-Induced Chlorophyll Fluorescence for Inferring Diurnal and Seasonal Dynamics of Photosynthesis in Crop Fields in the Midwestern USA

NASA Astrophysics Data System (ADS)

Miao, G.; Guan, K.; Yang, X.; Bernacchi, C.; DeLucia, E. H.; Cai, Y.; Masters, M. D.; Peng, B.

2016-12-01

Plants emitted photons of red and far-red light, called chlorophyll fluorescence, after sunlight absorption for photosynthesis. This solar-induced fluorescence (SIF) is generated simultaneously while plants actively photosynthesize. The link between photosynthesis and SIF resulting from the competition for the same excitation energy has long been investigated and applied for inferring the rate of photosynthesis. Recent development of continuous SIF observational technology is furthering the inferring potential as well as our understandings of fluctuations of SIF and photosynthesis with changes in environmental conditions. To better understand this photosynthesis-SIF link at multiple time scales and their relationships with environmental drivers, we deployed two newly developed tower-based SIF systems (FluoSpec) in a corn (Zea mays L., C4 plant) field and a soybean (Glycine max L., C3 plant) field at University of Illinois Energy Farm and conducted continuous near-surface SIF measurements at canopy scale from mid-growing season of 2016. Eddy covariance flux towers were installed in parallel at both sites for canopy-scale gas exchange measurements. Relationship between SIF and flux tower photosynthesis will be analyzed to derive the empirical models for photosynthesis retrieval from SIF signals. Preliminary results indicate that canopy SIF can reflect diurnal and seasonal dynamics of photosynthesis. Mechanistic analysis on SIF fluctuations and responses to environmental variations will be conducted as well for a closer look at mechanism of photosynthetic responses. Corn and soybean SIF and photosynthesis-SIF relationship will be compared to investigate the difference between C4 and C3 plants.

Improved analysis of C4 and C3 photosynthesis via refined in vitro assays of their carbon fixation biochemistry

PubMed Central

Sharwood, Robert E.; Sonawane, Balasaheb V.; Ghannoum, Oula; Whitney, Spencer M.

2016-01-01

Plants operating C3 and C4 photosynthetic pathways exhibit differences in leaf anatomy and photosynthetic carbon fixation biochemistry. Fully understanding this underpinning biochemical variation is requisite to identifying solutions for improving photosynthetic efficiency and growth. Here we refine assay methods for accurately measuring the carboxylase and decarboxylase activities in C3 and C4 plant soluble protein. We show that differences in plant extract preparation and assay conditions are required to measure NADP-malic enzyme and phosphoenolpyruvate carboxylase (pH 8, Mg2+, 22 °C) and phosphoenolpyruvate carboxykinase (pH 7, >2mM Mn2+, no Mg2+) maximal activities accurately. We validate how the omission of MgCl2 during leaf protein extraction, lengthy (>1min) centrifugation times, and the use of non-pure ribulose-1,5-bisphosphate (RuBP) significantly underestimate Rubisco activation status. We show how Rubisco activation status varies with leaf ontogeny and is generally lower in mature C4 monocot leaves (45–60% activation) relative to C3 monocots (55–90% activation). Consistent with their >3-fold lower Rubisco contents, full Rubisco activation in soluble protein from C4 leaves (<5min) was faster than in C3 plant samples (<10min), with addition of Rubisco activase not required for full activation. We conclude that Rubisco inactivation in illuminated leaves primarily stems from RuBP binding to non-carbamylated enzyme, a state readily reversible by dilution during cellular protein extraction. PMID:27122573

Commissioned Review. Carbon: freshwater plants

USGS Publications Warehouse

Keeley, J.E.; Sandquist, D.R.

1992-01-01

δ13C values for freshwater aquatic plant matter varies from −11 to −50‰ and is not a clear indicator of photosynthetic pathway as in terrestrial plants. Several factors affect δ13C of aquatic plant matter. These include: (1) The δ13C signature of the source carbon has been observed to range from +1‰ for HCO3− derived from limestone to −30‰ for CO2 derived from respiration. (2) Some plants assimilate HCO3−, which is –7 to –11‰ less negative than CO2. (3) C3, C4, and CAM photosynthetic pathways are present in aquatic plants. (4) Diffusional resistances are orders of magnitude greater in the aquatic environment than in the aerial environment. The greater viscosity of water acts to reduce mixing of the carbon pool in the boundary layer with that of the bulk solution. In effect, many aquatic plants draw from a finite carbon pool, and as in terrestrial plants growing in a closed system, biochemical discrimination is reduced. In standing water, this factor results in most aquatic plants having a δ13C value similar to the source carbon. Using Farquhar's equation and other physiological data, it is possible to use δ13C values to evaluate various parameters affecting photosynthesis, such as limitations imposed by CO2 diffusion and carbon source.

Relationship between Trophic Status and Methanogenic Pathways in Alaskan Peatlands

NASA Astrophysics Data System (ADS)

Zhang, L.; Liu, X.; Sidelinger, W.; Wang, Y.; Hines, M. E.; Langford, L.; Chanton, J.

2015-12-01

To improve predictions of naturally emitted CH4 from northern wetlands, it is necessary to further examine the methanogenic pathways in these wetlands. Stable isotope C ratios (δ13C) have been used as a robust tool to distinguish different pathways, but different sources of parent compounds (acetate and CO2) with unique δ13C may add complexity to previously established criteria. Large portions of peatlands accommodate a mixture of different sphagna and sedges. Plant species may look very similar and belong to the same genus but are different morphologically and physiologically. To better understand the relationships between surface vegetation patterns and methanogenic pathways, 26 peatland sites were studied in Fairbanks and Anchorage, Alaska in summers of 2014 and 2015. These sites were ordinated using multiple factor analysis into 3 clusters based on pH, temp, CH4 and volatile fatty acids production rates, δ13C values, and surface vegetation species/pattern. In the low-pH trophic cluster (pH~3.5), non-vascular/vascular plant ratios (NV/V) were ~ 0.87 and dominated by diverse Sphagnum species and specific sedges (Eriophorum vaginatum), and fermentation was the dominant end-point in decomposition with no CH4 detected. Although NV/V is about the same in the intermediate cluster (0.74) (pH~4.5), and Sphagnum squarrosum was largely present, both hydrogenotrophic (HM) and acetoclastic methanogenesis (AM) were very active. Syntrophy was present at certain sites, which may provide CO2 with unique δ13C for CH4 production. At the highest pH trophic cluster examined in this study (pH~5), non-vascular plants were almost not existent and Carex aquatilis dominated. CH4 production rates (mainly HM) were slower than those in the intermediate cluster and the apparent fractionation factor a was lower than in the sites with syntrophy, which warrants further investigation of the position and compound specific δ13C analysis of volatile fatty acids.

40 CFR 799.5085 - Chemical testing requirements for first group of high production volume chemicals (HPV1).

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Toxicity to Plants (Algae): ASTM E 1218 Test Group 2 for C1: 1. Chronic Toxicity to Daphnia: ASTM E 1193 2. Toxicity to Plants (Algae): ASTM E 1218 The following are the special conditions for C1, C2, C3, C4, C5.... Acute Toxicity to Daphnia: ASTM E 729 2. Toxicity to Plants (Algae): ASTM E 1218 Test Group 2 for C2: 1...

C4 plant isotopic composition (delta13C) evidence for urban CO2 pollution in the city of Cotonou, Benin (West Africa).

PubMed

Kèlomé, Nelly C; Lévêque, Jean; Andreux, Francis; Milloux, Marie-Jeanne; Oyédé, Lucien-Marc

2006-08-01

The carbon isotopic composition (delta13C) of plants can reveal the isotopic carbon content of the atmosphere in which they develop. The delta13C values of air and plants depend on the amount of atmospheric fossil fuel CO2, which is chiefly emitted in urban areas. A new indicator of CO2 pollution is tested using the delta13C variation in a C4 grass: Eleusine indica. A range of about 4 per thousand delta units was observed at different sites in Cotonou, the largest city in the Republic of Benin. The highest delta13C values, from -12 per thousand to -14 per thousand, were found in low traffic zones; low delta13C values, from -14 per thousand to -16 per thousand, were found in high traffic zones. The amount of fossil fuel carbon assimilated by plants represented about 20% of the total plant carbon content. An overall decrease in plant delta13C values was observed over a four-year monitoring period. This decrease was correlated with increasing vehicle traffic. The delta13C dataset and the corresponding geographical database were used to map and define zones of high and low 13C-depleted CO2 emissions in urban and sub-urban areas. The spatial distribution follows dominant wind directions, with the lowest emission zones found in the southwest of Cotonou. High CO2 emissions occurred in the north, the east and the center, providing evidence of intense anthropogenic activity related to industry and transportation.

[Effects of drought stress on growth and water use efficiency of two medicinal plants].

PubMed

Chen, Ping; Meng, Ping; Zhang, Jin-Song; He, Chun-Xia; Jia, Chang-Rong; Li, Jian-Zhong

2014-05-01

Growth characteristics, stable carbon isotope discrimination (Delta13C), water use efficiency (WUE), and their correlation of Cassia obtusifolia and Isatis indigotica were measured at three soil water levels, i. e., 30%, 50% and 75% of field water holding capacity (FWHC), and at three growth stages. The growth indices of the two medicinal plants at 75% of FWHC were higher than those at 30% and 50% of FWHC, suggesting that the two medicinal plants could obtain high production under sufficient moisture condition. The Delta13C(A) (aboveground biomass-based Delta13C) and Delta13C(T) (total biomass-based Delta13C) decreased, and the WUE(A) (aboveground biomass-based WUE) and WUE(T) (total biomass-based WUE) of C. obtusifolia and I. indigotica increased with the increasing degree of drought stress. The growth indices of the two medicinal plants had little difference in the different water treatments, which indicated that the two medicinal plants were insensitive to drought stress. Water use efficiency of I. indigotica had significant negative relationships with aboveground biomass and total biomass, while that of C. obtusifolia had a significant positive correlation with the root/shoot ratio.

Effect of nutrients on Chlorella pyrenoidosa for treatment of phenolic effluent of coal gasification plant.

PubMed

Stephen, Dayana Priyadharshini; Ayalur, Bakthavatsalam Kannappan

2017-05-01

The ability of Chlorella pyrenoidosa, a freshwater microalga, to degrade phenolic effluent of coal-based producer gas plant under ambient conditions was investigated. C. pyrenoidosa was able to grow in high-strength phenolic effluent. Major contaminant present in the effluent was phenol (C 6 H 5 OH). The effluent has 1475.3 ± 68 mg/L of initial total phenolic concentration. The effect of nutrients used for algal cultivation in phenol degradation was analyzed by inoculating four different concentrations, viz.,1, 2, 3, and 4 g of wet biomass/L of raw effluent of C. pyrenoidosa mixed with effluent into two batches (with and without nutrients). C. pyrenoidosa was able to degrade more than 95% of the phenol (C 6 H 5 OH) concentration with the algal concentrations of 3 and 4 g/L when supplemented with nutrients. With effluent devoid of nutrients, the average percent reduction in total phenolic compounds was observed to a maximum of 46%. No physical changes in the C. pyrenoidosa were observed during degradation. C. pyrenoidosa was able to consume the organic carbon present in the phenolic compounds as carbon source for its growth despite the inorganic carbon supplemented externally.

Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

2014-05-01

Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the contribution of different carbon sources for each snail individual: to cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone vary in a range of 66~80%, 16~24% and 0~13%, respectively. And to corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), they vary in 56~64%, 18~20% and 16~26%, respectively. We will discuss how these results could be consistent to the observations, which suggests our calculations are suitable and believable. In addition, we will discuss the carbon isotope fractionation during egg laying and hatching of land snails, too. [1] Goodfriend, 1992, Quaternary Sciences Reviews. 11, 665-685 [2] Yanes et al. 2009. Geochimica et Cosmochimica Acta, 73, 4077-4099 [3] Yanes et al., 2013. Palaeogeography, Plaeoclimatology, Palaeoecology, 378, 91-102 [4] Goodfriend and Hood, 1983. Radiocarbon, 25, 810-830 [5] Goodfriend and Stipp, 1983. Geology, 11, 575-577 [6] Stott, 2002. Earth and Planetary Science Letters, 195, 249-259 [7] Metref et al., 2003. Earth and Planetary Science Letters, 211, 381-393 [8] Romaniello et al., 2008. Quaternary Geochronology, 3, 68-75

Laboratory evaluation of traditionally used plant-based insect repellent against the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae).

PubMed

Karunamoorthi, Kaliyaperumal; Ilango, Kandan; Murugan, Kadarkarai

2010-04-01

A laboratory study was carried out to evaluate the repellent efficacy of a methanol-leaf extract of Ethiopian traditionally used insect repellent plant viz., Lomi sar [vernacular name (local native language, Amharic); Cymbopogon citratus (DC) Stapf. (Poaceae)] against Anopheles arabiensis at four different concentrations viz., 1.0, 1.5, 2.0, and 2.5 mg/cm(2). The percentage protection in relation to the dose method was performed. C. citratus extract has shown various degrees of repellency impact against A. arabiensis. It provided the maximum total percentage protection of 78.83% at 2.5 mg/cm(2) and followed 68.06% at 2.0 mg/cm(2) for 12 h. All four tested concentrations of C. citratus extract offered significant protection and Student's t test results shows statistically significant (p value = 0.001) [1.0 mg/cm(2) (t = 22.89; df = 4); 1.5 mg/cm(2) (t = 24.03; df = 4); 2.0 mg/cm(2) (t = 36.92; df = 4); 2.5 mg/cm(2) (t = 22.31; df = 4)] difference between treated and control groups. The result suggests that it could serve as a potent insect repellent against vectors of disease. Globally, C. citratus is renowned for its therapeutic values. Above and beyond, due to its user- as well as environmental-friendly nature, it should be promoted among the marginalized populations in order to reduce man-vector contact. In addition, this appropriate strategy affords the opportunity to minimize chemical repellent usage and the risks associated with adverse side effects. At the end of the day, traditionally used plant-based insect repellents could be viable safer alternative sources for chemical insect repellents.

Proxy of monsoon seasonality in carbon isotopes from paleosols of the southern Chinese Loess Plateau

USGS Publications Warehouse

Wang, Hongfang; Follmer, L.R.

1998-01-01

Soil organic matter (SOM) and soil carbonate (SC) are common constituents in soils and are directly related to plant growth. SOM accumulates gradually from the decomposition of plant material over time, whereas SC formation is biased to dry-season soil-dissolved CO2 that derives from plant respiration during a drying phase of the growing season. In some mixed C3-C4 environments, the peak of C3 and C4 plant metabolism differs seasonally, and the carbon source that contributes to the SOM and SC can be different. Consequently, ??13C(SOM) values reflect an annual average of the floral biomass, but ??13C(SC) values reflect a seasonal aspect of the plant community. The relationship between ??13C(SC) and ??13C(SOM) is mainly controlled by how different the seasonal conditions are. Our results suggest that the relationship is a seasonal proxy that can be used to differentiate the seasonality effects of Indian, East Asian, and Siberian monsoons on the Chinese Loess Plateau during the last interglacial-glacial cycle.

Differential resource utilization by extant great apes and australopithecines: towards solving the C4 conundrum.

PubMed

Sponheimer, Matt; Lee-Thorp, Julia A

2003-09-01

Morphological and biogeochemical evidence suggest that australopithecines had diets markedly different from those of extant great apes. Stable carbon isotope analysis, for example, has shown that significant amounts of the carbon consumed by australopithecines were derived from C(4) photosynthesis in plants. This means that australopithecines were eating large quantities of C(4) plants such as tropical grasses and sedges, or were eating animals that were themselves eating C(4) plants. In contrast, there is no evidence that modern apes consume appreciable amounts of any of these foods, even in the most arid extents of their ranges where these foods are most prevalent. Environmental reconstructions of early australopithecine environments overlap with modern chimpanzee habitats. This, in conjunction with the stable isotope evidence, suggests that australopithecines and great apes, even in similar environments, would utilize available resources differently. Thus, the desire or capacity to use C(4) foods may be a basal character of our lineage. We do not know, however, which of the nutritionally disparate C(4) foods were utilized by hominids. Here we discuss which C(4) resources were most likely consumed by australopithecines, as well as the potential nutritional, physiological, and social consequences of eating these foods.

Long-Term Instrumentation, Information, and Control Systems (II&C) Modernization Future Vision and Strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenneth Thomas

2012-02-01

Life extension beyond 60 years for the U.S operating nuclear fleet requires that instrumentation and control (I&C) systems be upgraded to address aging and reliability concerns. It is impractical for the legacy systems based on 1970's vintage technology operate over this extended time period. Indeed, utilities have successfully engaged in such replacements when dictated by these operational concerns. However, the replacements have been approached in a like-for-like manner, meaning that they do not take advantage of the inherent capabilities of digital technology to improve business functions. And so, the improvement in I&C system performance has not translated to bottom-line performancemore » improvement for the fleet. Therefore, wide-scale modernization of the legacy I&C systems could prove to be cost-prohibitive unless the technology is implemented in a manner to enable significant business innovation as a means of off-setting the cost of upgrades. A Future Vision of a transformed nuclear plant operating model based on an integrated digital environment has been developed as part of the Advanced Instrumentation, Information, and Control (II&C) research pathway, under the Light Water Reactor (LWR) Sustainability Program. This is a research and development program sponsored by the U.S. Department of Energy (DOE), performed in close collaboration with the nuclear utility industry, to provide the technical foundations for licensing and managing the long-term, safe and economical operation of current nuclear power plants. DOE's program focus is on longer-term and higher-risk/reward research that contributes to the national policy objectives of energy security and environmental security . The Advanced II&C research pathway is being conducted by the Idaho National Laboratory (INL). The Future Vision is based on a digital architecture that encompasses all aspects of plant operations and support, integrating plant systems, plant work processes, and plant workers in a seamless digital environment to enhance nuclear safety, increase productivity, and improve overall plant performance. The long-term goal is to transform the operating model of the nuclear power plants (NPP)s from one that is highly reliant on a large staff performing mostly manual activities to an operating model based on highly integrated technology with a smaller staff. This digital transformation is critical to addressing an array of issues facing the plants, including aging of legacy analog systems, potential shortage of technical workers, ever-increasing expectations for nuclear safety improvement, and relentless pressure to reduce cost. The Future Vision is based on research is being conducted in the following major areas of plant function: (1) Highly integrated control rooms; (2) Highly automated plant; (3) Integrated operations; (4) Human performance improvement for field workers; and (5) Outage safety and efficiency. Pilot projects will be conducted in each of these areas as the means for industry to collectively integrate these new technologies into nuclear plant work activities. The pilot projects introduce new digital technologies into the nuclear plant operating environment at host operating plants to demonstrate and validate them for production usage. In turn, the pilot project technologies serve as the stepping stones to the eventual seamless digital environment as described in the Future Vision.« less

Long-Term Instrumentation, Information, and Control Systems (II&C) Modernization Future Vision and Strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenneth Thomas; Bruce Hallbert

2013-02-01

Life extension beyond 60 years for the U.S operating nuclear fleet requires that instrumentation and control (I&C) systems be upgraded to address aging and reliability concerns. It is impractical for the legacy systems based on 1970’s vintage technology operate over this extended time period. Indeed, utilities have successfully engaged in such replacements when dictated by these operational concerns. However, the replacements have been approached in a like-for-like manner, meaning that they do not take advantage of the inherent capabilities of digital technology to improve business functions. And so, the improvement in I&C system performance has not translated to bottom-line performancemore » improvement for the fleet. Therefore, wide-scale modernization of the legacy I&C systems could prove to be cost-prohibitive unless the technology is implemented in a manner to enable significant business innovation as a means of off-setting the cost of upgrades. A Future Vision of a transformed nuclear plant operating model based on an integrated digital environment has been developed as part of the Advanced Instrumentation, Information, and Control (II&C) research pathway, under the Light Water Reactor (LWR) Sustainability Program. This is a research and development program sponsored by the U.S. Department of Energy (DOE), performed in close collaboration with the nuclear utility industry, to provide the technical foundations for licensing and managing the long-term, safe and economical operation of current nuclear power plants. DOE’s program focus is on longer-term and higher-risk/reward research that contributes to the national policy objectives of energy security and environmental security . The Advanced II&C research pathway is being conducted by the Idaho National Laboratory (INL). The Future Vision is based on a digital architecture that encompasses all aspects of plant operations and support, integrating plant systems, plant work processes, and plant workers in a seamless digital environment to enhance nuclear safety, increase productivity, and improve overall plant performance. The long-term goal is to transform the operating model of the nuclear power plants (NPP)s from one that is highly reliant on a large staff performing mostly manual activities to an operating model based on highly integrated technology with a smaller staff. This digital transformation is critical to addressing an array of issues facing the plants, including aging of legacy analog systems, potential shortage of technical workers, ever-increasing expectations for nuclear safety improvement, and relentless pressure to reduce cost. The Future Vision is based on research is being conducted in the following major areas of plant function: 1. Highly integrated control rooms 2. Highly automated plant 3. Integrated operations 4. Human performance improvement for field workers 5. Outage safety and efficiency. Pilot projects will be conducted in each of these areas as the means for industry to collectively integrate these new technologies into nuclear plant work activities. The pilot projects introduce new digital technologies into the nuclear plant operating environment at host operating plants to demonstrate and validate them for production usage. In turn, the pilot project technologies serve as the stepping stones to the eventual seamless digital environment as described in the Future Vision.« less

Effects of an inhibitor of phosphoenolpyruvate carboxylase on photosynthesis of the terrestrial forms of amphibious Eleocharis species.

PubMed

Ueno, Osamu; Ishimaru, Ken

2002-01-01

The leafless amphibious sedge Eleocharis vivipara develops culms with C(4) traits and Kranz anatomy under terrestrial conditions, but develops culms with C(3) traits and non-Kranz anatomy under submerged conditions. The culms of the terrestrial form have high C(4) enzyme activities, while those of the submerged form have decreased C(4) enzyme activities. The culms accumulate ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the mesophyll cells (MC) and the bundle sheath cells. The Rubisco in the MC may be responsible for the operation of the C(3) pathway in the submerged form. To verify the presence of the C(3) cycle in the MC, we examined the effects of 3,3-dichloro-2-(dihydroxyphosphinoylmethyl) -propenoate (DCDP), an inhibitor of phosphoenolpyruvate carboxylase (PEPC), on photosynthesis in culms of the terrestrial forms of E. vivipara and related amphibious species, E. baldwinii and E. retroflexa ssp. chaetaria. When 1 mM DCDP was fed via the transpiration stream to excised leaves, photosynthesis was inhibited completely in Fimbristylis dichotoma (C(4) control), but by only 20% in potato (C(3) control). In the terrestrial Eleocharis plants, the degree of inhibition of photosynthesis by DCDP was intermediate between those of the C(4) and C(3) plants, at 58-81%. These results suggest that photosynthesis under DCDP treatment in the terrestrial Eleocharis plants is due mainly to fixation of atmospheric CO(2) by Rubisco and probably the C(3) cycle in the MC. These features are reminiscent of those in C(4)-like plants. Differential effects of DCDP on photosynthesis of the 3 Eleocharis species are discussed in relation to differences in the degree of Rubisco accumulation and C(3) activity in the MC.

Crop-weed competition between sunflower (Helianthus annuus L.) and Convolvulus arvensis L. in substitutive experiments.

PubMed

Kazinczi, G; Takács, A; Horváth, J

2006-01-01

The main characteristics of a substitutive experiment is that the proportions of two species in the mixtures are varied while the overall density of the two species is maintained constant - a replacement series. In our experiments early competition between sunflower and field bindweed (Convolvulus arvensis) was studied in a replacement studies under glasshouse conditions. Pot experiments were set up with the following treatments: 1, sunflower 100% (6 plants pot(-1)); 2, sunflower 66.6% (4 plants pot(-1)) + C. arvensis 33.3% (2 plants pot(-1)); 3, sunflower 33.3% (2 plants pot(-1)) + C. arvensis 66.6% (4 plants pot(-1)); 4, C. arvensis 100% (6 plants pot(-1)). Sixty eight days after sowing dry weight of shoots and roots were measured and nitrogen (N), phosphorus (P) and potassium (K) content was also determined. Dry biomass production of sunflower was almost twice higher as compared to that of C. arvensis without interspecific competition. Dry weight of sunflower and C. arvensis shoots and roots for a plant continuously decreased by reducing their proportion in the mixtures. Higher biomass production of sunflower suggests, that its development is faster at the beginning of vegetation penod, therefore sunflower has better competitive ability in sunflower--C. arvensis mixtures in the early competition as compared to C. arvensis. Shoot:root ratio of plants did not change considerably in mixtures, but generally was ten times higher in sunflower plants, as compared to that of C. arvensis. Shoots generally contained macro elements at higher concentration as compared to those of roots. Total NPK content of sunflower was reduced by 53 and 82% for a pot, as its proportion decreased in the mixtures. More severe reduction in NPK content was observed in case of C. arvensis, which also proves stronger competitive ability of sunflower in the early vegetation.

MCPA (4-Chloro-2-ethylphenoxyacetate) resistance in hemp-nettle (Galeopsis tetrahit L.).

PubMed

Weinberg, Tsafrir; Stephenson, Gerald R; McLean, Michael D; Hall, J Christopher

2006-11-29

The physiological basis for MCPA resistance in a hemp-nettle (Galeopsis tetrahit L.) biotype, obtained from a MCPA-resistant field population, was investigated. Dose-response studies revealed that the resistance factor for MCPA, based on GR50 comparisons of total dry weight of resistant (R) and susceptible (S) plants, was 3.3. Resistance factors for fluroxypyr, dicamba, 2,4-D, glyphosate, and chlorsulfuron were 8.2, 1.7, 1.6, 0.7, and 0.6, respectively. MCPA resistance was not due to differences in absorption, because both R and S biotypes absorbed 54% of applied [14C]MCPA 72 h after treatment. However, R plants exported less (45 vs 58% S) recovered 14C out of treated leaves to the apical meristem (6 vs 13% S) and root (32 vs 38% S). In both biotypes, approximately 20% of the 14C recovered in planta was detected as MCPA metabolites. However, less of the 14C recovered in the roots of R plants was MCPA. Therefore, two different mechanisms protect R hemp-nettle from MCPA phytotoxicity: a lower rate of MCPA translocation and a higher rate of MCPA metabolism in the roots. In support of these results, genetic studies indicated that the inheritance of MCPA resistance is governed by at least two nuclear genes with additive effects.

Genome-Wide Identification and Analysis of Biotic and Abiotic Stress Regulation of C4 Photosynthetic Pathway Genes in Rice.

PubMed

Muthusamy, Senthilkumar K; Lenka, Sangram K; Katiyar, Amit; Chinnusamy, Viswanathan; Singh, Ashok K; Bansal, Kailash C

2018-06-19

Photosynthetic fixation of CO 2 is more efficient in C 4 than in C 3 plants. Rice is a C 3 plant and a potential target for genetic engineering of the C 4 pathway. It is known that genes encoding C 4 enzymes are present in C 3 plants. However, no systematic analysis has been conducted to determine if these C 4 gene family members are expressed in diverse rice genotypes. In this study, we identified 15 genes belonging to the five C 4 gene families in rice genome through BLAST search using known maize C 4 photosynthetic pathway genes. Phylogenetic relationship of rice C 4 photosynthetic pathway genes and their isoforms with other grass genomes (Brachypodium, maize, Sorghum and Setaria), showed that these genes were highly conserved across grass genomes. Spatiotemporal, hormone, and abiotic stress specific expression pattern of the identified genes revealed constitutive as well as inductive responses of the C 4 photosynthetic pathway in different tissues and developmental stages of rice. Expression levels of C 4 specific gene family members in flag leaf during tillering stage were quantitatively analyzed in five rice genotypes covering three species, viz. Oryza sativa, ssp. japonica (cv. Nipponbare), Oryza sativa, ssp. indica (cv IR64, Swarna), and two wild species Oryza barthii and Oryza australiensis. The results showed that all the identified genes expressed in rice and exhibited differential expression pattern during different growth stages, and in response to biotic and abiotic stress conditions and hormone treatments. Our study concludes that C 4 photosynthetic pathway genes present in rice play a crucial role in stress regulation and might act as targets for C 4 pathway engineering via CRISPR-mediated breeding.

α-Farnesene and ocimene induce metabolite changes by volatile signaling in neighboring tea (Camellia sinensis) plants.

PubMed

Zeng, Lanting; Liao, Yinyin; Li, Jianlong; Zhou, Ying; Tang, Jinchi; Dong, Fang; Yang, Ziyin

2017-11-01

Herbivore-induced plant volatiles (HIPVs) act as direct defenses against herbivores and as indirect defenses by attracting herbivore enemies. However, the involvement of HIPVs in within-plant or plant-to-plant signaling is not fully clarified. Furthermore, in contrast to model plants, HIPV signaling roles in crops have hardly been reported. Here, we investigated HIPVs emitted from tea (Camellia sinensis) plants, an important crop used for beverages, and their involvement in tea plant-to-plant signaling. To ensure uniform and sufficient exposure to HIPVs, jasmonic acid combined with mechanical damage (JAMD) was used to simulate herbivore attacks. Metabonomics techniques based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and gas chromatography-mass spectrometry were employed to determine metabolite changes in undamaged tea plants exposed to JAMD-stimulated volatiles. JAMD-stimulated volatiles mainly enhanced the amounts of 1-O-galloyl-6-O-luteoyl-α-d-glucose, assamicain C, 2,3,4,5-tetrahydroxy-6-oxohexyl gallate, quercetagitrin, 2-(2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-oxo-4H-chromen-8-yl)-4,5-dihydroxy-6-(hydroxymethyl)-tetrahydro-2H-pyran-3-yl, 3,4-dimethoxybenzoate, 1,3,4,5,6,7-hexahydroxyheptan-2-one, and methyl gallate in neighboring undamaged tea leaves. Furthermore, α-farnesene and β-ocimene, which were produced after JAMD treatments, were identified as two main JAMD-stimulated volatiles altering metabolite profiles of the neighboring undamaged tea leaves. This research advances our understanding of the ecological functions of HIPVs and can be used to develop crop biological control agents against pest insects in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Foxtail Mosaic Virus-Induced Gene Silencing in Monocot Plants.

PubMed

Liu, Na; Xie, Ke; Jia, Qi; Zhao, Jinping; Chen, Tianyuan; Li, Huangai; Wei, Xiang; Diao, Xianmin; Hong, Yiguo; Liu, Yule

2016-07-01

Virus-induced gene silencing (VIGS) is a powerful technique to study gene function in plants. However, very few VIGS vectors are available for monocot plants. Here we report that Foxtail mosaic virus (FoMV) can be engineered as an effective VIGS system to induce efficient silencing of endogenous genes in monocot plants including barley (Hordeum vulgare L.), wheat (Triticum aestivum) and foxtail millet (Setaria italica). This is evidenced by FoMV-based silencing of phytoene desaturase (PDS) and magnesium chelatase in barley, of PDS and Cloroplastos alterados1 in foxtail millet and wheat, and of an additional gene IspH in foxtail millet. Silencing of these genes resulted in photobleached or chlorosis phenotypes in barley, wheat, and foxtail millet. Furthermore, our FoMV-based gene silencing is the first VIGS system reported for foxtail millet, an important C4 model plant. It may provide an efficient toolbox for high-throughput functional genomics in economically important monocot crops. © 2016 American Society of Plant Biologists. All Rights Reserved.

The Late Miocene Rise of C4 Vegetation in Eastern Africa Documented by Terrestrial Plant Waxes in Marine Cores

NASA Astrophysics Data System (ADS)

Uno, K. T.; Polissar, P. J.; Jackson, K.; deMenocal, P. B.

2015-12-01

C4 plants are predominantly grasses and they account for ~20% of global net primary productivity, serve as important sources of food, and are the dominant plant type in non-forested tropical ecosystems. Yet the reasons behind their rise to such a globally significant component of the terrestrial biosphere within the last 10 million years are not well understood. In eastern Africa, the expansion of C4 grasslands led to long-term changes in faunal distributions and resulted in major dietary shifts in mammalian lineages. Potential mechanisms leading to the rise of C4 plants include a decrease in atmospheric CO2, ecosystem perturbations by fire or large herbivores, and increased aridity or seasonality of precipitation. Improvement of the temporal and spatial coverage of vegetation records in the Late Neogene of East Africa may help elucidate the mechanisms responsible for regional and global C4 grassland expansion. It will also improve our ability to assess the relationship between vegetation change and mammalian evolution. To evaluate the evolution of C4 grasslands in East Africa, we measured carbon isotope ratios of n-alkanes from four DSDP cores stretching from the Red Sea (19.1° N) to the Somali Basin (2.4° S) that range in age from ~24 Ma to 0.5 Ma. Carbon isotope data from Somali Basin sites 235 and 241 indicate the appearance of C4 vegetation by ca. 10 Ma, followed by a relatively steady increase through the late Pleistocene. Odd numbered n-alkane homologues (C29 ­to C35) exhibit up to a 10‰ increase in δ13C. We also established end member molecular distributions of n-alkanes and tracked changes in their proportional contributions through time. Changes in molecular distribution are broadly synchronous with increases in carbon isotope ratios, suggesting that n-alkane distributions reflect changes in C3 and C4 vegetation types.

Target-site mutations conferring resistance to glyphosate in feathertop Rhodes grass (Chloris virgata) populations in Australia.

PubMed

Ngo, The D; Krishnan, Mahima; Boutsalis, Peter; Gill, Gurjeet; Preston, Christopher

2018-05-01

Chloris virgata is a warm-season, C 4 , annual grass weed affecting field crops in northern Australia that has become an emerging weed in southern Australia. Four populations with suspected resistance to glyphosate were collected in South Australia, Queensland and New South Wales, Australia, and compared with one susceptible (S) population to confirm glyphosate resistance and elucidate possible mechanisms of resistance. Based on the rate of glyphosate required to kill 50% of treated plants (LD 50 ), glyphosate resistance (GR) was confirmed in four populations of C. virgata (V12, V14.2, V14.16 and V15). GR plants were 2-9.7-fold more resistant and accumulated less shikimate after glyphosate treatment than S plants. GR and S plants did not differ in glyphosate absorption and translocation. Target-site EPSPS mutations corresponding to Pro-106-Leu (V14.2) and Pro-106-Ser (V15, V14.16 and V12) substitutions were found in GR populations. The population with Pro-106-Leu substitution was 2.9-4.9-fold more resistant than the three other populations with Pro-106-Ser substitution. This report confirms glyphosate resistance in C. virgata and shows that target-site EPSPS mutations confer resistance to glyphosate in this species. The evolution of glyphosate resistance in C. virgata highlights the need to identify alternative control tactics. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Buffalo Metropolitan Area, New York Water Resources Management. Detailed Project Report for Flood Management in Cayuga Creek Watershed.

DTIC Science & Technology

1979-08-01

present within Cheektowaga’s industrial base implies that their markets and custo- mers extend throughout the Buffalo SNSA. Although the flood plain does...They include the growth of markets in the south and west, a high level of taxes, a low level of value added per dollar labor costs, older plants, and...and organic materials. 5.4 Possible Sources 5.4.1 General - Those sources listed on Plates C-9 through C-17 and contain suitable inplace stone to

Late Quaternary environments of the Waco Mammoth site, Texas USA

NASA Astrophysics Data System (ADS)

Nordt, Lee; Bongino, John; Forman, Steven; Esker, Don; Benedict, Anita

2015-11-01

The Waco Mammoth Site (WMS) in central Texas contains the remains of the largest mammoth herd (Mammuthus columbi) in North America that died in a single catastrophic event. Most mammoths at the site died on a gravel bar of the ancient Bosque River adjacent to a collapsing tributary wall. However, the timing and cause of death of the 26 mammoths documented to date are controversial. The objectives of this research are to: describe and interpret the alluvial stratigraphy and infer the cause of death, employ optically stimulated luminescence (OSL) dating to determine the timing of death, and analyze stable C isotopes of pedogenic carbonate to infer local plant communities, dietary habits, and summer temperatures. Dating of quartz from seven sediment samples by OSL places the death event to a weighted mean of 66.8 ± 5.0 ka. The site is coeval with Marine Oxygen Isotope Stage 4, consistent with our reconstructed mean July temperatures 4°C cooler than today based on a buried soil isotopic transfer function. Our buried soil isotopic interpretation of a dominance of C3 plants is contrary to previous studies of mammoth tooth enamel at the site suggesting a dietary preference for warm season grasses (C4).

The Allelochemical MDCA Inhibits Lignification and Affects Auxin Homeostasis1[OPEN

PubMed Central

Steenackers, Ward; Corneillie, Sander; Van de Wouwer, Dorien; Zažímalová, Eva

2016-01-01

The phenylpropanoid 3,4-(methylenedioxy)cinnamic acid (MDCA) is a plant-derived compound first extracted from roots of Asparagus officinalis and further characterized as an allelochemical. Later on, MDCA was identified as an efficient inhibitor of 4-COUMARATE-CoA LIGASE (4CL), a key enzyme of the general phenylpropanoid pathway. By blocking 4CL, MDCA affects the biosynthesis of many important metabolites, which might explain its phytotoxicity. To decipher the molecular basis of the allelochemical activity of MDCA, we evaluated the effect of this compound on Arabidopsis thaliana seedlings. Metabolic profiling revealed that MDCA is converted in planta into piperonylic acid (PA), an inhibitor of CINNAMATE-4-HYDROXYLASE (C4H), the enzyme directly upstream of 4CL. The inhibition of C4H was also reflected in the phenolic profile of MDCA-treated plants. Treatment of in vitro grown plants resulted in an inhibition of primary root growth and a proliferation of lateral and adventitious roots. These observed growth defects were not the consequence of lignin perturbation, but rather the result of disturbing auxin homeostasis. Based on DII-VENUS quantification and direct measurement of cellular auxin transport, we concluded that MDCA disturbs auxin gradients by interfering with auxin efflux. In addition, mass spectrometry was used to show that MDCA triggers auxin biosynthesis, conjugation, and catabolism. A similar shift in auxin homeostasis was found in the c4h mutant ref3-2, indicating that MDCA triggers a cross talk between the phenylpropanoid and auxin biosynthetic pathways independent from the observed auxin efflux inhibition. Altogether, our data provide, to our knowledge, a novel molecular explanation for the phytotoxic properties of MDCA. PMID:27506238

Pulsed-Field Gel Electrophoresis characterization of Listeria monocytogenes isolates from cheese manufacturing plants in São Paulo, Brazil.

PubMed

Barancelli, Giovana V; Camargo, Tarsila M; Gagliardi, Natália G; Porto, Ernani; Souza, Roberto A; Campioni, Fabio; Falcão, Juliana P; Hofer, Ernesto; Cruz, Adriano G; Oliveira, Carlos A F

2014-03-03

This study aimed to evaluate the occurrence of Listeria monocytogenes in cheese and in the environment of three small-scale dairy plants (A, B, C) located in the Northern region state of São Paulo, Brazil, and to characterize the isolates using conventional serotyping and PFGE. A total of 393 samples were collected and analyzed from October 2008 to September 2009. From these, 136 came from dairy plant A, where only L. seeligeri was isolated. In dairy plant B, 136 samples were analyzed, and L. innocua, L. seeligeri and L. welshimeri were isolated together with L. monocytogenes. In dairy plant C, 121 samples were analyzed, and L. monocytogenes and L. innocua were isolated. Cheese from dairy plants B and C were contaminated with Listeria spp, with L. innocua being found in Minas frescal cheese from both dairy plants, and L. innocua and L. monocytogenes in Prato cheese from dairy plant C. A total of 85 L. monocytogenes isolates were classified in 3 serotypes: 1/2b, 1/2c, and 4b, with predominance of serotype 4b in both dairy plants. The 85 isolates found in the dairy plants were characterized by genomic macrorestriction using ApaI and AscI with Pulsed Field Gel Electrophoresis (PFGE). Macrorestriction yielded 30 different pulsotypes. The presence of indistinguishable profiles repeatedly isolated during a 12-month period indicated the persistence of L. monocytogenes in dairy plants B and C, which were more than 100 km away from each other. Brine used in dairy plant C contained more than one L. monocytogenes lineage. The routes of contamination were identified in plants B and C, and highlighted the importance of using molecular techniques and serotyping to track L. monocytogenes sources of contamination, distribution, and routes of contamination in dairy plants, and to develop improved control strategies for L. monocytogenes in dairy plants and dairy products. Copyright © 2013 Elsevier B.V. All rights reserved.

Carbon flux from plants to soil microbes is highly sensitive to nitrogen addition and biochar amendment

NASA Astrophysics Data System (ADS)

Kaiser, C.; Solaiman, Z. M.; Kilburn, M. R.; Clode, P. L.; Fuchslueger, L.; Koranda, M.; Murphy, D. V.

2012-04-01

The release of carbon through plant roots to the soil has been recognized as a governing factor for soil microbial community composition and decomposition processes, constituting an important control for ecosystem biogeochemical cycles. Moreover, there is increasing awareness that the flux of recently assimilated carbon from plants to the soil may regulate ecosystem response to environmental change, as the rate of the plant-soil carbon transfer will likely be affected by increased plant C assimilation caused by increasing atmospheric CO2 levels. What has received less attention so far is how sensitive the plant-soil C transfer would be to possible regulations coming from belowground, such as soil N addition or microbial community changes resulting from anthropogenic inputs such as biochar amendments. In this study we investigated the size, rate and sensitivity of the transfer of recently assimilated plant C through the root-soil-mycorrhiza-microbial continuum. Wheat plants associated with arbuscular mycorrhizal fungi were grown in split-boxes which were filled either with soil or a soil-biochar mixture. Each split-box consisted of two compartments separated by a membrane which was penetrable for mycorrhizal hyphae but not for roots. Wheat plants were only grown in one compartment while the other compartment served as an extended soil volume which was only accessible by mycorrhizal hyphae associated with the plant roots. After plants were grown for four weeks we used a double-labeling approach with 13C and 15N in order to investigate interactions between C and N flows in the plant-soil-microorganism system. Plants were subjected to an enriched 13CO2 atmosphere for 8 hours during which 15NH4 was added to a subset of split-boxes to either the root-containing or the root-free compartment. Both, 13C and 15N fluxes through the plant-soil continuum were monitored over 24 hours by stable isotope methods (13C phospho-lipid fatty acids by GC-IRMS, 15N/13C in bulk plant material, microbial biomass and dissolved organic matter by IRMS, 13C and 15N in plant roots cells and intraradical mycorrhizal hyphae by NanoSims). Our results show that (1) C assimilated by plants was delivered within 4 hours to the soil microbial community both via roots and the mycorrhizal network (2) N addition during the labeling period strongly and rapidly increased the 13C flux of recently assimilated carbohydrates to the soil microbial biomass (3) the effect of N addition was not as rapid but was of the same magnitude when N was delivered to the plant exclusively by mycorrhizal hyphae as compared to taken up by roots (4) soils which had been amended with biochar (which were characterized by an increased abundance of mycorrhizal fungi) also showed a significant increase of C flux from plants to the soil. We conclude that plant belowground C allocation is highly sensitive to alterations of microbial community structure and nutritional status in the soil. Moreover, our results indicate that plants respond rapidly (within hours) to changing soil N availability by altering the rate of C transported belowground. Our results emphasise the ecological significance of plant-belowground interactions for ecosystem C cycling.

Effect of foliar treatments on distribution of /sup 14/C-glyphosate in Convolvulus arvensis L

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lauridson, T.C.

1986-01-01

Field bindweed is a perennial weed which produces shoots from buds on its roots. Herbicides, such as glyphosate (N-(phosphonomethyl)glycine) used for control of field bindweed usually do not kill all shoot buds on the roots, thus field bindweed often reinfests areas within 3 to 6 weeks of treatment. This dissertation deals with the development of a technique to change glyphosate distribution in field bindweed roots and could result in less shoot regrowth after glyphosate application. In field studies eight plant growth regulators were applied in September, 3 days before 2.24 kg/ha of 2.4-D((2,4-dichlorophenoxy) acetic acid) or 1.68 kg/ha of glyphosate.more » Eight months later, regrowth of shoots was least where glyphosate was applied at 0.028 kg/ha as a pretreatment, followed by a standard rate of 1.68 kg/ha. In subsequent greenhouse studies, typical patterns of shoot growth and /sup 14/C-glyphosate distribution in isolated root sections taken from 15-week-old intact plants were determined. In subsequent growth chamber studies, plants were decapitated to observe the effect of shoot apical dominance on /sup 14/C-glyphosate translocation. After /sup 14/C-glyphosate was applied, intact plants had about twice as much /sup 14/C in distal root sections as in proximal or middle root sections. Decapitated plants had more /sup 14/C in proximal and middle root sections than in distal sections, and about twice as much /sup 14/C was translocated to roots of decapitated plants than intact plants. Eight concentrations of 2,4,-D or glyphosate from 1 to 5000 ppm were applied in logarithmic series to 6-week old plants.« less

Standardization of Cassia spectabilis with respect to authenticity, assay and chemical constituent analysis.

PubMed

Torey, Angeline; Sasidharan, Sreenivasan; Yeng, Chen; Latha, Lachimanan Yoga

2010-05-10

Quality control standardizations of the various medicinal plants used in traditional medicine is becoming more important today in view of the commercialization of formulations based on these plants. An attempt at standardization of Cassia spectabilis leaf has been carried out with respect to authenticity, assay and chemical constituent analysis. The authentication involved many parameters, including gross morphology, microscopy of the leaves and functional group analysis by Fourier Transform Infrared (FTIR) spectroscopy. The assay part of standardization involved determination of the minimum inhibitory concentration (MIC) of the extract which could help assess the chemical effects and establish curative values. The MIC of the C. spectabilis leaf extracts was investigated using the Broth Dilution Method. The extracts showed a MIC value of 6.25 mg/mL, independent of the extraction time. The chemical constituent aspect of standardization involves quantification of the main chemical components in C. spectabilis. The GCMS method used for quantification of 2,4-(1H,3H)-pyrimidinedione in the extract was rapid, accurate, precise, linear (R(2) = 0.8685), rugged and robust. Hence this method was suitable for quantification of this component in C. spectabilis. The standardization of C. spectabilis is needed to facilitate marketing of medicinal plants, with a view to promoting the export of valuable Malaysian Traditional Medicinal plants such as C. spectabilis.

Protocol: high throughput silica-based purification of RNA from Arabidopsis seedlings in a 96-well format

PubMed Central

2011-01-01

The increasing popularity of systems-based approaches to plant research has resulted in a demand for high throughput (HTP) methods to be developed. RNA extraction from multiple samples in an experiment is a significant bottleneck in performing systems-level genomic studies. Therefore we have established a high throughput method of RNA extraction from Arabidopsis thaliana to facilitate gene expression studies in this widely used plant model. We present optimised manual and automated protocols for the extraction of total RNA from 9-day-old Arabidopsis seedlings in a 96 well plate format using silica membrane-based methodology. Consistent and reproducible yields of high quality RNA are isolated averaging 8.9 μg total RNA per sample (~20 mg plant tissue). The purified RNA is suitable for subsequent qPCR analysis of the expression of over 500 genes in triplicate from each sample. Using the automated procedure, 192 samples (2 × 96 well plates) can easily be fully processed (samples homogenised, RNA purified and quantified) in less than half a day. Additionally we demonstrate that plant samples can be stored in RNAlater at -20°C (but not 4°C) for 10 months prior to extraction with no significant effect on RNA yield or quality. Additionally, disrupted samples can be stored in the lysis buffer at -20°C for at least 6 months prior to completion of the extraction procedure providing a flexible sampling and storage scheme to facilitate complex time series experiments. PMID:22136293

Protocol: high throughput silica-based purification of RNA from Arabidopsis seedlings in a 96-well format.

PubMed

Salvo-Chirnside, Eliane; Kane, Steven; Kerr, Lorraine E

2011-12-02

The increasing popularity of systems-based approaches to plant research has resulted in a demand for high throughput (HTP) methods to be developed. RNA extraction from multiple samples in an experiment is a significant bottleneck in performing systems-level genomic studies. Therefore we have established a high throughput method of RNA extraction from Arabidopsis thaliana to facilitate gene expression studies in this widely used plant model. We present optimised manual and automated protocols for the extraction of total RNA from 9-day-old Arabidopsis seedlings in a 96 well plate format using silica membrane-based methodology. Consistent and reproducible yields of high quality RNA are isolated averaging 8.9 μg total RNA per sample (~20 mg plant tissue). The purified RNA is suitable for subsequent qPCR analysis of the expression of over 500 genes in triplicate from each sample. Using the automated procedure, 192 samples (2 × 96 well plates) can easily be fully processed (samples homogenised, RNA purified and quantified) in less than half a day. Additionally we demonstrate that plant samples can be stored in RNAlater at -20°C (but not 4°C) for 10 months prior to extraction with no significant effect on RNA yield or quality. Additionally, disrupted samples can be stored in the lysis buffer at -20°C for at least 6 months prior to completion of the extraction procedure providing a flexible sampling and storage scheme to facilitate complex time series experiments.

Polyesters Based on Linoleic Acid for Biolubricant Basestocks: Low-Temperature, Tribological and Rheological Properties.

PubMed

Abdullah, Bashar Mudhaffar; Zubairi, Saiful Irwan; Huri, Hasniza Zaman; Hairunisa, Nany; Yousif, Emad; Basu, Roma Choudhury

2016-01-01

Presently, plant oils which contain high percentage of linoleic acid 1 are perceived to be a viable alternative to mineral oil for biolubricant applications due to their biodegradability and technical properties. In order to get biodegradable lubricant, triester derivatives compounds (1-5) were synthesized and characterized. The processes involved were monoepoxidation of linoleic acid 2, oxirane ring opening 3, esterification 4 and acylation 5. The structures of the products were confirmed by FTIR, 1H and 13C-NMR and LC-MS. The results that showed lowest temperature properties were obtained for triester 5, with a pour point value (PP) of -73°C, highest onset temperature (260°C) and lowest volatility at 0.30%. Viscosity index (VI) increased for the ester's synthetic compounds (2, 3, 4, 5), while the PP decreased. This behavior is the result of the increase of the chain length of the branching agents. Triester based linoleic acid has improved properties such as low-temperature and tribological properties. These results will make it feasible for plant oil to be used for biolubricants, fuels in chain saws, transmission oil and brake fluid.

Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from laboratory culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

2014-10-01

The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail subspecies, Acusta despecta sieboldiana, collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on results obtained from previous works and this study, a simple but credible framework is presented to illustrate how each source and environmental parameter affects shell carbonate δ13C values. According to this framework and some reasonable assumptions, we estimated the contributions of different carbon sources for each snail individual: for cabbage-fed (C3 plant) groups, the contributions of diet, atmospheric CO2, and ingested limestone vary in the ranges of 66-80, 16-24, and 0-13%, respectively. For corn-fed (C4 plant) groups, because of the possible food stress (less ability to consume C4 plants), the values vary in the ranges of 56-64, 18-20, and 16-26%, respectively. Moreover, according to the literature and our observations, the subspecies we cultured in this study show preferences towards different plant species for food. Therefore, we suggest that the potential food preference should be considered adequately for some species in paleoenvironment studies. Finally, we inferred that only the isotopic exchange of the calcite-HCO3--aragonite equilibrium during egg laying and hatching of our cultured snails controls carbon isotope fractionation.

Contribution of the Alternative Respiratory Pathway to PSII Photoprotection in C3 and C4 Plants.

PubMed

Zhang, Zi-Shan; Liu, Mei-Jun; Scheibe, Renate; Selinski, Jennifer; Zhang, Li-Tao; Yang, Cheng; Meng, Xiang-Long; Gao, Hui-Yuan

2017-01-09

The mechanism by which the mitochondrial alternative oxidase (AOX) pathway contributes to photosystem II (PSII) photoprotection is in dispute. It was generally thought that the AOX pathway protects photosystems by dissipating excess reducing equivalents exported from chloroplasts through the malate/oxaloacetate (Mal/OAA) shuttle and thus preventing the over-reduction of chloroplasts. In this study, using the aox1a Arabidopsis mutant and nine other C3 and C4 plant species, we revealed an additional action model of the AOX pathway in PSII photoprotection. Although the AOX pathway contributes to PSII photoprotection in C3 leaves treated with high light, this contribution was observed to disappear when photorespiration was suppressed. Disruption or inhibition of the AOX pathway significantly decreased the photorespiration in C3 leaves. Moreover, the AOX pathway did not respond to high light and contributed little to PSII photoprotection in C4 leaves possessing a highly active Mal/OAA shuttle but with little photorespiration. These results demonstrate that the AOX pathway contributes to PSII photoprotection in C3 plants by maintaining photorespiration to detoxify glycolate and via the indirect export of excess reducing equivalents from chloroplasts by the Mal/OAA shuttle. This new action model explains why the AOX pathway does not contribute to PSII photoprotection in C4 plants. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

δ13C values of soil organic matter in semiarid grassland with mesquite (Prosopis) encroachment in southeastern Arizona

USGS Publications Warehouse

Biggs, Thomas H.; Quade, Jay; Webb, Robert H.

2002-01-01

Over the past century, C3 woody plants and trees have increased in abundance in many semiarid ecosystems, displacing native C4 grasses. Livestock grazing, climatic fluctuations, and fire suppression are several reasons proposed for this shift. Soil carbon isotopic signatures are an ideal technique to evaluate carbon turnover rates in such ecosystems. On the gunnery ranges of Fort Huachuca in southeastern Arizona, study sites were established on homogeneous granitic alluvium to investigate the effects of fire frequency on δ13C values in surface soil organic matter (SOM). These ranges have had no livestock grazing for 50 years and a well-documented history of fires. Prosopis velutina Woot. (mesquite) trees have altered SOM δ13C pools by the concentration of plant nutrients and the addition of isotopically light litter. These soil carbon changes do not extend beyond canopy margins. Elevated total organic carbon (TOC), plant nutrient (N and P) concentrations, and depleted SOM δ13C values are associated with C3Prosopis on an unburned plot, which enables recognition of former Prosopis-occupied sites on plots with recent fire histories. Elevated nutrient concentrations associated with former Prosopis are retained in SOM for many decades. Surface SOM δ13C values indicate the estimated minimum turnover time of C4-derived carbon beneath large mature Prosopis is about 100–300 years. In contrast, complete turnover of original C3 carbon to C4 carbon under grasslands is estimated to take a minimum of 150–500 years. Our study confirms that C4 grass cover has declined over the past 100 years, although isolated C3 trees or shrubs were not uncommon on the historic C4-dominated grasslands. We find evidence in surface soil layers for a modern C3 plant expansion reflected in the substantial shift of SOM δ13C values from C4 grasses to C3 shrublands.

Initial Expansion of C4 Vegetation in Australia During the Late Pliocene

NASA Astrophysics Data System (ADS)

Andrae, J. W.; McInerney, F. A.; Polissar, P. J.; Sniderman, J. M. K.; Howard, S.; Hall, P. A.; Phelps, S. R.

2018-05-01

Since the late Miocene, plants using the C4 photosynthetic pathway have increased to become major components of many tropical and subtropical ecosystems. However, the drivers for this expansion remain under debate, in part because of the varied histories of C4 vegetation on different continents. Australia hosts the highest dominance of C4 vegetation of all continents, but little is known about the history of C4 vegetation there. Carbon isotope ratios of plant waxes from scientific ocean drilling sediments off north-western Australia reveal the onset of Australian C4 expansion at 3.5 Ma, later than in many other regions. Pollen analysis from the same sediments reveals increasingly open C3-dominated biomes preceding the shift to open C4-dominated biomes by several million years. We hypothesize that the development of a summer monsoon climate beginning in the late Pliocene promoted a highly seasonal precipitation regime favorable to the expansion of C4 vegetation.

A defined, plant-based diet utilized in an outpatient cardiovascular clinic effectively treats hypercholesterolemia and hypertension and reduces medications.

PubMed

Najjar, Rami S; Moore, Carolyn E; Montgomery, Baxter D

2018-03-01

Cardiovascular disease (CVD) is a major economic burden in the United States. CVD risk factors, particularly hypertension and hypercholesterolemia, are typically treated with drug therapy. Five-year efficacy of such drugs to prevent CVD is estimated to be 5%. Plant-based diets have emerged as effective mitigators of these risk factors. The implementation of a defined, plant-based diet for 4 weeks in an outpatient clinical setting may mitigate CVD risk factors and reduce patient drug burden. Participants consumed a plant-based diet consisting of foods prepared in a defined method in accordance with a food-classification system. Participants consumed raw fruits, vegetables, seeds, and avocado. All animal products were excluded from the diet. Participant anthropometric and hemodynamic data were obtained weekly for 4 weeks. Laboratory biomarkers were collected at baseline and at 4 weeks. Medication needs were assessed weekly. Data were analyzed using paired-samples t tests and 1-way repeated-measures ANOVA. Significant reductions were observed for systolic (-16.6 mmHg) and diastolic (-9.1 mmHg) blood pressure (P < 0.0005), serum lipids (P ≤ 0.008), and total medication usage (P < 0.0005). Other CVD risk factors, including weight (P < 0.0005), waist circumference (P < 0.0005), heart rate (P = 0.018), insulin (P < 0.0005), glycated hemoglobin (P = 0.002), and high-sensitivity C-reactive protein (P = 0.001) were also reduced. A defined, plant-based diet can be used as an effective therapeutic strategy in the clinical setting to mitigate cardiovascular risk factors and reduce patient drug burden. © 2018 Wiley Periodicals, Inc.

C4 Photosynthesis in the Rice Paddy: Insights from the Noxious Weed Echinochloa glabrescens1[OPEN

PubMed Central

Covshoff, Sarah; Szecowka, Marek; Hughes, Thomas E.; Kelly, Steven; Bailey, Karen J.; Sage, Tammy L.; Pachebat, Justin A.; Leegood, Richard

2016-01-01

The C4 pathway is a highly complex trait that increases photosynthetic efficiency in more than 60 plant lineages. Although the majority of C4 plants occupy disturbed, arid, and nutrient-poor habitats, some grow in high-nutrient, waterlogged conditions. One such example is Echinochloa glabrescens, which is an aggressive weed of rice paddies. We generated comprehensive transcriptome datasets for C4 E. glabrescens and C3 rice to identify genes associated with adaption to waterlogged, nutrient-replete conditions, but also used the data to better understand how C4 photosynthesis operates in these conditions. Leaves of E. glabrescens exhibited classical Kranz anatomy with lightly lobed mesophyll cells having low chloroplast coverage. As with rice and other hygrophytic C3 species, leaves of E. glabrescens accumulated a chloroplastic phosphoenolpyruvate carboxylase protein, albeit at reduced amounts relative to rice. The arid-grown species Setaria italica (C4) and Brachypodium distachyon (C3) were also found to accumulate chloroplastic phosphoenolpyruvate carboxylase. We identified a molecular signature associated with C4 photosynthesis in nutrient-replete, waterlogged conditions that is highly similar to those previously reported from C4 plants that grow in more arid conditions. We also identified a cohort of genes that have been subjected to a selective sweep associated with growth in paddy conditions. Overall, this approach highlights the value of using wild species such as weeds to identify adaptions to specific conditions associated with high-yielding crops in agriculture. PMID:26527656

26. Photograph of a line drawing. 'PLAN LAYOUT AND CROSS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

26. Photograph of a line drawing. 'PLAN LAYOUT AND CROSS SECTION OF PART I, SECTION 8, BUILDINGS NO. C-1, C-3, C-5, C-6, C-7, C-9, MIXING, MANUFACTURING AREA, PLANT B AS OF 4-24-44.' From the U.S. Army Corps of Engineers. Industrial Facilities Inventory, Holston Ordnance Works, Kingsport, Tennessee. Plant B, Parts II, III. (Nashville, TN: Office of the District Engineer, 1944). - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

An Efficient Method for Adventitious Root Induction from Stem Segments of Brassica Species

PubMed Central

Srikanth, Sandhya; Choong, Tsui Wei; Yan, An; He, Jie; Chen, Zhong

2016-01-01

Plant propagation via in vitro culture is a very laborious and time-consuming process. The growth cycle of some of the crop species is slow even in the field and the consistent commercial production is hard to maintain. Enhanced methods of reduced cost, materials and labor significantly impact the research and commercial production of field crops. In our studies, stem-segment explants of Brassica species were found to generate adventitious roots (AR) in aeroponic systems in less than a week. As such, the efficiency of rooting from stem explants of six cultivar varieties of Brassica spp was tested without using any plant hormones. New roots and shoots were developed from Brassica alboglabra (Kai Lan), B. oleracea var. acephala (purple kale), B. rapa L. ssp. chinensis L (Pai Tsai, Nai Bai C, and Nai Bai T) explants after 3 to 5 days of growing under 20 ± 2°C cool root zone temperature (C-RZT) and 4 to 7 days in 30 ± 2°C ambient root zone temperature (A-RZT). At the base of cut end, anticlinal and periclinal divisions of the cambial cells resulted in secondary xylem toward pith and secondary phloem toward cortex. The continuing mitotic activity of phloem parenchyma cells led to a ring of conspicuous white callus. Root initials formed from the callus which in turn developed into ARs. However, B. rapa var. nipposinica (Mizuna) explants were only able to root in C-RZT. All rooted explants were able to develop into whole plants, with higher biomass obtained from plants that grown in C-RZT. Moreover, explants from both RZTs produced higher biomass than plants grown from seeds (control plants). Rooting efficiency was affected by RZTs and explant cuttings of donor plants. Photosynthetic CO2 assimilation rate (Asat) and stomatal conductance (gssat) were significantly differentiated between plants derived from seeds and explants at both RZTs. All plants in A-RZT had highest transpiration rates. PMID:27446170

Synergistic binding of bHLH transcription factors to the promoter of the maize NADP-ME gene used in C4 photosynthesis is based on an ancient code found in the ancestral C3 state.

PubMed

Borba, Ana Rita; Serra, Tânia S; Górska, Alicja; Gouveia, Paulo; Cordeiro, André M; Reyna-Llorens, Ivan; Knerová, Jana; Barros, Pedro M; Abreu, Isabel A; Oliveira, M Margarida; Hibberd, Julian M; Saibo, Nelson J M

2018-04-05

C4 photosynthesis has evolved repeatedly from the ancestral C3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the world's most productive crops. The C4 cycle is accomplished through cell-type specific accumulation of enzymes but cis-elements and transcription factors controlling C4 photosynthesis remain largely unknown. Using the NADP-Malic Enzyme (NADP-ME) gene as a model we tested whether mechanisms impacting on transcription in C4 plants evolved from ancestral components found in C3 species. Two basic Helix-Loop-Helix (bHLH) transcription factors, ZmbHLH128 and ZmbHLH129, were shown to bind the C4NADP-ME promoter from maize. These proteins form heterodimers and ZmbHLH129 impairs trans-activation by ZmbHLH128. Electrophoretic mobility shift assays indicate that a pair of cis-elements separated by a seven base pair spacer synergistically bind either ZmbHLH128 or ZmbHLH129. This pair of cis-elements is found in both C3 and C4 Panicoid grass species of the PACMAD clade. Our analysis is consistent with this cis-element pair originating from a single motif present in the ancestral C3 state. We conclude that C4 photosynthesis has co-opted an ancient C3 regulatory code built on G-box recognition by bHLH to regulate the NADP-ME gene. More broadly, our findings also contribute to the understanding of gene regulatory networks controlling C4 photosynthesis.

Development of a sensitive Luminex xMAP-based microsphere immunoassay for specific detection of Iris yellow spot virus.

PubMed

Yu, Cui; Yang, Cuiyun; Song, Shaoyi; Yu, Zixiang; Zhou, Xueping; Wu, Jianxiang

2018-04-04

Iris yellow spot virus (IYSV) is an Orthotospovirus that infects most Allium species. Very few approaches for specific detection of IYSV from infected plants are available to date. We report the development of a high-sensitive Luminex xMAP-based microsphere immunoassay (MIA) for specific detection of IYSV. The nucleocapsid (N) gene of IYSV was cloned and expressed in Escherichia coli to produce the His-tagged recombinant N protein. A panel of monoclonal antibodies (MAbs) against IYSV was generated by immunizing the mice with recombinant N protein. Five specific MAbs (16D9, 11C6, 7F4, 12C10, and 14H12) were identified and used for developing the Luminex xMAP-based MIA systems along with a polyclonal antibody against IYSV. Comparative analyses of their sensitivity and specificity in detecting IYSV from infected tobacco leaves identified 7F4 as the best-performed MAb in MIA. We then optimized the working conditions of Luminex xMAP-based MIA in specific detection of IYSV from infected tobacco leaves by using appropriate blocking buffer and proper concentration of biotin-labeled antibodies as well as the suitable ratio between the antibodies and the streptavidin R-phycoerythrin (SA-RPE). Under the optimized conditions the Luminex xMAP-based MIA was able to specifically detect IYSV with much higher sensitivity than conventional enzyme-linked immunosorbent assay (ELISA). Importantly, the Luminex xMAP-based MIA is time-saving and the whole procedure could be completed within 2.5 h. We generated five specific MAbs against IYSV and developed the Luminex xMAP-based MIA method for specific detection of IYSV in plants. This assay provides a sensitive, high-specific, easy to perform and likely cost-effective approach for IYSV detection from infected plants, implicating potential broad usefulness of MIA in plant virus diagnosis.

Seasonal change in CO2 and H2O exchange between grassland and atmosphere

NASA Astrophysics Data System (ADS)

Saigusa, N.; Liu, S.; Oikawa, T.; Watanabe, T.

1996-03-01

The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3) dominated in early spring, and Imperata cylindrica (C4) and Andropogon virginicus (C4) grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution of C4 plants decreased in September, and daily variations of CO2 exchange were mainly due to C3 plants in October. The results also suggested that the decrease in the net canopy CO2 exchange from August to October was induced partly by the decrease of net photosynthesis on the individual leaves in both C4 and C3 plants, which could be due to aging of the leaves.

Physiological advantages of C4 grasses in the field: a comparative experiment demonstrating the importance of drought.

PubMed

Taylor, Samuel H; Ripley, Brad S; Martin, Tarryn; De-Wet, Leigh-Ann; Woodward, F Ian; Osborne, Colin P

2014-06-01

Global climate change is expected to shift regional rainfall patterns, influencing species distributions where they depend on water availability. Comparative studies have demonstrated that C4 grasses inhabit drier habitats than C3 relatives, but that both C3 and C4 photosynthesis are susceptible to drought. However, C4 plants may show advantages in hydraulic performance in dry environments. We investigated the effects of seasonal variation in water availability on leaf physiology, using a common garden experiment in the Eastern Cape of South Africa to compare 12 locally occurring grass species from C4 and C3 sister lineages. Photosynthesis was always higher in the C4 than C3 grasses across every month, but the difference was not statistically significant during the wettest months. Surprisingly, stomatal conductance was typically lower in the C3 than C4 grasses, with the peak monthly average for C3 species being similar to that of C4 leaves. In water-limited, rain-fed plots, the photosynthesis of C4 leaves was between 2.0 and 7.4 μmol m(-2) s(-1) higher, stomatal conductance almost double, and transpiration 60% higher than for C3 plants. Although C4 average instantaneous water-use efficiencies were higher (2.4-8.1 mmol mol(-1)) than C3 averages (0.7-6.8 mmol mol(-1)), differences were not as great as we expected and were statistically significant only as drought became established. Photosynthesis declined earlier during drought among C3 than C4 species, coincident with decreases in stomatal conductance and transpiration. Eventual decreases in photosynthesis among C4 plants were linked with declining midday leaf water potentials. However, during the same phase of drought, C3 species showed significant decreases in hydrodynamic gradients that suggested hydraulic failure. Thus, our results indicate that stomatal and hydraulic behaviour during drought enhances the differences in photosynthesis between C4 and C3 species. We suggest that these drought responses are important for understanding the advantages of C4 photosynthesis under field conditions. © 2014 The Authors Global Change Biology Published by John Wiley & Sons Ltd.

Physiological advantages of C4 grasses in the field: a comparative experiment demonstrating the importance of drought

PubMed Central

Taylor, Samuel H; Ripley, Brad S; Martin, Tarryn; De-Wet, Leigh-Ann; Woodward, F Ian; Osborne, Colin P

2014-01-01

Global climate change is expected to shift regional rainfall patterns, influencing species distributions where they depend on water availability. Comparative studies have demonstrated that C4 grasses inhabit drier habitats than C3 relatives, but that both C3 and C4 photosynthesis are susceptible to drought. However, C4 plants may show advantages in hydraulic performance in dry environments. We investigated the effects of seasonal variation in water availability on leaf physiology, using a common garden experiment in the Eastern Cape of South Africa to compare 12 locally occurring grass species from C4 and C3 sister lineages. Photosynthesis was always higher in the C4 than C3 grasses across every month, but the difference was not statistically significant during the wettest months. Surprisingly, stomatal conductance was typically lower in the C3 than C4 grasses, with the peak monthly average for C3 species being similar to that of C4 leaves. In water-limited, rain-fed plots, the photosynthesis of C4 leaves was between 2.0 and 7.4 μmol m−2 s−1 higher, stomatal conductance almost double, and transpiration 60% higher than for C3 plants. Although C4 average instantaneous water-use efficiencies were higher (2.4–8.1 mmol mol−1) than C3 averages (0.7–6.8 mmol mol−1), differences were not as great as we expected and were statistically significant only as drought became established. Photosynthesis declined earlier during drought among C3 than C4 species, coincident with decreases in stomatal conductance and transpiration. Eventual decreases in photosynthesis among C4 plants were linked with declining midday leaf water potentials. However, during the same phase of drought, C3 species showed significant decreases in hydrodynamic gradients that suggested hydraulic failure. Thus, our results indicate that stomatal and hydraulic behaviour during drought enhances the differences in photosynthesis between C4 and C3 species. We suggest that these drought responses are important for understanding the advantages of C4 photosynthesis under field conditions. PMID:24677339

Arabidopsis C3HC4-RING finger E3 ubiquitin ligase AtAIRP4 positively regulates stress-responsive abscisic acid signaling.

PubMed

Yang, Liang; Liu, Qiaohong; Liu, Zhibin; Yang, Hao; Wang, Jianmei; Li, Xufeng; Yang, Yi

2016-01-01

Degradation of proteins via the ubiquitin system is an important step in many stress signaling pathways in plants. E3 ligases recognize ligand proteins and dictate the high specificity of protein degradation, and thus, play a pivotal role in ubiquitination. Here, we identified a gene, named Arabidopsis thaliana abscisic acid (ABA)-insensitive RING protein 4 (AtAIRP4), which is induced by ABA and other stress treatments. AtAIRP4 encodes a cellular protein with a C3HC4-RING finger domain in its C-terminal side, which has in vitro E3 ligase activity. Loss of AtAIRP4 leads to a decrease in sensitivity of root elongation and stomatal closure to ABA, whereas overexpression of this gene in the T-DNA insertion mutant atairp4 effectively recovered the ABA-associated phenotypes. AtAIRP4 overexpression plants were hypersensitive to salt and osmotic stresses during seed germination, and showed drought avoidance compared with the wild-type and atairp4 mutant plants. In addition, the expression levels of ABA- and drought-induced marker genes in AtAIRP4 overexpression plants were markedly higher than those in the wild-type and atairp4 mutant plants. Hence, these results indicate that AtAIRP4 may act as a positive regulator of ABA-mediated drought avoidance and a negative regulator of salt tolerance in Arabidopsis. © 2015 The Authors. Journal of Integrative Plant Biology published by Wiley Publishing Asia Pty Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.

Functional analysis of the omega-6 fatty acid desaturase (CaFAD2) gene family of the oil seed crop Crambe abyssinica

PubMed Central

2013-01-01

Background Crambe abyssinica produces high erucic acid (C22:1, 55-60%) in the seed oil, which can be further increased by reduction of polyunsaturated fatty acid (PUFA) levels. The omega-6 fatty acid desaturase enzyme (FAD2) is known to be involved in PUFA biosynthesis. In crambe, three CaFAD2 genes, CaFAD2-C1, CaFAD2-C2 and CaFAD2-C3 are expressed. Results The individual effect of each CaFAD2 gene on oil composition was investigated through studying transgenic lines (CaFAD2-RNAi) for differential expression levels in relation to the composition of seed-oil. Six first generation transgenic plants (T1) showed C18:1 increase (by 6% to 10.5%) and PUFA reduction (by 8.6% to 10.2%). The silencing effect in these T1-plants ranged from the moderate silencing (40% to 50% reduction) of all three CaFAD2 genes to strong silencing (95% reduction) of CaFAD2-C3 alone. The progeny of two T1-plants (WG4-4 and WG19-6) was further analysed. Four or five transgene insertions are characterized in the progeny (T2) of WG19-6 in contrast to a single insertion in the T2 progeny of WG4-4. For the individual T2-plants of both families (WG19-6 and WG4-4), seed-specific silencing of CaFAD2-C1 and CaFAD2-C2 was observed in several individual T2-plants but, on average in both families, the level of silencing of these genes was not significant. A significant reduction in expression level (P < 0.01) in both families was only observed for CaFAD2-C3 together with significantly different C18:1 and PUFA levels in oil. Conclusions CaFAD2-C3 expression is highly correlated to levels of C18:1 (r = -0.78) and PUFA (r = 0.75), which suggests that CaFAD2-C3 is the most important one for changing the oil composition of crambe. PMID:24083776

Comparative study of rhizobacterial community structure of plant species in oil-contaminated soil.

PubMed

Lee, Eun-Hee; Cho, Kyong-Suk; Kim, Jaisoo

2010-09-01

In this study, the identity and distribution of plants and the structure of their associated rhizobacterial communities were examined in an oil-contaminated site. The number of plant species that formed a community or were scattered was 24. The species living in soil highly contaminated with total petroleum hydrocarbon (TPH) (9,000-4,5000 mg/g-soil) were Cynodon dactylon, Persicaria lapathifolia, and Calystegia soldanella (a halophytic species). Among the 24 plant species, the following have been known to be effective for oil removal: C. dactylon, Digitaria sanguinalis, and Cyperus orthostachyus. Denaturing gradient gel electrophoresis (DGGE) profile analysis showed that the following pairs of plant species had highly similar (above 70%) rhizobacterial community structures: Artemisia princeps and Hemistepta lyrata; C. dactylon and P. lapathifolia; Carex kobomugi and Cardamine flexuosa; and Equisetum arvense and D. sanguinalis. The major groups of rhizobacteria were Betaproteobacteria, Gamma-proteobacteria, Chloroflexi, Actinobacteria, and unknown. Based on DGGE analysis, P. lapathifolia, found for the first time in this study growing in the presence of high TPH, may be a good species for phytoremediation of oil-contaminated soils and in particular, C. soldanella may be useful for soils with high TPH and salt concentrations. Overall, this study suggests that the plant roots, regardless of plant species, may have a similar influence on the bacterial community structure in oil-contaminated soil.

SEUSS and PIF4 Coordinately Regulate Light and Temperature Signaling Pathways to Control Plant Growth.

PubMed

Huai, Junling; Zhang, Xinyu; Li, Jialong; Ma, Tingting; Zha, Ping; Jing, Yanjun; Lin, Rongcheng

2018-05-02

Plants continuously monitor environmental conditions (such as light and temperature) and adjust their growth and development accordingly. The transcription factor PHYTOCHROME-INTERACTING FACTOR4 (PIF4) regulates both light and temperature signaling pathways. Here, we identified ENHANCED PHOTOMORPHOGENIC2 (EPP2) as a new repressor of photomorphogenesis in red, far-red, and blue light. Map-based cloning revealed that EPP2 encodes the SEUSS (SEU) transcription regulator. The C-terminus of SEU has transcriptional activation activity and SEU physically interacts with PIF4. Moreover, SEU promotes the expression of many genes, including auxin biosynthetic and responsive genes, and regulates IAA levels in plants. SEU associates with regulatory regions in INDOLE-3-ACETIC ACID INDUCIBLE6 (IAA6) and IAA19 in a PIF4-independent manner, whereas the binding of PIF4 to these genes requires SEU. Furthermore, mutations in SEU affect H3K4me3 methylation at IAA6 and IAA19, and SEU positively regulates warm temperature-mediated hypocotyl growth together with PIF4. Therefore, our results reveal that SEU acts as a central regulator to integrate light and temperature signals to control plant growth by coordinating with PIF4. Copyright © 2018 The Author. Published by Elsevier Inc. All rights reserved.

Investigation of Some Potent Medicinal Plants of N.E.INDIA with Respect to Thermophysical, Chromatographic and Crystallographic Properties

NASA Astrophysics Data System (ADS)

Bora, M. N.; Kalita, Mahendra

2010-06-01

North East India is readily available of various kinds of medicinal plants. A lot of studies on thermophysical properties of plant leaves, fluids, stems and roots had already been made[3,4,8]. In the present studies of thermophysical properties, chromatographic and crystallographic properties of specific medicinal plant leaves (Azadirechta indica)A, (Vinca rosea)B, (Clerodrendrum colebrookianum)C, (Osimum sanctum)D and fruits (Chisocheton paniculatus) E, and (Cudrania javanensis) F have been made plant based drugs for curing for different chronic diseases. The thermophysical properties of these leaves and fruits have been studies with XRD, XRF, TG, DTG, DTA, and DSC thermograms. From weight loss(%), time and temperature variations, the Activation Energies of these medicinal plant samples have been computed. The thermal stability is found more for the fruits samples than that of the leave samples. Thermal behaviours of all six samples have shown hygroscopic behaviour. The results TG, DTG and DTA thermograms confirmed that all samples show similar dehydration and decomposition reactions and hydrophilic nature. Both chromatographic techniques thin layer (TLC) and Column chromatography have been used for separation of components of the mixtures of samples. From these methods of the fruit sample E a pure crystalline white solids have been identified and confirm them as (MK 01) α-isomer. Our interest to study the molecular and crystal structure of the sample E. The single crystal of (MK 01) is found to be orthorhombic cell with lattice parameters a = 10ṡ699(3)Å b = 15ṡ5100(4)Å c = 16ṡ626(4)Å α = 90° β = 90° γ = 90° with space group P212121 Again from fruit sample F a light yellow solid is isolated and on crystallization give crystalline solid MN-01 and MN-02 and it is confirmed that these two compounds are unsaturated isoflavonoids. The single crystal of MN-01 has been found monoclinic with lattice parameters a = 6.2374(11)Å, b = 8.4243(11)Å, c = 21.181(4)Å, α = 96.083(13)°, β = 95.602(10)° and γ = 107.419(7)° with Space group P-1. Again single crystal MN-02 has been found monoclinic with lattice parameters being a = 25.2732 Å, b = 7.4414 Å, c = 22.3113 Å, α = 90°, β = 93.063°, γ = 90°, with space group C2/c.

Plant phospholipase C family: Regulation and functional role in lipid signaling.

PubMed

Singh, Amarjeet; Bhatnagar, Nikita; Pandey, Amita; Pandey, Girdhar K

2015-08-01

Phospholipase C (PLC), a major membrane phospholipid hydrolyzing enzyme generates signaling messengers such as diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) in animals, and their phosphorylated forms such as phosphatidic acid (PA) and inositol hexakisphosphate (IP6) are thought to regulate various cellular processes in plants. Based on substrate specificity, plant PLC family is sub-divided into phosphatidylinositol-PLC (PI-PLC) and phosphatidylcholine-PLC (PC-PLC) groups. The activity of plant PLCs is regulated by various factors and the major ones include, Ca(2+) concentration, phospholipid substrate, post-translational modifications and interacting proteins. Most of the PLC members have been localized at the plasma membrane, suited for their function of membrane lipid hydrolysis. Several PLC members have been implicated in various cellular processes and signaling networks, triggered in response to a number of environmental cues and developmental events in different plant species, which makes them potential candidates for genetically engineering the crop plants for stress tolerance and enhancing the crop productivity. In this review article, we are focusing mainly on the plant PLC signaling and regulation, potential cellular and physiological role in different abiotic and biotic stresses, nutrient deficiency, growth and development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reduced plant water status under sub-ambient pCO2 limits plant productivity in the wild progenitors of C3 and C4 cereals

PubMed Central

Cunniff, Jennifer; Charles, Michael; Jones, Glynis; Osborne, Colin P.

2016-01-01

Background and Aims The reduction of plant productivity by low atmospheric CO2 partial pressure (pCO2) during the last glacial period is proposed as a limiting factor for the establishment of agriculture. Supporting this hypothesis, previous work has shown that glacial pCO2 limits biomass in the wild progenitors of C3 and C4 founder crops, in part due to the direct effects of glacial pCO2 on photosynthesis. Here, we investigate the indirect role of pCO2 mediated via water status, hypothesizing that faster soil water depletion at glacial (18 Pa) compared to post-glacial (27 Pa) pCO2, due to greater stomatal conductance, feeds back to limit photosynthesis during drying cycles. Methods We grew four wild progenitors of C3 and C4 crops at glacial and post-glacial pCO2 and investigated physiological changes in gas exchange, canopy transpiration, soil water content and water potential between regular watering events. Growth parameters including leaf area were measured. Key Results Initial transpiration rates were higher at glacial pCO2 due to greater stomatal conductance. However, stomatal conductance declined more rapidly over the soil drying cycle in glacial pCO2 and was associated with decreased intercellular pCO2 and lower photosynthesis. Soil water content was similar between pCO2 levels as larger leaf areas at post-glacial pCO2 offset the slower depletion of water. Instead the feedback could be linked to reduced plant water status. Particularly in the C4 plants, soil–leaf water potential gradients were greater at 18 Pa compared with 27 Pa pCO2, suggesting an increased ratio of leaf evaporative demand to supply. Conclusions Reduced plant water status appeared to cause a negative feedback on stomatal aperture in plants at glacial pCO2, thereby reducing photosynthesis. The effects were stronger in C4 species, providing a mechanism for reduced biomass at 18 Pa. These results have added significance when set against the drier climate of the glacial period. PMID:27578764

Atmospheric CO2 effect on stable carbon isotope composition of terrestrial fossil archives.

PubMed

Hare, Vincent J; Loftus, Emma; Jeffrey, Amy; Ramsey, Christopher Bronk

2018-01-17

The 13 C/ 12 C ratio of C 3 plant matter is thought to be controlled by the isotopic composition of atmospheric CO 2 and stomatal response to environmental conditions, particularly mean annual precipitation (MAP). The effect of CO 2 concentration on 13 C/ 12 C ratios is currently debated, yet crucial to reconstructing ancient environments and quantifying the carbon cycle. Here we compare high-resolution ice core measurements of atmospheric CO 2 with fossil plant and faunal isotope records. We show the effect of pCO 2 during the last deglaciation is stronger for gymnosperms (-1.4 ± 1.2‰) than angiosperms/fauna (-0.5 ± 1.5‰), while the contributions from changing MAP are -0.3 ± 0.6‰ and -0.4 ± 0.4‰, respectively. Previous studies have assumed that plant 13 C/ 12 C ratios are mostly determined by MAP, an assumption which is sometimes incorrect in geological time. Atmospheric effects must be taken into account when interpreting terrestrial stable carbon isotopes, with important implications for past environments and climates, and understanding plant responses to climate change.

Rhizosphere Microbiome Recruited from a Suppressive Compost Improves Plant Fitness and Increases Protection against Vascular Wilt Pathogens of Tomato

PubMed Central

Antoniou, Anastasis; Tsolakidou, Maria-Dimitra; Stringlis, Ioannis A.; Pantelides, Iakovos S.

2017-01-01

Suppressive composts represent a sustainable approach to combat soilborne plant pathogens and an alternative to the ineffective chemical fungicides used against those. Nevertheless, suppressiveness to plant pathogens and reliability of composts are often inconsistent with unpredictable effects. While suppressiveness is usually attributed to the compost’s microorganisms, the mechanisms governing microbial recruitment by the roots and the composition of selected microbial communities are not fully elucidated. Herein, the purpose of the study was to evaluate the impact of a compost on tomato plant growth and its suppressiveness against Fusarium oxysporum f. sp. lycopersici (Foxl) and Verticillium dahliae (Vd). First, growth parameters of tomato plants grown in sterile peat-based substrates including 20 and 30% sterile compost (80P/20C-ST and 70P/30C-ST) or non-sterile compost (80P/20C and 70P/30C) were evaluated in a growth room experiment. Plant height, total leaf surface, and fresh and dry weight of plants grown in the non-sterile compost mixes were increased compared to the plants grown in the sterile compost substrates, indicating the plant growth promoting activity of the compost’s microorganisms. Subsequently, compost’s suppressiveness against Foxl and Vd was evaluated with pathogenicity experiments on tomato plants grown in 70P/30C-ST and 70P/30C substrates. Disease intensity was significantly less in plants grown in the non-sterile compost than in those grown in the sterile compost substrate; AUDPC was 2.3- and 1.4-fold less for Foxl and Vd, respectively. Moreover, fungal quantification in planta demonstrated reduced colonization in plants grown in the non-sterile mixture. To further investigate these findings, we characterized the culturable microbiome attracted by the roots compared to the unplanted compost. Bacteria and fungi isolated from unplanted compost and the rhizosphere of plants were sequence-identified. Community-level analysis revealed differential microbial communities between the compost and the rhizosphere, suggesting a clear effect of the plant in the microbiome assembly. Proteobacteria and Actinobacteria were highly enriched in the rhizosphere whereas Firmicutes were strongly represented in both compartments with Bacillus being the most abundant species. Our results shed light on the composition of a microbial consortium that could protect plants against the wilt pathogens of tomato and improve plant overall health. PMID:29238353

Antifungal Indole and Pyrrolidine-2,4-Dione Derivative Peptidomimetic Lead Design Based on In Silico Study of Bioactive Peptide Families

PubMed Central

Moradi, Shoeib; Azerang, Parisa; Khalaj, Vahid; Sardari, Soroush

2013-01-01

Background The rise of opportunistic fungal infections highlights the need for development of new antimicrobial agents. Antimicrobial Peptides (AMPs) and Antifungal Peptides (AFPs) are among the agents with minimal resistance being developed against them, therefore they can be used as structural templates for design of new antimicrobial agents. Methods In the present study four antifungal peptidomimetic structures named C1 to C4 were designed based on plant defensin of Pisum sativum. Minimum inhibitory concentrations (MICs) for these structures were determined against Aspergillus niger N402, Candida albicans ATCC 10231, and Saccharomyces cerevisiae PTCC 5052. Results C1 and C2 showed more potent antifungal activity against these fungal strains compared to C3 and C4. The structure C2 demonstrated a potent antifungal activity among them and could be used as a template for future study on antifungal peptidomemetics design. Sequences alignments led to identifying antifungal decapeptide (KTCENLADTY) named KTC-Y, which its MIC was determined on fungal protoplast showing 25 (µg/ml) against Aspergillus fumigatus Af293. Conclusion The present approach to reach the antifungal molecules seems to be a powerful approach in design of bioactive agents based on AMP mimetic identification. PMID:23626876

The Ditylenchus destructor genome provides new insights into the evolution of plant parasitic nematodes.

PubMed

Zheng, Jinshui; Peng, Donghai; Chen, Ling; Liu, Hualin; Chen, Feng; Xu, Mengci; Ju, Shouyong; Ruan, Lifang; Sun, Ming

2016-07-27

Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plant-parasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants. © 2016 The Author(s).

Mesophyll cells of C4 plants have fewer chloroplasts than those of closely related C3 plants.

PubMed

Stata, Matt; Sage, Tammy L; Rennie, Troy D; Khoshravesh, Roxana; Sultmanis, Stefanie; Khaikin, Yannay; Ludwig, Martha; Sage, Rowan F

2014-11-01

The evolution of C(4) photosynthesis from C(3) ancestors eliminates ribulose bisphosphate carboxylation in the mesophyll (M) cell chloroplast while activating phosphoenolpyruvate (PEP) carboxylation in the cytosol. These changes may lead to fewer chloroplasts and different chloroplast positioning within M cells. To evaluate these possibilities, we compared chloroplast number, size and position in M cells of closely related C(3), C(3) -C(4) intermediate and C(4) species from 12 lineages of C(4) evolution. All C(3) species had more chloroplasts per M cell area than their C(4) relatives in high-light growth conditions. C(3) species also had higher chloroplast coverage of the M cell periphery than C(4) species, particularly opposite intercellular air spaces. In M cells from 10 of the 12 C(4) lineages, a greater fraction of the chloroplast envelope was pulled away from the plasmalemma in the C(4) species than their C(3) relatives. C(3) -C(4) intermediate species generally exhibited similar patterns as their C(3) relatives. We interpret these results to reflect adaptive shifts that facilitate efficient C(4) function by enhancing diffusive access to the site of primary carbon fixation in the cytosol. Fewer chloroplasts in C(4) M cells would also reduce shading of the bundle sheath chloroplasts, which also generate energy required by C(4) photosynthesis. © 2014 John Wiley & Sons Ltd.

Stable isotopes to discriminate lambs fed herbage or concentrate both obtained from C(3) plants.

PubMed

Moreno-Rojas, Jose M; Vasta, Valentina; Lanza, Alfio; Luciano, Giuseppe; Ladroue, Virginie; Guillou, Claude; Priolo, Alessandro

2008-12-01

This study was aimed at determining whether isotopic ratio mass spectrometry (IRMS) enables us to discriminate between lambs fed herbage or concentrate, both obtained from C(3) plants, and those fed a concentrate obtained from C(4) plants. Thirty-four Comisana male lambs (age 45 days) were assigned to three feeding treatments. Fourteen lambs were fed vetch (Vicia sativa) ad libitum. Another fourteen lambs received a barley-based concentrate. The remaining six lambs were fed a maize-based concentrate. After 60 days of experimental treatment the animals were slaughtered and the wool, perirenal fat and muscle longissimus dorsi were sampled. The delta(13)C and delta(15)N values of the muscle, wool and feed were measured by continuous flow elemental analysis (CF-EA)-IRMS. The delta(13)C of the fat was determined likewise. The isotopic composition of the tissues reflected that of the three diets. For the lambs which were fed herbage the muscle delta(13)C values were higher (P < 0.0005) and delta(15)N values were lower (P < 0.0005) than those of the lambs receiving concentrates. The delta(15)N and delta(13)C values in the muscle and delta(13)C values in the adipose tissue allowed perfect discrimination between the lambs fed the three different diets. The regression between the delta(13)C values measured in muscle and in wool of lambs was linear (R(2) = 0.99; P < 0.0005). This result shows that delta(13)C measured in the wool can predict muscle delta(13)C distribution, suggesting that wool is a valuable matrix for meat authentication.

A mechanistic, globally-applicable model of plant nitrogen uptake, retranslocation and fixation

NASA Astrophysics Data System (ADS)

Fisher, J. B.; Tan, S.; Malhi, Y.; Fisher, R. A.; Sitch, S.; Huntingford, C.

2008-12-01

Nitrogen is one of the nutrients that can most limit plant growth, and nitrogen availability may be a controlling factor on biosphere responses to climate change. We developed a plant nitrogen assimilation model based on a) advective transport through the transpiration stream, b) retranslocation whereby carbon is expended to resorb nitrogen from leaves, c) active uptake whereby carbon is expended to acquire soil nitrogen, and d) biological nitrogen fixation whereby carbon is expended for symbiotic nitrogen fixers. The model relies on 9 inputs: 1) net primary productivity (NPP), 2) plant C:N ratio, 3) available soil nitrogen, 4) root biomass, 5) transpiration rate, 6) saturated soil depth,7) leaf nitrogen before senescence, 8) soil temperature, and 9) ability to fix nitrogen. A carbon cost of retranslocation is estimated based on leaf nitrogen and compared to an active uptake carbon cost based on root biomass and available soil nitrogen; for nitrogen fixers both costs are compared to a carbon cost of fixation dependent on soil temperature. The NPP is then allocated to optimize growth while maintaining the C:N ratio. The model outputs are total plant nitrogen uptake, remaining NPP available for growth, carbon respired to the soil and updated available soil nitrogen content. We test and validate the model (called FUN: Fixation and Uptake of Nitrogen) against data from the UK, Germany and Peru, and run the model under simplified scenarios of primary succession and climate change. FUN is suitable for incorporation into a land surface scheme of a General Circulation Model and will be coupled with a soil model and dynamic global vegetation model as part of a land surface model (JULES).

Transpiration efficiency of a tropical pioneer tree (Ficus insipida) in relation to soil fertility.

PubMed

Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Turner, Benjamin L; Marshall, John D

2007-01-01

The response of whole-plant water-use efficiency, termed transpiration efficiency (TE), to variation in soil fertility was assessed in a tropical pioneer tree, Ficus insipida Willd. Measurements of stable isotope ratios (delta(13)C, delta(18)O, delta(15)N), elemental concentrations (C, N, P), plant growth, instantaneous leaf gas exchange, and whole-plant water use were used to analyse the mechanisms controlling TE. Plants were grown individually in 19 l pots with non-limiting soil moisture. Soil fertility was altered by mixing soil with varying proportions of rice husks, and applying a slow release fertilizer. A large variation was observed in leaf photosynthetic rate, mean relative growth rate (RGR), and TE in response to experimental treatments; these traits were well correlated with variation in leaf N concentration. Variation in TE showed a strong dependence on the ratio of intercellular to ambient CO(2) mole fractions (c(i)/c(a)); both for instantaneous measurements of c(i)/c(a) (R(2)=0.69, P <0.0001, n=30), and integrated estimates based on C isotope discrimination (R(2)=0.88, P <0.0001, n=30). On the other hand, variations in the leaf-to-air humidity gradient, unproductive water loss, and respiratory C use probably played only minor roles in modulating TE in the face of variable soil fertility. The pronounced variation in TE resulted from a combination of the strong response of c(i)/c(a) to leaf N, and inherently high values of c(i)/c(a) for this tropical tree species; these two factors conspired to cause a 4-fold variation among treatments in (1-c(i)/c(a)), the term that actually modifies TE. Results suggest that variation in plant N status could have important implications for the coupling between C and water exchange in tropical forest trees.

Physiological and biochemical responses of wheat (Triticum aestivum L.) seedlings to three imidazolium-based ionic liquids in soil.

PubMed

Xu, Yaqi; Wang, Jun; Zhu, Lusheng; Du, Zhongkun; Wang, Jinhua; Wei, Kai

2018-01-01

Ionic liquids (ILs) are considered environmentally friendly solvents and are widely applied in various fields; however, some researchers have noted the toxicity of ILs to plants cultivated in nutrient solution. To evaluate the toxicities of ILs to wheat seedlings in soil, the natural growth environment of plants, a study was performed using three imidazolium-based ionic liquids with different anions: 1-octyl-3-methylimidazolium chloride ([C 8 mim]Cl), 1-octyl-3-methylimidazolium bromide ([C 8 mim]Br) and 1-octyl-3-methylimidazolium tetrafluoroborate ([C 8 mim]BF 4 ). After 13 d of exposure to these three ILs at 0, 100, 200, 400, 600 and 800 mg kg -1 in brown soil, wheat seedlings were randomly sampled to evaluate growth (shoot length, root length, pigment content and proline content), lipid peroxidation, oxygen species (H 2 O 2 and O 2 - ) and activities of the detoxification enzyme glutathione-s-transferase and other antioxidant enzymes, including superoxide dismutase, catalase and peroxidase. The experimental results showed that all three ILs had inhibitory effects on the growth of wheat seedlings and induced the generation of reactive oxygen species, which indicated that the wheat seedlings suffered oxidative stress. Moreover, antioxidant enzyme activity was enhanced after exposure to [C 8 mim]Cl, [C 8 mim]Br and [C 8 mim]BF 4 , demonstrating that oxidative damage may be the primary underlying mechanism of IL toxicity in wheat. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification and Analysis of Jasmonate Pathway Genes in Coffea canephora (Robusta Coffee) by In Silico Approach.

PubMed

Bharathi, Kosaraju; Sreenath, H L

2017-07-01

Coffea canephora is the commonly cultivated coffee species in the world along with Coffea arabica . Different pests and pathogens affect the production and quality of the coffee. Jasmonic acid (JA) is a plant hormone which plays an important role in plants growth, development, and defense mechanisms, particularly against insect pests. The key enzymes involved in the production of JA are lipoxygenase, allene oxide synthase, allene oxide cyclase, and 12-oxo-phytodienoic reductase. There is no report on the genes involved in JA pathway in coffee plants. We made an attempt to identify and analyze the genes coding for these enzymes in C. canephora . First, protein sequences of jasmonate pathway genes from model plant Arabidopsis thaliana were identified in the National Center for Biotechnology Information (NCBI) database. These protein sequences were used to search the web-based database Coffee Genome Hub to identify homologous protein sequences in C. canephora genome using Basic Local Alignment Search Tool (BLAST). Homologous protein sequences for key genes were identified in the C. canephora genome database. Protein sequences of the top matches were in turn used to search in NCBI database using BLAST tool to confirm the identity of the selected proteins and to identify closely related genes in species. The protein sequences from C. canephora database and the top matches in NCBI were aligned, and phylogenetic trees were constructed using MEGA6 software and identified the genetic distance of the respective genes. The study identified the four key genes of JA pathway in C. canephora , confirming the conserved nature of the pathway in coffee. The study expected to be useful to further explore the defense mechanisms of coffee plants. JA is a plant hormone that plays an important role in plant defense against insect pests. Genes coding for the 4 key enzymes involved in the production of JA viz., LOX, AOS, AOC, and OPR are identified in C. canephora (robusta coffee) by bioinformatic approaches confirming the conserved nature of the pathway in coffee. The findings are useful to understand the defense mechanisms of C. canephora and coffee breeding in the long run. JA is a plant hormone that plays an important role in plant defense against insect pests. Genes coding for the 4 key enzymes involved in the production of JA viz., LOX, AOS, AOC and OPR were identified and analyzed in C. canephora (robusta coffee) by in silico approach. The study has confirmed the conserved nature of JA pathway in coffee; the findings are useful to further explore the defense mechanisms of coffee plants. Abbreviations used: C. canephora : Coffea canephora ; C. arabica : Coffea arabica ; JA: Jasmonic acid; CGH: Coffee Genome Hub; NCBI: National Centre for Biotechnology Information; BLAST: Basic Local Alignment Search Tool; A. thaliana : Arabidopsis thaliana ; LOX: Lipoxygenase, AOS: Allene oxide synthase; AOC: Allene oxide cyclase; OPR: 12 oxo phytodienoic reductase.

Planting richness affects the recovery of vegetation and soil processes in constructed wetlands following disturbance

USGS Publications Warehouse

Means, Mary M.; Ahn, Changwoo; Noe, Gregory

2017-01-01

The resilience of constructed wetland ecosystems to severe disturbance, such as a mass herbivory eat-out or soil disturbance, remains poorly understood. In this study, we use a controlled mesocosm experiment to examine how original planting diversity affects the ability of constructed freshwater wetlands to recover structurally and functionally after a disturbance (i.e., aboveground harvesting and soil coring). We assessed if the planting richness of macrophyte species influences recovery of constructed wetlands one year after a disturbance. Mesocosms were planted in richness groups with various combinations of either 1, 2, 3, or 4 species (RG 1–4) to create a gradient of richness. Structural wetland traits measured include morphological regrowth of macrophytes, soil bulk density, soil moisture, soil %C, and soil %N. Functional wetland traits measured include above ground biomass production, soil potential denitrification, and soil potential microbial respiration. Total mesocosm cover increased along the gradient of plant richness (43.5% in RG 1 to 84.5% in RG 4) in the growing season after the disturbance, although not all planted individuals recovered. This was largely attributed to the dominance of the obligate annual species. The morphology of each species was affected negatively by the disturbance, producing shorter, and fewer stems than in the years prior to the disturbance, suggesting that the communities had not fully recovered one year after the disturbance. Soil characteristics were almost uniform across the planting richness gradient, but for a few exceptions (%C, C:N, and non-growing season soil moisture were higher slightly in RG 2). Denitrification potential (DEA) increased with increasing planting richness and was influenced by the abundance and quality of soil C. Increased open space in unplanted mesocosms and mesocosms with lower species richness increased labile C, leading to higher C mineralization rates.

C4 Cycles: Past, Present, and Future Research on C4 Photosynthesis

PubMed Central

Langdale, Jane A.

2011-01-01

In the late 1960s, a vibrant new research field was ignited by the discovery that instead of fixing CO2 into a C3 compound, some plants initially fix CO2 into a four-carbon (C4) compound. The term C4 photosynthesis was born. In the 20 years that followed, physiologists, biochemists, and molecular and developmental biologists grappled to understand how the C4 photosynthetic pathway was partitioned between two morphologically distinct cell types in the leaf. By the early 1990s, much was known about C4 biochemistry, the types of leaf anatomy that facilitated the pathway, and the patterns of gene expression that underpinned the biochemistry. However, virtually nothing was known about how the pathway was regulated. It should have been an exciting time, but many of the original researchers were approaching retirement, C4 plants were proving recalcitrant to genetic manipulation, and whole-genome sequences were not even a dream. In combination, these factors led to reduced funding and the failure to attract young people into the field; the endgame seemed to be underway. But over the last 5 years, there has been a resurgence of interest and funding, not least because of ambitious multinational projects that aim to increase crop yields by introducing C4 traits into C3 plants. Combined with new technologies, this renewed interest has resulted in the development of more sophisticated approaches toward understanding how the C4 pathway evolved, how it is regulated, and how it might be manipulated. The extent of this resurgence is manifest by the publication in 2011 of more than 650 pages of reviews on different aspects of C4. Here, I provide an overview of our current understanding, the questions that are being addressed, and the issues that lie ahead. PMID:22128120

Interfacial coupling induced direct Z scheme water splitting in metal-free photocatalyst: C3N/g-C3N4 heterojunctions.

PubMed

Wang, Jiajun; Li, Xiaoting; You, Ya; Xintong, Yang; Wang, Ying; Li, Qunxiang

2018-06-21

Mimicking the natural photosynthesis in green plants, artificial Z-scheme photocatalysis enables more efficient utilization of solar energy for photocatalytic water splitting. Most currently designed g-C3N4-based Z-scheme heterojunctions are usually based on metal-containing semiconductor photocatalysts, thus exploiting metal-free photocatalysts for Z-scheme water splitting is of huge interest. Herein, we propose two metal-free C3N/g-C3N4 heterojunctions with the C3N monolayer covering g-C3N4 sheet (monolayer or bilayer) and systematically explore their electronic structures, charge distributions and photocatalytic properties by performing extensive hybrid density functional calculations. We clearly reveal that the relative strong built-in electric fields around their respective interface regions, caused by the charge transfer from C3N monolayer to g-C3N4 monolayer or bilayer, result in the bands bending, renders the transfer of photogenerated carriers in these two heterojunctions following the Z-scheme instead of the type-II pathway. Moreover, the photogenerated electrons and holes in these two C3N/g-C3N4 heterojunctions not only can be efficiently separated, but also have strong redox abilities for water oxidation and reduction. Compared with the isolated g-C3N4 sheets, the light absorption in visible to near-infrared region are significantly enhanced in these proposed heterojunctions. These theoretical findings suggest that these proposed metal-free C3N/g-C3N4 heterojunctions are promising direct Z-scheme photocatalysts for solar water splitting. © 2018 IOP Publishing Ltd.

Phytoremediation of carbamazepine and its metabolite 10,11-epoxycarbamazepine by C3 and C4 plants.

PubMed

Ryšlavá, Helena; Pomeislová, Alice; Pšondrová, Šárka; Hýsková, Veronika; Smrček, Stanislav

2015-12-01

The anticonvulsant drug carbamazepine is considered as an indicator of sewage water pollution: however, its uptake by plants and effect on metabolism have not been sufficiently documented, let alone its metabolite (10,11-epoxycarbamazepine). In a model system of sterile, hydroponically cultivated Zea mays (as C4 plant) and Helianthus annuus (as C3 plant), the uptake and effect of carbamazepine and 10,11-epoxycarbamazepine were studied in comparison with those of acetaminophen and ibuprofen. Ibuprofen and acetaminophen were effectively extracted from drug-supplemented media by both plants, while the uptake of more hydrophobic carbamazepine was much lower. On the other hand, the carbamazepine metabolite, 10,11-epoxycarbamazepine, was, unlike sunflower, willingly taken up by maize plants (after 96 h 88 % of the initial concentration) and effectively stored in maize tissues. In addition, the effect of the studied pharmaceuticals on the plant metabolism (enzymes of Hatch-Slack cycle, peroxidases) was followed. The activity of bound peroxidases, which could cause xylem vessel lignification and reduction of xenobiotic uptake, was at the level of control plants in maize leaves contrary to sunflower. Therefore, our results indicate that maize has the potential to remove 10,11-epoxycarbamazepine from contaminated soils.

Foxtail Mosaic Virus-Induced Gene Silencing in Monocot Plants1[OPEN

PubMed Central

Liu, Na; Xie, Ke; Jia, Qi; Zhao, Jinping; Chen, Tianyuan; Li, Huangai; Wei, Xiang; Diao, Xianmin; Hong, Yiguo

2016-01-01

Virus-induced gene silencing (VIGS) is a powerful technique to study gene function in plants. However, very few VIGS vectors are available for monocot plants. Here we report that Foxtail mosaic virus (FoMV) can be engineered as an effective VIGS system to induce efficient silencing of endogenous genes in monocot plants including barley (Hordeum vulgare L.), wheat (Triticum aestivum) and foxtail millet (Setaria italica). This is evidenced by FoMV-based silencing of phytoene desaturase (PDS) and magnesium chelatase in barley, of PDS and Cloroplastos alterados1 in foxtail millet and wheat, and of an additional gene IspH in foxtail millet. Silencing of these genes resulted in photobleached or chlorosis phenotypes in barley, wheat, and foxtail millet. Furthermore, our FoMV-based gene silencing is the first VIGS system reported for foxtail millet, an important C4 model plant. It may provide an efficient toolbox for high-throughput functional genomics in economically important monocot crops. PMID:27225900

Long-term sampling of CO(2) from waste-to-energy plants: (14)C determination methodology, data variation and uncertainty.

PubMed

Fuglsang, Karsten; Pedersen, Niels Hald; Larsen, Anna Warberg; Astrup, Thomas Fruergaard

2014-02-01

A dedicated sampling and measurement method was developed for long-term measurements of biogenic and fossil-derived CO(2) from thermal waste-to-energy processes. Based on long-term sampling of CO(2) and (14)C determination, plant-specific emission factors can be determined more accurately, and the annual emission of fossil CO(2) from waste-to-energy plants can be monitored according to carbon trading schemes and renewable energy certificates. Weekly and monthly measurements were performed at five Danish waste incinerators. Significant variations between fractions of biogenic CO(2) emitted were observed, not only over time, but also between plants. From the results of monthly samples at one plant, the annual mean fraction of biogenic CO(2) was found to be 69% of the total annual CO(2) emissions. From weekly samples, taken every 3 months at the five plants, significant seasonal variations in biogenic CO(2) emissions were observed (between 56% and 71% biogenic CO(2)). These variations confirmed that biomass fractions in the waste can vary considerably, not only from day to day but also from month to month. An uncertainty budget for the measurement method itself showed that the expanded uncertainty of the method was ± 4.0 pmC (95 % confidence interval) at 62 pmC. The long-term sampling method was found to be useful for waste incinerators for determination of annual fossil and biogenic CO(2) emissions with relatively low uncertainty.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leakey, Andrew D. B.

This project funded the C 4 and CAM (crassulacean acid metabolism) Plant Biology 2013 symposium, held at the University of Illinois at Urbana-Champaign, IL, on August 6-9, 2013. The symposium brought together a diverse group of scientists to discuss the evolution, ecology, functional biology, genomics and biotechnological engineering of C 4 and CAM plants. These two groups of plants possess evolutionary modifications to their photosynthetic machinery that improve their performance in hot and dry conditions. Maize and pineapple are classic examples of C 4 and CAM plants, respectively. The meeting discussed how lessons learned from these groups of plants canmore » be harnessed to improve crop production of biofuel feedstocks in an era of global climate change. The interdisciplinary nature of the meeting meant that the delegation members typically do not collectively attend any one scientific society meeting. As a result, the symposium was a unique opportunity for knowledge transfer, initiation of new collaborations, and recruitment and exposure of early career scientists.« less

Genome wide identification of cotton (Gossypium hirsutum)-encoded microRNA targets against Cotton leaf curl Burewala virus.

PubMed

Shweta; Akhter, Yusuf; Khan, Jawaid Ahmad

2018-01-05

Cotton leaf curl Burewala virus (CLCuBV, genus Begomovirus) causes devastating cotton leaf curl disease. Among various known virus controlling strategies, RNAi-mediated one has shown potential to protect host crop plants. Micro(mi) RNAs, are the endogenous small RNAs and play a key role in plant development and stress resistance. In the present study we have identified cotton (Gossypium hirsutum)-encoded miRNAs targeting the CLCuBV. Based on threshold free energy and maximum complementarity scores of host miRNA-viral mRNA target pairs, a number of potential miRNAs were annotated. Among them, ghr-miR168 was selected as the most potent candidate, capable of targeting several vital genes namely C1, C3, C4, V1 and V2 of CLCuBV genome. In addition, ghr-miR395a and ghr-miR395d were observed to target the overlapping transcripts of C1 and C4 genes. We have verified the efficacy of these miRNA targets against CLCuBV following suppression of RNAi-mediated virus control through translational inhibition or cleavage of viral mRNA. Copyright © 2017 Elsevier B.V. All rights reserved.

Transformations of Heavy Metals and Plant Nutrients in Dredged Sediments as Affected by Oxidation Reduction Potential and pH. Volume 2. Materials and Methods/Results and Discussion

DTIC Science & Technology

1977-05-01

D )EGED IATWRAL WI0, 00 EEACHPRGAFT4- CONTRACT REPORT D -77-4 TRANSFORMATIONS OF HEAVY METALS AND PLANT NUTRIENTS IN DREDGED SEDIMENTS AS AFFECTED BY...Engineers, U. S. Army C=) Washington, D . C. 20314 Q-2 Under Contract No. DACW39-74-C-0076 CM-1 (DMRP Work Unit No. IC05) Monitored by Environmental...Sa70mB COMPLETING FOM T -IMPORT PUNIeRf oTACSINN ESCTLGNME Contract Report D -77-4GOTACSINN C NTSAAOGUMR RAAN SFORATIONS OFPEAV71ETALS AND

Contamination Assessment Report Chemical Sewers - North Plants and South Plants Version 3.2, Task 10

DTIC Science & Technology

1988-09-01

co coo coo U.A 0 0 0.0 L Vc 04 a 0. C -. C r 0 48 w c 0j ft 1-4 0~ W UU 4e & 0 0 0 0 0 0 0 0 0- 1 I I C 1 W; V; W ; ’A C 209 0 0 U u et M SC A 04 4124 ...David Shelton, CDB Lt. Col. Scott P. Isaacson Chris Hahn, Shell Oil Company R. D. Lundahl, Shell Oil Company Thomas Sick, Department of Justice David

C4 grasses prosper as carbon dioxide eliminates desiccation in warmed semi-arid grassland.

PubMed

Morgan, Jack A; LeCain, Daniel R; Pendall, Elise; Blumenthal, Dana M; Kimball, Bruce A; Carrillo, Yolima; Williams, David G; Heisler-White, Jana; Dijkstra, Feike A; West, Mark

2011-08-03

Global warming is predicted to induce desiccation in many world regions through increases in evaporative demand. Rising CO(2) may counter that trend by improving plant water-use efficiency. However, it is not clear how important this CO(2)-enhanced water use efficiency might be in offsetting warming-induced desiccation because higher CO(2) also leads to higher plant biomass, and therefore greater transpirational surface. Furthermore, although warming is predicted to favour warm-season, C(4) grasses, rising CO(2) should favour C(3), or cool-season plants. Here we show in a semi-arid grassland that elevated CO(2) can completely reverse the desiccating effects of moderate warming. Although enrichment of air to 600 p.p.m.v. CO(2) increased soil water content (SWC), 1.5/3.0 °C day/night warming resulted in desiccation, such that combined CO(2) enrichment and warming had no effect on SWC relative to control plots. As predicted, elevated CO(2) favoured C(3) grasses and enhanced stand productivity, whereas warming favoured C(4) grasses. Combined warming and CO(2) enrichment stimulated above-ground growth of C(4) grasses in 2 of 3 years when soil moisture most limited plant productivity. The results indicate that in a warmer, CO(2)-enriched world, both SWC and productivity in semi-arid grasslands may be higher than previously expected.

Partitioning Ecosystem Respiration Using Stable Carbon Isotopes in a Mixed C3 Annual Grassland

NASA Astrophysics Data System (ADS)

Tu, K. P.

2001-12-01

The stable carbon isotope ratio (δ 13C) of respired CO2 has been used to partition soil respiration into root and microbial components by exploiting the different δ 13C signals from C3 plants growing in a previously C4 dominated system (Rouchette, Angers and Flanagan 1999). We extend this approach and present data that attempts to partition ecosystem respiration using δ 13C analyses of all of the ecosystem compartments in a mixed C3 annual grassland that has not experienced recent C4 inputs. From December 2000 to February 2001 we measured δ 13C-CO2 respired from leaves, roots and sieved soil collected from a winter-active grassland near Ione, California. Two-source mixing models were used to calculate the contribution of each source to total system respiration by comparing their isotope signals to those from whole ecosystem respiration and soil surface efflux. Isotope ratios were measured on 10mL air samples in septum-capped vials using a Finnigan MAT Delta PlusXL IRMS/Gas Bench II interfaced to an autosampler (after Tu et al. 2001). The vials were filled with sample air in the field using a double-holed needle connected in a closed loop to a LI-6200 IRGA and a bottle containing the isolated samples (leaf, root, sieved soil, etc.). Leaves were clipped at ground level and roots and soil were separated by sieving soil cores. Sample δ 13CO2 signatures were determined by plotting the change in δ 13C against the inverse of CO2 concentration. On average, CO2 respired from sieved soil (-27.4o/oo+/-1.4) was slightly more depleted than that from leaves (-27.2o/oo+/-0.5), but much more depleted than the whole ecosystem (-24.9o/oo+/-0.6), the soil surface efflux (-23.8o/oo+/-0.9), and plant roots (-20.5o/oo+/-0.8). Based on these isotope values, leaf respiration comprised 33% of ecosystem respiration with 36% from roots and 31% from soil microbial respiration. Thus, over two-thirds of ecosystem respiration was autotrophic (plant-based) in origin with roughly one-third being heterotrophic. Belowground respiration, comprised of both autotrophic (root) and heterotrophic (microbial) components, accounted for nearly two-thirds of total ecosystem respiration. Root and microbial respiration each contributed to nearly half of total belowground respiration (53% and 47%, respectively). Similarly, plant respiration was divided nearly equally between that from roots (52%) and leaves (48%). Partitioning using natural abundance stable carbon isotope ratios was made possible because of the relatively large differences in δ 13C values among the various sources in this entirely C3 system. To our knowledge, such large isotopic differences in respired CO2 among different plant tissues and belowground components have not been documented before. Further research is needed to determine how such differences may arise and to establish if similar differences exist in other ecosystems or at different times of the growing season. Our results also imply that interpretation of above-canopy Keeling plot intercepts may be complicated by both multiple (and isotopically distinct) sources and by isotopic fractionation that occurs either during the respiration process itself or during the transfer of carbon compounds prior to respiration.

[Minimal effective dose on serum cholesterol concentration and the safety evaluation of dressing containing plant sterol in Japanese subjects].

PubMed

Kurokawa, Masanori; Masuda, Yasunobu; Noda, Mitsuhiro; Marushima, Ranko; Usuda, Mika; Takeda, Sayaka; Hasegawa, Mineo; Homma, Yasuhiko; Sugano, Michihiro

2008-01-01

We examined the minimal effective dose on serum cholesterol concentration and the safety of dressing containing plant sterol in humans. EXP.1: Sixty-eight healthy Japanese males (total cholesterol (TC) > or = 170 mg/dL) were randomly divided into four groups, and were given 0, 400, 800 or 1200 mg/day of plant sterol in 15 g dressing for 4 weeks followed by the washout period of 4 weeks. Although there were no significant differences in serum TC and low-density lipoprotein cholesterol (LDL-C) concentrations among all groups after feeding plant sterol for 4 weeks, in 36 subjects with TC > or = 220 mg/dL, serum LDL-C concentration tended to reduce when received 800 or 1200 mg of plant sterol, and the difference between 0 and 1200 mg groups was statistically significant. The difference between 0 and 800 mg groups was near significant (p=0.053). Intake of 400 mg of plant sterol did not change serum LDL-C concentration. EXP.2: Twenty-one healthy Japanese subjects (TC > or = 180 mg/dL, 10 men, 11 women) were given 2400 mg/day of plant sterol in 45 g dressing for 4 weeks. Clinical data were all remained normal. These results indicated that minimal effective dose of the plant sterol on serum cholesterol concentration in healthy male subjects is around 800 mg/day, and intake of 2400 mg/day of plant sterol is regarded to be safe.

Thermal Degradation Kinetics Modeling of Benzophenones and Xanthones during High-Temperature Oxidation of Cyclopia genistoides (L.) Vent. Plant Material.

PubMed

Beelders, Theresa; de Beer, Dalene; Joubert, Elizabeth

2015-06-10

Degradation of the major benzophenones, iriflophenone-3-C-glucoside-4-O-glucoside and iriflophenone-3-C-glucoside, and the major xanthones, mangiferin and isomangiferin, of Cyclopia genistoides followed first-order reaction kinetics during high-temperature oxidation of the plant material at 80 and 90 °C. Iriflophenone-3-C-glucoside-4-O-glucoside was shown to be the most thermally stable compound. Isomangiferin was the second most stable compound at 80 °C, while its degradation rate constant was influenced the most by increased temperature. Mangiferin and iriflophenone-3-C-glucoside had comparable degradation rate constants at 80 °C. The thermal degradation kinetic model was subsequently evaluated by subjecting different batches of plant material to oxidative conditions (90 °C/16 h). The model accurately predicted the individual contents of three of the compounds in aqueous extracts prepared from oxidized plant material. The impact of benzophenone and xanthone degradation was reflected in the decreased total antioxidant capacity of the aqueous extracts, as determined using the oxygen radical absorbance capacity and DPPH(•) scavenging assays.

Presence of Emerging Per- and Polyfluoroalkyl Substances (PFASs) in River and Drinking Water near a Fluorochemical Production Plant in the Netherlands.

PubMed

Gebbink, Wouter A; van Asseldonk, Laura; van Leeuwen, Stefan P J

2017-10-03

The present study investigated the presence of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in river water collected in 2016 up- and downstream from a fluorochemical production plant, as well as in river water from control sites, in The Netherlands. Additionally, drinking water samples were collected from municipalities in the vicinity from the production plant, as well as in other regions in The Netherlands. The PFOA replacement chemical GenX was detected at all downstream river sampling sites with the highest concentration (812 ng/L) at the first sampling location downstream from the production plant, which was 13 times higher than concentrations of sum perfluoroalkylcarboxylic acids and perfluoroalkanesulfonates (∑PFCA+∑PFSA). Using high resolution mass spectrometry, 11 polyfluoroalkyl acids belonging to the C 2n H 2n F 2n O 2 , C 2n H 2n+2 F 2n SO 4 or C 2n+1 H 2n F 2n+4 SO 4 homologue series were detected, but only in downstream water samples. These emerging PFASs followed a similar distribution as GenX among the downstream sampling sites, suggesting the production plant as the source. Polyfluoroalkyl sulfonates (C 2n H 2 F 4n SO 3 ) were detected in all collected river water samples, and therefore appear to be ubiquitous contaminants in Dutch rivers. GenX was also detected in drinking water collected from 3 out of 4 municipalities in the vicinity of the production plant, with highest concentration at 11 ng/L. Drinking water containing the highest level of GenX also contained two C 2n H 2n F 2n O 2 homologues.

Presence of Emerging Per- and Polyfluoroalkyl Substances (PFASs) in River and Drinking Water near a Fluorochemical Production Plant in the Netherlands

PubMed Central

2017-01-01

The present study investigated the presence of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in river water collected in 2016 up- and downstream from a fluorochemical production plant, as well as in river water from control sites, in The Netherlands. Additionally, drinking water samples were collected from municipalities in the vicinity from the production plant, as well as in other regions in The Netherlands. The PFOA replacement chemical GenX was detected at all downstream river sampling sites with the highest concentration (812 ng/L) at the first sampling location downstream from the production plant, which was 13 times higher than concentrations of sum perfluoroalkylcarboxylic acids and perfluoroalkanesulfonates (∑PFCA+∑PFSA). Using high resolution mass spectrometry, 11 polyfluoroalkyl acids belonging to the C2nH2nF2nO2, C2nH2n+2F2nSO4 or C2n+1H2nF2n+4SO4 homologue series were detected, but only in downstream water samples. These emerging PFASs followed a similar distribution as GenX among the downstream sampling sites, suggesting the production plant as the source. Polyfluoroalkyl sulfonates (C2nH2F4nSO3) were detected in all collected river water samples, and therefore appear to be ubiquitous contaminants in Dutch rivers. GenX was also detected in drinking water collected from 3 out of 4 municipalities in the vicinity of the production plant, with highest concentration at 11 ng/L. Drinking water containing the highest level of GenX also contained two C2nH2nF2nO2 homologues. PMID:28853567

Biochemical analysis of plant protection afforded by a nonpathogenic endophytic mutant of Colletotrichum magna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redman, R.S.; Rodriguez, R.J.; Clifton, D.R.

1999-02-01

A nonpathogenic mutant of Colletotrichum magna (path-1) was previously shown to protect watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) seedlings from anthracnose disease elicited by wild-type C. magna. Disease protection was observed in stems of path-1-colonized cucurbits but not in cotyledons, indicating that path-1 conferred tissue-specific and/or localized protection. Plant biochemical indicators of a localized and systemic (peroxidase, phenylalanine ammonia-lyase, lignin, and salicylic acid) plant-defense response were investigated in anthracnose-resistant and-susceptible cultivars of cucurbit seedlings exposed to four treatments: (1) water (control), (2) path-1 conidia, (3) wild-type conidia, and (4) challenge conditions (inoculation into path-1 conidia for 48 h andmore » then exposure to wild-type conidia). Collectively, these analyses indicated that disease protection in path-1-colonized plants was correlated with the ability of these plants to mount a defense response more rapidly and to equal or greater levels than plants exposed to wild-type C. magna alone. Watermelon plants colonized with path-1 were also protected against disease caused by Colletotrichum orbiculare and Fusarium oxysporum. A model based on the kinetics of plant-defense activation is presented to explain the mechanism of path-1-conferred disease protection.« less

Biochemical analysis of plant protection afforded by a nonpathogenic endophytic mutant of Colletotrichum magna

USGS Publications Warehouse

Redman, R.S.; Freeman, S.; Clifton, D.R.; Morrel, J.; Brown, G.; Rodriguez, R.J.

1999-01-01

A nonpathogenic mutant of Colletotrichum magna (path-1) was previously shown to protect watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) seedlings from anthracnose disease elicited by wild-type C. magna. Disease protection was observed in stems of path-1-colonized cucurbits but not in cotyledons, indicating that path-1 conferred tissue-specific and/or localized protection. Plant biochemical indicators of a localized and systemic (peroxidase, phenylalanine ammonia-lyase, lignin, and salicylic acid) 'plant-defense' response were investigated in anthracnose-resistant and -susceptible cultivars of cucurbit seedlings exposed to four treatments: (1) water (control), (2) path-1 conidia, (3) wild-type conidia, and (4) challenge conditions (inoculation into path-1 conidia for 48 h and then exposure to wild-type conidia). Collectively, these analyses indicated that disease protection in path-1 colonized plants was correlated with the ability of these plants to mount a defense response more rapidly and to equal or greater levels than plants exposed to wild-type C. magna alone. Watermelon plants colonized with path-1 were also protected against disease caused by Colletotrichum orbiculare and Fusarium oxysporum. A model based on the kinetics of plant-defense activation is presented to explain the mechanism of path-1-conferred disease protection.

Elevated CO2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea-level rise

USGS Publications Warehouse

Cherry, J.A.; McKee, K.L.; Grace, J.B.

2009-01-01

1. Sea-level rise, one indirect consequence of increasing atmospheric CO2, poses a major challenge to long-term stability of coastal wetlands. An important question is whether direct effects of elevated CO 2 on the capacity of marsh plants to accrete organic material and to maintain surface elevations outweigh indirect negative effects of stressors associated with sea-level rise (salinity and flooding). 2. In this study, we used a mesocosm approach to examine potential direct and indirect effects of atmospheric CO2 concentration, salinity and flooding on elevation change in a brackish marsh community dominated by a C3 species, Schoenoplectus americanus, and a C4 grass, Spartina patens. This experimental design permitted identification of mechanisms and their role in controlling elevation change, and the development of models that can be tested in the field. 3. To test hypotheses related to CO2 and sea-level rise, we used conventional anova procedures in conjunction with structural equation modelling (SEM). SEM explained 78% of the variability in elevation change and showed the direct, positive effect of S. americanus production on elevation. The SEM indicated that C3 plant response was influenced by interactive effects between CO2 and salinity on plant growth, not a direct CO2 fertilization effect. Elevated CO2 ameliorated negative effects of salinity on S. americanus and enhanced biomass contribution to elevation. 4. The positive relationship between S. americanus production and elevation change can be explained by shoot-base expansion under elevated CO 2 conditions, which led to vertical soil displacement. While the response of this species may differ under other environmental conditions, shoot-base expansion and the general contribution of C3 plant production to elevation change may be an important mechanism contributing to soil expansion and elevation gain in other coastal wetlands. 5. Synthesis. Our results revealed previously unrecognized interactions and mechanisms contributing to marsh elevation change, including amelioration of salt stress by elevated CO2 and the importance of plant production and shoot-base expansion for elevation gain. Identification of biological processes contributing to elevation change is an important first step in developing comprehensive models that permit more accurate predictions of whether coastal marshes will persist with continued sea-level rise or become submerged. ?? 2008 The Authors.

Confirmation of conjugation processes during TNT metabolism by axenic plant roots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhadra, R.; Wayment, D.G.; Hughes, J.B.

1999-02-01

This paper examines processes in plants for the formation of fate products of TNT beyond its animated reduction products, 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. TNT metabolites were isolated and characterized in combination with temporal analyses of production profiles and {sup 14}C distribution, in microbe-free, axenic root cultures of Catharanthus roseus. Four unique TNT-derived compounds were isolated. Using evidence from {sup 1}H NMR, mass spectroscopy, HPLC, acid hydrolysis, and enzymatic hydrolysis with {beta}-glucuronidase and {beta}-glucosidase, they were established as conjugates formed by reactions of the amine groups of 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. From the mass spectral evidence, at least a six-carbon unit from themore » plant intracellular milleu was involved in conjugate formation. Mass balance analysis indicated that, by 75 h after TNT amendment of the initial TNT radiolabel, extractable conjugates comprised 22%, bound residues comprised another 29%, 2-amino-4,6-dinitrotoluene was 4%, and the rest remained unidentified. Isolates from TNT-amended roots versus monoamino-dinitrotoluene-amended roots were not identical, suggesting numerous possible outcomes for the plant-based conjugation of 2-amino-2,6-dinitrotoluene or 4-amino-2,6-dinitrotoluene. This study is the first direct evidence for the involvement of the primary reduction products of TNT--2-amino-4,6-dinitrotoluene ad 4-amino--2,6-dinitrotoluene--in conjugation process in plant detoxification of TNT.« less

Himalayan orogeny and palaeovegetational changes: a relook into the factors controlling global expansion of C4 grasslands.

NASA Astrophysics Data System (ADS)

Singh, S.; Awasthi, A.; Parkash, B.; Kumar, S.

2012-04-01

The Himalayan orogeny constitutes a significant tectonic event in the Earth's Cenozoic history which encompasses a series of events resulting in long-term climatic cooling and drying. Establishing synchroneity of palaeoecological events through floral and faunal changes in proxy-records could help in documenting factors responsible for this change in global climate. Based on geological evidences, various workers in different parts of the world have established C4 grassland appearance during late Cenozoic, though the expansion is confined largely to Late Miocene. However, causes of this worldwide C4 grassland expansion have remained controversial since its discovery. Resolution of such controversies ultimately lies in undertaking more detailed local palaeo-vegetational studies of Cenozoic sediments and subsequent correlation at regional and global scale. The aim of the present work is to study the Himalayan Cenozoic sediments of India and the results are then compared with other similar studies done in different parts of the world. Carbon isotope analysis of soil carbonate, largely nodules, had been carried out from Samba-Mansar (S-M) section in the Jammu & Kashmir state of India which is placed laterally ~ 40-50Km along strike from another comparable Jammu-Nandni (J-N) section. Analyses of a total of 141 samples in the Ramnagar sub-basin, spanning a period from ~ 12Ma to ~ 0.4Ma, have been coherent so as to have a better view of palaeovegetational change across the sub-basin, both at comparable temporal and spatial regional scale. Herein the isotopic results show the dominance of C3 vegetation pre-7Ma and C4 vegetation post-5Ma with first appearance of C4 plants at ~6.8Ma. Percentage abundance of C4 vegetation was less than 20% pre-7Ma but was increased to more than 40% post-5Ma reaching up to 100% in the youngest analyzed sediments. The results are in conformity with patterns of change in vegetation documented in other parts of the Himalayan belt. These indicate that though there is worldwide temporal variability in appearance of C4 plants but in the Himalayan Cenozoic sediments, C4 plants first appeared with their subsequent expansion during Late Miocene. It could be possible that at different places different factors or a combination of different factors played their roles which might be linked to each other directly or indirectly with major tectonic events of the Cenozoic Era. Further, such studies could greatly help in gleaning out possible causes responsible for the long term global climatic change over the past 40Ma.

Carbon balance modification in Sphagnum-dominated peat mesocosms invaded by Molinia caerulea

NASA Astrophysics Data System (ADS)

Leroy, Fabien; Gogo, Sébastien; Guimbaud, Christophe; Bernard-Jannin, Léonard; Laggoun-Défarge, Fatima

2017-04-01

Plant communities have a key role in regulating greenhouse gas (GHG) emissions in peatland ecosystems and thus on their capacity to act as carbon (C) sink. However, in response to global change, boreal and temperate peatlands may shift from Sphagnum to vascular plant-dominated peatlands that may alter their C-sink function. We set up a mesocosm experiment to investigate how the main GHG fluxes (CO2 and CH4) are affected by plant community modification from Sphagnum mosses to Molinia caerulea dominance. Gross primary production (GPP), ecosystem respiration (ER) and CH4 emissions models were used to compare the C balance and global warming potential under both vegetation cover. While the annual CO2 and CH4 emissions modeling estimated an output of respectively 652 and 18 gC m-2 y-1 in Sphagnum mesocosms, it represented a release of 1473 and 50 gC m-2 y-1 with Molinia caerulea occurrence. Annual modeled GPP was respectively -495 and -1968 gC m-2 y-1 in Sphagnum and Molinia mesocosms leading to a net ecosystem carbon balance (NECB) of 175 g gC m-2 y-1 in Sphagnum mesocosms (i.e., a C-source) and of -445 gC m-2 y-1 for Molinia ones (i.e., a C-sink). Even if CH4 emission accounted for a small part of the gaseous C efflux ( 3%), its global warming potential value to get CO2 equivalent makes both plant communities acting as a warming climate effect. The vegetation shift from Sphagnum mosses to Molinia caerulea seems beneficial for C sequestration regarding the gaseous pool. However, roots and litters of Molinia caerulea could further provide substrates for C emissions and dissolved organic C release.

Novel approach for computing photosynthetically active radiation for productivity modeling using remotely sensed images in the Great Plains, United States

USGS Publications Warehouse

Singh, Ramesh K.; Liu, Shu-Guang; Tieszen, Larry L.; Suyker, Andrew E.; Verma, Shashi B.

2012-01-01

Gross primary production (GPP) is a key indicator of ecosystem performance, and helps in many decision-making processes related to environment. We used the Eddy covariancelight use efficiency (EC-LUE) model for estimating GPP in the Great Plains, United States in order to evaluate the performance of this model. We developed a novel algorithm for computing the photosynthetically active radiation (PAR) based on net radiation. A strong correlation (R2=0.94,N=24) was found between daily PAR and Landsat-based mid-day instantaneous net radiation. Though the Moderate Resolution Spectroradiometer (MODIS) based instantaneous net radiation was in better agreement (R2=0.98,N=24) with the daily measured PAR, there was no statistical significant difference between Landsat based PAR and MODIS based PAR. The EC-LUE model validation also confirms the need to consider biological attributes (C3 versus C4 plants) for potential light use efficiency. A universal potential light use efficiency is unable to capture the spatial variation of GPP. It is necessary to use C3 versus C4 based land use/land cover map for using EC-LUE model for estimating spatiotemporal distribution of GPP.

Desert Tortoise (Gopherus agassizii) Dietary Specialization Decreases across a Precipitation Gradient

PubMed Central

Murray, Ian W.; Wolf, Blair O.

2013-01-01

We studied the plant resource use between and within populations of desert tortoise (Gopherus agassizii) across a precipitation gradient in the Sonoran Desert of Arizona. The carbon and nitrogen stable isotope values in animal tissues are a reflection of the carbon and nitrogen isotope values in diet, and consequently represent a powerful tool to study animal feeding ecology. We measured the δ13C and δ15N values in the growth rings on the shells of tortoises in different populations to characterize dietary specialization and track tortoise use of isotopically distinct C4/CAM versus C3 plant resources. Plants using C3 photosynthesis are generally more nutritious than C4 plants and these trait differences can have important growth and fitness consequences for consumers. We found that dietary specialization decreases in successively drier and less vegetated sites, and that broader population niche widths are accompanied by an increase in the dietary variability between individuals. Our results highlight how individual consumer plant resource use is bounded under a varying regime of precipitation and plant productivity, lending insight into how intra-individual dietary specialization varies over a spatial scale of environmental variability. PMID:23840495

78 FR 8185 - Endangered and Threatened Wildlife and Plants; Initiation of 5-Year Status Reviews of 44 Species...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-05

...-FF01E00000] Endangered and Threatened Wildlife and Plants; Initiation of 5- Year Status Reviews of 44 Species....C. 1531 et seq.), we maintain Lists of Endangered and Threatened Wildlife and Plants (which we... 17.12 (for plants). Section 4(c)(2)(A) of the Act requires us to review each listed species' status...

Prospects for improving CO2 fixation in C3-crops through understanding C4-Rubisco biogenesis and catalytic diversity.

PubMed

Sharwood, Robert E; Ghannoum, Oula; Whitney, Spencer M

2016-06-01

By operating a CO2 concentrating mechanism, C4-photosynthesis offers highly successful solutions to remedy the inefficiency of the CO2-fixing enzyme Rubisco. C4-plant Rubisco has characteristically evolved faster carboxylation rates with low CO2 affinity. Owing to high CO2 concentrations in bundle sheath chloroplasts, faster Rubisco enhances resource use efficiency in C4 plants by reducing the energy and carbon costs associated with photorespiration and lowering the nitrogen investment in Rubisco. Here, we show that C4-Rubisco from some NADP-ME species, such as maize, are also of potential benefit to C3-photosynthesis under current and future atmospheric CO2 pressures. Realizing this bioengineering endeavour necessitates improved understanding of the biogenesis requirements and catalytic variability of C4-Rubisco, as well as the development of transformation capabilities to engineer Rubisco in a wider variety of food and fibre crops. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative Analysis of the Base Compositions of the Pre-mRNA 3′ Cleaved-Off Region and the mRNA 3′ Untranslated Region Relative to the Genomic Base Composition in Animals and Plants

PubMed Central

Li, Xiu-Qing

2014-01-01

The precursor messenger RNA (pre-mRNA) three-prime cleaved-off region (3′COR) and the mRNA three-prime untranslated region (3′UTR) play critical roles in regulating gene expression. The differences in base composition between these regions and the corresponding genomes are still largely uncharacterized in animals and plants. In this study, the base compositions of non-redundant 3′CORs and 3′UTRs were compared with the corresponding whole genomes of eleven animals, four dicotyledonous plants, and three monocotyledonous (cereal) plants. Among the four bases (A, C, G, and U for adenine, cytosine, guanine, and uracil, respectively), U (which corresponds to T, for thymine, in DNA) was the most frequent, A the second most frequent, G the third most frequent, and C the least frequent in most of the species in both the 3′COR and 3′UTR regions. In comparison with the whole genomes, in both regions the U content was usually the most overrepresented (particularly in the monocotyledonous plants), and the C content was the most underrepresented. The order obtained for the species groups, when ranked from high to low according to the U contents in the 3′COR and 3′UTR was as follows: dicotyledonous plants, monocotyledonous plants, non-mammal animals, and mammals. In contrast, the genomic T content was highest in dicotyledonous plants, lowest in monocotyledonous plants, and intermediate in animals. These results suggest the following: 1) there is a mechanism operating in both animals and plants which is biased toward U and against C in the 3′COR and 3′UTR; 2) the 3′UTR and 3′COR, as functional units, minimized the difference between dicotyledonous and monocotyledonous plants, while the dicotyledonous and monocotyledonous genomes evolved into two extreme groups in terms of base composition. PMID:24941005

In VIVO tracer kinetics of plant function using positron emission technology

NASA Astrophysics Data System (ADS)

Fares, Y.; Goeschl, J. D.; Magnuson, C. E.; Mckinney, C. J.; Musser, R. L.; Strain, B. R.

1989-04-01

A 11CO 2 storage and dispensing system was developed and used successfully to deliver constant activity levels for 2 h plant tracer experiments. Using tracer kinetics of a step input function the relationships between diurnal patterns of carbon partitioning and gas exchange properties of leaves in C 3 and C 4 plants were studied. We also studied the immediate and long term effects of the abrupt changes in CO 2 concentrations on carbon partitioning of these species. Results indicate that raising the CO 2 concentration above ambient immediately increases 11C storage over export rates, while lowering the CO 2 concentration immediately decreases storage more than export rates. This long term accumulation of starch may depend as much on the biochemistry of partitioning within the leaf as on limitations in the sink capacity of plants. Although gas exchange remained constant during the photoperiod, the photosynthate storage rate increased and the export rate decreased. These changes were more pronounced in C 4 plants.

EPSPS gene amplification conferring resistance to glyphosate in windmill grass (Chloris truncata) in Australia.

PubMed

Ngo, The D; Malone, Jenna M; Boutsalis, Peter; Gill, Gurjeet; Preston, Christopher

2018-05-01

Five glyphosate-resistant populations of Chloris truncata originally collected from New South Wales were compared with one susceptible (S) population from South Australia to confirm glyphosate resistance and elucidate possible mechanisms of resistance. Based on the amounts of glyphosate required to kill 50% of treated plants (LD 50 ), glyphosate resistance (GR) was confirmed in five populations of C. truncata (A536, A528, T27, A534 and A535.1). GR plants were 2.4-8.7-fold more resistant and accumulated less shikimate after glyphosate treatment than S plants. There was no difference in glyphosate absorption and translocation between GR and S plants. The EPSPS gene did not contain any point mutation that had previously been associated with resistance to glyphosate. The resistant plants (A528 and A536) contained up to 32-48 more copies of the EPSPS gene than the susceptible plants. This study has identified EPSPS gene amplification contributing to glyphosate resistance in C. truncata. In addition, a Glu-91-Ala mutation within EPSPS was identified that may contribute to glyphosate resistance in this species. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

C1 metabolism plays an important role during formaldehyde metabolism and detoxification in petunia under liquid HCHO stress.

PubMed

Zhang, Wei; Tang, Lijuan; Sun, Huiqun; Han, Shuang; Wang, Xinjia; Zhou, Shengen; Li, Kunzhi; Chen, Limei

2014-10-01

Petunia hybrida is a model ornamental plant grown worldwide. To understand the HCHO-uptake efficiency and metabolic mechanism of petunia, the aseptic petunia plants were treated in HCHO solutions. An analysis of HCHO-uptake showed that petunia plants effectively removed HCHO from 2, 4 and 6 mM HCHO solutions. The (13)C NMR analyses indicated that H(13)CHO was primarily used to synthesize [5-(13)C]methionine (Met) via C1 metabolism in petunia plants treated with 2 mM H(13)CHO. Pretreatment with cyclosporin A (CSA) or l-carnitine (LC), the inhibitors of mitochondrial permeability transition pores, did not affect the synthesis of [5-(13)C]Met in petunia plants under 2 mM H(13)CHO stress, indicating that the Met-generated pathway may function in the cytoplasm. Under 4 or 6 mM liquid H(13)CHO stress, H(13)CHO metabolism in petunia plants produced considerable amount of H(13)COOH and [2-(13)C]glycine (Gly) through C1 metabolism and a small amount of [U-(13)C]Gluc via the Calvin Cycle. Pretreatment with CSA or LC significantly inhibited the production of [2-(13)C]Gly in 6 mM H(13)CHO-treated petunia plants, which suggests that chloroplasts and peroxisomes might be involved in the generation of [2-(13)C]Gly. These results revealed that the C1 metabolism played an important role, whereas the Calvin Cycle had only a small contribution during HCHO metabolism and detoxification in petunia under liquid HCHO stress. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

C4 photosynthesis and water stress

PubMed Central

Ghannoum, Oula

2009-01-01

Background In contrast to C3 photosynthesis, the response of C4 photosynthesis to water stress has been less-well studied in spite of the significant contribution of C4 plants to the global carbon budget and food security. The key feature of C4 photosynthesis is the operation of a CO2-concentrating mechanism in the leaves, which serves to saturate photosynthesis and suppress photorespiration in normal air. This article reviews the current state of understanding about the response of C4 photosynthesis to water stress, including the interaction with elevated CO2 concentration. Major gaps in our knowledge in this area are identified and further required research is suggested. Scope Evidence indicates that C4 photosynthesis is highly sensitive to water stress. With declining leaf water status, CO2 assimilation rate and stomatal conductance decrease rapidly and photosynthesis goes through three successive phases. The initial, mainly stomatal phase, may or may not be detected as a decline in assimilation rates depending on environmental conditions. This is because the CO2-concentrating mechanism is capable of saturating C4 photosynthesis under relatively low intercellular CO2 concentrations. In addition, photorespired CO2 is likely to be refixed before escaping the bundle sheath. This is followed by a mixed stomatal and non-stomatal phase and, finally, a mainly non-stomatal phase. The main non-stomatal factors include reduced activity of photosynthetic enzymes; inhibition of nitrate assimilation, induction of early senescence, and changes to the leaf anatomy and ultrastructure. Results from the literature about CO2 enrichment indicate that when C4 plants experience drought in their natural environment, elevated CO2 concentration alleviates the effect of water stress on plant productivity indirectly via improved soil moisture and plant water status as a result of decreased stomatal conductance and reduced leaf transpiration. Conclusions It is suggested that there is a limited capacity for photorespiration or the Mehler reaction to act as significant alternative electron sinks under water stress in C4 photosynthesis. This may explain why C4 photosynthesis is equally or even more sensitive to water stress than its C3 counterpart in spite of the greater capacity and water use efficiency of the C4 photosynthetic pathway. PMID:18552367

Evolution of C4 plants: a new hypothesis for an interaction of CO2 and water relations mediated by plant hydraulics

PubMed Central

Osborne, Colin P.; Sack, Lawren

2012-01-01

C4 photosynthesis has evolved more than 60 times as a carbon-concentrating mechanism to augment the ancestral C3 photosynthetic pathway. The rate and the efficiency of photosynthesis are greater in the C4 than C3 type under atmospheric CO2 depletion, high light and temperature, suggesting these factors as important selective agents. This hypothesis is consistent with comparative analyses of grasses, which indicate repeated evolutionary transitions from shaded forest to open habitats. However, such environmental transitions also impact strongly on plant–water relations. We hypothesize that excessive demand for water transport associated with low CO2, high light and temperature would have selected for C4 photosynthesis not only to increase the efficiency and rate of photosynthesis, but also as a water-conserving mechanism. Our proposal is supported by evidence from the literature and physiological models. The C4 pathway allows high rates of photosynthesis at low stomatal conductance, even given low atmospheric CO2. The resultant decrease in transpiration protects the hydraulic system, allowing stomata to remain open and photosynthesis to be sustained for longer under drying atmospheric and soil conditions. The evolution of C4 photosynthesis therefore simultaneously improved plant carbon and water relations, conferring strong benefits as atmospheric CO2 declined and ecological demand for water rose. PMID:22232769

System Evaluation and Economic Analysis of a HTGR Powered High-Temperature Electrolysis Hydrogen Production Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael G. McKellar; Edwin A. Harvego; Anastasia A. Gandrik

2010-10-01

A design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production has been developed. The HTE plant is powered by a high-temperature gas-cooled reactor (HTGR) whose configuration and operating conditions are based on the latest design parameters planned for the Next Generation Nuclear Plant (NGNP). The current HTGR reference design specifies a reactor power of 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 322°C and 750°C, respectively. The power conversion unit will be a Rankine steam cycle with a power conversion efficiency of 40%. The reference hydrogen production plantmore » operates at a system pressure of 5.0 MPa, and utilizes a steam-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The overall system thermal-to-hydrogen production efficiency (based on the higher heating value of the produced hydrogen) is 40.4% at a hydrogen production rate of 1.75 kg/s and an oxygen production rate of 13.8 kg/s. An economic analysis of this plant was performed with realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a cost of $3.67/kg of hydrogen assuming an internal rate of return, IRR, of 12% and a debt to equity ratio of 80%/20%. A second analysis shows that if the power cycle efficiency increases to 44.4%, the hydrogen production efficiency increases to 42.8% and the hydrogen and oxygen production rates are 1.85 kg/s and 14.6 kg/s respectively. At the higher power cycle efficiency and an IRR of 12% the cost of hydrogen production is $3.50/kg.« less

Co-expression of hepatitis C virus polytope-HBsAg and p19-silencing suppressor protein in tobacco leaves.

PubMed

Mohammadzadeh, Sara; Roohvand, Farzin; Memarnejadian, Arash; Jafari, Anis; Ajdary, Soheila; Salmanian, Ali-Hatef; Ehsani, Parastoo

2016-01-01

Plants transformed by virus-based vectors have emerged as promising tools to rapidly express large amounts and inexpensive antigens in transient condition. We studied the possibility of transient-expression of an HBsAg-fused polytopic construct (HCVpc) [containing H-2d and HLA-A2-restricted CD8+CTL-epitopic peptides of C (Core; aa 132-142), E6 (Envelope2; aa 614-622), N (NS3; aa 1406-1415), and E4 (Envelope2; aa 405-414) in tandem of CE6NE4] in tobacco (Nicotiana tabacum) leaves for the development of a plant-based HCV vaccine. A codon-optimized gene encoding the Kozak sequence, hexahistidine (6×His)-tag peptide, and HCVpc in tandem was designed, chemically synthesized, fused to HBsAg gene, and inserted into Potato virus X (PVX-GW) vector under the control of duplicated PVX coat protein promoter (CPP). The resulted recombinant plasmids (after confirmation by restriction and sequencing analyses) were transferred into Agrobacterium tumefaciens strain GV3101 and vacuum infiltrated into tobacco leaves. The effect of gene-silencing suppressor, p19 protein from tomato bushy stunt virus, on the expression yield of HCVpc-HBsAg was also evaluated by co-infiltration of a p19 expression vector. Codon-optimized gene increased adaptation index (CAI) value (from 0.61 to 0.92) in tobacco. The expression of the HCVpc-HBsAg was confirmed by western blot and HBsAg-based detection ELISA on total extractable proteins of tobacco leaves. The expression level of the fusion protein was significantly higher in p19 co-agroinfiltrated plants. The results indicated the possibility of expression of HCVpc-HBsAg constructs with proper protein conformations in tobacco for final application as a plant-derived HCV vaccine.

A two-dimensional microscale model of gas exchange during photosynthesis in maize (Zea mays L.) leaves.

PubMed

Retta, Moges; Ho, Quang Tri; Yin, Xinyou; Verboven, Pieter; Berghuijs, Herman N C; Struik, Paul C; Nicolaï, Bart M

2016-05-01

CO2 exchange in leaves of maize (Zea mays L.) was examined using a microscale model of combined gas diffusion and C4 photosynthesis kinetics at the leaf tissue level. Based on a generalized scheme of photosynthesis in NADP-malic enzyme type C4 plants, the model accounted for CO2 diffusion in a leaf tissue, CO2 hydration and assimilation in mesophyll cells, CO2 release from decarboxylation of C4 acids, CO2 fixation in bundle sheath cells and CO2 retro-diffusion from bundle sheath cells. The transport equations were solved over a realistic 2-D geometry of the Kranz anatomy obtained from light microscopy images. The predicted responses of photosynthesis rate to changes in ambient CO2 and irradiance compared well with those obtained from gas exchange measurements. A sensitivity analysis showed that the CO2 permeability of the mesophyll-bundle sheath and airspace-mesophyll interfaces strongly affected the rate of photosynthesis and bundle sheath conductance. Carbonic anhydrase influenced the rate of photosynthesis, especially at low intercellular CO2 levels. In addition, the suberin layer at the exposed surface of the bundle sheath cells was found beneficial in reducing the retro-diffusion. The model may serve as a tool to investigate CO2 diffusion further in relation to the Kranz anatomy in C4 plants. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Responses of C4 grasses to atmospheric CO2 enrichment : I. Effect of irradiance.

PubMed

Sionit, Nasser; Patterson, David T

1984-12-01

The growth and photosynethetic responses to atmospheric CO 2 enrichment of 4 species of C 4 grasses grown at two levels of irradiance were studied. We sought to determine whether CO 2 enrichment would yield proportionally greater growth enhancement in the C 4 grasses when they were grown at low irradiance than when grown at high irradiance. The species studied were Echinochloa crusgalli, Digitaria sanguinalis, Eleusine indica, and Setaria faberi. Plants were grown in controlled environment chambers at 350, 675 and 1,000 μl 1 -1 CO 2 and 1,000 or 150 μmol m -2 s -1 photosynthetic photon flux density (PPFD). An increase in CO 2 concentration and PPFD significantly affected net photosynthesis and total biomass production of all plants. Plants grown at low PPFD had significantly lower rates of photosynthesis, produced less biomass, and had reduced responses to increases in CO 2 . Plants grown in CO 2 -enriched atmosphere had lower photosynthetic capacity relative to the low CO 2 grown plants when exposed to lower CO 2 concentration at the time of measurement, but had greater rate of photosynthesis when exposed to increasing PPFD. The light level under which the plants were growing did not influence the CO 2 compensation point for photosynthesis.

Construction of a SSR-Based Genetic Map and Identification of QTLs for Catechins Content in Tea Plant (Camellia sinensis)

PubMed Central

Ma, Chun-Lei; Wang, Xin-Chao; Jin, Ji-Qiang; Wang, Xue-Min; Chen, Liang

2014-01-01

Catechins are the most important bioactive compounds in tea, and have been demonstrated to possess a wide variety of pharmacological activities. To characterize quantitative trait loci (QTLs) for catechins content in the tender shoots of tea plant, we constructed a moderately saturated genetic map using 406 simple sequence repeat (SSR) markers, based on a pseudo-testcross population of 183 individuals derived from an intraspecific cross of two Camellia sinensis varieties with diverse catechins composition. The map consisted of fifteen linkage groups (LGs), corresponding to the haploid chromosome number of tea plant (2n = 2x = 30). The total map length was 1,143.5 cM, with an average locus spacing of 2.9 cM. A total of 25 QTLs associated with catechins content were identified over two measurement years. Of these, nine stable QTLs were validated across years, and clustered into four main chromosome regions on LG03, LG11, LG12 and LG15. The population variability explained by each QTL was predominantly at moderate-to-high levels and ranged from 2.4% to 71.0%, with an average of 17.7%. The total number of QTL for each trait varied from four to eight, while the total population variability explained by all QTLs for a trait ranged between 38.4% and 79.7%. This is the first report on the identification of QTL for catechins content in tea plant. The results of this study provide a foundation for further cloning and functional characterization of catechin QTLs for utilization in improvement of tea plant. PMID:24676054

[Influence of 175-m-impoundment in Three Gorges Reservoir area on the food web energy sources of main commercial fishes in backwater area of xiaojiang River].

PubMed

Li, Bin; Wang, Zhi-Jian; Yue, Xing-Jian; Wang, Yong-Ming; Jin, Li; Zhang, Yao-Guang

2013-06-01

The impoundment in the Three Gorges Reservoir Area (TGRA) was first reached 175 m in 2010. To approach the influence of this impoundment on the food web energy sources of fishes in the tributaries of TRGA, an analysis was made on the food web energy sources of seven economically important fishes (Carassius auratus, Cyprinus carpio, Silurus asotus, Culter mongolicus mongolicus, Mystus macropterus, Pelteobagrus vachelli, and Pelteobagrus nitidus) in the backwater area of Xiaojiang River by using stable isotope method in combining with IsoSource Model. The results showed that before this impoundment (July 2010), microalgae were the main energy sources for the seven species. After this impoundment (December 2010), the contribution ratio of the microalgae decreased somewhat, while the relative contribution of terrestrial C4 plants had an obvious increase. Especially for crucian carp (C. auratus) and catfish (S. asotus), the contribution rate of the C4 plants reached 38-54% and 32-50%, respectively. After the impoundment, at least 30% of the energy resources of these two fishes were come from terrestrial C4 plants, suggesting that the impoundment in TGRA increased the contribution rate of exogenous terrestrial C4 plants as the energy sources of fishes.

UPLC-MS/MS Profile of Alkaloids with Cytotoxic Properties of Selected Medicinal Plants of the Berberidaceae and Papaveraceae Families

PubMed Central

Och, Anna; Pecio, Łukasz

2017-01-01

Cancer is one of the most occurring diseases in developed and developing countries. Plant-based compounds are still researched for their anticancer activity and for their quantity in plants. Therefore, the modern chromatographic methods are applied to quantify them in plants, for example, UPLC-MS/MS (ultraperformance liquid chromatography tandem mass spectrometry). Therefore, the aim of the present study was to evaluate the content of sanguinarine, berberine, protopine, and chelidonine in Dicentra spectabilis (L.) Lem., Fumaria officinalis L., Glaucium flavum Crantz, Corydalis cava L., Berberis thunbergii DC., Meconopsis cambrica (L.) Vig., Mahonia aquifolium (Pursh) Nutt., Macleaya cordata Willd., and Chelidonium majus L. For the first time, N,N-dimethyl-hernovine was identified in M. cambrica, B. thunbergii, M. aquifolium, C. cava, G. flavum, and C. majus; methyl-hernovine was identified in G. flavum; columbamine was identified in B. thunbergii; and methyl-corypalmine, chelidonine, and sanguinarine were identified in F. officinalis L. The richest source of protopine among all the examined species was M. cordata (5463.64 ± 26.3 μg/g). The highest amounts of chelidonine and sanguinarine were found in C. majus (51,040.0 ± 1.8 μg/g and 7925.8 ± 3.3 μg/g, resp.), while B. thunbergi contained the highest amount of berberine (6358.4 ± 4.2 μg/g). PMID:28951771

UPLC-MS/MS Profile of Alkaloids with Cytotoxic Properties of Selected Medicinal Plants of the Berberidaceae and Papaveraceae Families.

PubMed

Och, Anna; Szewczyk, Katarzyna; Pecio, Łukasz; Stochmal, Anna; Załuski, Daniel; Bogucka-Kocka, Anna

2017-01-01

Cancer is one of the most occurring diseases in developed and developing countries. Plant-based compounds are still researched for their anticancer activity and for their quantity in plants. Therefore, the modern chromatographic methods are applied to quantify them in plants, for example, UPLC-MS/MS (ultraperformance liquid chromatography tandem mass spectrometry). Therefore, the aim of the present study was to evaluate the content of sanguinarine, berberine, protopine, and chelidonine in Dicentra spectabilis (L.) Lem., Fumaria officinalis L., Glaucium flavum Crantz, Corydalis cava L., Berberis thunbergii DC., Meconopsis cambrica (L.) Vig., Mahonia aquifolium (Pursh) Nutt., Macleaya cordata Willd., and Chelidonium majus L. For the first time, N,N-dimethyl-hernovine was identified in M. cambrica , B. thunbergii , M. aquifolium , C. cava , G. flavum , and C. majus ; methyl-hernovine was identified in G. flavum ; columbamine was identified in B. thunbergii ; and methyl-corypalmine, chelidonine, and sanguinarine were identified in F. officinalis L. The richest source of protopine among all the examined species was M. cordata (5463.64 ± 26.3  μ g/g). The highest amounts of chelidonine and sanguinarine were found in C. majus (51,040.0 ± 1.8  μ g/g and 7925.8 ± 3.3  μ g/g, resp.), while B. thunbergi contained the highest amount of berberine (6358.4 ± 4.2  μ g/g).

Crystal structure of inhibitor of growth 4 (ING4) dimerization domain reveals functional organization of ING family of chromatin-binding proteins.

PubMed

Culurgioni, Simone; Muñoz, Inés G; Moreno, Alberto; Palacios, Alicia; Villate, Maider; Palmero, Ignacio; Montoya, Guillermo; Blanco, Francisco J

2012-03-30

The protein ING4 binds to histone H3 trimethylated at Lys-4 (H3K4me3) through its C-terminal plant homeodomain, thus recruiting the HBO1 histone acetyltransferase complex to target promoters. The structure of the plant homeodomain finger bound to an H3K4me3 peptide has been described, as well as the disorder and flexibility in the ING4 central region. We report the crystal structure of the ING4 N-terminal domain, which shows an antiparallel coiled-coil homodimer with each protomer folded into a helix-loop-helix structure. This arrangement suggests that ING4 can bind simultaneously two histone tails on the same or different nucleosomes. Dimerization has a direct impact on ING4 tumor suppressor activity because monomeric mutants lose the ability to induce apoptosis after genotoxic stress. Homology modeling based on the ING4 structure suggests that other ING dimers may also exist.

Monoglyceride contents in biodiesel from various plants oil and the effect to low temperature properties

NASA Astrophysics Data System (ADS)

Aisyah, L.; Wibowo, C. S.; Bethari, S. A.; Ufidian, D.; Anggarani, R.

2018-03-01

Monoglyceride is a by-product component of biodiesel process that relates to sedimentation problem at low temperature environment. To prevent the problem in using biodiesel-diesel fuel blends, it is necessary to limit of the monoglyceride content. The factor affecting monoglyceride content in biodiesel is the transesterification reaction and also the plant that is used. In this study, we investigate the monoglyceride content in biodiesel made from 4 plant oils; kemiri sunan (Reutealis trisperma) oil, coconut oil, nyamplung (Calophyllum inophyllum) oil, and waste cooking oil. These oils are purified and checked for its critical properties then converted to biodiesel. The biodiesel tested refer to Standard National of Indonesia for biodiesel (SNI 7182:2015). The monoglyceride content of biodiesel from kemiri sunan (Reutealis trisperma) oil, coconut oil, nyamplung (Calophyllum inophyllum) oil, and waste cooking oil, are 8.86%, 0.69%, 4.0%, and 2.69% consecutively. The low temperature properties represented by viscosity (@40 0C) for the 4 samples in the same order as before are 6.1 cSt, 2.7 cSt, 4.71 cSt, and 4.90 cSt. The cloud point is measured with the result of 30 °C, -20 °C, -60 °C and 30 °C respectively. The conclusions indicate that monoglyceride content can affect the low temperature properties of biodiesel.

Germination shifts of C3 and C4 species under simulated global warming scenario.

PubMed

Zhang, Hongxiang; Yu, Qiang; Huang, Yingxin; Zheng, Wei; Tian, Yu; Song, Yantao; Li, Guangdi; Zhou, Daowei

2014-01-01

Research efforts around the world have been increasingly devoted to investigating changes in C3 and C4 species' abundance or distribution with global warming, as they provide important insight into carbon fluxes and linked biogeochemical cycles. However, changes in the early life stage (e.g. germination) of C3 and C4 species in response to global warming, particularly with respect to asymmetric warming, have received less attention. We investigated germination percentage and rate of C3 and C4 species under asymmetric (+3/+6°C at day/night) and symmetric warming (+5/+5°C at day/night), simulated by alternating temperatures. A thermal time model was used to calculate germination base temperature and thermal time constant. Two additional alternating temperature regimes were used to test temperature metrics effect. The germination percentage and rate increased continuously for C4 species, but increased and then decreased with temperature for C3 species under both symmetric and asymmetric warming. Compared to asymmetric warming, symmetric warming significantly overestimated the speed of germination percentage change with temperature for C4 species. Among the temperature metrics (minimum, maximum, diurnal temperature range and average temperature), maximum temperature was most correlated with germination of C4 species. Our results indicate that global warming may favour germination of C4 species, at least for the C4 species studied in this work. The divergent effects of asymmetric and symmetric warming on plant germination also deserve more attention in future studies.

Making C4 crops more water efficient under current and future climate: Tradeoffs between carbon gain and water loss

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Pignon, C.

2017-12-01

C4 plants have a carbon concentrating mechanism that has evolved under historically low CO2 concentrations of around 200 ppm. However, increases in global CO2 concentrations in recent times (current CO2 concentrations are at 400 ppm and it is projected to be 550 ppm by mid-century) have diminished the relative advantage of C4 plants over C3 plants, which lack the expensive carbon concentrating machinery. Here we show by employing model simulations that under pre-historic CO2 concentrations, C4 plants are near optimal in their stomatal behavior and nitrogen partitioning between carbon concentrating machinery and carboxylation machinery, and they are significantly supra-optimal under current and future elevated CO2 concentrations. Model simulations performed at current CO2 concentrations of 400 ppm show that, under high light conditions, decreasing stomatal conductance by 20% results in a 15% increase in water use efficiency with negligible loss in photosynthesis. Under future elevated CO2 concentrations of 550 ppm, a 40% decrease in stomatal conductance produces a 35% increase in water use efficiency. Furthermore, stomatal closure is shown to be more effective in decreasing whole canopy transpiration compared to canopy top leaf transpiration, since shaded leaves are more supra-optimal than sunlit leaves. Model simulations for optimizing nitrogen distribution in C4 leaves show that under high light conditions, C4 plants over invest in carbon concentrating machinery and under invest in carboxylation machinery. A 20% redistribution in leaf nitrogen results in a 10% increase in leaf carbon assimilation without significant increases in transpiration under current CO2 concentrations of 400 ppm. Similarly, a 40% redistribution in leaf nitrogen results in a 15% increase in leaf carbon assimilation without significant increases in transpiration under future elevated CO2 concentrations of 550 ppm. Our model optimality simulations show that C4 leaves a supra optimal in their stomatal behavior and leaf nitrogen distribution and by decreasing stomatal conductance and redistributing nitrogen away from carbon concentrating mechanism and towards carboxylation machinery, we can significantly decrease transpiration and increase carbon assimilation thereby increasing water use efficiency.

Regulation and Functional Expression of Cinnamate 4-Hydroxylase from Parsley

PubMed Central

Koopmann, Edda; Logemann, Elke; Hahlbrock, Klaus

1999-01-01

A previously isolated parsley (Petroselinum crispum) cDNA with high sequence similarity to cinnamate 4-hydroxylase (C4H) cDNAs from several plant sources was expressed in yeast (Saccharomyces cerevisiae) containing a plant NADPH:cytochrome P450 oxidoreductase and verified as encoding a functional C4H (CYP73A10). Low genomic complexity and the occurrence of a single type of cDNA suggest the existence of only one C4H gene in parsley. The encoded mRNA and protein, in contrast to those of a functionally related NADPH:cytochrome P450 oxidoreductase, were strictly coregulated with phenylalanine ammonia-lyase mRNA and protein, respectively, as demonstrated by coinduction under various conditions and colocalization in situ in cross-sections from several different parsley tissues. These results support the hypothesis that the genes encoding the core reactions of phenylpropanoid metabolism form a tight regulatory unit. PMID:9880345

Carbon and Nitrogen Isotopic Survey of Northern Peruvian Plants: Baselines for Paleodietary and Paleoecological Studies

PubMed Central

Szpak, Paul; White, Christine D.; Longstaffe, Fred J.; Millaire, Jean-François; Vásquez Sánchez, Víctor F.

2013-01-01

The development of isotopic baselines for comparison with paleodietary data is crucial, but often overlooked. We review the factors affecting the carbon (δ13C) and nitrogen (δ15N) isotopic compositions of plants, with a special focus on the carbon and nitrogen isotopic compositions of twelve different species of cultivated plants (n = 91) and 139 wild plant species collected in northern Peru. The cultivated plants were collected from nineteen local markets. The mean δ13C value for maize (grain) was −11.8±0.4 ‰ (n = 27). Leguminous cultigens (beans, Andean lupin) were characterized by significantly lower δ15N values and significantly higher %N than non-leguminous cultigens. Wild plants from thirteen sites were collected in the Moche River Valley area between sea level and ∼4,000 meters above sea level (masl). These sites were associated with mean annual precipitation ranging from 0 to 710 mm. Plants growing at low altitude sites receiving low amounts of precipitation were characterized by higher δ15N values than plants growing at higher altitudes and receiving higher amounts of precipitation, although this trend dissipated when altitude was >2,000 masl and MAP was >400 mm. For C3 plants, foliar δ13C was positively correlated with altitude and precipitation. This suggests that the influence of altitude may overshadow the influence of water availability on foliar δ13C values at this scale. PMID:23341996

Macrocarpal C isolated from Eucalyptus globulus inhibits dipeptidyl peptidase 4 in an aggregated form.

PubMed

Kato, Eisuke; Kawakami, Kazuhiro; Kawabata, Jun

2018-12-01

Dipeptidyl peptidase 4 (DPP-4) inhibitors are used for the treatment of type-2 diabetes mellitus. Various synthetic inhibitors have been developed to date, and plants containing natural DPP-4 inhibitors have also been identified. Here, 13 plant samples were tested for their DPP-4 inhibitory activity. Macrocarpals A-C were isolated from Eucalyptus globulus through activity-guided fractionation and shown to be DPP-4 inhibitors. Of these, macrocarpal C showed the highest inhibitory activity, demonstrating an inhibition curve characterised by a pronounced increase in activity within a narrow concentration range. Evaluation of macrocarpal C solution by turbidity, nuclear magnetic resonance spectroscopy and mass spectrometry indicated its aggregation, which may explain the characteristics of the inhibition curve. These findings will be valuable for further study of potential small molecule DPP-4 inhibitors.

Investigating CH4 production in an oxic plant-soil system -a new approach combining isotopic labelling (13C) and inhibitors

NASA Astrophysics Data System (ADS)

Lenhart, Katharina; Keppler, Frank

2017-04-01

Typically, aerated soil are net sinks of atmospheric methane (CH4), being highest in native ecosystems (pristine forests > managed forests > grasslands > crop fields). However, this does not exclude a simultaneous endogenic CH4 production in the plant-soil system, which cannot be detected simply via CH4 flux measurements. Methanogenic archaea producing CH4 under anoxic conditions were thought to be the only biotic source of CH4 in the soil. However, until recently a non-archaeal pathway of CH4 formation is known where CH4 is produced under oxic conditions in plants (Keppler et al. 2006) and fungi (Lenhart et al. 2012). Additionally, abiotic formation of CH4 from soil organic matter was reported (Jugold et al. 2012) and may be ubiquitous in terrestrial ecosystems. The major goal of this project was to determine soil endogenic CH4 sources and to estimate their contribution to the endogenic CH4 production. Especially the effect of plants and fungi on soil CH4 production was investigated. Therefore, a series of experiments was carried out on field fresh soil collected in a grassland and a forest ecosystem under controlled laboratory conditions. By combining selective inhibitors and 13C labelling, CH4 production rates of several CH4 sources were quantified. The major difficulty was to detect the comparatively small flux of CH4 production against the background of the high CH4 consumption rates due to methanotrophic bacteria. Therefore, we supplemented bare soil and soil with vegetation with selective inhibitors and 13C labelled substrates in a closed chamber system. In a first step, CH4 production was determined by the inhibition of CH4 oxidizing bacteria with Difluoromethane (DFM, 2ml l-1). In the following, a 13C labelled substrate (either CO2, Acetate, or Methionine -S-CH3 labelled) was added in combination with a specific inhibitor -either for archaeal methanogenesis (Bromoethanesulfonate), bacteria (Streptomycin), or fungi (Captan, Cycloheximide). Gas samples were taken during the incubation for CH4 and CO2 concentration measurements and isotope ratio mass spectrometry (CH4, CO2). Grassland and forest soils showed differences in CO2 and CH4 production rates. Based on the 13C-CH4 signature we found that all substrates were metabolized to CH4, but to a different degree. Inhibitors reduced CH4 production and conversion of certain substrates to a different degree. Using the example of acetate and cycloheximide, in both soils acetate increased respiration, whereas cycloheximide reduced respiration by 56 and 62 %, respectively. For CH4 production, however, no effect was visible for the grassland soil, but in the forest soil CH4 production increased by 69 %. Cycloheximide inhibited the substrate-induced CH4 production by 63 %, indicating that fungi were responsible for this pathway. Moreover, the finding that fungi use the methyl group of acetate to produce CH4 was also verified with a sterile culture. References Lenhart, K. et al. Evidence for methane production by saprotrophic fungi. Nat Commun 3, 1046, (2012). Keppler, F., et al. Methane emissions from terrestrial plants under aerobic conditions. Nature 439, 187-191 (2006). Jugold, A. et al. Non-microbial methane formation in oxic soils. Biogeosciences 9, 5291-5301, (2012).

Amounts, isotopic character and ages of organic and inorganic carbon exported from rivers to ocean margins: Assessment of natural and anthropogenic controls

NASA Astrophysics Data System (ADS)

Bauer, J. E.; Hossler, K.

2012-12-01

Riverine exports of carbon (C) and organic matter (OM) are regulated by a variety of natural and anthropogenic factors. Understanding the relationships between these various factors and C and OM exports can help to constrain global C budgets, as well allow assessment of current and future anthropogenic impacts on both riverine and global C cycles. We quantified the effects of multiple natural and anthropogenic controls on riverine export fluxes and compositions of particulate organic C (POC), dissolved organic C (DOC), and dissolved inorganic C (DIC) for a regional group of eight rivers in the northeastern U.S. For allochthonous and aged C contributions to POC, DOC and DIC exports, we first estimated fractional contributions from six potential sources for POC and DOC (i.e., modern C3 plant material (C3-OC), modern C4 plant material (C4-OC), modern algal material (algal OC), slow-turnover soil OC (slow SOC; turnover time 25 yr), passive-turnover soil OC (passive SOC; turnover time 5,000 yr) and fossil OC and four potential sources for DIC (i.e., modern atmospheric CO2 exchange, carbonate dissolution, POC remineralization and DOC remineralization) using a novel time-varying isotope mixing model. Using these estimated source contributions, we then estimated the allochthonous proportions of (a) the POC and DOC pools to be the C3-OC, C4-OC, slow SOC, passive SOC, and fossil OC contributions; and (b) the DIC pools to be the dissolved carbonates, remineralized allochthonous POC, and remineralized allochthonous DOC contributions. We considered aged C to be anything older than ˜ 60 yr, which included passive SOC and fossil OC for POC and DOC and dissolved carbonates and aged fractions of remineralized POC and DOC for DIC. Potential controls related to hydrogeomorphology and regional climate, soil order, soil texture, bedrock lithology, land use, and additional anthropogenic factors were analyzed collectively, individually, and at scales of both local and regional influence. Factors related either to hydrogeomorphology and climate or to anthropogenic factors exhibited the strongest impacts on riverine C exports and compositions, particularly at broader regional scales. The effect of hydrogeomorphology and climate was primarily one of size, as larger watersheds with greater discharge exported more total C and terrestrial C. Principal anthropogenic factors included impacts of wastewater treatment plants (WWTPs) and river impoundments. The presence of WWTPs as well as anthropogenic use of carbonate-based materials (e.g., limestone) may have substantially increased riverine C exports, particularly fossil C exports, in the study region. The presence of nuclear power plants in the associated watersheds is also discussed because of the potential for anthropogenic 14C inputs and subsequent biasing of aquatic C studies utilizing natural abundance 14C.

Chemical profile and in vivo hypoglycemic effects of Syzygium jambos, Costus speciosus and Tapeinochilos ananassae plant extracts used as diabetes adjuvants in Puerto Rico.

PubMed

Gavillán-Suárez, Jannette; Aguilar-Perez, Alexandra; Rivera-Ortiz, Natalie; Rodríguez-Tirado, Karla; Figueroa-Cuilan, Wanda; Morales-Santiago, Lorelein; Maldonado-Martínez, Gerónimo; Cubano, Luis A; Martínez-Montemayor, Michelle M

2015-07-22

The increasing numbers of people who use plant-based remedies as alternative or complementary medicine call for the validation of less known herbal formulations used to treat their ailments. Since Puerto Rico has the highest rate of Type 2 diabetes within all the states and territories of the United States, and Puerto Ricans commonly use plants as diabetes adjuvants, it is important to study the plants' physiological effects, and identify their bioactive compounds to understand their role in modulation of blood glucose levels. We present the phytochemical profiles and hypoglycemic effects of Tapeinochilus ananassae, Costus speciosus and Syzygium jambos. Phytochemicals in methanolic and aqueous extracts were analyzed by thin layer chromatography (TLC). Alkaloids (Bromocresol green, λ=470 nm), flavonoids (AlCl3, λ=415 nm), saponins (DNS, λ=760 nm), tannins (FeCl3/K4Fe(CN)6, λ=395 nm) and phenolics (Folin-Ciocalteau, λ=765 nm) were quantified. Male C57BLKS/J (db/db) and C57BL/J (ob/ob) genetically obese mice were orally gavaged with aqueous extracts of lyophilized plant decoctions for 10 wks. Our results show that T. ananassae had significantly greater amounts of flavonoids and tannins, while S. jambos showed the greatest concentration of phenolics and C. speciosus exhibited higher amounts of alkaloids. C57BLKS/J db/db treated with plant extracts show better glucose modulation when the extracts are administered in complement with an insulin injection. Finally, C57BL/J ob/ob mice on T. ananassae and S. jambos treatments show better blood glucose modulation over time. These results document for the first time the chemical profile of T. ananassae and provide evidence for a potential anti-diabetic efficacy of T. ananassae and S. jambos.

Thyroid hormones in chronic heat exposed men

NASA Astrophysics Data System (ADS)

Gertner, A.; Israeli, R.; Lev, A.; Cassuto, Y.

1983-03-01

Previous reports have indicated that thyroid gland activity, is depressed in the heat. Total thyroxine (T4) and triiodothyronine (T3) serum levels in 17 workers of the metal work shop at a plant near the Dead Sea and 8 workers in Beer Sheva, Israel were examined. The metal workshop of the plant near the Dead Sea is part of a large chemical plant. The one in Beer Sheva is part of a large construction company. Maintenance work, as well as metal work projects are performed in both workshops. During the work shifts, the workers of the Dead Sea plant were exposed to temperatures ranging from 30 36°C (May Oct.) and 14 21°C (Dec. Feb). In Beer Sheva the range was 25 32°C (June Sept.) and 10 17°C (Dec. Feb.). Total T4 was measured by competitive protein binding and total T3 by radioimmunoassay in blood drawn before work (0700) in July and January. In summer. T4 was higher and T3 was lower for both groups than in winter. The observed summer T3 decrease may result from depressed extrathyroidal conversion of T4 to T3. We conclude that the regulation of energy metabolism in hot climates may be related to extrathyroidal conversion of T4 to T3.

Angiosperm n-alkane distribution patterns and the geologic record of C4 grassland evolution

NASA Astrophysics Data System (ADS)

Henderson, A.; Graham, H. V.; Patzkowsky, M.; Fox, D. L.; Freeman, K. H.

2012-12-01

n-Alkane average chain-length (ACL) patterns vary regionally with community composition and climate. To clarify the influence of phylogenetic and community patterns, we compiled and analyzed a global database of published n-alkane abundance for n-C27 to C35 homologs in modern plant specimens (n=205). ACL for waxes in C4 non-woody plants are longer than for woody plants, suggesting ACL can serve as an indicator of the three-dimensional structure of local vegetation. Further, these findings suggest compound-specific isotopic data for longer alkane homologs (C31, C33, C35) will proportionately represent non-woody vegetation and isotope measurements of C29 are more representative of woody vegetation. Thus, the combination of ACL and carbon isotope compositions should allow us to disentangle C3 woody, C3 non-woody, and C4 non-woody signals in terrestrial paleorecords. Application of this approach to the geologic record of Miocene C4 grassland expansion in the US Great Plains and the Siwaliks in Pakistan illustrate two very different transition scenarios. Alkane-specific isotopic data indicate C4 grasslands appeared 2.5 Ma in the Great Plains and 6.5 Ma in the Siwaliks, and ACL analysis indicates that this transition involved the replacement of woody vegetation in the US and the replacement of C3 grasses in Pakistan. Our analysis illustrates that, consistent with differences in the timing of C4 grassland, the drivers of change were likely not the same in these regions. Oxygen isotope records suggest that the more recent transition in the Great Plains was associated with climate cooling and possibly changes in disturbance regimes and that the transition in the Siwaliks was likely associated with warming and drying.

Effects of Plant Herb Combination Supplementation on Rumen Fermentation and Nutrient Digestibility in Beef Cattle

PubMed Central

Wanapat, M.; Kang, S.; Khejornsart, P.; Wanapat, S.

2013-01-01

Four rumen-fistulated crossbred beef cattle (Brahman native) were randomly assigned according to a 4×4 Latin square design experiment to be fed plant herb supplements in their concentrate mixture. The treatments were: without herb supplementation (Control), lemongrass meal supplementation at 100 g/d (L), lemongrass meal supplementation at 100 g/d plus peppermint powder at 10 g/d (LP), and lemongrass meal supplementation at 100 g/d plus peppermint powder at 10 g/d with garlic powder 40 g/d (LPG), respectively. Based on the present study, the DMI and apparent digestibility of DM, OM, aNDF and ADF were not affected by dietary herb supplementation while CP digestibility tended to be decreased by herb supplement. Moreover, NH3-N and BUN were decreased in all herb supplemented treatments and there was a tendency to an increase in ruminal pH in all herb supplemented groups. While there was no change in TVFA and C4 among lemongrass treatments, C2 was decreased in all herb supplemented treatments while C3 was increased. Methane production by calculation was the lowest in the LP and LPG groups. Population sizes of bacteria and protozoa were decreased in all herb supplemented groups, but not fungal zoospores. In all supplemented groups, total viable and proteolytic bacteria were decreased, while amylolytic and cellulolytic bacteria were similar. More importantly, in all herb supplemented groups, there were higher N balances, while there was no difference among treatments on purine derivative (PD) excretion or microbial N. Based on the results above, it could be concluded that there was no negative effect on ruminal fermentation characteristics and nutrient utilization by plant herb supplement, but protozoal population and CH4 production were reduced. Thus, lemongrass alone or in combination with peppermint and garlic powder could be used as feed additives to improve rumen fermentation efficiency. PMID:25049893

Middle to Late Holocene Fluctuations of C3 and C4 Vegetation in a Northern New England Salt Marsh, Sprague Marsh, Phippsburg Maine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, B J; Moore, K A; Lehmann, C

2006-05-26

A 3.1 meter sediment core was analyzed for stable carbon isotope composition of organic matter and higher plant leaf wax (HPLW) lipid biomarkers to determine Holocene shifts in C{sub 3} (higher high marsh) and C{sub 4} (low and/or high marsh) plant deposition at the Sprague River Salt Marsh, Phippsburg, Maine. The carbon isotope composition of the bulk sediment and the HPLW parallel each other throughout most of the core, suggesting that terrestrial plants are an important source of organic matter to the sediments, and diagenetic alteration of the bulk sediments is minimal. The current salt marsh began to form 2500more » cal yr BP. Low and/or high C{sub 4} marsh plants dominated deposition at 2000 cal yr BP, 700 cal yr BP, and for the last 200 cal yr BP. Expansion of higher high marsh C{sub 3} plants occurred at 1300 and 600 cal yr BP. These major vegetation shifts result from a combination of changes in relative sea-level rise and sediment accumulation rates. Average annual carbon sequestration rates for the last 2500 years approximate 40 g C yr{sup -1} m{sup -2}, and are in strong agreement with other values published for the Gulf of Maine. Given that Maine salt marshes cover an area of {approx}79 km{sup 2}, they represent an important component of the terrestrial carbon sink. More detailed isotopic and age records from a network of sediment cores at Sprague Marsh are needed to truly evaluate the long term changes in salt marsh plant communities and the impact of more recent human activity, including global warming, on salt marsh vegetation.« less

ImprimatinC1, a novel plant immune-priming compound, functions as a partial agonist of salicylic acid

PubMed Central

Noutoshi, Yoshiteru; Jikumaru, Yusuke; Kamiya, Yuji; Shirasu, Ken

2012-01-01

Plant activators are agrochemicals that protect crops from pathogens. They confer durable resistance to a broad range of diseases by activating intrinsic immune mechanisms in plants. To obtain leads regarding useful compounds, we have screened a chemical library using an established method that allows selective identification of immune-priming compounds. Here, we report the characterisation of one of the isolated chemicals, imprimatinC1, and its structural derivative imprimatinC2. ImprimatinC1 functions as a weak analogue of salicylic acid (SA) and activates the expression of defence-related genes. However, it lacks antagonistic activity toward jasmonic acid. Structure-activity relationship analysis suggests that imprimatinC1 and C2 can be metabolised to 4-chlorobenzoic acid and 3,4-chlorobenzoic acid, respectively, to function in Arabidopsis. We also found that imprimatinC1 and C2 and their potential functional metabolites acted as partial agonists of SA. Thus, imprimatinC compounds could be useful tools for dissecting SA-dependent signal transduction pathways. PMID:23050089

ImprimatinC1, a novel plant immune-priming compound, functions as a partial agonist of salicylic acid.

PubMed

Noutoshi, Yoshiteru; Jikumaru, Yusuke; Kamiya, Yuji; Shirasu, Ken

2012-01-01

Plant activators are agrochemicals that protect crops from pathogens. They confer durable resistance to a broad range of diseases by activating intrinsic immune mechanisms in plants. To obtain leads regarding useful compounds, we have screened a chemical library using an established method that allows selective identification of immune-priming compounds. Here, we report the characterisation of one of the isolated chemicals, imprimatinC1, and its structural derivative imprimatinC2. ImprimatinC1 functions as a weak analogue of salicylic acid (SA) and activates the expression of defence-related genes. However, it lacks antagonistic activity toward jasmonic acid. Structure-activity relationship analysis suggests that imprimatinC1 and C2 can be metabolised to 4-chlorobenzoic acid and 3,4-chlorobenzoic acid, respectively, to function in Arabidopsis. We also found that imprimatinC1 and C2 and their potential functional metabolites acted as partial agonists of SA. Thus, imprimatinC compounds could be useful tools for dissecting SA-dependent signal transduction pathways.

Determination of oxidation products of 5-methylcytosine in plants by chemical derivatization coupled with liquid chromatography/tandem mass spectrometry analysis.

PubMed

Tang, Yang; Xiong, Jun; Jiang, Han-Peng; Zheng, Shu-Jian; Feng, Yu-Qi; Yuan, Bi-Feng

2014-08-05

Cytosine methylation (5-methylcytosine, 5-mC) in DNA is an important epigenetic mark that has regulatory roles in various biological processes. In plants, active DNA demethylation can be achieved through direct cleavage by DNA glycosylases, followed by replacement of 5-mC with cytosine by base excision repair (BER) machinery. Recent studies in mammals have demonstrated 5-mC can be sequentially oxidized to 5-hydroxymethylcytosine (5-hmC), 5-formylcytosine (5-foC), and 5-carboxylcytosine (5-caC) by Ten-eleven translocation (TET) proteins. The consecutive oxidations of 5-mC constitute the active DNA demethylation pathway in mammals, which raised the possible presence of oxidation products of 5-mC (5-hmC, 5-foC, and 5-caC) in plant genomes. However, there is no definitive evidence supporting the presence of these modified bases in plant genomic DNA, especially for 5-foC and 5-caC. Here we developed a chemical derivatization strategy combined with liquid chromatography-electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method to determine 5-formyl-2'-deoxycytidine (5-fodC) and 5-carboxyl-2'-deoxycytidine (5-cadC). Derivatization of 5-fodC and 5-cadC by Girard's reagents (GirD, GirT, and GirP) significantly increased the detection sensitivities of 5-fodC and 5-cadC by 52-260-fold. Using this method, we demonstrated the widespread existence of 5-fodC and 5-cadC in genomic DNA of various plant tissues, indicating that active DNA demethylation in plants may go through an alternative pathway similar to mammals besides the pathway of direct DNA glycosylases cleavage combined with BER. Moreover, we found that environmental stresses of drought and salinity can change the contents of 5-fodC and 5-cadC in plant genomes, suggesting the functional roles of 5-fodC and 5-cadC in response to environmental stresses.

Changes in community-level riparian plant traits over inundation gradients, Colorado River, Grand Canyon

USGS Publications Warehouse

McCoy-Sulentic, Miles; Kolb, Thomas; Merritt, David; Palmquist, Emily C.; Ralston, Barbara E.; Sarr, Daniel; Shafroth, Patrick B.

2017-01-01

Comparisons of community-level functional traits across environmental gradients have potential for identifying links among plant characteristics, adaptations to stress and disturbance, and community assembly. We investigated community-level variation in specific leaf area (SLA), plant mature height, seed mass, stem specific gravity (SSG), relative cover of C4 species, and total plant cover over hydrologic zones and gradients in years 2013 and 2014 in the riparian plant community along the Colorado River in the Grand Canyon. Vegetation cover was lowest in the frequently inundated active channel zone, indicating constraints on plant establishment and production by flood disturbance and anaerobic stress. Changes in trait values over hydrologic zones and inundation gradients indicate that frequently inundated plots exhibit a community-level ruderal strategy with adaptation to submergence (high SLA and low SSG, height, seed mass, C4 relative cover), whereas less frequently inundated plots exhibit adaptation to drought and infrequent flood disturbance (low SLA and high SSG, height, seed mass, C4 relative cover). Variation in traits not associated with inundation suggests niche differentiation and multiple modes of community assembly. The results enhance understanding of future responses of riparian communities of the Grand Canyon to anticipated drying and changes in hydrologic regime.

Towards a Better Understanding of the Oxygen Isotope Signature of Atmospheric CO2: Determining the 18O-Exchange Between CO2 and H2O in Leaves and Soil On-line with Laser-Based Spectroscopy

NASA Astrophysics Data System (ADS)

Gangi, L.; Rothfuss, Y.; Vereecken, H.; Brueggemann, N.

2013-12-01

The oxygen isotope signature of carbon dioxide (δ18O-CO2) is a powerful tool to disentangle CO2 fluxes in terrestrial ecosystems, as CO2 attains a contrasting 18O signature by the interaction with isotopically different soil and leaf water pools during soil respiration and photosynthesis, respectively. However, using the δ18O-CO2 signal to quantify plant-soil-atmosphere CO2 fluxes is still challenging due to a lack of knowledge concerning the magnitude and effect of individual fractionation processes during CO2 and H2O diffusion and during CO2-H2O isotopic exchange in soils and leaves, especially related to short-term changes in environmental conditions (non-steady state). This study addresses this research gap by combined on-line monitoring of the oxygen isotopic signature of CO2 and water vapor during gas exchange in soil and plant leaves with laser-based spectroscopy, using soil columns and plant chambers. In both experimental setups, the measured δ18O of water vapor was used to infer the δ18O of liquid water, and, together with the δ18O-CO2, the degree of oxygen isotopic equilibrium between the two species (θ). Gas exchange experiments with different functional plant types (C3 coniferous, C3 monocotyledonous, C3 dicotyledonous, C4) revealed that θ and the influence of the plant on the ambient δ18O-CO2 (CO18O-isoforcing) not only varied on a diurnal timescale but also when plants were exposed to limited water availability, elevated air temperature, and abrupt changes in light intensity (sunflecks). Maximum θ before treatments ranged between 0.7 and 0.8 for the C3 dicotyledonous (poplar) and C3 monocotyledonous (wheat) plants, and between 0.5 and 0.6 for the conifer (spruce) and C4 plant (maize) while maximum CO18O-isoforcing was highest in wheat (0.03 m s-1 ‰), similar in poplar and maize (0.02 m s-1 ‰), and lowest in spruce (0.01 m s-1 ‰). Multiple regression analysis showed that up to 97 % of temporal dynamics in CO18O-isoforcing could be explained by variations in stomatal conductance, θ, and δ18O of H2O at the evaporation site. The determined maximum in vivo activity of carbonic anhydrase, the enzyme which catalyzes the CO2-H2O oxygen isotope exchange inside leaves, varied between the different plant species and was, as observed for θ, higher in poplar and wheat, and lower in maize and spruce. Preliminary experiments with soil columns filled with sand demonstrated that gas-permeable microporous polypropylene tubing, which was installed at different depths in the soil columns, was appropriate for determining δ18O-H2O and δ18O-CO2 simultaneously without fractionation. Hence, this new methodology is promising for further studies on the oxygen isotopic exchange between CO2 and H2O in soils. Altogether, this study highlights that the δ18O-CO2 exchange in the soil-plant-atmosphere continuum is highly dynamic in response to short-term variations in environmental conditions, and emphasizes the need for an improved parameterization of models simulating δ18O-CO2.

Origin of Phytolith Carbon Revealed by Isotopic Measurements of Extracted Phytoliths from FACE Grasses

NASA Astrophysics Data System (ADS)

Reyerson, P. E.; Santos, G.; Alexandre, A. E.; Harutyunyan, A.; Badeck, F.; Cattivelli, L.

2013-12-01

Radiocarbon dating of C encapsulated in phytoliths (phytC) is being explored as an age control tool in many Earth Science disciplines with limited success. However, because plants take up small amounts of C (1-3%) of varying ages from soils, recent studies have suggested that phytC is at least partially derived from soil organic matter (SOM) based on anomalously old 14C phytC ages derived from living plants. It appears that most phytolith digestion methods are not able to fully dissolve the more weathering-resistant SOM already stored in plant tissue [2,3], leading to a proportional increase of transported soil-C residues, thus biasing the 14C values [4]. We extracted phytoliths from graminae spp. grown in free-air carbon enrichment experiments (FACE). For each grass set, one group was grown under 14C-free elevated CO2 conditions (shifting the bulk plant tissue towards thousands of years old) while the other was grown under ambient atmospheric CO2. We used two newly developed protocols, which produce pure phytoliths [5]: a multiple-step wet-oxidation process with KOH digestion (pH≥14); and a multiple-step dry ashing at 500°C coupled with wet-oxidation. Radiocarbon analyses of phytC yielded initially contradictory results: a) when phytoliths were extracted by both protocols, ambient-air phytC 14C ages were thousands of years old; b) when a mild wet-oxidation extraction was employed (KOH; pH≥11), ambient-air 14C phytC values were post-bomb (modern), but still 14C depleted. To evaluate the thermal behavior of the C species of phytC, we used a thermal-optical C aerosol analyzer, with a stepwise temperature ramp from zero to 860°C under an oxidizing atmosphere. Thermograms indicate that the phytoliths contain a complex array of phytC molecules, with some of the C species released at temperatures as low as 300°C, and suggesting that phytC is formed by a continuum of C (possibly of several ages). This was verified by 'roasting' duplicates of pure phytolith extracts obtained through wet-oxidation protocol (enriched and ambient), which yielded ages thousands of years old, similar to the previous 14C results. These findings suggest that aggressive cleaning steps (ashing at 500°C, high pH) isolate this oldest C fraction, as less recalcitrant forms of C were lost. These results imply that most phytC is of photosynthetic origin; however, phytC from living plants often fail to produce contemporaneous 14C values, which also implies that some of the old soil-C stored in plant tissue can be transported and encapsulated within phytoliths leading to erroneous 14C age chronologies. We also attempted to map the Si distribution of individual phytoliths and biosilica fragments through SEM and NanoSIMS, which will also be shown and discussed. [1] Santos et al. 2010 Radiocarbon 52:113 [2] Santos et al. 2012 Biogeosci. 9:1873 [3] Sullivan and Parr 2013 Biogeosci. 10:977 [4] Santos et al. 2012 Biogeosci. Discussion 9:C6114 [5] Corbineau et al. 2013 R. Paleobot. Palyn. 197: 179

Chemical Mowing: Effect of Plant Growth Retardants on Plant Roots

DTIC Science & Technology

1991-08-01

nature of the turf. The retardation effects of mefluidide in this case ( field -treated) are consistent with other researchers (Nielsen and Wakefield...CONTRACT REPORT EL-91-1 CHEMICAL MOWING: EFFECT OF PLANT Of 5,’’ ’,i em GROWTH RETARDANTS ON PLANT ROOTS AD-A2 4 0 88 byI/l!ll//I, I/ll/lil/l///l/o.P...Chemical Mowing: Effect of Plant Growth Retardants on Plant Roots 6. AUTHOR(S) DACW39-88-C-0043 0. P. Vadhwa DACW39-88-C-0043-P 00002 7. PERFORMING

Diets and environments of late Cenozoic mammals in the Qaidam Basin, Tibetan Plateau: Evidence from stable isotopes

NASA Astrophysics Data System (ADS)

Zhang, Chunfu; Wang, Yang; Li, Qiang; Wang, Xiaoming; Deng, Tao; Tseng, Zhijie J.; Takeuchi, Gary T.; Xie, Gangpu; Xu, Yingfeng

2012-06-01

The timing history and driving mechanisms of C4 expansion and Tibetan uplift are hotly debated issues. Paleoenvironmental evidence from within the Tibetan Plateau is essential to help resolve these issues. Here we report results of stable C and O isotope analyses of tooth enamel samples from a variety of late Cenozoic mammals, including deer, giraffe, horse, rhino, and elephant, from the Qaidam Basin in the northeastern Tibetan Plateau. The enamel-δ13C values are <-8‰ for modern samples and ≤-7‰ for fossils, except for one late Miocene rhino (CD0722, with δ13C values up to -4.1‰). If the Qaidam Basin was as arid as today in the Mio-Pliocene, these data would indicate that the majority of the animals had C3 diets and only a few individuals (besides the exceptional rhino CD0722) may have consumed some C4 plants. Based on geological evidence, however, the Qaidam Basin was probably warmer and more humid during the late Miocene and early Pliocene than today. Thus, these δ13C values likely indicate that many individuals had significant dietary intakes of C4 plants, and the Qaidam Basin had more C4 plants in the late Miocene and early Pliocene than today. Moreover, the Qaidam Basin likely had much denser vegetation at those times in order to support such large mammals as rhinos and elephants. While the δ18O values did not increase monotonously with time, the range of variation seems to have increased considerably since the early Pliocene, indicating increased aridification in the basin. The mean δ18O values of large mammals and those reconstructed for local meteoric waters display a significant negative shift in the late Miocene, consistent with the marine δ18O record which shows a cooling trend in the same period. Taken together, the isotope data suggest a warmer, wetter, and perhaps lower Qaidam Basin during the late Miocene and early Pliocene. Increased aridification after the early Pliocene is likely due to a combined effect of regional tectonism, which resulted in a more effective barrier preventing moisture from the Indian Ocean or Bay of Bengal from reaching the basin, and global cooling.

Monitoring Metabolite Profiles of Cannabis sativa L. Trichomes during Flowering Period Using 1H NMR-Based Metabolomics and Real-Time PCR.

PubMed

Happyana, Nizar; Kayser, Oliver

2016-08-01

Cannabis sativa trichomes are glandular structures predominantly responsible for the biosynthesis of cannabinoids, the biologically active compounds unique to this plant. To the best of our knowledge, most metabolomic works on C. sativa that have been reported previously focused their investigations on the flowers and leaves of this plant. In this study, (1)H NMR-based metabolomics and real-time PCR analysis were applied for monitoring the metabolite profiles of C. sativa trichomes, variety Bediol, during the last 4 weeks of the flowering period. Partial least squares discriminant analysis models successfully classified metabolites of the trichomes based on the harvest time. Δ (9)-Tetrahydrocannabinolic acid (1) and cannabidiolic acid (2) constituted the vital differential components of the organic preparations, while asparagine, glutamine, fructose, and glucose proved to be their water-extracted counterparts. According to RT-PCR analysis, gene expression levels of olivetol synthase and olivetolic acid cyclase influenced the accumulation of cannabinoids in the Cannabis trichomes during the monitoring time. Moreover, quantitative (1)H NMR and RT-PCR analysis of the Cannabis trichomes suggested that the gene regulation of cannabinoid biosynthesis in the C. sativa variety Bediol is unique when compared with other C. sativa varieties. Georg Thieme Verlag KG Stuttgart · New York.

Optimization of Acidothermus Celluloyticus Endoglucanase (E1) Production in Transgenic Tobacco Plants by Transcriptional, Post-transcription and Post-Translational Modification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Ziyu; Hooker, Brian S.; Quesenberry, Ryan D.

2005-10-01

Biochemical characteristics of Acidothermus cellulolyticus endoglucanase (E1) and its physiological effects in transgenic tobacco (Nicotiana tabacum) has been studied previously. In an attempt to obtain a high level of production of intact E1 in transgenic plants, the E1 gene was expressed under the control of strong Mac promoter (a hybrid promoter of manopine synthase promoter and cauliflower mosaic virus 35S promoter enhancer region) or tomato Rubisco small subunit (RbcS-3C) promoter with different 5’ untranslated leader (UTL) sequence and targeted to different subcellular comartmentations with various transit peptides. The expression of E1 protein in transgenic tobacco plants was determined via E1more » activity, protein immunobloting, and RNA gel-blotting analyses. Effects of different transit peptides on E1 protein production and its stability were examined in transgenic tobacco plants carrying one of six transgene expression vectors with the same (Mac) promoter and transcription terminator (Tmas). Transgenic tobacco plants with apoplast transit peptide (Mm-apo) had the highest average E1 activity and protein accumulation , while E1 protein was more stable in transgenic plants with no transit peptide (Mm) than others. The E1 expression under tomato RbcS-3C promoter was higher than that under Mac promoter based on the average E1 activity, E1 protein accumulation, and RNA gel-blotting. The E1 expression was increased more than two fold when the 5’-UTL of alfalfa mosaic virus RNA4 gene replaced the UTL of RbcS-3C promoter, while the UTL of alfalfa mosaic virus RNA4 gene was less effective than the UTL of Mac promoter. The optimal combination of promoter, 5’-UTL, and subcellular compartmentation (transit peptide) for E1 protein production in transgenic tobacco plants are discussed.« less

Invasive C4 Perennial Grass Alters Net Ecosystem Exchange in Mixed C3/C4 Savanna Grassland

NASA Astrophysics Data System (ADS)

Basham, T. S.; Litvak, M.

2006-12-01

The invasion of ecosystems by non-native plants that differ from native plants in physiological characteristics and phenology has the potential to alter ecosystem function. In Texas and other regions of the southern central plains of the United States, the introduced C4 perennial grass, Bothriochloa ischaemum, invades C3/C4 mixed grasslands and savannas, resulting in decreased plant community diversity (Gabbard 2003; Harmoney et al 2004). The objective of this study was to quantify how the conversion of these mixed grass communities to C4 dominated, B. ischaemum monocultures impacts carbon cycling and sequestration. Seasonal measurements of Net Ecosystem Exchange (NEE) of CO2, leaf level gas exchange and soil respiration were compared between savanna grassland plots composed of either naturally occurring B. ischaemum monocultures or native mixed grasses (n=16). NEE was measured using a closed system chamber that attached to permanently installed stainless steel bases. Temperature, soil moisture, aerial percent species cover and leaf area index were also monitored in plots to explain variability in measured responses. Results showed that NEE differed seasonally between invaded and native plots due to 1) greater leaf surface area per unit ground area in invaded plots, 2) differences in phenological patterns of plant activity and 3) differences in responses to water limitation between invaded and native plots. Cold season and summer drought NEE were driven primarily by belowground respiration in both plot types, however spring uptake activity commenced two months later in invaded plots. This later start in invaded plots was compensated for by greater uptake throughout the growing season and in particular during the drier summer months. Differences in NEE between plot types were not due to differences in soil respiration nor were they due to greater leaf level photosynthetic capabilities of B. ischaemum relative to the dominant native grasses. NEE, soil respiration and biomass accumulation were limited by temperature and soil moisture in both native and invaded plots; however, invaded areas were less sensitive to both higher temperatures and lower soil moisture. Preliminary modeling results suggest that from January-August 2006, invaded grasslands stored approximately one third more carbon than native grasslands, making them 20% less of a carbon source than native plots during this year of record high temperatures and drought. Gabbard, BL. 2003. The Population Dynamics and Distribution of the Exotic Grass,Bothriochloa ischaemum, PhD Dissertation, University of Texas, Austin, TX Harmoney et al. 2004. Herbicide Effects on Established Yellow Old World Bluestem (Bothriochloa ischaemum). Weed Technology 18:545 550

Stable Isotope Analysis Reveals Detrital Resource Base Sources of the Tree Hole Mosquito, Aedes triseriatus

PubMed Central

Kaufman, Michael G.; Pelz-Stelinski, Kirsten S.; Yee, Donald A.; Juliano, Steven A.; Ostrom, Peggy H.; Walker, Edward D.

2010-01-01

1. Detritus that forms the basis for mosquito production in tree hole ecosystems can vary in type and timing of input. We investigated the contributions of plant- and animal-derived detritus to the biomass of Aedes triseriatus (Say) pupae and adults by using stable isotope (15N and 13C) techniques in lab experiments and field collections. 2. Lab-reared mosquito isotope values reflected their detrital resource base, providing a clear distinction between mosquitoes reared on plant or animal detritus. 3. Isotope values from field-collected pupae were intermediate between what would be expected if a single (either plant or animal) detrital source dominated the resource base. However, mosquito isotope values clustered most closely with plant-derived values, and a mixed feeding model analysis indicated tree floral parts contributed approximately 80% of mosquito biomass. The mixed model also indicated that animal detritus contributed approximately 30% of mosquito tissue nitrogen. 4. Pupae collected later in the season generally had isotope values that were consistent with an increased contribution from animal detritus, suggesting this resource became more nutritionally important for mosquitoes as plant inputs declined over the summer. PMID:21132121

Assessment of genetic fidelity in Rauvolfia serpentina plantlets grown from synthetic (encapsulated) seeds following in vitro storage at 4 °C.

PubMed

Faisal, Mohammad; Alatar, Abdulrahman A; Ahmad, Naseem; Anis, Mohammad; Hegazy, Ahmad K

2012-05-03

An efficient method was developed for plant regeneration and establishment from alginate encapsulated synthetic seeds of Rauvolfia serpentina. Synthetic seeds were produced using in vitro proliferated microshoots upon complexation of 3% sodium alginate prepared in Llyod and McCown woody plant medium (WPM) and 100 mM calcium chloride. Re-growth ability of encapsulated nodal segments was evaluated after storage at 4 °C for 0, 1, 2, 4, 6 and 8 weeks and compared with non-encapsulated buds. Effects of different media viz; Murashige and Skoog medium; Lloyd and McCown woody Plant medium, Gamborg’s B5 medium and Schenk and Hildebrandt medium was also investigated for conversion into plantlets. The maximum frequency of conversion into plantlets from encapsulated nodal segments stored at 4 °C for 4 weeks was achieved on woody plant medium supplement with 5.0 μM BA and 1.0 μM NAA. Rooting in plantlets was achieved in half-strength Murashige and Skoog liquid medium containing 0.5 μM indole-3-acetic acid (IAA) on filter paper bridges. Plantlets obtained from stored synseeds were hardened, established successfully ex vitro and were morphologically similar to each other as well as their mother plant. The genetic fidelity of Rauvolfia clones raised from synthetic seeds following four weeks of storage at 4 °C were assessed by using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. All the RAPD and ISSR profiles from generated plantlets were monomorphic and comparable to the mother plant, which confirms the genetic stability among the clones. This synseed protocol could be useful for establishing a particular system for conservation, short-term storage and production of genetically identical and stable plants before it is released for commercial purposes.

Sucrose Synthase Expression during Cold Acclimation in Wheat 1

PubMed Central

Crespi, Martin D.; Zabaleta, Eduardo J.; Pontis, Horacio G.; Salerno, Graciela L.

1991-01-01

When wheat (Triticum aestivum) seedlings are exposed to a cold temperature (2-4°C) above 0°C, sucrose accumulates and sucrose synthase activity increases. The effect of a cold period on the level of sucrose synthase (SS) was investigated. Using antibodies against wheat germ SS, Western blots studies showed that the amount of the SS peptide increased during 14 days in the cold, when plants were moved from 23°C to 4°C. The level of SS diminished when plants were moved back to 23°C. Northern blots of poly(A)+ RNA, confirmed a five- to sixfold induction of SS in wheat leaves during cold acclimation. These results indicate that SS is involved in the plant response to a chilling stress. ImagesFigure 1Figure 2Figure 3 PMID:16668270

Differentially regulated NADPH:cytochrome P450 oxidoreductases in parsley

PubMed Central

Koopmann, Edda; Hahlbrock, Klaus

1997-01-01

Two NADPH:cytochrome P450 oxidoreductases (CPRs) from parsley (Petroselinum crispum) were cloned, and the complete proteins were expressed and functionally identified in yeast. The two enzymes, designated CPR1 and CPR2, are 80% identical in amino acid sequence with one another and about 75% identical with CPRs from several other plant species. The mRNA accumulation patterns for CPR1 and CPR2 in fungal elicitor-treated or UV-irradiated cultured parsley cells and in developing or infected parsley plants were compared with those for cinnamate 4-hydroxylase (C4H), one of the most abundant CPR-dependent P450 enzymes in plants. All treatments strongly induced the mRNAs for C4H and CPR1 but not for CPR2, suggesting distinct metabolic roles of CPR1 and CPR2 and a functional relationship between CPR1 and C4H. PMID:9405720

Exposure to Fibres, Crystalline Silica, Silicon Carbide and Sulphur Dioxide in the Norwegian Silicon Carbide Industry

PubMed Central

Føreland, S.; Bye, E.; Bakke, B.; Eduard, W.

2008-01-01

Objectives: The aim of this study was to assess personal exposure to fibres, crystalline silica, silicon carbide (SiC) and sulphur dioxide in the Norwegian SiC industry. Methods: Approximately 720 fibre samples, 720 respirable dust samples and 1400 total dust samples were collected from randomly chosen workers from the furnace, processing and maintenance departments in all three Norwegian SiC plants. The respirable dust samples were analysed for quartz, cristobalite and non-fibrous SiC content. Approximately 240 sulphur dioxide samples were collected from workers in the furnace department. Results: The sorting operators from all plants, control room and cleaning operators in Plant A and charger, charger/mix and payloader operators in Plant C had a geometric mean (GM) of fibre exposure above the Norwegian occupational exposure limit (OEL) (0.1 fibre cm−3). The cleaner operators in Plant A had the highest GM exposure to respirable quartz (20 μg m−3). The charger/mix operators in Plant C had the highest GM exposure to respirable cristobalite (38 μg m−3) and the refinery crusher operators in Plant A had the highest GM exposure to non-fibrous SiC (0.65 mg m−3). Exposure to the crystalline silica and non-fibrous SiC was generally low and between 0.4 and 2.1% of the measurements exceeded the OELs. The cleaner operators in Plant A had the highest GM exposure to respirable dust (1.3 mg m−3) and total dust (21 mg m−3). GM exposures for respirable dust above the Norwegian SiC industry-specific OEL of 0.5 mg m−3 were also found for refinery crusher operators in all plants and mix, charger, charger/mix and sorting operators in Plant C. Only 4% of the total dust measurements exceeded the OEL for nuisance dust of (10 mg m−3). Exposure to sulphur dioxide was generally low. However, peaks in the range of 10–100 p.p.m. were observed for control room and crane operators in Plants A and B and for charger and charger/mix operators in Plant C. Conclusion: Workers in the SiC industry are exposed to a mixture of several agents including SiC fibres, quartz, cristobalite, non-fibrous SiC and sulphur dioxide. Exposure levels were generally below the current Norwegian OELs; however, high exposure to fibres and respirable dust still occurs in the furnace department. PMID:18550624

Plant and soil carbon accumulation following fire in Mediterranean woodlands in Spain.

PubMed

Kaye, Jason Philip; Romanyà, Joan; Vallejo, V Ramón

2010-10-01

We measured plant and soil carbon (C) storage following canopy-replacing wildfires in woodlands of northeastern Spain that include an understory of shrubs dominated by Quercus coccifera and an overstory of Pinus halepensis trees. Established plant succession models predict rapid shrub recovery in these ecosystems, and we build on this model by contrasting shrub succession with long-term C storage in soils, trees, and the whole ecosystem. We used chronosequence and repeated sampling approaches to detect change over time. Aboveground plant C increased from <100 to ~3,000 g C m(-2) over 30 years following fire, which is substantially less than the 5,942 ± 487 g C m(-2) (mean ±1 standard error) in unburned sites. As expected, shrubs accumulated C rapidly, but the capacity for C storage in shrubs was <600 g C m(-2). Pines were the largest plant C pool in sites >20 years post fire, and accounted for all of the difference in plant C between older burned sites and unburned sites. In contrast, soil C was initially higher in burned sites (~4,500 g C m(-2)) than in unburned sites (3,264 ± 261 g C m(-2)) but burned site C declined to unburned levels within 10 years after fire. Combining these results with prior research suggests two states for C storage. When pine regeneration is successful, ~9,200 g C m(-2) accumulate in woodlands but when tree regeneration fails (due to microclimatic stress or short fire return intervals), ecosystem C storage of ~4,000 g C m(-2) will occur in the resulting shrublands.

Re-evaluating the isotopic divide between angiosperms and gymnosperms using n-alkane δ13C values

NASA Astrophysics Data System (ADS)

Bush, R. T.; McInerney, F. A.

2009-12-01

Angiosperm δ13C values are typically 1-3‰ more negative than those of co-occurring gymnosperms. This is known for both bulk leaf and compound-specific values from n-alkanes, which are stable, straight-chain hydrocarbons (C23-C35) found in the epicuticular leaf wax of vascular plants. For n-alkanes, there is a second distinction between the δ13C values of angiosperms and gymnosperms—δ13C values generally decrease with increasing chain-length in angiosperms, while in gymnosperms they increase. These two distinctions have been used to support the ‘plant community change hypothesis’ explaining the difference between the terrestrial and marine carbon isotope excursions during the Paleocene-Eocene Thermal Maximum (PETM.) Preserved n-alkanes from terrestrial paleosols in the Bighorn Basin, Wyoming reveal a negative carbon isotope excursion during the PETM of 4-5‰, which is 1-2‰ greater than the excursion recorded by marine carbonates. The local plant community, known from macrofossils as well as palynoflora, shifted from a deciduous, mixed angiosperm/gymnosperm flora to a suite of evergreen angiosperm species during the PETM. At the end of the PETM, the community returned to a mixed deciduous flora very similar to the original. This change in the plant community could thus magnify the terrestrial negative carbon isotope excursion to the degree necessary to explain its divergence from the marine record. However, the comparison between modern angiosperms and gymnosperms has been made mostly between broadleaf, deciduous angiosperms and evergreen, coniferous gymnosperms. New data analyzing deciduous, coniferous gymnosperms, including Metasequoia glyptostroboides and Taxodium distichum, suggests that the division previously ascribed to taxonomy may actually be based on leaf habit and physiology, specifically broadleaf, deciduous versus needle-leaf, evergreen plants. If differences in n-alkane δ13C values can be described not as angiosperms versus gymnosperms, but as deciduous versus evergreen plants, then a re-examination of the PETM terrestrial carbon isotope excursion and its causes may be necessary.

The projected effect on insects, vertebrates, and plants of limiting global warming to 1.5°C rather than 2°C.

PubMed

Warren, R; Price, J; Graham, E; Forstenhaeusler, N; VanDerWal, J

2018-05-18

In the Paris Agreement on Climate Change, the United Nations is pursuing efforts to limit global warming to 1.5°C, whereas earlier aspirations focused on a 2°C limit. With current pledges, corresponding to ~3.2°C warming, climatically determined geographic range losses of >50% are projected in ~49% of insects, 44% of plants, and 26% of vertebrates. At 2°C, this falls to 18% of insects, 16% of plants, and 8% of vertebrates and at 1.5°C, to 6% of insects, 8% of plants, and 4% of vertebrates. When warming is limited to 1.5°C as compared with 2°C, numbers of species projected to lose >50% of their range are reduced by ~66% in insects and by ~50% in plants and vertebrates. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

A preliminary identification of Rf*-A619, a novel restorer gene for CMS-C in maize (Zea mays L.).

PubMed

Yongming, Liu; Zhuofan, Zhao; Yanli, Lu; Chuan, Li; Jing, Wang; Boxiao, Dong; Bing, Liang; Tao, Qiu; Wenbing, Zeng; Moju, Cao

2016-01-01

C-type cytoplasmic male sterility (CMS-C) is widely utilized for hybrid maize seed production. However, genetic mechanisms underlying the fertility restoration are very complicated. At present, there is a divergence on the number of fertility restorer genes in maize inbred line A619 for CMS-C. To further elucidate the restoring mechanism of A619, we used genetic analysis and molecular markers to confirm the restorer genes of maize inbred line A619 for C-type male sterile line C48-2 in this study. Firstly, the fertility segregations of (C48-2 × A619)F 2 populations were investigated under three environments during 2013-2015. The segregation ratio of fertile and sterile plants in the F 2 population fit to 15:1 via chi-square test and this result suggested that there are two dominant restorer genes in A619 for CMS-C, i.e., Rf4 and a novel gene named Rf*-A619 . Next, based on the sequence differences between Rf4 and its recessive allelic rf4 , a novel dominant marker F2/R2 was developed and validated to genotyping Rf4 in the F 2 population. Through genotypic analysis, we found that there were a certain amount of fertile individuals without Rf4 which accounted for 3/16 in the F 2 population via chi-square test at the 0.05 level. These results provided another proof to sustain that the inbred line A619 contains one additional restorer gene for CMS-C fertility restoration except Rf4 . At last, we used one SSR marker which is tightly linked with the dominant restorer gene Rf5 to analyze those fertile plants without Rf4 in the F 2 population. The PCR amplification results showed that Rf*-A619 is not allelic to Rf5 but a novel restorer gene for CMS-C. These results not only provide a basis for the mapping and characterization of a novel restorer gene but also give a new insight into the mechanism of CMS-C fertility restoration.

Legacy effects of drought on plant growth and the soil food web.

PubMed

de Vries, Franciska Trijntje; Liiri, Mira E; Bjørnlund, Lisa; Setälä, Heikki M; Christensen, Søren; Bardgett, Richard D

2012-11-01

Soils deliver important ecosystem services, such as nutrient provision for plants and the storage of carbon (C) and nitrogen (N), which are greatly impacted by drought. Both plants and soil biota affect soil C and N availability, which might in turn affect their response to drought, offering the potential to feed back on each other's performance. In a greenhouse experiment, we compared legacy effects of repeated drought on plant growth and the soil food web in two contrasting land-use systems: extensively managed grassland, rich in C and with a fungal-based food web, and intensively managed wheat lower in C and with a bacterial-based food web. Moreover, we assessed the effect of plant presence on the recovery of the soil food web after drought. Drought legacy effects increased plant growth in both systems, and a plant strongly reduced N leaching. Fungi, bacteria, and their predators were more resilient after drought in the grassland soil than in the wheat soil. The presence of a plant strongly affected the composition of the soil food web, and alleviated the effects of drought for most trophic groups, regardless of the system. This effect was stronger for the bottom trophic levels, whose resilience was positively correlated to soil available C. Our results show that plant belowground inputs have the potential to affect the recovery of belowground communities after drought, with implications for the functions they perform, such as C and N cycling.

Remotely-sensed phenologies of C3 and C4 grasses in Hawaii using MODIS Vegetation Indices

NASA Astrophysics Data System (ADS)

Pau, S.; Still, C. J.

2010-12-01

The C3 and C4 photosynthetic pathway is a fundamental physiological and ecological distinction in tropical and subtropical savannas and grasslands. Although C4 plants account for 20-25% of global terrestrial productivity, large uncertainties remain regarding their response to climate variability and future climate change. Recent work has shown that key differences in the ecology of C3 and C4 grasses may have been pre-adaptations to environments prior to the evolution of the C4 grasses and not attributable to photosynthetic pathway. The Hawaiian Islands are ideal for studying C3 and C4 grass plant functional types (PFTs) because of the combination of broad climatic gradients within a small geographic area. This study uses MODIS NDVI and EVI time-series data to examine the phenologies of C3 and C4 grasses in a phylogenetic context. Specifically we address 3 primary questions: (1) Do C3 and C4 sister taxa, and C4 subtypes exhibit distinct timing in phenological metrics (onset of greening, onset of senescence, maximum and minimum greenness, length of growing season)? (2) How does the interannual variation in these phenological metrics correlate with interannual variations in climate such as precipitation, air temperature, land surface temperature, and sea surface temperature? (3) How does the length of the growing season translate into differences in productivity?

Effects of arbuscular mycorrhizal colonization and phosphorus application on nuclear ploidy in Allium porrum plants.

PubMed

Fusconi, Anna; Lingua, Guido; Trotta, Antonio; Berta, Graziella

2005-07-01

Arbuscular mycorrhizal (AM) colonization can strongly affect the plant cell nucleus, causing displacement from the periphery to the center of the cell, hypertrophy and polyploidization. The hypertrophy response has been shown in a variety of AM plants whilst polyploidization has been reported only in Lycopersicon esculentum, a multiploid species with a small genome. In order to determine whether polyploidization is a general plant response to AM colonization, analyses were performed on Allium porrum, a plant with a large genome, which is much less subject to polyploidization than L. esculentum. The ploidy status of leaves, complete root systems and four zones of the adventitious roots was investigated in relation to phosphorus content, AM colonization and root differentiation in A. porrum plants grown under two different regimes of phosphate nutrition in order to distinguish direct effects of the fungus from those of improved nutrition. Results showed the presence of two nuclear populations (2C and 4C) in all treatments and samples. Linear regression analyses suggested a general negative correlation between phosphorus content and the proportion of 2C nuclei. The percentage of 2C nuclei (and consequently that of 4C nuclei), was also influenced by AM colonization, differentiation and ageing of the root cells, which resulted in earlier occurrence, in time and space, of polyploid nuclei.

Cadmium accumulation is enhanced by ammonium compared to nitrate in two hyperaccumulators, without affecting speciation

PubMed Central

Cheng, Miaomiao; Wang, Peng; Kopittke, Peter M.; Wang, Anan; Sale, Peter W.G.

2016-01-01

Nitrogen fertilization could improve the efficiency of Cd phytoextraction in contaminated soil and thus shorten the remediation time. However, limited information is available on the effect of N form on Cd phytoextraction and associated mechanisms in plants. This study examined the effect of N form on Cd accumulation, translocation, and speciation in Carpobrotus rossii and Solanum nigrum. Plants were grown in nutrient solution with 5–15 μM Cd in the presence of 1000 µM NH4 + or NO3 −. Plant growth and Cd uptake were measured, and Cd speciation was analyzed using synchrotron-based X-ray absorption spectroscopy. Shoot Cd accumulation was 30% greater with NH4 + than NO3 − supply. Carpobrotus rossii accumulated three times more Cd than S. nigrum. However, Cd speciation in the plants was not influenced by N form, but it did vary with species and tissues. In C. rossii, up to 91% of Cd was bound to S-containing ligands in all tissues except the xylem sap where 87–95% were Cd-OH complexes. Furthermore, the proportion of Cd-S in shoots was substantially lower in S. nigrum (44–69%) than in C. rossii (60–91%). It is concluded that the application of NH4 + (instead of NO3 −) increased shoot Cd accumulation by increasing uptake and translocation, rather than changing Cd speciation, and is potentially an effective approach for increasing Cd phytoextraction. PMID:27385767

Metabolic Reconstruction of Setaria italica: A Systems Biology Approach for Integrating Tissue-Specific Omics and Pathway Analysis of Bioenergy Grasses.

PubMed

de Oliveira Dal'Molin, Cristiana G; Orellana, Camila; Gebbie, Leigh; Steen, Jennifer; Hodson, Mark P; Chrysanthopoulos, Panagiotis; Plan, Manuel R; McQualter, Richard; Palfreyman, Robin W; Nielsen, Lars K

2016-01-01

The urgent need for major gains in industrial crops productivity and in biofuel production from bioenergy grasses have reinforced attention on understanding C4 photosynthesis. Systems biology studies of C4 model plants may reveal important features of C4 metabolism. Here we chose foxtail millet (Setaria italica), as a C4 model plant and developed protocols to perform systems biology studies. As part of the systems approach, we have developed and used a genome-scale metabolic reconstruction in combination with the use of multi-omics technologies to gain more insights into the metabolism of S. italica. mRNA, protein, and metabolite abundances, were measured in mature and immature stem/leaf phytomers, and the multi-omics data were integrated into the metabolic reconstruction framework to capture key metabolic features in different developmental stages of the plant. RNA-Seq reads were mapped to the S. italica resulting for 83% coverage of the protein coding genes of S. italica. Besides revealing similarities and differences in central metabolism of mature and immature tissues, transcriptome analysis indicates significant gene expression of two malic enzyme isoforms (NADP- ME and NAD-ME). Although much greater expression levels of NADP-ME genes are observed and confirmed by the correspondent protein abundances in the samples, the expression of multiple genes combined to the significant abundance of metabolites that participates in C4 metabolism of NAD-ME and NADP-ME subtypes suggest that S. italica may use mixed decarboxylation modes of C4 photosynthetic pathways under different plant developmental stages. The overall analysis also indicates different levels of regulation in mature and immature tissues in carbon fixation, glycolysis, TCA cycle, amino acids, fatty acids, lignin, and cellulose syntheses. Altogether, the multi-omics analysis reveals different biological entities and their interrelation and regulation over plant development. With this study, we demonstrated that this systems approach is powerful enough to complement the functional metabolic annotation of bioenergy grasses.

Metabolic Reconstruction of Setaria italica: A Systems Biology Approach for Integrating Tissue-Specific Omics and Pathway Analysis of Bioenergy Grasses

PubMed Central

de Oliveira Dal'Molin, Cristiana G.; Orellana, Camila; Gebbie, Leigh; Steen, Jennifer; Hodson, Mark P.; Chrysanthopoulos, Panagiotis; Plan, Manuel R.; McQualter, Richard; Palfreyman, Robin W.; Nielsen, Lars K.

2016-01-01

The urgent need for major gains in industrial crops productivity and in biofuel production from bioenergy grasses have reinforced attention on understanding C4 photosynthesis. Systems biology studies of C4 model plants may reveal important features of C4 metabolism. Here we chose foxtail millet (Setaria italica), as a C4 model plant and developed protocols to perform systems biology studies. As part of the systems approach, we have developed and used a genome-scale metabolic reconstruction in combination with the use of multi-omics technologies to gain more insights into the metabolism of S. italica. mRNA, protein, and metabolite abundances, were measured in mature and immature stem/leaf phytomers, and the multi-omics data were integrated into the metabolic reconstruction framework to capture key metabolic features in different developmental stages of the plant. RNA-Seq reads were mapped to the S. italica resulting for 83% coverage of the protein coding genes of S. italica. Besides revealing similarities and differences in central metabolism of mature and immature tissues, transcriptome analysis indicates significant gene expression of two malic enzyme isoforms (NADP- ME and NAD-ME). Although much greater expression levels of NADP-ME genes are observed and confirmed by the correspondent protein abundances in the samples, the expression of multiple genes combined to the significant abundance of metabolites that participates in C4 metabolism of NAD-ME and NADP-ME subtypes suggest that S. italica may use mixed decarboxylation modes of C4 photosynthetic pathways under different plant developmental stages. The overall analysis also indicates different levels of regulation in mature and immature tissues in carbon fixation, glycolysis, TCA cycle, amino acids, fatty acids, lignin, and cellulose syntheses. Altogether, the multi-omics analysis reveals different biological entities and their interrelation and regulation over plant development. With this study, we demonstrated that this systems approach is powerful enough to complement the functional metabolic annotation of bioenergy grasses. PMID:27559337

Colour and spreadability of Neem (Azadirachta Indica A. juss) ointment and cream formulations

NASA Astrophysics Data System (ADS)

Zawiyyah, Azierah; Shamsul Anuar, Mohd

2018-04-01

Herbal plants are a major source of raw material for traditional medicines. Recently there has been an increase of interest to study the therapeutic potential of herbal plants as herbal care products. In this study, a preliminary study on the formulation of neem (Azadirachta Indica) ointment and cream have been conducted. The neem leaves were extracted and formulated into ointment and cream. The raw neem extract is added into the ointment and cream bases at four different concentrations (0% w/w, 0.5% w/w, 1% w/w and 2% w/w) and stored at three different storage temperatures (4°C, 25°C and 45°C). The semambu ointment and cream formulated were evaluated in terms of their colour and spreadability. It has been found that the extract content and storage temperature influence the colour and spreadability of the formulated neem ointment and cream.

Halomonas alkalicola sp. nov., isolated from a household product plant.

PubMed

Tang, Xiaoli; Zhai, Lei; Lin, Yafang; Yao, Su; Wang, Lijiang; Ge, Yuanyuan; Liu, Yang; Zhang, Xin; Zhang, Tianci; Zhang, Lu; Liu, Jiquan; Cheng, Chi

2017-05-01

A Gram-stain-negative, alkaliphilic and moderately halophilic bacterium, designated 56-L4-10aEnT, was isolated from a household product plant in China. Cells of the novel isolate were rod-shaped, non-spore-forming and non-motile. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 56-L4-10aEnT belongs to the genus Halomonas, with the six closest neighbours being Halomonas mongoliensis Z-7009T (97.59 % 16S rRNA gene sequence similarity), Halomonas ventosae Al12T (97.35 %), Halomonas campaniensis 5AGT (97.22 %), Halomonas alimentaria YKJ-16T (97.22 %), Halomonas shengliensis SL014B-85T (97.12 %) and Halomonas fontilapidosi 5CRT (97.09 %). The main polar lipids of strain 56-L4-10aEnT contained diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The predominant respiratory quinone was Q-9, with Q-8 as a minor component. The major fatty acids were C18 : 1ω7c/C18 : 1ω6c and C16 : 0. Strain 56-L4-10aEnT was clearly distinguished from the type strains mentioned above through phylogenetic analysis, DNA-DNA hybridization, fatty acid composition data and a range of physiological and biochemical characteristics comparisons. It is evident from the genotypic and phenotypic data that strain 56-L4-10aEnTcould be classified as a representative of a novel species of the genus Halomonas, for which the name Halomonas alkalicola sp. nov. is proposed. The type strain is 56-L4-10aEnT (=CICC 11012sT=DSM 103354T).

Molecular cloning and functional expression of Lewis type α1,3/α1,4-fucosyltransferase cDNAs from Mangifera indica L.

PubMed

Okada, Takahiro; Ihara, Hideyuki; Ito, Ritsu; Ikeda, Yoshitaka

2017-12-01

In higher plants, complex type N-glycans contain characteristic carbohydrate moieties that are not found in mammals. In particular, the attachment of the Lewis a (Le a ) epitope is currently the only known outer chain elongation that is present in plant N-glycans. Such a modification is of great interest in terms of the biological function of complex type N-glycans in plant species. However, little is known regarding the exact molecular basis underlying their Le a expression. In the present study, we cloned two novel Lewis type fucosyltransferases (MiFUT13) from mango fruit, Mangifera indica L., heterologously expressed the proteins and structurally and functionally characterized them. Using an HPLC-based assay, we demonstrated that the recombinant MiFUT13 proteins mediate the α1,4-fucosylation of acceptor tetrasaccharides with a strict preference for type I-based structure to type II. The results and other findings suggest that MiFUT13s are involved in the biosynthesis of Le a containing glycoconjugates in mango fruits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elimination of Redwater Formation from TNT Manufacture

DTIC Science & Technology

2007-12-21

I TNT) or 80.4oC for Type II [11]. Further studies made after 1980 where novel reagents and modified techniques were employed are now summarized...compound, based on the oxidation of N2O4 using ozone [71-73], or electrolytic methods [74-76]. QinetiQ has also addressed aspects of the economics of...that can be utilized in the design of pilot plant and as a screening technique for suitability of continuous processing. The initial experiment was

Changes of Soil Aggregate C Isotopes in No-Till Corn Following Bromegrass.

NASA Astrophysics Data System (ADS)

Follett, R. F.; Varvel, G.; Vogel, K. P.

2007-12-01

This field study is near Ithaca, Nebraska, USA (lat. 41.151, long. 96.401) on a Filbert silt loam (fine, smectitic, mesic Vertic Argialboll). The site was in bromegrass since 1986. Corn was no-till seeded into the bromegrass sod in spring 1999. A randomized complete block design with three replicates was used. No-till corn was the main treatment with nitrogen (N) as subplots. N was broadcast at the start of each growing season at 60 or 120 kg N/ha as NH4NO3. Total biomass was measured by weighing 4.4 m of row in each plot. Soil samples were obtained in May 1999 (baseline sampling), Sept 1999, June 2000, Oct 2000, Sept 2001, Nov 2002, Sept 2003, and Oct 2005 from pre-selected areas by removal of plant material from the soil surface and removing the 0-5, 5- 10, and at 4 of the 8 harvests also sampling the 10-30 cm depths with a flat-bladed shovel. Soil bulk densities were determined on clods from each layer. The moist soil was passed through an 8 mm sieve before air drying and storing. Aggregate size fractions were obtained with a Yoder wet-aggregate method. Soil size fractions obtained were > 2, 1, 0.5, 0.25, 0.125, 0.045 and < 0.045 mm. Detritus was floated to the surface and skimmed off for transfer to a separate container. Aggregates were dried at 55°C, weighed, ground, and analyzed for total C and N and 13C:12C isotope ratio. Because soil organic carbon (SOC) was labeled with the bromegrass (C3 plant) isotope signature, then during the 77 months of this experiment the re-labeling of each fraction and the total SOC with the corn (C4 plant) isotope signature and the amounts of SOC lost from aggregate size fractions with conversion of the bromegrass sod to no-till corn was measured. During 6.5 years, total SOC decreased from 21.1, 17.0, and 55.8 t/ha in the 0-5, 5-10, and 10-30 cm depths to 20.1, 16.7, and 55.5 t/ha, respectively. However the SOC in the < 2, 0.5-2, and < 0.5 mm fractions of the 0 - 5 cm depth changed from 62, 21, and 16 % of the total SOC at the studies beginning to 31, 40, and 29 %, respectively, by the end of 77 months. Weight of SOC from C4 plants was 34.8, 49.8, and 73.2 % of total SOC in the 0-5, 5-10, and 0-30 cm depths, respectively at the beginning of the study, but after 77 months of no-till corn was 47.3, 59.0, and 71.8 % of total SOC for these same depths. In summary, it is important to evaluate losses or gains of SOC under cultivation. Use of the 13C:12C ratios, as influenced by reversing the growing sequence of C3 vs. C4 plants, allows losses of older SOC from C3 plants (bromegrass) vs. that added by growing C4 plants (corn) to be determined over time and allows rates of change of the SOC associated with various soil fractions to be evaluated.

Terrestrial biomarker records in Seomjin Estuary in the South Sea of Korea: Implication for terrestrial flux and environmental changes

NASA Astrophysics Data System (ADS)

kim, Songyi; hyun, Sangmin; Kim, Wonnyon; Hyeong, Kiseong

2016-04-01

High-resolution records of terrestrial biomarkers, n-alkane compounds, were investigated in two gravity cores (SJP-2 and SJP-4) to evaluate variations in terrestrial organic matter influx. Based on 14C dating, sediments in both cores were deposited during the mid-Holocene; the ages of the bottom sediments of SJP-2 and SJP-4 reached 5,500 Cal yr BP and 5,000 Cal yr BP, respectively. High concentrations of total n-alkanes (nC25-35) in the two cores showed an increasing tendency from 4,500 yr to ca. 2,000 yr. The composition changed at the boundary of 2,500 yr in both cores, suggesting a variation in terrestrial biomarker influx at this time. Several indices including average chain length (ACL), carbon preference index (ICP), and paleo-vegetation index (Paq) showed coincident variations in both cores; ACL exhibited a narrow range of variations with a slight shift at 2,500 yr, CPI showed a decreasing tendency from 4,000 yr to 2,500 yr, and Paq increased during these intervals. Furthermore, the ratios of C23/C31 and C25/C31, indicate a relative abundance of epicuticular wax from vascular plants with coincident variations in both cores, and this also marched well with Paq. CPI excursions suggested that the total n-alkane proxy of the two cores might not only be linked to local climatic variability but also to local oceanographic conditions due to the different sedimentation rates. Variations in paleovegetation and paleoclimate around the study area might be strongly associated with the influx of terrestrial organic compounds derived from vascular plants. Additional 14C dating and isotope study of individual n-alkane biomarkers will provide detailed information on paleoclimatic and paleovegetation changes.

Multiscale Metabolic Modeling of C4 Plants: Connecting Nonlinear Genome-Scale Models to Leaf-Scale Metabolism in Developing Maize Leaves

PubMed Central

Bogart, Eli; Myers, Christopher R.

2016-01-01

C4 plants, such as maize, concentrate carbon dioxide in a specialized compartment surrounding the veins of their leaves to improve the efficiency of carbon dioxide assimilation. Nonlinear relationships between carbon dioxide and oxygen levels and reaction rates are key to their physiology but cannot be handled with standard techniques of constraint-based metabolic modeling. We demonstrate that incorporating these relationships as constraints on reaction rates and solving the resulting nonlinear optimization problem yields realistic predictions of the response of C4 systems to environmental and biochemical perturbations. Using a new genome-scale reconstruction of maize metabolism, we build an 18000-reaction, nonlinearly constrained model describing mesophyll and bundle sheath cells in 15 segments of the developing maize leaf, interacting via metabolite exchange, and use RNA-seq and enzyme activity measurements to predict spatial variation in metabolic state by a novel method that optimizes correlation between fluxes and expression data. Though such correlations are known to be weak in general, we suggest that developmental gradients may be particularly suited to the inference of metabolic fluxes from expression data, and we demonstrate that our method predicts fluxes that achieve high correlation with the data, successfully capture the experimentally observed base-to-tip transition between carbon-importing tissue and carbon-exporting tissue, and include a nonzero growth rate, in contrast to prior results from similar methods in other systems. PMID:26990967

Cowpeas and pinto beans: Performance and yields of candidate space crops in the laboratory biosphere closed ecological system

NASA Astrophysics Data System (ADS)

Nelson, M.; Dempster, W. F.; Allen, J. P.; Silverstone, S.; Alling, A.; van Thillo, M.

An experiment utilizing cowpeas ( Vigna unguiculata L.), pinto beans ( Phaseolus vulgaris L.) and Apogee ultra-dwarf wheat ( Triticum sativa L.) was conducted in the soil-based closed ecological facility, Laboratory Biosphere, from February to May 2005. The lighting regime was 13 h light/11 h dark at a light intensity of 960 μmol m -2 s -1, 45 mol m -2 day -1 supplied by high-pressure sodium lamps. The pinto beans and cowpeas were grown at two different planting densities. Pinto bean production was 341.5 g dry seed m -2 (5.42 g m -2 day -1) and 579.5 dry seed m -2 (9.20 g m -2 day -1) at planted densities of 32.5 plants m -2 and 37.5 plants m -2, respectively. Cowpea yielded 187.9 g dry seed m -2 (2.21 g m -2 day -1) and 348.8 dry seed m -2 (4.10 g m -2 day -1) at planted densities of 20.8 plants m -2 and 27.7 plants m -2, respectively. The crop was grown at elevated atmospheric carbon dioxide levels, with levels ranging from 300-3000 ppm daily during the majority of the crop cycle. During early stages (first 10 days) of the crop, CO 2 was allowed to rise to 7860 ppm while soil respiration dominated, and then was brought down by plant photosynthesis. CO 2 was injected 27 times during days 29-71 to replenish CO 2 used by the crop during photosynthesis. Temperature regime was 24-28 °C day/deg 20-24 °C night. Pinto bean matured and was harvested 20 days earlier than is typical for this variety, while the cowpea, which had trouble establishing, took 25 days more for harvest than typical for this variety. Productivity and atmospheric dynamic results of these studies contribute toward the design of an envisioned ground-based test bed prototype Mars base.

Structural characterization and identification of biflavones in Selaginella tamariscina by liquid chromatography-diode-array detection/electrospray ionization tandem mass spectrometry.

PubMed

Zhang, Yi-Xuan; Li, Qiu-Yue; Yan, Li-Li; Shi, Yue

2011-08-15

Biflavonoids, a special class of flavonoids, are widely distributed in gymnosperm plants and have various biological activities. They are also major bioactive ingredients in Selaginella tamariscina. In this work, we report the use of high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) to study the fragmentation behavior of three main types of biflavonoids using seven biflavonoid reference compounds and analyze the biflavonoids in Selaginella tamariscina. The most useful fragmentations in terms of structural identification are those involving the C-ring cleavage of biflavonoids. For amentoflavone-type biflavonoids (containing flavonoid parts I and II), fragmentation on the flavonoid part II at positions 1/3 and 0/4 are the primary pathways, whereas the chances are greater for C-ring cleavage fragmentation occurring on flavonoid part I at positions 1/3 and 1/4 for robustaflavone-type biflavonoids. However, the predominant diagnostic ions of the specific C-O-C-connected hinokiflavone-type biflavonoids are a series of ions resulting from the rupture of the connective C-O bond. Based on the fragmentation patterns of these reference compounds, 17 biflavonoids were identified in an extract of Selaginella tamariscina, three of which have not been previously reported as constituents of this plant. This study provides a powerful approach for the online structural elucidation and identification of different types of biflavonoids and positional isomers from Selaginella tamariscina and other biflavonoids distributed in related plants and prescriptions. Copyright © 2011 John Wiley & Sons, Ltd.

Auxin-induced nitric oxide, cGMP and gibberellins were involved in the gravitropism

NASA Astrophysics Data System (ADS)

Cai, Weiming; Hu, Liwei; Hu, Xiangyang; Cui, Dayong; Cai, Weiming

Gravitropism is the asymmetric growth or curvature of plant organs in response to gravistimulation. There is a complex signal transduction cascade which involved in the differential growth of plants in response to changes in the gravity vector. The role of auxin in gravitropism has been demonstrated by many experiments, but little is known regarding the molecular details of such effects. In our studies before, mediation of the gravitropic bending of soybean roots and rice leaf sheath bases by nitric oxide, cGMP and gibberellins, are induced by auxin. The asymmetrical distribution of nitric oxide, cGMP and gibberellins resulted from the asymmetrical synthesis of them in bending sites. In soybean roots, inhibitions of NO and cGMP synthesis reduced differential NO and cGMP accumulation respectively, which both of these effects can lead to the reduction of gravitropic bending. Gibberellin-induced OsXET, OsEXPA4 and OsRWC3 were also found involved in the gravitropic bending. These data indicated that auxin-induced nitric oxide, cGMP and gibberellins were involved in the gravitropism. More experiments need to prove the more detailed mechanism of them.

Sugarcane White Leaf Disease Incidences and Population Dynamic of Leafhopper Insect Vectors in Sugarcane Plantations in Northeast Thailand.

PubMed

Rattanabunta, Chiranan; Hanboonsong, Yupa

2015-04-01

The work consisted of two experiments, i.e. Experiment 1 was conducted under controlled environments where sugarcane plants were used as hosts. This investigation aimed to monitor the occurrence of the Sugarcane White Leaf disease and the abundance of Leafhopper insect vectors and also the work aimed to provide useful information in understanding some aspects on epidemiology of the Sugarcane White Leaf disease. A Completely Randomized Design with three replications was used to justify growth and development of Leafhopper insects as affected by different temperatures: 20 (T1), 25 (T2), 30 (T3) and 35 degrees C (T4). Experiment 2 was carried out to determine the numbers of Leafhopper insects with the use of light traps in the sugarcane Field 1 (ratoon plants), Field 2 (newly planted), Field 3 (newly planted) and Field 4 (ratoon plants). The results of Experiment 1 showed that growth and development of Leafhopper insects were highly affected by temperatures i.e. the higher the environmental temperature the faster the growth and development of the insects to reach its full adulthood. At 20 degrees C, Leafhopper insects took 12 days to lay eggs whereas at 25 degrees C the insects took only 6 days. Male reached its adulthood approximately 9 days earlier than female when cultured at 25 degrees C and became approximately one week at 30 degrees C or higher. The results of Experiment 2 showed that the majority of Leafhopper insects were found within the months of June and July for both newly planted and ratoon crops. A small amount was found in May and August with an exceptional case of Field 4 where the highest number of Leafhopper insects was found in April followed by June and July. For Sugarcane White Leaf disease, the disease was found in all months of the year except February for Fields 2 and 3. Newly planted sugarcane plants attained much smaller percentages of disease than those of the ratoon plants.

Tomato SlERF.A1, SlERF.B4, SlERF.C3 and SlERF.A3, Members of B3 Group of ERF Family, Are Required for Resistance to Botrytis cinerea

PubMed Central

Ouyang, Zhigang; Liu, Shixia; Huang, Lihong; Hong, Yongbo; Li, Xiaohui; Huang, Lei; Zhang, Yafen; Zhang, Huijuan; Li, Dayong; Song, Fengming

2016-01-01

The Ethylene-Responsive Factors (ERFs) comprise a large family of transcriptional factors that play critical roles in plant immunity. Gray mold disease caused by Botrytis cinerea, a typical necrotrophic fungal pathogen, is the serious disease that threatens tomato production worldwide. However, littler is known about the molecular mechanism regulating the immunity to B. cinerea in tomato. In the present study, virus-induced gene silencing (VIGS)-based functional analyses of 18 members of B3 group (also called Group IX) in tomato ERF family were performed to identify putative ERFs that are involved in disease resistance against B. cinerea. VIGS-based silencing of either SlERF.B1 or SlERF.C2 had lethal effect while silencing of SlERF.A3 (Pit4) significantly suppressed vegetative growth of tomato plants. Importantly, silencing of SlERF.A1, SlERF.A3, SlERF.B4, or SlERF.C3 resulted in increased susceptibility to B. cinerea, attenuated the B. cinerea-induced expression of jasmonic acid/ethylene-mediated signaling responsive defense genes and promoted the B. cinerea-induced H2O2 accumulation. However, silencing of SlERF.A3 also decreased the resistance against Pseudomonas syringae pv. tomato (Pst) DC3000 but silencing of SlERF.A1, SlERF.B4 or SlERF.C3 did not affect the resistance to this bacterial pathogen. Expression of SlERF.A1, SlERF.A3, SlERF.B4, or SlERF.C3 was induced by B. cinerea and by defense signaling hormones such as salicylic acid, methyl jasmonate, and 1-aminocyclopropane-1-carboxylic acid (an ethylene precursor). SlERF.A1, SlERF.B4, SlERF.C3, and SlERF.A3 proteins were found to localize in nucleus of cells and possess transactivation activity in yeasts. These data suggest that SlERF.A1, SlERF.B4, and SlERF.C3, three previously uncharacterized ERFs in B3 group, and SlERF.A3, a previously identified ERF with function in immunity to Pst DC3000, play important roles in resistance against B. cinerea in tomato. PMID:28083004

Sensitivity of wheat and rice to low levels of atmospheric ethylene

NASA Technical Reports Server (NTRS)

Klassen, Stephen P.; Bugbee, Bruce

2002-01-01

Ethylene (C2H4) gas is produced throughout the life cycle of plants and can accumulate in closed growth chambers to levels 100 times higher than in outside environments. Elevated atmospheric C2H4 can cause a variety of abnormal responses, but the sensitivity to elevated C2H4 is not well characterized. We evaluated the C2H4 sensitivity of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) in five studies. The first three studies compared the effects of continuous C2H4 levels ranging from 0 to 1000 nmol mol-1 (ppb) in a growth chamber throughout the life cycle of the plants. A short-term 1000 nmol mol-1 treatment was included in which exposure was stopped at anthesis. Yield was reduced by 36% in wheat and 63% in rice at 50 nmol mol-1 and both species were virtually sterile when continuously exposed to 1000 nmol mol-1. However, the yield reductions were much less with exposure that stopped at anthesis, suggesting the detrimental effect of C2H4 on yield was greatest around the time of seed set. Two additional studies evaluated the differential sensitivity of two wheat cultivars (Super Dwarf and USU-Apogee) to 50 nmol mol-1 C2H4 at three CO2 levels [350, 1200, 5000 micromoles mol-1 (ppm)] in a greenhouse. Yield of USU-Apogee was not significantly reduced by C2H4 but the yield of Super Dwarf was reduced by 60%. Elevated CO2 did not influence the sensitivity to C2H4. A difference in the C2H4 sensitivity of USU-Apogee between greenhouse and growth chamber trials suggests that C2H4 sensitivity is dependent on the environment. Collectively, the data suggest that relatively low levels of C2H4 could induce anomalous plant responses by accumulation in greenhouses and growth chambers with inadequate ventilation. The data also suggest that C2H4 sensitivity can be reduced by both genetic and environmental manipulations. 2002 Crop Science Society of America.

Towards efficient photosynthesis: overexpression of Zea mays phosphoenolpyruvate carboxylase in Arabidopsis thaliana.

PubMed

Kandoi, Deepika; Mohanty, Sasmita; Govindjee; Tripathy, Baishnab C

2016-12-01

Plants with C4 photosynthesis are efficient in carbon assimilation and have an advantage over C3 photosynthesis. In C4 photosynthesis, the primary CO 2 fixation is catalyzed by phosphoenolpyruvate carboxylase (PEPC). Here, we show that overexpression of Zea mays PEPC cDNA, under the control of 35 S promoter, in Arabidopsis thaliana resulted in ~7-10 fold higher protein abundance and ~7-10 fold increase in PEPC activity in the transgenic lines than that in the vector control. We suggest that overexpression of PEPC played an anaplerotic role to increase the supply of 4-carbon carboxylic acids, which provided carbon skeletons for increased amino acid and protein synthesis. Higher protein content must have been responsible for increased metabolic processes including chlorophyll biosynthesis, photosynthesis, and respiration. Consequently, the PEPC-overexpressed transgenic plants had higher chlorophyll content, enhanced electron transport rate (ETR), lower non-photochemical quenching (NPQ) of chlorophyll a fluorescence, and a higher performance index (PI) than the vector control. Consistent with these observations, the rate of CO 2 assimilation, the starch content, and the dry weight of PEPC-overexpressed plants increased by 14-18 %, 10-18 %, and 6.5-16 %, respectively. Significantly, transgenics were tolerant to salt stress as they had increased ability to synthesize amino acids, including the osmolyte proline. NaCl (150 mM)-treated transgenic plants had higher variable to maximum Chl a fluorescence (F v /F m ) ratio, higher PI, higher ETR, and lower NPQ than the salt-treated vector controls. These results suggest that expression of C4 photosynthesis enzyme(s) in a C3 plant can improve its photosynthetic capacity with enhanced tolerance to salinity stress.

Methane transport mechanisms and isotopic fractionation in emergent macrophytes of an Alaskan tundra lake

NASA Technical Reports Server (NTRS)

Chanton, Jeffrey P.; Martens, Christopher S.; Kelley, Cheryl A.; Crill, Patrick M.; Showers, William J.

1992-01-01

The stable carbon isotopic composition of methane associated with and emitted by the two dominant emergent macrophytes abundant in the many Alaskan tundra lakes, Carex rostrata and Arctophila fulva, is determined. The carbon isotopic composition of the methane was -58.6 +/- 0.5 (n=2) for Arctophila and -66.6 +/- 2.5 (n=6) for Carex. The methane emitted by these species is depleted in C-13 by 12 per mil for Arctophila and 18 per mil for Carex relative to methane withdrawn from plant stems 1-2 cm below the waterline. The results suggest more rapid transport of (C-12)H4 relative to (C-13)H4 through plants to the atmosphere. Plant stem methane concentrations ranged from 0.2 to 4.0 percent in Arctophila, with an isotopic composition of -46.1 +/- 4.3 percent (n=8). Carex stem methane concentrations ranged from 150 to 1200 ppm, with an isotopic composition of -48.3 +/- 1.4 per mil (n=3).

Arabidopsis ERG28 Tethers the Sterol C4-Demethylation Complex to Prevent Accumulation of a Biosynthetic Intermediate That Interferes with Polar Auxin Transport[C][W

PubMed Central

Mialoundama, Alexis Samba; Jadid, Nurul; Brunel, Julien; Di Pascoli, Thomas; Heintz, Dimitri; Erhardt, Mathieu; Mutterer, Jérôme; Bergdoll, Marc; Ayoub, Daniel; Van Dorsselaer, Alain; Rahier, Alain; Nkeng, Paul; Geoffroy, Philippe; Miesch, Michel; Camara, Bilal; Bouvier, Florence

2013-01-01

Sterols are vital for cellular functions and eukaryotic development because of their essential role as membrane constituents. Sterol biosynthetic intermediates (SBIs) represent a potential reservoir of signaling molecules in mammals and fungi, but little is known about their functions in plants. SBIs are derived from the sterol C4-demethylation enzyme complex that is tethered to the membrane by Ergosterol biosynthetic protein28 (ERG28). Here, using nonlethal loss-of-function strategies focused on Arabidopsis thaliana ERG28, we found that the previously undetected SBI 4-carboxy-4-methyl-24-methylenecycloartanol (CMMC) inhibits polar auxin transport (PAT), a key mechanism by which the phytohormone auxin regulates several aspects of plant growth, including development and responses to environmental factors. The induced accumulation of CMMC in Arabidopsis erg28 plants was associated with diagnostic hallmarks of altered PAT, including the differentiation of pin-like inflorescence, loss of apical dominance, leaf fusion, and reduced root growth. PAT inhibition by CMMC occurs in a brassinosteroid-independent manner. The data presented show that ERG28 is required for PAT in plants. Furthermore, it is accumulation of an atypical SBI that may act to negatively regulate PAT in plants. Hence, the sterol pathway offers further prospects for mining new target molecules that could regulate plant development. PMID:24326590

Aliphatic hydrocarbons recovered in vegetables from soils based on their in-situ distribution in various soil humus fractions using a successive extraction method.

PubMed

Zhang, Juan; Fan, Shu-Kai; Zhang, Ming-Hua; Grieneisen, Michael L; Zhang, Jian-Feng

2018-03-15

Aliphatic hydrocarbons (AHs) are major petroleum contaminants in the environment. In this study, the AHs bound to various soil endogenetic humus fractions were separated through successive extraction. Most of the AHs (46.1%) in soils were adsorbed onto/into humic acids (HA) and a small quantity of AHs (9.6%) were organic solvent extractable. AHs in B. chinensis were also analyzed since their potential risks to the residents through ingestion. AHs from C 21 to C 34 , so called high molecular weight AHs (HMWAHs), were dominant AHs in B. chinensis (85.5%) and soils (70.4%), followed by AHs from C 16 to C 21, whose mobility can be enhanced via binding to fulvic acids and then can be taken up by plant root lipids (soil-plant pathway). HMWAHs were mainly HA-bound and then were detained in the top soil layers. HMWAHs associated with fine topsoil particles could be transported to B. chinensis via the soil-air-plant pathway, including resuspension and aboveground plant cuticle capture. Results from Principal Component Analysis combined with Regression Analysis supported this assumption due to the positive correlations between HMWAHs concentration in B. chinensis and fine particle contents in soils. This work presents the distributions of petroleum contaminants that result from previously described behavior mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in plant functional groups, litter quality, and soil carbon and nitrogen mineralization with sheep grazing in an Inner Mongolian Grassland

USGS Publications Warehouse

Barger, N.N.; Ojima, D.S.; Belnap, J.; Shiping, W.; Yanfen, W.; Chen, Z.

2004-01-01

This study reports on changes in plant functional group composition, litter quality, and soil C and N mineralization dynamics from a 9-year sheep grazing study in Inner Mongolia. Addressed are these questions: 1) How does increasing grazing intensity affect plant community composition? 2) How does increasing grazing intensity alter soil C and N mineralization dynamics? 3) Do changes in soil C and N mineralization dynamics relate to changes in plant community composition via inputs of the quality or quantity of litter? Grazing plots were set up near the Inner Mongolia Grassland Ecosystem Research Station (IMGERS) with 5 grazing intensities: 1.3, 2.7, 4.0, 5.3, and 6.7 sheep ha -1??yr-1. Plant cover was lower with increasing grazing intensity, which was primarily due to a dramatic decline in grasses, Carex duriuscula, and Artemisia frigida. Changes in litter mass and percentage organic C resulted in lower total C in the litter layer at 4.0 and 5.3 sheep ha-1??yr-1 compared with 2.7 sheep ha -1??yr-1. Total litter N was lower at 5.3 sheep ha-1??yr-1 compared with 2.7 sheep ha -1??yr-1. Litter C:N ratios, an index of litter quality, were significantly lower at 4.0 sheep ha-1??yr -1 relative to 1.3 and 5.3 sheep ha-1??yr -1. Cumulative C mineralized after 16 days decreased with increasing grazing intensity. In contrast, net N mineralization (NH4+ + NO3-) after a 12-day incubation increased with increasing grazing intensity. Changes in C and N mineralization resulted in a narrowing of CO2-C:net Nminratios with increasing grazing intensity. Grazing explained 31% of the variability in the ratio of CO 2-C:net Nmin. The ratio of CO2-C:net N min was positively correlated with litter mass. Furthermore, there was a positive correlation between litter mass and A. frigida cover. Results suggest that as grazing intensity increases, microbes become more C limited resulting in decreased microbial growth and demand for N.

Phytoremediated marine sediments as suitable peat-free growing media for production of red robin photinia (Photinia x fraseri).

PubMed

Mattei, Paola; Gnesini, Alessandro; Gonnelli, Cristina; Marraccini, Chiara; Masciandaro, Grazia; Macci, Cristina; Doni, Serena; Iannelli, Renato; Lucchetti, Stefano; Nicese, Francesco P; Renella, Giancarlo

2018-06-01

Sediments dredged by an industrial port, slightly contaminated by heavy metals and petroleoum hydrocarbons, were phytoremediated and used as peat-free growing media for the red robin photinia (Photinia x fraseri L.). Plants were grown on sediment only (S), sediment mixed with composted pruning residues (S + PR), sediment fertilized with controlled release fertilizers (S + F) and peat-based growing media as control (C). Plant elongation and dry weight, leaf contents of chlorophyll, malondialdehyde (MDA), macronutrients and heavy metals were determined at the end of one growing season. Environmental impact related to the use of sediment-based as compared to peat-based growing media was assessed by the Life Cycle Analysis (LCA). Sediment-based growing media presented significantly higher bulk density, pH and electrical conductivity values, lower C and N contents, and significantly higher total and available P. Red robin photinia grown on S + F growing media showed morphological and chemical parameters similar to those of control plants (C), whereas plants grown on S and S + PR showed lower growth. Leaf concentration of nutrients and heavy metals varied depending on the considered element and growing media, but were all within the common values for ornamental plants, whereas the highest MDA concentrations were found in plants grown on traditional growing media. The LCA indicated the use of sediments as growing media reduced the C footprint of ornamental plant production and the contribute of growing media to the environmental impact per produced plant. We concluded that sediments phytoremediation and use in plant nursery is a practical alternative re-use option for dredged sediments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Elevated CO2 shifts the functional structure and metabolic potentials of soil microbial communities in a C4 agroecosystem.

PubMed

Xiong, Jinbo; He, Zhili; Shi, Shengjing; Kent, Angela; Deng, Ye; Wu, Liyou; Van Nostrand, Joy D; Zhou, Jizhong

2015-03-20

Atmospheric CO2 concentration is continuously increasing, and previous studies have shown that elevated CO2 (eCO2) significantly impacts C3 plants and their soil microbial communities. However, little is known about effects of eCO2 on the compositional and functional structure, and metabolic potential of soil microbial communities under C4 plants. Here we showed that a C4 maize agroecosystem exposed to eCO2 for eight years shifted the functional and phylogenetic structure of soil microbial communities at both soil depths (0-5 cm and 5-15 cm) using EcoPlate and functional gene array (GeoChip 3.0) analyses. The abundances of key genes involved in carbon (C), nitrogen (N) and phosphorus (P) cycling were significantly stimulated under eCO2 at both soil depths, although some differences in carbon utilization patterns were observed between the two soil depths. Consistently, CO2 was found to be the dominant factor explaining 11.9% of the structural variation of functional genes, while depth and the interaction of depth and CO2 explained 5.2% and 3.8%, respectively. This study implies that eCO2 has profound effects on the functional structure and metabolic potential/activity of soil microbial communities associated with C4 plants, possibly leading to changes in ecosystem functioning and feedbacks to global change in C4 agroecosystems.

Potential individual versus simultaneous climate change effects on soybean (C 3) and maize (C 4) crops: An agrotechnology model based study

NASA Astrophysics Data System (ADS)

Mera, Roberto J.; Niyogi, Dev; Buol, Gregory S.; Wilkerson, Gail G.; Semazzi, Fredrick H. M.

2006-11-01

Landuse/landcover change induced effects on regional weather and climate patterns and the associated plant response or agricultural productivity are coupled processes. Some of the basic responses to climate change can be detected via changes in radiation ( R), precipitation ( P), and temperature ( T). Past studies indicate that each of these three variables can affect LCLUC response and the agricultural productivity. This study seeks to address the following question: What is the effect of individual versus simultaneous changes in R, P, and T on plant response such as crop yields in a C 3 and a C 4 plant? This question is addressed by conducting model experiments for soybean (C 3) and maize (C 4) crops using the DSSAT: Decision Support System for Agrotechnology Transfer, CROPGRO (soybean), and CERES-Maize (maize) models. These models were configured over an agricultural experiment station in Clayton, NC [35.65°N, 78.5°W]. Observed weather and field conditions corresponding to 1998 were used as the control. In the first set of experiments, the CROPGRO (soybean) and CERES-Maize (maize) responses to individual changes in R and P (25%, 50%, 75%, 150%) and T (± 1, ± 2 °C) with respect to control were studied. In the second set, R, P, and T were simultaneously changed by 50%, 150%, and ± 2 °C, and the interactions and direct effects of individual versus simultaneous variable changes were analyzed. For the model setting and the prescribed environmental changes, results from the first set of experiments indicate: (i) precipitation changes were most sensitive and directly affected yield and water loss due to evapotranspiration; (ii) radiation changes had a non-linear effect and were not as prominent as precipitation changes; (iii) temperature had a limited impact and the response was non-linear; (iv) soybeans and maize responded differently for R, P, and T, with maize being more sensitive. The results from the second set of experiments indicate that simultaneous change analyses do not necessarily agree with those from individual changes, particularly for temperature changes. Our analysis indicates that for the changing climate, precipitation (hydrological), temperature, and radiative feedbacks show a non-linear effect on yield. Study results also indicate that for studying the feedback between the land surface and the atmospheric changes, (i) there is a need for performing simultaneous parameter changes in the response assessment of cropping patterns and crop yield based on ensembles of projected climate change, and (ii) C 3 crops are generally considered more sensitive than C 4; however, the temperature-radiation related changes shown in this study also effected significant changes in C 4 crops. Future studies assessing LCLUC impacts, including those from agricultural cropping patterns and other LCULC-climate couplings, should advance beyond the sensitivity mode and consider multivariable, ensemble approaches to identify the vulnerability and feedbacks in estimating climate-related impacts.

A safety vs efficiency trade-off identified in the hydraulic pathway of grass leaves is decoupled from photosynthesis, stomatal conductance and precipitation.

PubMed

Ocheltree, Troy W; Nippert, Jesse B; Prasad, P V Vara

2016-04-01

A common theme in plant physiological research is the trade-off between stress tolerance and growth; an example of this trade-off at the tissue level is the safety vs efficiency hypothesis, which suggests that plants with the greatest resistance to hydraulic failure should have low maximum hydraulic conductance. Here, we quantified the leaf-level drought tolerance of nine C4 grasses as the leaf water potential at which plants lost 50% (P50 × RR ) of maximum leaf hydraulic conductance (Ksat ), and compared this trait with other leaf-level and whole-plant functions. We found a clear trade-off between Ksat and P50 × RR when Ksat was normalized by leaf area and mass (P = 0.05 and 0.01, respectively). However, no trade-off existed between P50 × RR and gas-exchange rates; rather, there was a positive relationship between P50 × RR and photosynthesis (P = 0.08). P50 × RR was not correlated with species distributions based on precipitation (P = 0.70), but was correlated with temperature during the wettest quarter of the year (P < 0.01). These results suggest a trade-off between safety and efficiency in the hydraulic system of grass leaves, which can be decoupled from other leaf-level functions. The unique physiology of C4 plants and adaptations to pulse-driven systems may provide mechanisms that could decouple hydraulic conductance from other plant functions. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Alluvial deposits and plant distribution in an Amazonian lowland megafan

NASA Astrophysics Data System (ADS)

Zani, H.; Rossetti, D.; Cremon; Cohen, M.; Pessenda, L. C.

2012-12-01

A large volume of sandy alluvial deposits (> 1000 km2) characterizes a flat wetland in northern Amazonia. These have been recently described as the sedimentary record of a megafan system, which have a distinct triangular shape produced by highly migratory distributary rivers. The vegetation map suggests that this megafan is dominated by open vegetation in sharp contact with the surround rainforest. Understanding the relationship between geomorphological processes and vegetation distribution is crucial to decipher and conserve the biodiversity in this Amazonian ecosystem. In this study we interpret plant dynamics over time, and investigate its potential control by sedimentary processes during landscape evolution. The study area is located in the Viruá National Park. Two field campaigns were undertaken in the dry seasons of 2010 and 2011 and the sampling sites were selected by combining accessibility and representativeness. Vegetation contrasts were recorded along a transect in the medial section of the Viruá megafan. Due to the absence of outcrops, samples were extracted using a core device, which allowed sampling up to a depth of 7.5 m. All cores were opened and described in the field, with 5 cm3 samples collected at 20 cm intervals. The δ13C of organic matter was used as a proxy to distinguish between C3 and C4 plant communities. The chronology was established based on radiocarbon dating. The results suggest that the cores from forested areas show the most depleted values of δ13C, ranging from -32.16 to -27.28‰. The δ13C curve in these areas displays typical C3 land plant values for the entire record, which covers most of the Holocene. This finding indicates that either the vegetation remained stable over time or the sites were dominated by aquatic environments with freshwater plants before forest establishment. The cores from the open vegetation areas show a progressive upward enrichment in δ13C values, which range from -28.50 to -19.59‰. This trend is more pronounced after de mid-Holocene, suggesting that the open vegetation, represented mostly by C4 land plants, evolved only more recently. Based on our isotope data, a model is proposed taking into account the influence of sedimentary dynamics on the modern pattern of plan distribution. The establishment of open vegetation occurred at different times depending on location over the megafan area, varying from around 3,000 to 6,400 cal yrs BP. As sedimentation took place, areas located far from the surrounding rainforest were prone to inputs of organic matter derived from open vegetation, whereas the contribution of organic matter derived from arboreous vegetation increases toward the areas located closer to the rainforest. In general, open vegetation is constrained to depositional sites that remained active until relatively recent Holocene times, while surrounding areas with a relatively older geological history are covered by dense forest. The results presented here consist in a striking example of the influence of sedimentary processes during the Late Pleistocene-Holocene on the development of modern plants of this Amazonian lowland.

Impact of simulated atmospheric nitrogen deposition on nutrient cycling and carbon sink via mycorrhizal fungi in two nutrient-poor peatlands

NASA Astrophysics Data System (ADS)

Larmola, Tuula; Kiheri, Heikki; Bubier, Jill L.; van Dijk, Netty; Dise, Nancy; Fritze, Hannu; Hobbie, Erik A.; Juutinen, Sari; Laiho, Raija; Moore, Tim R.; Pennanen, Taina

2017-04-01

Peatlands store one third of the global soil carbon (C) pool. Long-term fertilization experiments in nutrient-poor peatlands showed that simulated atmospheric nitrogen (N) deposition does not enhance ecosystem C uptake but reduces C sink potential. Recent studies have shown that a significant proportion of C input to soil in low-fertility forests entered the soil through mycorrhizal fungi, rather than as plant litter. Is atmospheric N deposition diminishing peatland C sink potential due to the suppression of ericoid mycorrhizal fungi? We studied how nutrient addition influences plant biomass allocation and the extent to which plants rely on mycorrhizal N uptake at two of the longest-running nutrient addition experiments on peatlands, Whim Bog, United Kingdom, and Mer Bleue Bog, Canada. We determined the peak growing season aboveground biomass production and coverage of vascular plants using the point intercept method. We also analyzed isotopic δ15N patterns and nutrient contents in leaves of dominant ericoid mycorrhizal shrubs as well as the non-mycorrhizal sedge Eriophorum vaginatum under different nutrient addition treatments. The treatments receive an additional load of 1.6-6.4 N g m-2 y-1 either as ammonium (NH4) nitrate (NO3) or NH4NO3 and with or without phosphorus (P) and potassium (K), alongside unfertilized controls. After 11-16 years of nutrient addition, the vegetation structure had changed remarkably. Ten of the eleven nutrient addition treatments showed an increase of up to 60% in total vascular plant abundance. Only three (NH4Cl, NH4ClPK, NaNO3PK) of the nutrient addition treatments showed a concurrent decrease of down to 50% in the relative proportion of ericoid mycorrhizal shrubs to total vascular plant abundance. The response to nutrient load may be explained by the water table depth, the form of N added and whether N was added with PK. Shrubs were strong competitors at the dry Mer Bleue bog while sedges gained in abundance at the wetter Whim bog. Our results also suggest that the impacts of reduced and oxidized N on above ground biomass of ericoid shrubs differ and that plants have become increasingly P limited under high simulated atmospheric N deposition. Combined with mycorrhizal abundance and foliar isotopic δ15N patterns, the data will allow us to estimate the extent to which plants rely on mycorrhizal N uptake and whether mycorrhizal responses are linked to diminished C sink potential. This evidence is needed to establish critical loads for C sink potential in peatlands.

77 FR 34463 - Endangered and Threatened Wildlife and Plants; Listing 38 Species on Molokai, Lanai, and Maui as...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-11

... section 4 of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), including...'' denotes endangered status under the Act; ``C'' denotes a species currently on the candidate list... Endangered Plants: Bidens campylotheca ssp. kookoolau Proposed--Endangered Proposed. pentamera. (C). Bidens...

Diurnal Changes in Volume and Specific Tissue Weight of Crassulacean Acid Metabolism Plants 1

PubMed Central

Chen, Sheng-Shu; Black, Clanton C.

1983-01-01

The diurnal variations in volume and in specific weight were determined for green stems and leaves of Crassulacen acid metabolism (CAM) plants. Volume changes were measured by a water displacement method. Diurnal variations occurred in the volume of green CAM tissues. Their volume increased early in the light period reaching a maximum about mid-day, then the volume decreased to a minimum near midnight. The maximum volume increase each day was about 2.7% of the total volume. Control leaves of C3 and C4 plants exhibited reverse diurnal volume changes of 0.2 to 0.4%. The hypothesis is presented and supported that green CAM tissues should exhibit a diurnal increase in volume due to the increase of internal gas pressure from CO2 and O2 when their stomata are closed. Conversely, the volume should decrease when the gas pressure is decreased. The second hypothesis presented and supported was that the specific weight (milligrams of dry weight per square centimeter of green surface area) of green CAM tissues should increase at night due to the net fixation of CO2. Green CAM tissues increased their specific weight at night in contrast to control C3 and C4 leaves which decreased their specific weight at night. With Kalanchoë daigremontiana leaves, the calculated increase in specific leaf weight at night based on estimates of carbohydrate available for net CO2 fixation was near 6% and the measured increase in specific leaf weight was 6%. Diurnal measurements of CAM tissue water content were neither coincident nor reciprocal with their diurnal patterns of either volume or specific weight changes. PMID:16662833

Vegetation and climate variability in East Asia driven by low-latitude oceanic forcing during the middle to late Holocene

NASA Astrophysics Data System (ADS)

Lim, Jaesoo; Fujiki, Toshiyuki

2011-09-01

At centennial to millennial timescales, little is known of C 3 and C 4 plant productivity's responses to past regional climate changes and the dominant forcing factors during the Holocene, although large-scale changes in glacial-interglacial periods have been attributed to changes in aridity, temperature, and CO 2 concentration. We investigated the δ 13C of TOC, C/N ratios, and pollen in samples from a wetland on Jeju Island, Korea. The bulk isotopic signal ranging from -17‰ to -29‰ was partitioned into C 3 and C 4 plant signals by using a binary mixing model and calculating separate organic carbon-accumulation rates for C 3 and C 4 plants (OCAR 3 and OCAR 4) during the last 6500 years. Pollen data indicated that the temperate deciduous broadleaved trees replaced grassland dominated by Artemisia, dry-tolerant grass, and further expanded in the maar. The long-term decreasing trend of Artemisia-dominated grassland was similar to those of δ 13C values and OCAR 4. The multi-centennial to millennial variability superimposed on the gradual increasing trend of OCAR 3 was inversely correlated with those of the sea surface temperature (SST) in the western tropical Pacific (WTP) and El Niño-Southern Oscillation (ENSO) activity, suggesting that C 3 plants have stronger sensitivity to regional climate change driven by oceanic forcing. Our data suggest that vegetation changes in a coastal area in East Asia were affected by monsoonal changes coupled with SST in WTP and ENSO activity. The vegetation change on Jeju Island varied quite differently from change in the westerly pathway, suggesting only a weak influence from high-latitude-driven atmospheric circulation changes. We conclude that centennial- to millennial-scale climate changes in coastal regions of East Asia during the mid- to late-Holocene may have been mainly controlled by low-latitudinal oceanic forcing, including forcing by SST and ENSO activity.

Shallow cumulus rooted in photosynthesis

NASA Astrophysics Data System (ADS)

Vila-Guerau Arellano, J.; Ouwersloot, H.; Horn, G.; Sikma, M.; Jacobs, C. M.; Baldocchi, D.

2014-12-01

We investigate the interaction between plant evapotranspiration, controlled by photosynthesis (for a low vegetation cover by C3 and C4 grasses), and the moist thermals that are responsible for the formation and development of shallow cumulus clouds (SCu). We perform systematic numerical experiments at fine spatial scales using large-eddy simulations explicitly coupled to a plant-physiology model. To break down the complexity of the vegetation-atmospheric system at the diurnal scales, we design the following experiments with increasing complexity: (a) clouds that are transparent to radiation, (b) clouds that shade the surface from the incoming shortwave radiation and (c) plant stomata whose apertures react with an adjustment in time to cloud perturbations. The shading by SCu leads to a strong spatial variability in photosynthesis and the surface energy balance. As a result, experiment (b) simulates SCu that are characterized by less extreme and less skewed values of the liquid water path and cloud-base height. These findings are corroborated by the calculation of characteristics lengths scales of the thermals and clouds using autocorrelation and spectral analysis methods. We find that experiments (a) and (b) are characterized by similar cloud cover evolution, but different cloud population characteristics. Experiment (b), including cloud shading, is characterized by smaller clouds, but closer to each other. By performing a sensitivity analysis on the exchange of water vapor and carbon dioxide at the canopy level, we show that the larger water-use efficiency of C4 grass leads to two opposing effects that directly influence boundary-layer clouds: the thermals below the clouds are more vigorous and deeper driven by a larger buoyancy surface flux (positive effect), but are characterized by less moisture content (negative effect). We conclude that under the investigated mid-latitude atmospheric and well-watered soil conditions, SCu over C4 grass fields is characterized by larger cloud cover and an enhanced liquid water path compared to C3 grass fields.

Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

NASA Astrophysics Data System (ADS)

Harper, Anna B.; Cox, Peter M.; Friedlingstein, Pierre; Wiltshire, Andy J.; Jones, Chris D.; Sitch, Stephen; Mercado, Lina M.; Groenendijk, Margriet; Robertson, Eddy; Kattge, Jens; Bönisch, Gerhard; Atkin, Owen K.; Bahn, Michael; Cornelissen, Johannes; Niinemets, Ülo; Onipchenko, Vladimir; Peñuelas, Josep; Poorter, Lourens; Reich, Peter B.; Soudzilovskaia, Nadjeda A.; van Bodegom, Peter

2016-07-01

Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycle-climate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf life spans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the leaf turnover and growth rates to include a trade-off between leaf life span and leaf mass per unit area.Overall, the simulation of gross and net primary productivity (GPP and NPP, respectively) is improved with the nine PFTs when compared to FLUXNET sites, a global GPP data set based on FLUXNET, and MODIS NPP. Compared to the standard five PFTs, the new nine PFTs simulate a higher GPP and NPP, with the exception of C3 grasses in cold environments and C4 grasses that were previously over-productive. On a biome scale, GPP is improved for all eight biomes evaluated and NPP is improved for most biomes - the exceptions being the tropical forests, savannahs, and extratropical mixed forests where simulated NPP is too high. With the new PFTs, the global present-day GPP and NPP are 128 and 62 Pg C year-1, respectively. We conclude that the inclusion of trait-based data and the evergreen/deciduous distinction has substantially improved productivity fluxes in JULES, in particular the representation of GPP. These developments increase the realism of JULES, enabling higher confidence in simulations of vegetation dynamics and carbon storage.

Carbon Isotope Composition of Nighttime Leaf-Respired CO2 in the Agricultural-Pastoral Zone of the Songnen Plain, Northeast China

PubMed Central

Cui, Haiying; Wang, Yunbo; Jiang, Qi; Chen, Shiping; Ma, Jian-Ying; Sun, Wei

2015-01-01

Variations in the carbon isotope signature of leaf dark-respired CO2 (δ13CR) within a single night is a widely observed phenomenon. However, it is unclear whether there are plant functional type differences with regard to the amplitude of the nighttime variation in δ13CR. These differences, if present, would be important for interpreting the short-term variations in the stable carbon signature of ecosystem respiration and the partitioning of carbon fluxes. To assess the plant functional type differences relating to the magnitude of the nighttime variation in δ13CR and the respiratory apparent fractionation, we measured the δ13CR, the leaf gas exchange, and the δ13C of the respiratory substrates of 22 species present in the agricultural-pastoral zone of the Songnen Plain, northeast China. The species studied were grouped into C3 and C4 plants, trees, grasses, and herbs. A significant nocturnal shift in δ13CR was detected in 20 of the studied species, with the magnitude of the shift ranging from 1‰ to 5.8‰. The magnitude of the nighttime variation in δ13CR was strongly correlated with the daytime cumulative carbon assimilation, which suggests that variation in δ13CR were influenced, to some extent, by changes in the contribution of malate decarboxylation to total respiratory CO2 flux. There were no differences in the magnitude of the nighttime variation in δ13CR between the C3 and C4 plants, as well as among the woody plants, herbs and graminoids. Leaf respired CO2 was enriched in 13C compared to biomass, soluble carbohydrates and lipids; however the magnitude of enrichment differed between 8 pm and 4 am, which were mainly caused by the changes in δ13CR. We also detected the plant functional type differences in respiratory apparent fractionation relative to biomass at 4 am, which suggests that caution should be exercised when using the δ13C of bulk leaf material as a proxy for the δ13C of leaf-respired CO2. PMID:26356083

Natural Forest Biomass Estimation Based on Plantation Information Using PALSAR Data

PubMed Central

Avtar, Ram; Suzuki, Rikie; Sawada, Haruo

2014-01-01

Forests play a vital role in terrestrial carbon cycling; therefore, monitoring forest biomass at local to global scales has become a challenging issue in the context of climate change. In this study, we investigated the backscattering properties of Advanced Land Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) data in cashew and rubber plantation areas of Cambodia. The PALSAR backscattering coefficient (σ0) had different responses in the two plantation types because of differences in biophysical parameters. The PALSAR σ0 showed a higher correlation with field-based measurements and lower saturation in cashew plants compared with rubber plants. Multiple linear regression (MLR) models based on field-based biomass of cashew (C-MLR) and rubber (R-MLR) plants with PALSAR σ0 were created. These MLR models were used to estimate natural forest biomass in Cambodia. The cashew plant-based MLR model (C-MLR) produced better results than the rubber plant-based MLR model (R-MLR). The C-MLR-estimated natural forest biomass was validated using forest inventory data for natural forests in Cambodia. The validation results showed a strong correlation (R2 = 0.64) between C-MLR-estimated natural forest biomass and field-based biomass, with RMSE  = 23.2 Mg/ha in deciduous forests. In high-biomass regions, such as dense evergreen forests, this model had a weaker correlation because of the high biomass and the multiple-story tree structure of evergreen forests, which caused saturation of the PALSAR signal. PMID:24465908

Rising plant-mediated methane emissions from arctic wetlands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andresen, Christian G.; Lara, Mark J.; Tweedie, Craig E.

Plant-mediated CH 4 flux is an important pathway for land–atmosphere CH 4 emissions, but the magnitude, timing, and environmental controls, spanning scales of space and time, remain poorly understood in arctic tundra wetlands, particularly under the long-term effects of climate change. CH 4 fluxes were measured in situ during peak growing season for the dominant aquatic emergent plants in the Alaskan arctic coastal plain, Carex aquatilis and Arctophila fulva, to assess the magnitude and species-specific controls on CH 4 flux. Plant biomass was a strong predictor of A. fulva CH 4 flux while water depth and thaw depth were copredictorsmore » for C. aquatilis CH 4 flux. Here, we used plant and environmental data from 1971 to 1972 from the historic International Biological Program (IBP) research site near Barrow, Alaska, which we resampled in 2010–2013, to quantify changes in plant biomass and thaw depth, and used these to estimate species-specific decadal-scale changes in CH 4 fluxes. A ~60% increase in CH 4 flux was estimated from the observed plant biomass and thaw depth increases in tundra ponds over the past 40 years. In spite of our covering only ~5% of the landscape, we estimate that aquatic C. aquatilis and A. fulva account for two-thirds of the total regional CH 4 flux of the Barrow Peninsula. The regionally observed increases in plant biomass and active layer thickening over the past 40 years not only have major implications for energy and water balance, but also have significantly altered land–atmosphere CH 4 emissions for this region, potentially acting as a positive feedback to climate warming.« less

Rising plant-mediated methane emissions from arctic wetlands

DOE PAGES

Andresen, Christian G.; Lara, Mark J.; Tweedie, Craig E.; ...

2016-09-14

Plant-mediated CH 4 flux is an important pathway for land–atmosphere CH 4 emissions, but the magnitude, timing, and environmental controls, spanning scales of space and time, remain poorly understood in arctic tundra wetlands, particularly under the long-term effects of climate change. CH 4 fluxes were measured in situ during peak growing season for the dominant aquatic emergent plants in the Alaskan arctic coastal plain, Carex aquatilis and Arctophila fulva, to assess the magnitude and species-specific controls on CH 4 flux. Plant biomass was a strong predictor of A. fulva CH 4 flux while water depth and thaw depth were copredictorsmore » for C. aquatilis CH 4 flux. Here, we used plant and environmental data from 1971 to 1972 from the historic International Biological Program (IBP) research site near Barrow, Alaska, which we resampled in 2010–2013, to quantify changes in plant biomass and thaw depth, and used these to estimate species-specific decadal-scale changes in CH 4 fluxes. A ~60% increase in CH 4 flux was estimated from the observed plant biomass and thaw depth increases in tundra ponds over the past 40 years. In spite of our covering only ~5% of the landscape, we estimate that aquatic C. aquatilis and A. fulva account for two-thirds of the total regional CH 4 flux of the Barrow Peninsula. The regionally observed increases in plant biomass and active layer thickening over the past 40 years not only have major implications for energy and water balance, but also have significantly altered land–atmosphere CH 4 emissions for this region, potentially acting as a positive feedback to climate warming.« less

Fullerene C60 for enhancing phytoremediation of urea plant wastewater by timber plants.

PubMed

Yavari, Sara; Malakahmad, Amirhossein; Sapari, Nasiman B; Yavari, Saba

2018-04-01

Phytoremediation has been applied as a promising and cost-effective technique for removing nutrient pollutants from wastewater. In this study, the effect of fullerene C60 was assessed on enhancing the phytoremediation efficiency of teak plants over a period of 1 month. Teak plants were supplied with fullerene C60 (0, 25, or 50 mg L -1 ) and fed daily with two types of urea plant wastewater (with and without adding optimum ratio of phosphorus and potassium). The required volume of wastewater by the teak plants, nitrogen removal percentage, plant growth parameters (plant height, number of leaves, leaf surface area, and dry biomass), and nutrient content was recorded throughout the study. The results showed that addition of 25 mg L -1 fullerene C60 to urea plant wastewater could increase water uptake and nitrogen recovery of the teak plants. Plant growth and nutrient contents of teak plants were also increased in the presence of 25 mg L -1 fullerene C60. However, addition of 50 mg L -1 fullerene C60 to the wastewater decreased the values for water uptake and nitrogen recovery. The findings indicated that addition of proper amount of fullerene C60 to the teak-based remediation system can increase the efficiency of the plants for nitrogen removal.

10 CFR 110.8 - List of nuclear facilities and equipment under NRC export licensing authority.

Code of Federal Regulations, 2013 CFR

2013-01-01

... based enrichment plants, plasma separation enrichment plants, electromagnetic enrichment plants, and... enrichment equipment—Appendix G; and electromagnetic enrichment equipment—Appendix H.) (c) Plants for the...

10 CFR 110.8 - List of nuclear facilities and equipment under NRC export licensing authority.

Code of Federal Regulations, 2014 CFR

2014-01-01

... based enrichment plants, plasma separation enrichment plants, electromagnetic enrichment plants, and... enrichment equipment—Appendix G; and electromagnetic enrichment equipment—Appendix H.) (c) Plants for the...

10 CFR 110.8 - List of nuclear facilities and equipment under NRC export licensing authority.

Code of Federal Regulations, 2012 CFR

2012-01-01

... based enrichment plants, plasma separation enrichment plants, electromagnetic enrichment plants, and... enrichment equipment—Appendix G; and electromagnetic enrichment equipment—Appendix H.) (c) Plants for the...

10 CFR 110.8 - List of nuclear facilities and equipment under NRC export licensing authority.

Code of Federal Regulations, 2011 CFR

2011-01-01

... based enrichment plants, plasma separation enrichment plants, electromagnetic enrichment plants, and... enrichment equipment—Appendix G; and electromagnetic enrichment equipment—Appendix H.) (c) Plants for the...

10 CFR 110.8 - List of nuclear facilities and equipment under NRC export licensing authority.

Code of Federal Regulations, 2010 CFR

2010-01-01

... based enrichment plants, plasma separation enrichment plants, electromagnetic enrichment plants, and... enrichment equipment—Appendix G; and electromagnetic enrichment equipment—Appendix H.) (c) Plants for the...

Old plants newly discovered: Cassia sieberiana D.C. and Cassia abbreviata Oliv. Oliv. root extracts inhibit in vitro HIV-1c replication in peripheral blood mononuclear cells (PBMCs) by different modes of action.

PubMed

Leteane, Melvin M; Ngwenya, Barbara N; Muzila, Mbaki; Namushe, Amos; Mwinga, John; Musonda, Rosemary; Moyo, Sikhulile; Mengestu, Yehualashete B; Abegaz, Berhanu M; Andrae-Marobela, Kerstin

2012-05-07

Despite advances in anti-retroviral therapy which has transformed HIV/AIDS from a fatal to a manageable chronic disease, increasing viral drug resistance, side effects and uneven access to anti-retroviral drugs remain considerable therapeutic challenges. Partly as a consequence of these shortcomings and partly based on the fact that HIV/AIDS gives rise to opportunistic infections whose symptoms have been managed in Africa in an HIV/AIDS-independent context by traditional healers for centuries, many HIV/AIDS patients use herbal medicines. The aim of this study was to screen selected medicinal plants from Botswana, used by traditional healers to treat/manage HIV/AIDS, for inhibitory activities on HIV replication. Based on an ethnomedical survey, ethanolic tannin-containing and tannin-free extracts from 10 medicinal plants were tested for inhibitory properties against a clone of HIV-1c (MJ(4)) measuring cytopathic effect protection and levels of viral p24 antigen in infected PBMCs. Cassia sieberiana D.C., Cassia abbreviata Oliv. Oliv. and Plumbago zeylanica L. extracts showed significant inhibition of HIV-1c (MJ(4)) replication. The inhibitory activity of the Plumbago zeylanica extract could be attributed to its tannin content. Anti-HIV activity of Cassia sieberiana root and bark extracts, and Cassia abbreviata root extracts occurred in a concentration-dependent manner with an effective concentration (EC(50)) of 65.1μg/ml, 85.3μg/ml and 102.8μg/ml, respectively. Experiments to elucidate possible mechanism(s) of action revealed that Cassia sieberiana root and bark extracts blocked HIV replication at its binding- (EC(50)=70.2μg/ml and 90.8μg/ml, respectively) and entry stage (EC(50)=88.9μg/ml and 100.5μg/ml, respectively) while Cassia abbreviata extracts did not. We report here for the first time a direct inhibitory effect on HIV-1c replication of extracts from two extremely popular medicinal plants, Cassia sieberiana and Cassia abbreviata. Considering the traditional uses of both Cassia species, our findings strongly suggest pilot clinical observational studies involving traditional healers to further evaluate the therapeutic potential of the Cassia extracts. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Patton's tracks in the Mojave Desert, USA: An ecological legacy

USGS Publications Warehouse

Belnap, Jayne; Warren, Steven D.

2002-01-01

Recovery of soil properties from World War II-era military training exercises in the Mojave Desert was measured approximately 55 years following disturbance. Tracks from military vehicles were still visible, particularly in areas of desert pavement. Soil penetrability was much lower in visible tracks than outside the tracks. Soils in tracks had fewer rocks in the top 10cm of the soil profile than adjacent untracked soils. Larger particles (> 4.8mm) formed a moderately well-developed pavement outside of the tracks, while smaller, loose particles ( h 4.8mm) dominated the surface of the tracks. The time required to restore the desert pavement is likely to be measured in centuries. Based on biomass estimates, the cyanobacterial component of biological soil crusts had recovered 46-65% in tracks, compared to outside the tracks. Overall recovery of lichen cover has been much slower. Under plant canopies, cover of Collema tenax was not significantly different between areas inside and outside the tracks; however, recovery of Catapyrenium squamulosum was only 36%. In plant interspaces with less favorable moisture and temperature conditions, C. tenax showed a 6% recovery and C. squamulosum a 3% recovery. Assuming recovery of the biological soil crust is linear, and complete only when the most sensitive species (C. squamulosum) has fully recovered in the most limiting microhabitats (plant interspaces), it may require almost two millennia for full recovery of these areas.

40 CFR 799.5089 - Chemical testing requirements for third group of high production volume chemicals (HPV3).

Code of Federal Regulations, 2014 CFR

2014-07-01

... Toxicity to Daphnia: ASTM E 729-96 (Reapproved 2007). 3. Toxicity to Plants (Algae): ASTM E 1218-04 e1 Test... (Algae): ASTM E 1218-04 e1 The following are the special conditions for C1, C2, C3, C4, C5, and C7.... Toxicity to Plants (Algae): ASTM E 1218-04 e1 Test Group 2 for C2: 1. Chronic Toxicity to Daphnia: ASTM E...

Determining the biomass fraction of mixed waste fuels: A comparison of existing industry and {sup 14}C-based methodologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muir, G.K.P., E-mail: Graham.Muir@glasgow.ac.uk; Hayward, S.; Tripney, B.G.

2015-01-15

Highlights: • Compares industry standard and {sup 14}C methods for determining bioenergy content of MSW. • Differences quantified through study at an operational energy from waste plant. • Manual sort and selective dissolution are unreliable measures of feedstock bioenergy. • {sup 14}C methods (esp. AMS) improve precision and reliability of bioenergy determination. • Implications for electricity generators and regulators for award of bio-incentives. - Abstract: {sup 14}C analysis of flue gas by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) were used to determine the biomass fraction of mixed waste at an operational energy-from-waste (EfW) plant. Results were convertedmore » to bioenergy (% total) using mathematical algorithms and assessed against existing industry methodologies which involve manual sorting and selective dissolution (SD) of feedstock. Simultaneous determinations using flue gas showed excellent agreement: 44.8 ± 2.7% for AMS and 44.6 ± 12.3% for LSC. Comparable bioenergy results were obtained using a feedstock manual sort procedure (41.4%), whilst a procedure based on selective dissolution of representative waste material is reported as 75.5% (no errors quoted). {sup 14}C techniques present significant advantages in data acquisition, precision and reliability for both electricity generator and industry regulator.« less

Compound-specific stable carbon isotopic signature of carbohydrate pyrolysis products from C3 and C4 plants.

PubMed

González-Pérez, José A; Jiménez-Morillo, Nicasio T; de la Rosa, José M; Almendros, Gonzalo; González-Vila, Francisco J

2016-02-01

Pyrolysis-compound specific isotopic analysis (Py-CSIA: Py-GC-(FID)-C-IRMS) is a relatively novel technique that allows on-line quantification of stable isotope proportions in chromatographically separated products released by pyrolysis. Validation of the Py-CSIA technique is compulsory for molecular traceability in basic and applied research. In this work, commercial sucrose from C4 (sugarcane) and C3 (sugarbeet) photosystem plants and admixtures were studied using analytical pyrolysis (Py-GC/MS), bulk δ(13)C IRMS and δ(13)C Py-CSIA. Major pyrolysis compounds were furfural (F), furfural-5-hydroxymethyl (HMF) and levoglucosan (LV). Bulk and main pyrolysis compound δ(13)C (‰) values were dependent on plant origin: C3 (F, -24.65 ± 0.89; HMF, -22.07 ± 0.41‰; LV, -21.74 ± 0.17‰) and C4 (F, -14.35 ± 0.89‰; HMF, -11.22 ± 0.54‰; LV, -11.44 ± 1.26‰). Significant regressions were obtained for δ(13)C of bulk and pyrolysis compounds in C3 and C4 admixtures. Furfural (F) was found (13)C depleted with respect to bulk and HMF and LV, indicating the incorporation of the light carbon atom in position 6 of carbohydrates in the furan ring after pyrolysis. This is the first detailed report on the δ(13)C signature of major pyrolytically generated carbohydrate-derived molecules. The information provided by Py-CSIA is valuable for identifying source marker compounds of use in food science/fraud detection or in environmental research. © 2015 Society of Chemical Industry.

Seasonal plant water uptake patterns in the saline southeast Everglades ecotone.

PubMed

Ewe, Sharon M L; Sternberg, Leonel da S L; Childers, Daniel L

2007-07-01

The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (delta(18)O) was enriched (4.8 +/- 0.2 per thousand) in the DS relative to the WS (0.0 +/- 0.1 per thousand), but groundwater delta(18)O remained constant between seasons (DS: 2.2 +/- 0.4 per thousand; WS: 2.1 +/- 0.1 per thousand). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil-groundwater mix (delta 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on delta(18)O data, the roots of R. mangle roots were exposed to salinities of 25.4 +/- 1.4 PSU, less saline than either C. jamaicense (39.1 +/- 2.2 PSU) or S. portulacastrum (38.6 +/- 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to global sea level rise and human-induced changes in freshwater flows.

Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols

NASA Astrophysics Data System (ADS)

Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

2011-09-01

The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (δ13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (ωC2). δ13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ωC2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller δ13C values than TC. Based on comparisons of δ13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in δ13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in δ13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

Investigating the context-dependency of plant-soil-AMF-microbe interactions along a pollution gradient

NASA Astrophysics Data System (ADS)

Glassman, S. I.; Casper, B. B.

2010-12-01

Background/Question/Methods Investigating how arbuscular mycorrhizal fungi (AMF)-plant interactions vary with edaphic conditions provides an opportunity to test the context-dependency of interspecific interactions, which is currently recognized as a major avenue of future research. We study plant-mycorrhiza symbiotic relationships along a gradient of heavy metal contamination at a recently revegetated “Superfund” site on Blue Mountain, in Palmerton, Pennsylvania. We investigated the interactions involving the native mycorrhizal fungi, non-mycorrhizal soil microbes, soil, and two plant species (a C3 and C4 grass) along the contamination gradient. The native C3 study species Deschampsia flexuosa, is dominant along the gradient and established naturally; the C4 Sorghastrum nutans, is native to Pennsylvania but not to the site and was introduced during restoration. Because C4 grasses are obligate mycotrophs, we expected S. nutans to have a different effect on and response to the soil symbiont community than the C3 grass. We carried out a full factorial greenhouse experiment using field-collected seeds of D. flexuosa and S. nutans, soil, AMF spores, and non-mycorrhizal microbes from both high and low contaminated ends of the gradient. After 11 weeks of growth in the greenhouses, we harvested above and belowground plant biomass, and quantified AMF root colonization and AMF sporulation. Results/Conclusions Our results indicate that context-dependent function is an important factor driving specific ecological interactions between plants and soil microbes. We found that soil origin significantly affected plant growth. Plants from both species grew much larger in soil from low contaminated (LC) origin than high contaminated (HC) origin. Furthermore, we found that the efficacy of AMF in promoting plant growth depended on AMF origin. Specifically, AMF from LC improved growth of D. flexuosa best in either soil background and improved survivorship of S. nutans in HC soil compared to AMF from HC. We also found that the origin of non-mycorrhizal soil microbes affects the benefit provided to plants and likely interacts with AMF in affecting AMF function. Non-mycorrhizal soil microbes from HC origin decreased mean plant size in D. flexuosa while microbes from LC origin increased mean plant size compared to plants with no non-mycorrhizal soil microbes added. Our results may be useful for improving our basic ecological understanding of plant-soil interactions and ecotypic variation/context-dependent function. There are also potential applications for restoration of heavy metal polluted sites.

C4 Protein of Sweet Potato Leaf Curl Virus Regulates Brassinosteroid Signaling Pathway through Interaction with AtBIN2 and Affects Male Fertility in Arabidopsis

PubMed Central

Bi, Huiping; Fan, Weijuan; Zhang, Peng

2017-01-01

Sweepoviruses have been identified globally and cause substantial yield losses and cultivar decline in sweet potato. This study aimed to investigate the interaction between sweepovirus and plant host by analyzing the function of the viral protein C4 of Sweet potato leaf curl virus-Jiangsu (SPLCV-JS), a sweepovirus cloned from diseased sweet potato plants in East China. Ectopic expression of the C4 in Arabidopsis altered plant development drastically with phenotypic changes including leaf curling, seedling twisting, deformation of floral tissues and reduction of pollen fertility, and seed number. Using bimolecular fluorescence complementation analysis, this study demonstrated that the SPLCV-JS C4 protein interacted with brassinosteroid-insensitive 2 (AtBIN2) in the plasma membrane of Nicotiana benthamiana cells. The C4 AtBIN2 interaction was further confirmed by yeast two-hybrid assays. This interaction led to the re-localization of AtBIN2-interacting proteins AtBES1/AtBZR1 into the nucleus which altered the expression of brassinosteroid (BR)-response genes, resulting in the activation of BR-signaling pathway. The interaction of SPLCV-JS C4 and AtBIN2 also led to the down-regulated expression of key genes involved in anther and pollen development, including SPROROCYTELESS/NOZZLE, DEFECTIVE IN TAPEL DEVELOPMENT AND FUNCTION 1, and ABORTED MICROSPORES, which caused abnormal tapetal development, followed by defective exine pattern formation of microspores and pollen release. Consequently, male fertility in the C4 transgenic Arabidopsis was reduced. The present study illustrated how the sweepovirus C4 protein functioned in host cells and affected male fertility by interacting with the key components of BR-signaling pathway. PMID:29021807

Mutations in the gravity persistence signal loci in Arabidopsis disrupt the perception and/or signal transduction of gravitropic stimuli

NASA Technical Reports Server (NTRS)

Wyatt, Sarah E.; Rashotte, Aaron M.; Shipp, Matthew J.; Robertson, Dominique; Muday, Gloria K.; Brown, C. S. (Principal Investigator)

2002-01-01

Gravity plays a fundamental role in plant growth and development, yet little is understood about the early events of gravitropism. To identify genes affected in the signal perception and/or transduction phase of the gravity response, a mutant screen was devised using cold treatment to delay the gravity response of inflorescence stems of Arabidopsis. Inflorescence stems of Arabidopsis show no response to gravistimulation at 4 degrees C for up to 3 h. However, when gravistimulated at 4 degrees C and then returned to vertical at room temperature (RT), stems bend in response to the previous, horizontal gravistimulation (H. Fukaki, H. Fujisawa, M. Tasaka [1996] Plant Physiology 110: 933-943). This indicates that gravity perception, but not the gravitropic response, occurs at 4 degrees C. Recessive mutations were identified at three loci using this cold effect on gravitropism to screen for gravity persistence signal (gps) mutants. All three mutants had an altered response after gravistimulation at 4 degrees C, yet had phenotypically normal responses to stimulations at RT. gps1-1 did not bend in response to the 4 degrees C gravity stimulus upon return to RT. gps2-1 responded to the 4 degrees C stimulus but bent in the opposite direction. gps3-1 over-responded after return to RT, continuing to bend to an angle greater than wild-type plants. At 4 degrees C, starch-containing statoliths sedimented normally in both wild-type and the gps mutants, but auxin transport was abolished at 4 degrees C. These results are consistent with GPS loci affecting an aspect of the gravity signal perception/transduction pathway that occurs after statolith sedimentation, but before auxin transport.

Transgenerational changes in plant physiology and in transposon expression in response to UV-C stress in Arabidopsis thaliana

PubMed Central

Migicovsky, Zoe; Kovalchuk, Igor

2014-01-01

Stress has a negative impact on crop yield by altering a gain in biomass and affecting seed set. Recent reports suggest that exposure to stress also influences the response of the progeny. In this paper, we analyzed seed size, leaf size, bolting time and transposon expression in 2 consecutive generations of Arabidopsis thaliana plants exposed to moderate UV-C stress. Since previous reports suggested a potential role of Dicer-like (DCL) proteins in the establishment of transgenerational response, we used dcl2, dcl3 and dcl4 mutants in parallel with wild-type plants. These studies revealed that leaf number decreased in the progeny of UV-C stressed plants, and bolting occurred later. Transposons were also re-activated in the progeny of stressed plants. Changes in the dcl mutants were less prominent than in wild-type plants. DCL2 and DCL3 appeared to be more important in the transgenerational stress memory than DCL4 because transgenerational changes were less profound in the dcl2 and dcl3 mutants. PMID:25482751

Transgenerational changes in plant physiology and in transposon expression in response to UV-C stress in Arabidopsis thaliana.

PubMed

Migicovsky, Zoe; Kovalchuk, Igor

2014-01-01

Stress has a negative impact on crop yield by altering a gain in biomass and affecting seed set. Recent reports suggest that exposure to stress also influences the response of the progeny. In this paper, we analyzed seed size, leaf size, bolting time and transposon expression in 2 consecutive generations of Arabidopsis thaliana plants exposed to moderate UV-C stress. Since previous reports suggested a potential role of Dicer-like (DCL) proteins in the establishment of transgenerational response, we used dcl2, dcl3 and dcl4 mutants in parallel with wild-type plants. These studies revealed that leaf number decreased in the progeny of UV-C stressed plants, and bolting occurred later. Transposons were also re-activated in the progeny of stressed plants. Changes in the dcl mutants were less prominent than in wild-type plants. DCL2 and DCL3 appeared to be more important in the transgenerational stress memory than DCL4 because transgenerational changes were less profound in the dcl2 and dcl3 mutants.

A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame.

PubMed

Sage, Rowan F

2016-07-01

Fifty years ago, the C4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C4 plants, such that it is now possible to place nearly all C4 species into their respective evolutionary lineages. Sixty-one independent lineages of C4 photosynthesis are identified, with additional, ancillary C4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C4 lineages are estimated to be younger than 15 million years. Older C4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C4 species is presented. Over the next 50 years, preservation of the Earth's C4 diversity is a concern, largely because of habitat loss due to elevated CO2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C4 Hall of Fame are leading threats to the natural C4 flora due to their association with human activities on landscapes where most C4 plants occur. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame.

PubMed

Sage, Rowan F

2017-01-01

Fifty years ago, the C 4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C 4 plants, such that it is now possible to place nearly all C 4 species into their respective evolutionary lineages. Sixty-one independent lineages of C 4 photosynthesis are identified, with additional, ancillary C 4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C 4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C 4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C 4 lineages are estimated to be younger than 15 million years. Older C 4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C 4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C 4 species is presented. Over the next 50 years, preservation of the Earth's C 4 diversity is a concern, largely because of habitat loss due to elevated CO 2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C 4 Hall of Fame are leading threats to the natural C 4 flora due to their association with human activities on landscapes where most C 4 plants occur. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Greenhouse Gas Source Detection and Attribution in the San Francisco Bay Area of California Using a Mobile Measurement Platform

NASA Astrophysics Data System (ADS)

Martien, P. T.; Guha, A.; Newman, S.; Young, A.; Bower, J.; Perkins, I.; Randall, S.; Stevenson, E.; Hilken, H.

2017-12-01

The Bay Area Air Quality Management District, the San Francisco Bay Area's air quality regulatory agency, has set a goal to reduce the region's greenhouse gas (GHG) emissions 80% below 1990 levels by 2050, consistent with the State of California's climate goals. Recently, the Air District's governing board adopted a 2017 Clean Air Plan advancing the agency's vision and including actions to put the region on a path to achieving the 2050 goal while also reducing air pollution and related health impacts. The Plan includes GHG rule-making efforts, policy initiatives, local government partnerships, outreach, grants and incentives, encompassing over 250 specific implementation actions across all economic sectors to effect ambitious emission reductions in the region. To support the 2017 Plan, the Air District has built a mobile measurement platform (GHG research van) to perform targeted CH4 emissions hotspot detection and source attribution. Instruments in the van measure CH4, CO2 and N2O in ambient plumes. Coincident measurements of source tracers like isotopic methane (13C - CH4), CO and ethane (C2H6) provide the capability to distinguish between biogenic, combustion-based and fossil-based fugitive methane sources. We report observations of CH4 plumes from source-specific measurements in and around facilities including a wastewater treatment plant, a composting operation, a waste-to-energy anaerobic digestion plant and a few refineries. We performed leak surveys inside several electric utility-operated facilities including a power plant and an underground natural gas storage facility. We sampled exhaust from a roadway tunnel and computed fleet-averaged automobile-related CH4 and N2O emission factors. We used tracer-to-tracer emission ratios to create chemical signatures of emissions from each sampled source category. We compare measurement-based ratios with those used to derive the regional GHG inventory. Data from these and other sources will lead to an improved understanding of GHG emissions from well- and lesser-known CH4 sources in the region, key to resolving the differences between top-down estimates (Fairley and Fischer, 2015; Jeong et al., 2016) and the regional bottom-up inventory.

Bundle Sheath Diffusive Resistance to CO2 and Effectiveness of C4 Photosynthesis and Refixation of Photorespired CO2 in a C4 Cycle Mutant and Wild-Type Amaranthus edulis1

PubMed Central

Kiirats, Olavi; Lea, Peter J.; Franceschi, Vincent R.; Edwards, Gerald E.

2002-01-01

A mutant of the NAD-malic enzyme-type C4 plant, Amaranthus edulis, which lacks phosphoenolpyruvate carboxylase (PEPC) in the mesophyll cells was studied. Analysis of CO2 response curves of photosynthesis of the mutant, which has normal Kranz anatomy but lacks a functional C4 cycle, provided a direct means of determining the liquid phase-diffusive resistance of atmospheric CO2 to sites of ribulose 1,5-bisphosphate carboxylation inside bundle sheath (BS) chloroplasts (rbs) within intact plants. Comparisons were made with excised shoots of wild-type plants fed 3,3-dichloro-2-(dihydroxyphosphinoyl-methyl)-propenoate, an inhibitor of PEPC. Values of rbs in A. edulis were 70 to 180 m2 s−1 mol−1, increasing as the leaf matured. This is about 70-fold higher than the liquid phase resistance for diffusion of CO2 to Rubisco in mesophyll cells of C3 plants. The values of rbs in A. edulis are sufficient for C4 photosynthesis to elevate CO2 in BS cells and to minimize photorespiration. The calculated CO2 concentration in BS cells, which is dependent on input of rbs, was about 2,000 μbar under maximum rates of CO2 fixation, which is about six times the ambient level of CO2. High re-assimilation of photorespired CO2 was demonstrated in both mutant and wild-type plants at limiting CO2 concentrations, which can be explained by high rbs. Increasing O2 from near zero up to ambient levels under low CO2, resulted in an increase in the gross rate of O2 evolution measured by chlorophyll fluorescence analysis in the PEPC mutant; this increase was simulated from a Rubisco kinetic model, which indicates effective refixation of photorespired CO2 in BS cells. PMID:12376660

N-C isotopic investigation of a zeolite-amended agricultural field

NASA Astrophysics Data System (ADS)

Ferretti, Giacomo; Natali, Claudio; Faccini, Barbara; Di Giuseppe, Dario; Bianchini, Gianluca; Coltorti, Massimo

2016-04-01

In this study, a C and N isotopic investigation in the soil-plant system of the ZeoLIFE project experimental field have been carried out. Since many years, natural and NH4-enriched zeolites have been used as soil amendant in agricultural context in order to reduce N losses, increase NUE (Nitrogen Use Efficiency) and crop yield. Nevertheless up to now there are no studies that, using the stable isotopes approach, highlighted the interaction between zeolites and plants in agricultural systems. The main aims of this study is to verify if natural zeolites amendment can enhance chemical fertilization efficiency and if N transfer from NH4-enriched zeolites to plants really occurs. Plants grown following traditional cultivation methods (with no zeolite addition) and plants grown on soils amended with natural and NH4-enriched zeolites (the latter obtained after mixing with pig-slurry with a very high 15N) were compared for two cultivation cycles (maize and wheat). As widely known, plants grown under conventional farming systems (use of chemical fertilizers as urea) and plants grown under organic farming can be discriminated by the isotopic signatures of plant tissues. For both years the main results of the study reveals that plants grown on plots amended with natural zeolites generally have their nitrogen isotopic signature more similar to that of the chemical fertilizers employed during the cultivation with respect to the plants cultivated in the non-amended plot. This suggests an enhanced N uptake by the plant from this specific N source with respect to the non-amended plot. On the other hand, plants grown on NH4-enriched zeolites registered a higher 15N, approaching the pig-slurry isotopic signature, confirming that this material can constitute an N pool for plants at least for two cultivation cycles. The distinct agricultural practices seem to be reflected in the plant physiology as recorded by the carbon discrimination factor (13C) which generally increases in plots amended with natural zeolites indicating better water/nutrient conditions. At similar N availability it seems that plant prefer to use natural N from pig slurry instead of using that coming from chemical fertilizers.

Long-chain (C19-C29) 1-chloro-n-alkanes in leaf waxes of halophytes of the Chenopodiaceae.

PubMed

Grossi, Vincent; Raphel, Danielle

2003-07-01

The hydrocarbon fraction of leaf waxes of three halophytes of the Chenopodiaceae common to Mediterranean salt marshes (Suaeda vera, Sarcocornia fruticosa and Halimione portulacoides) revealed the presence of a minor series of odd and even chains 1-chloro-n-alkanes ranging from C(19) to C(29). The identification of these new chlorinated plant constituents was based on a combination of mass spectrometry data with selective chlorine detection (CPG-AED) and was confirmed by comparison with authentic standards. The qualitative and quantitative distributions of these 1-chloro-n-alkanes varied inter-specifically. Homologues with an odd carbon-chain were predominant in all species but maximised at C(25) and C(27) in S. vera and S. fruticosa, and at C(27) and C(29) in H. portulacoides. Remarkably, 1-chloro-nonacosane was an abundant homologue only in this latter species. Leaves of S. vera contained 4 to 7 times more of total chloroalkanes than leaves of the other two species. These compounds accounted for 10, 4 and 1% of the hydrocarbon fraction of leaf waxes of S. vera, S. fruticosa and H. portulacoides, respectively. Attempts to link the occurrence of these chloroalkanes with other classes of leaf waxes (n-alkenes, n-aldehydes and n-alcohols) did not allowed a clear precursor-product relationship to be established. The biological functions as well as the mode of synthesis of alkylchlorides in (halophyte) plants remain unknown but undoubtedly deserve further attention.

Oral Vaccination Against Anthrax Using a Transgenic Plant Expressing Protective Antigen.

DTIC Science & Technology

1996-09-01

unpublished results). In Phase II, development of a tomato -based system for edible vaccine delivery will be carried out in parallel with experiments testing...Frederick, MD 21702-5012. AUTHORITY USAMRMC ltr, 4 Dec 2002 THIS PAGE IS UNCLASSIFIED AD CONTRACT NUMBER: DAMD17-95-C-5102 TITLE: Oral Vaccination ...COVERED I September 1996 Final - Phase I, 15 Auxg 95-14 Aug 96 4. TITLE AND 9UBTITLE 5. FUNDING NUMBERS Oral Vaccination Against Anthrax Using a Transgenic

Stable Carbon Isotope Ratios of Individual Pollen Grains as a Proxy for C3- Versus C4-Grass Abundance in Paleorecords: A Validation Study

NASA Astrophysics Data System (ADS)

Nelson, D. M.; Hu, F.; Pearson, A.

2007-12-01

C3 and C4 grasses have distinct influences on major biogeochemical processes and unique responses to important environmental controls. Difficulties in distinguishing between these two functional groups of grasses have hindered paleoecological studies of grass-dominated ecosystems. We recently developed a technique to analyze the stable carbon isotope composition of individual grass-pollen grains using a spooling- wire microcombustion device interfaced with an isotope-ratio mass spectrometer (Nelson et al. 2007). This technique holds promise for improving C3 and C4 grass reconstructions. It requires ~90% fewer grains than typical methods and avoids assumptions associated with mixing models. However, our previous work was based on known C3 and C4 grasses from herbarium specimens and field collections and the technique had not been test using geological samples. To test the ability of this technique to reproduce the abundance of C3 and C4 grasses on the landscape, we measured δ13C values of >1500 individual grains of grass pollen isolated from the surface sediments of 10 North American lakes that span a large gradient of C3 and C4 grass abundance. Results indicate a strong positive correlation (r=0.94) between % C4-grass pollen (derived from classifying δ13C values from single grains as C3 and C4) and the literature-reported abundance of C4 grasses on the landscape. However, the measured % C4-grass pollen shows some deviation from the actual abundance at sites with high proportions of C4 grasses. This is likely caused by uncertainty in the magnitude, composition, and variability of the analytical blank associated with these measurements. Correcting for this deviation using regression analysis improves the estimation of the abundance of C4 grasses on the landscape. Comparison of the % C4-grass pollen with C/N and δ13C measurements of total organic matter in the same lake-sediment samples illustrates the distinct advantage of grass-pollen δ13C as a proxy for distinguishing C3 and C4 shifts. At 9 of the 10 sites C/N values indicate that surface-sediment organic matter was derived primarily from aquatic production. At the one site where organic matter was produced primarily by vascular plants the δ13C value (-29.3°) suggests organic matter derived exclusively from C3 plants. However, ~80% of the grasses on the landscape at this site are C4 grasses. The C3- like bulk-sediment δ13C value likely represents woody species, which comprise >90% of the pollen spectra. Thus δ13C analysis of single grains of grass pollen offers a new tool to classify grass pollen into two major functional groups and promises to advance our understanding of grassland ecology and evolution. Reference Nelson, D.M., Hu, F.S., Mikucki, J., Tian, J., and Pearson, A., 2007, Carbon isotopic analysis of individual pollen grains from C3 and C4 grasses using a spooling wire microcombustion interface: Geochimica et Cosmochimica Acta, v. 71, p. 4005-4014.

Increased belowground C release during initial plant development of Populus deltoides x nigra grown under light and C reserve limited conditions

NASA Astrophysics Data System (ADS)

Studer, Mirjam S.; Siegwolf, Rolf T. W.; Schmidt, Michael W. I.; Abiven, Samuel

2014-05-01

Plants might be a key factor for the long-term stabilisation of carbon (C) in the soil, e.g. through enhanced physical protection of root-derived C against microbial decomposition in soil aggregates. On the other hand C released by the plants into the soil might promote the decomposition of native soil organic matter (SOM) through the stimulation of microbial activity. We measured the C budget of developing plant-soil systems (Populus deltoides x nigra, Cambisol soil) in the laboratory under controlled environmental conditions. In order to distinguish plant-derived from native C in the SOM and the soil CO2 efflux, we labelled the poplar shoots continuously with 13C-CO2 from first emergence of leaves (sprouting from stem cuttings). Throughout the experiment the CO2 fluxes (photosynthetic assimilation, dark respiratory loss, soil CO2 efflux) were measured frequently (every 30 min) and the 13C was traced in the soil CO2 efflux (1-2 times a week). After 10 weeks the plant-soil systems were destructively harvested and the distribution of the 13C distribution was analysed. The plants developed slowly (compared to previous experiments), most likely due to limitation in C reserves (long term cutting storage) and C supply (low light intensities). The amount of 13C recovered in the roots, microbial biomass and soil CO2 efflux was directly correlated with the leaf area of the different plant individuals. After 3-4 weeks of plant development we observed a high peak in the total soil CO2 efflux. During this time the relative belowground C release was increased massively over the basal rate of 17 % of net C assimilated, whereby the variability between the plant individuals was large. The smallest plants, i.e. the plants that were most resource limited, obtained the highest belowground C release accounting at the peak time for up to 57 % of net assimilated C. We hypothesize that the plants released specific compounds, which either directly (enzymatically) or indirectly (priming) enhanced the decomposition of native SOM as a survival mechanisms (e.g. mine for nutrients). The results of this study confirm linear correlations between aboveground plant traits (leaf area) and belowground C allocation into roots, microbial biomass and plant-derived respiration. However it also highlights that plant-soil systems are not permanently in a steady state. C allocation patterns can change massively when the plant is under stress, which affects other fluxes within the terrestrial C cycle, such as the microbial decomposition of SOM.

A New Metabolite with a unique 4-pyranone-ylactam-1,4-thiazine moiety from a Hawaiian-plant associated fungus

USDA-ARS?s Scientific Manuscript database

An endophytic fungus Paraphaeosphaeria neglecta FT462 isolated from the Hawaiian-plant Lycopodiella cernua (L.) Pic. Serm produced one unusual compound (1, paraphaeosphaeride A) with the 4-pyranone-'-lactam-1,4-thiazine moiety, along with two new compounds (2 and 3, paraphaeosphaerides B and C, resp...

Biodiversity, photosynthetic mode, and ecosystem services differ between native and novel ecosystems.

PubMed

Martin, Leanne M; Polley, H Wayne; Daneshgar, Pedram P; Harris, Mary A; Wilsey, Brian J

2014-06-01

Human activities have caused non-native plant species with novel ecological interactions to persist on landscapes, and it remains controversial whether these species alter multiple aspects of communities and ecosystems. We tested whether native and exotic grasslands differ in species diversity, ecosystem services, and an important aspect of functional diversity (C3:C4 proportions) by sampling 42 sites along a latitudinal gradient and conducting a controlled experiment. Exotic-dominated grasslands had drastically lower plant diversity and slightly higher tissue N concentrations and forage quality compared to native-dominated sites. Exotic sites were strongly dominated by C4 species at southern and C3 species at northern latitudes with a sharp transition at 36-38°, whereas native sites contained C3:C4 mixtures. Large differences in C3:C4 proportions and temporal niche partitioning were found between native and exotic mixtures in the experiment, implying that differences in C3:C4 proportions along the latitudinal gradient are caused partially by species themselves. Our results indicate that the replacement of native- by exotic-dominated grasslands has created a management tradeoff (high diversity versus high levels of certain ecosystem services) and that models of global change impacts and C3/C4 distribution should consider effects of exotic species.

Determination of the 13C/12C ratio of ethanol derived from fruit juices and maple syrup by isotope ratio mass spectrometry: collaborative study.

PubMed

Jamin, Eric; Martin, Frédérique; Martin, Gilles G

2004-01-01

A collaborative study of the carbon-13 isotope ratio mass spectrometry (13C-IRMS) method based on fermentation ethanol for detecting some sugar additions in fruit juices and maple syrup is reported. This method is complementary to the site-specific natural isotope fractionation by nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in the same products (AOAC Official Methods 995.17 and 2000.19), and uses the same initial steps to recover pure ethanol. The fruit juices or maple syrups are completely fermented with yeast, and the alcohol is distilled with a quantitative yield (>96%). The carbon-13 deviation (delta13C) of ethanol is then determined by IRMS. This parameter becomes less negative when exogenous sugar derived from plants exhibiting a C4 metabolism (e.g., corn or cane) is added to a juice obtained from plants exhibiting a C3 metabolism (most common fruits except pineapple) or to maple syrup. Conversely, the delta13C of ethanol becomes more negative when exogenous sugar derived from C3 plants (e.g., beet, wheat, rice) is added to pineapple products. Twelve laboratories analyzed 2 materials (orange juice and pure cane sugar) in blind duplicate and 4 sugar-adulterated materials (orange juice, maple syrup, pineapple juice, and apple juice) as Youden pairs. The precision of that method for measuring delta13C was similar to that of other methods applied to wine ethanol or extracted sugars in juices. The within-laboratory (Sr) values ranged from 0.06 to 0.16%o (r = 0.17 to 0.46 percent per thousand), and the among-laboratories (SR) values ranged from 0.17 to 0.26 percent per thousand (R = 0.49 to 0.73 percent per thousand). The Study Directors recommend that the method be adopted as First Action by AOAC INTERNATIONAL.

Mapping of a major QTL for salt tolerance of mature field-grown maize plants based on SNP markers.

PubMed

Luo, Meijie; Zhao, Yanxin; Zhang, Ruyang; Xing, Jinfeng; Duan, Minxiao; Li, Jingna; Wang, Naishun; Wang, Wenguang; Zhang, Shasha; Chen, Zhihui; Zhang, Huasheng; Shi, Zi; Song, Wei; Zhao, Jiuran

2017-08-15

Salt stress significantly restricts plant growth and production. Maize is an important food and economic crop but is also a salt sensitive crop. Identification of the genetic architecture controlling salt tolerance facilitates breeders to select salt tolerant lines. However, the critical quantitative trait loci (QTLs) responsible for the salt tolerance of field-grown maize plants are still unknown. To map the main genetic factors contributing to salt tolerance in mature maize, a double haploid population (240 individuals) and 1317 single nucleotide polymorphism (SNP) markers were employed to produce a genetic linkage map covering 1462.05 cM. Plant height of mature maize cultivated in the saline field (SPH) and plant height-based salt tolerance index (ratio of plant height between saline and control fields, PHI) were used to evaluate salt tolerance of mature maize plants. A major QTL for SPH was detected on Chromosome 1 with the LOD score of 22.4, which explained 31.2% of the phenotypic variation. In addition, the major QTL conditioning PHI was also mapped at the same position on Chromosome 1, and two candidate genes involving in ion homeostasis were identified within the confidence interval of this QTL. The detection of the major QTL in adult maize plant establishes the basis for the map-based cloning of genes associated with salt tolerance and provides a potential target for marker assisted selection in developing maize varieties with salt tolerance.

Similar cholesterol-lowering properties of rice bran oil, with varied gamma-oryzanol, in mildly hypercholesterolemic men.

PubMed

Berger, Alvin; Rein, Dietrich; Schäfer, Angela; Monnard, Irina; Gremaud, Gérard; Lambelet, Pierre; Bertoli, Constantin

2005-03-01

The cholesterol lowering properties of rice bran oil (RBO) containing differing amounts of non-saponifiable components have not been studied in humans, to our knowledge. To evaluate cholesterol lowering effects of RBO, with low and high amounts of gamma-oryzanol (ferulated plant sterols) in mildly hypercholesterolemic men. Mildly hypercholesterolemic men, 38-64 y, starting cholesterol 4.9-8.4 mmol/l (n = 30), consumed 50 g/d peanut oil (PNO) in vehicles for 2 wks during a run-in period, then, without wash-out, were randomly equilibrated (based on initial level of cholesterol) into two groups to consume 50 g/d RBO low (0.05 g/d) or high (0.8 g/d) gamma-oryzanol for 4 wks, in a randomized, controlled, parallel design study. Subjects were free-living and consumed habitual diets with some restrictions. Plasma concentrations of total, LDL-,HDL-cholesterol and triacylglycerol were measured at base line and after 2, 4, and 6 wks. The two RBO types were not significantly different with respect to effects on various cholesterol parameters, at 2 and 4 wks, including total cholesterol, LDL-, HDL- and LDL/HDL cholesterol ratio. Low and high gamma-oryzanolcontaining RBO feeding for 4 wks lowered total plasma cholesterol (6.3 %), LDL-C (10.5 %) and the LDL-C/HDL-C ratio (18.9 %). RBO supplementation at ca. 50% total fat intake improved lipoprotein pattern in mildly hypercholesterolemic men. Methylated sterols in gamma-oryzanol are thought to be largely ineffective at inhibiting dietary cholesterol absorption, but could enhance cholesterol-lowering ability of 4-desmethylsterols. Assuming all ferulated sterols become de-ferulated in the gut, low and high gamma-oryzanolcontaining RBOs provided intestinal loads of 453 and 740 mg/d free 4-desmethylsterols, respectively. This intestinal load of 453-740 mg/d of efficacious free plant sterol equivalents had identical effects on lipoproteins.

Improving Photosynthesis

PubMed Central

Evans, John R.

2013-01-01

Photosynthesis is the basis of plant growth, and improving photosynthesis can contribute toward greater food security in the coming decades as world population increases. Multiple targets have been identified that could be manipulated to increase crop photosynthesis. The most important target is Rubisco because it catalyses both carboxylation and oxygenation reactions and the majority of responses of photosynthesis to light, CO2, and temperature are reflected in its kinetic properties. Oxygenase activity can be reduced either by concentrating CO2 around Rubisco or by modifying the kinetic properties of Rubisco. The C4 photosynthetic pathway is a CO2-concentrating mechanism that generally enables C4 plants to achieve greater efficiency in their use of light, nitrogen, and water than C3 plants. To capitalize on these advantages, attempts have been made to engineer the C4 pathway into C3 rice (Oryza sativa). A simpler approach is to transfer bicarbonate transporters from cyanobacteria into chloroplasts and prevent CO2 leakage. Recent technological breakthroughs now allow higher plant Rubisco to be engineered and assembled successfully in planta. Novel amino acid sequences can be introduced that have been impossible to reach via normal evolution, potentially enlarging the range of kinetic properties and breaking free from the constraints associated with covariation that have been observed between certain kinetic parameters. Capturing the promise of improved photosynthesis in greater yield potential will require continued efforts to improve carbon allocation within the plant as well as to maintain grain quality and resistance to disease and lodging. PMID:23812345

Nutrient dynamics and plant assemblages of Macrotermes falciger mounds in a savanna ecosystem

NASA Astrophysics Data System (ADS)

Muvengwi, Justice; Ndagurwa, Hilton G. T.; Nyenda, Tatenda; Mbiba, Monicah

2016-10-01

Termites through mound construction and foraging activities contribute significantly to carbon and nutrient fluxes in nutrient-poor savannas. Despite this recognition, studies on the influence of termite mounds on carbon and nitrogen dynamics in sub-tropical savannas are limited. In this regard, we examined soil nutrient concentrations, organic carbon and nitrogen mineralization in incubation experiments in mounds of Macrotermes falciger and surrounding soils of sub-tropical savanna, northeast Zimbabwe. We also addressed whether termite mounds altered the plant community and if effects were similar across functional groups i.e. grasses, forbs or woody plants. Mound soils had significantly higher silt and clay content, pH and concentrations of calcium (Ca), magnesium (Mg), potassium (K), organic carbon (C), ammonium (NH4+) and nitrate (NO3-) than surrounding soils, with marginal differences in phosphorus (P) and sodium (Na) between mounds and matrix soils. Nutrient enrichment increased by a factor ranging from 1.5 for C, 4.9 for Mg up to 10.3 for Ca. Although C mineralization, nitrification and nitrification fraction were similar between mounds and matrix soils, nitrogen mineralization was elevated on mounds relative to surrounding matrix soils. As a result, termite mounds supported unique plant communities rich and abundant in woody species but less diverse in grasses and forbs than the surrounding savanna matrix in response to mound-induced shifts in soil parameters specifically increased clay content, drainage and water availability, nutrient status and base cation (mainly Ca, Mg and Na) concentration. In conclusion, by altering soil properties such as texture, moisture content and nutrient status, termite mounds can alter the structure and composition of sub-tropical savanna plant communities, and these results are consistent with findings in other savanna systems suggesting that increase in soil clay content, nutrient status and associated changes in the plant community assemblage may be a general property of mound building termites.

Ecological differences in three autochthonous equid species in Mongolian Gobi inferred from stable isotopes in tail hair

NASA Astrophysics Data System (ADS)

Burnik Šturm, Martina; Voigt, Christian C.; Oyunsaikhan, Ganbaatar; Kaczensky, Petra

2014-05-01

In the Dzungarian Gobi of Mongolia three equid species, Asiatic wild ass (Equus hemionus), domestic horse (Equus caballus), and re-introduced Przewalski's horse (Equus ferus przewalskii) share the same habitat and thus provide a unique opportunity for comparative ecological studies. In our project we use the stable isotope analysis of tail hair as a tool to study feeding ecology, water use and movement pattern of the three extant sympatric equid species to reveal species specific differences and thus strengthen our understanding of the ecological adaptations of the three species to the harsh environment of the Gobi desert. Since tail hair grow continuously and is isotopically inert after formation, when sampled and analysed longitudinally, provides temporary explicit information on dietary regime and movement pattern. We use the carbon isotopes in the tail hair to determine the quantitative dependence of each animal on isotopically distinct C3 (grasses) and C4 (multitude of annuals and perennials) diet. Nitrogen isotopes reflect the isotopic composition of the diet and hydrogen isotopes reflect the isotopic composition of the water that animals utilize, while both elements have been reported to also give information on the physical status of the animal. Combined isotope data will be used to describe the movement patterns and habitat use of the three equid species. We will present the methodology and first preliminary results of carbon and nitrogen isotope analysis of potential forage plants of the study area and of the tail hair analysis. Among the analysed plants, collected in the pilot sampling campaign in 2012 (n = 192), we identified 14 C3 and two C4species and found no general trend that could explain the effect of altitude on carbon isotopic composition in C3 plants and no correlation between carbon isotopic composition and longitude or latitude. We performed additional, more detailed plant sampling in 2013. The first results obtained from the tail hair analysis indicate differences in feeding preferences between extant wild asses (n = 6) and Przewalski's (n = 6) and domestic horses (n = 6). While wild asses switch regularly between periods with predominantly feeding on C3 diet with low incorporation of C4 diet (wet season) and periods with high incorporation of C4 (dry season) diet, Przewalski's and domestic horses predominantly feed on C3 plant diet but seem to also include C4plants in their diet during extreme conditions (i.e. extremely harsh winters).

Enhanced algae removal by Ti-based coagulant: comparison with conventional Al- and Fe-based coagulants.

PubMed

Xu, Jie; Zhao, Yanxia; Gao, Baoyu; Zhao, Qian

2018-05-01

The water eutrophication caused by cyanobacteria seasonally proliferates, which is a hot potato to be resolved for water treatment plants. This study firstly investigated coagulation performance of titanium tetrachloride (TiCl 4 ) for Microcystis aeruginosa synthetic water treatment. Results show complete algal cell removal by TiCl 4 coagulation without damage to cell membrane integrity even under harsh conditions; 60 mg/L TiCl 4 was effective in removing the microcystins up to 85%. Furthermore, besides having stronger UV 254 removal capability and the higher removal of fluorescent substances over Al- and Fe-based coagulants, TiCl 4 coagulant required more compact coagulation and sedimentation tanks due to its significantly improved floc growth and sedimentation speed. Meanwhile, its' short hydraulic retention time avoided algal cell breakage and subsequent algal organic matter release. Microcystin concentrations were kept at a low level during sludge storage period, indicating that the TiCl 4 flocs could prevent algal cells from natural lysis. To facilitate water recycling without secondary contamination, the algae-containing sludge after TiCl 4 coagulation ought to be disposed within 12 days at 20 °C and 8 days at 35 °C.

Carbon, Hydrogen, and Oxygen Isotope Ratios of Cellulose from Plants Having Intermediary Photosynthetic Modes 1

PubMed Central

Sternberg, Leonel O'Reilly; Deniro, Michael J.; Ting, Irwin P.

1984-01-01

Carbon and hydrogen isotope ratios of cellulose nitrate and oxygen isotope ratios of cellulose from species of greenhouse plants having different photosynthetic modes were determined. When hydrogen isotope ratios are plotted against carbon isotope ratios, four clusters of points are discernible, each representing different photosynthetic modes: C3 plants, C4 plants, CAM plants, and C3 plants that can shift to CAM or show the phenomenon referred to as CAM-cycling. The combination of oxygen and carbon isotope ratios does not distinguish among the different photosynthetic modes. Analysis of the carbon and hydrogen isotope ratios of cellulose nitrate should prove useful for screening different photosynthetic modes in field specimens that grew near one another. This method will be particularly useful for detection of plants which show CAM-cycling. PMID:16663360

Effects of Down- and Up-regulated Lignin Biosynthesis in Populus of Soil Carbon Transformation and Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiang, Vincent, L.; Pregitzer, Kurt, S.

2010-03-30

Our objective is to understand how rates of soil C formation and plant biomass are influenced by changes in plant growth and performance resulting from lowered lignin and altered lignin S/G ratios. A greenhouse study of the effects of altered lignin in SOC formation and plant biomass has been completed as of November 2009. Wild-type (control) and three transgenic aspen lines expressing reduced stem lignin concentrations and/or increased syringyl (S) to guaiacyl (G) ratio lignin were grown in greenhouse mesocosms. Soil was collected from the Colorado Central Plains Experimental Range (CPER) northeast of Fort Collins, Colorado. The Colorado soil ismore » an Olney fine sandy loam (fine-loamy, mixed, superactive, mesic Ultic Haplargrid). Plants at the surface mineral soil up to 5 cm depth were removed and the underlying soil was sampled to a depth of 30 cm. Soils were immediately shipped to Reno, NV. This C4 soil was then used to trace belowground C inputs by the C3 plants into the soil using the 13C natural abundance methods as described in the DOE proposal. Transgenic quaking aspen were generated by the Forest Biotechnology Group at North Carolina State University (NCSU) using Agrobacterium-mediated transformation, the seedlings were then shipped to Reno, NV. Rooted seedlings were transferred from sterile agar into small pots with 250 g of C4 grass-dominated soil and kept in mist chambers in a greenhouse for four to six weeks. Plants were arranged randomly in adjacent greenhouse benches, soil blanks were placed randomly among the plants and treated in the same manner as pots with plants. Growth measurements were conducted for all plants in both groups and consisted of height, width at base of stem, number of leaves and length and width of every leaf in every tree. Plants were grown for a period of 120-140 days. At harvest, the aboveground portions of the trees were separated into leaves, litter, and stems. Soils were immediately frozen after harvest and roots were subsequently removed from thawed soil. Roots were further separated into coarse (> 1mm) and fine (< 1mm) roots. All tissue samples were dried for 48 h at 65 ºC, weighed, and then milled for analysis. Fine roots were analyzed for C and N concentrations and 13C (± 0.25‰). All other plant tissues were analyzed for C and N concentrations. Soils were analyzed for available soil nutrients, after harvest and root extraction, soils (including soil blanks pots) were analyzed for C and N concentrations and 13C using the same procedure as the fine roots. Growth measurements from both experiments showed that plant lines differed in heights, number of leaves, total biomass, and total leaf area; but did not differ in average leaf size or stem width. The low lignin line (23) and the control line (271) were similar to each other for all measured characteristics and were significantly larger than the low lignin + high S/G ratio lines (72 and 75). C/N ratios were highest for low lignin plants (line 23) in the woody tissue (roots and stems). The soil C concentrations and total C contents in the soil did not vary significantly among lines. There were no significant difference among lines in the amount (g) of new soil C, however, the soil from the control line (271) and low lignin line (23) had the highest new C concentration and total new C input into the soil. All soils with plants lost some of the existing “old” C, but the loss of old C was not significantly different among lines. Our findings support our first hypothesis, that high S/G ratio lines (72, 75, and 93) have less biomass, and soil C formation is affected as a result of the lower biomass. Our second hypothesis, that low lignin lines (23) would have more biomass and greater soil C formation, was partially supported. Although line 23 did not significantly out-perform the control line (271), the values for all measured growth and soil C characteristics were either comparable or greater than those for 271. The second part of this hypothesis, that line 23 would mobilize more old soil C and alter C/N ratios, was only partially supported by our data. Line 23 did not mobilize more old soil C, but the woody tissue C/N ratios were significantly higher than other lines, suggesting that tissue from line 23 plants is possibly more recalcitrant to decomposition. The comparable performance to the control lines coupled with the reduced lignin in the wood structure gives line 23 an advantage over line 271 in terms of pulping efficiency. The higher C/N ratios in the woody tissue could also suggest it has an advantage for C sequestration in tissue.« less

75 FR 13909 - Endangered and Threatened Wildlife and Plants; 12-Month Findings for Petitions to List the...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-23

...) of the Act (16 U.S.C. 1531 et seq.), requires that, for any petition containing substantial...) warranted, or (c) warranted, but that immediate proposal of a regulation implementing the petitioned action... and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we treat a petition...

The fate of the herbicide propanil in plants of the littoral zone of the Three Gorges Reservoir (TGR), China.

PubMed

Chen, Zhongli; Schäffer, Andreas

2016-10-01

The anti-seasonal hydrology with 30m water fluctuations in the Three Gorges Reservoir (TGR) of China attracts growing environmental and ecological concerns. We investigated the biotransformation of the herbicide propanil in plants dominating in the littoral zone of the TGR by applying the 14 C-ring-labeled herbicide into non-aseptic hydroponic plant systems (Cynodon dactylon, Nelumbo nucifera and Bidens pilosa), aseptic plants (Lemna minor and Lemna gibba) and cell suspension cultures (C. dactylon and L. minor). (1) Propanil absorbed in plants of the hydroponic systems was (12.46±1.63)% of applied radioactivity (AR) (C. dactylon), (52.36±6.38)% (N. nucifera) and (76.55±6.07)% (B. pilosa), respectively. The 14 C-residues in the plant extractable fractions and the corresponding media were confirmed by radio-Thin Layer Chromatography (TLC), radio-High Performance Liquid Chromatography (HPLC) and Gas Chromatography-Electron Ionization Mass Spectrometry (GC-EIMS) as propanil, 3,4-dichloroaniline (DCA) and N-(3,4-dichlorophenyl)-β-d-glucopyranosylamine (Glu-DCA). (2) About 8% of AR was taken up by both aseptic plants, from which 7.0% of AR was extracted and identified also as propanil, DCA and Glu-DCA. (3) Concerning cell suspension cultures, (39.22±9.39)% of AR was absorbed by C. dactylon after 72hr, whereas the accumulated 14 C-propanil by L. minor cell suspension culture amounted to (65.04±1.72)% after 7days. The identified compounds in cell cultures are consistent with those in the tested plants. Most of the pesticide residues in the intact plants were un-extractable, which are recognized as the end of the detoxification process. We therefore consider these plants as suitable for the phytoremediation of the herbicide propanil in the TGR region. Copyright © 2016. Published by Elsevier B.V.

Allocate carbon for a reason: priorities are reflected in the ¹³C/¹²C ratios of plant lipids synthesized via three independent biosynthetic pathways.

PubMed

Zhou, Youping; Stuart-Williams, Hilary; Grice, Kliti; Kayler, Zachary E; Zavadlav, Saša; Vogts, Angela; Rommerskirchen, Florian; Farquhar, Graham D; Gessler, Arthur

2015-03-01

It has long been theorized that carbon allocation, in addition to the carbon source and to kinetic isotopic effects associated with a particular lipid biosynthetic pathway, plays an important role in shaping the carbon isotopic composition ((13)C/(12)C) of lipids (Park and Epstein, 1961). If the latter two factors are properly constrained, valuable information about carbon allocation during lipid biosynthesis can be obtained from carbon isotope measurements. Published work of Chikaraishi et al. (2004) showed that leaf lipids isotopic shifts from bulk leaf tissue Δδ(13)C(bk-lp) (defined as δ(13)C(bulkleaftissue)-δ(13)C(lipid)) are pathway dependent: the acetogenic (ACT) pathway synthesizing fatty lipids has the largest isotopic shift, the mevalonic acid (MVA) pathway synthesizing sterols the lowest and the phytol synthesizing 1-deoxy-D-xylulose 5-phosphate (DXP) pathway gives intermediate values. The differences in Δδ(13)C(bk-lp) between C3 and C4 plants Δδ(13)C(bk-lp,C4-C3) are also pathway-dependent: Δδ(13)C(ACT)(bk-lp,C4-C3) > Δδ(13)C(DXP(bk-lp,C4-C3) > Δδ(13)C(MVA)(bk-lp,C4-C3). These pathway-dependent differences have been interpreted as resulting from kinetic isotopic effect differences of key but unspecified biochemical reactions involved in lipids biosynthesis between C3 and C4 plants. After quantitatively considering isotopic shifts caused by (dark) respiration, export-of-carbon (to sink tissues) and photorespiration, we propose that the pathway-specific differences Δδ(13)C(bk-lp,C4-C3) can be successfully explained by C4-C3 carbon allocation (flux) differences with greatest flux into the ACT pathway and lowest into the MVA pathways (when flux is higher, isotopic shift relative to source is smaller). Highest carbon allocation to the ACT pathway appears to be tied to the most stringent role of water-loss-minimization by leaf waxes (composed mainly of fatty lipids) while the lowest carbon allocation to the MVA pathway can be largely explained by the fact that sterols act as regulatory hormones and membrane fluidity modulators in rather low concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Economics of Third-Party Central Heating Plants to Supply the Army

DTIC Science & Technology

1992-01-01

Third-Party Gas-Fired Boiler Economics 52 APPENDIX C: Third-Party Gas Turbine Cogeneration Economics ( PURPA ) 58 APPENDIX D: Government Gas Turbine...Turbine Cogeneration Economics (Installation and PURPA Purchase) 76 APPENDIX G: Checklist for Identifying Optimal Third-Party Projects and Bidders 82...of scale 37 4 Relative costs of thermal energy from third-party cogeneration plants (@ 4C/kWh PURPA payment) 38 5 Comparison of life-cycle costs for

Transcript Quantification of Genes Involved in Steviol Glycoside Biosynthesis in Stevia rebaudiana Bertoni by Real-Time Polymerase Chain Reaction (RT-PCR).

PubMed

Modi, Arpan; Kumar, Nitish; Narayanan, Subhash

2016-01-01

Stevia (Stevia rebaudiana Bertoni) is a medicinal plant having sweet, diterpenoid glycosides known as steviol glycosides which are 200-300 times sweeter than sucrose (0.4 % solution). They are synthesized mainly in the leaves via plastid localized 2-C-methyl-D-erythrose-4-phosphate pathway (MEP pathway). Fifteen genes are involved in the formation of these glycosides. In the present protocol, a method for the quantification of transcripts of these genes is shown. The work involves RNA extraction and cDNA preparation, and therefore, procedures for the confirmation of DNA-free cDNA preparation have also been illustrated. Moreover, details of plant treatments are not mentioned as this protocol may apply to relative gene expression profile in any medicinal plant with any treatment. The treatments are numbered as T0 (Control), T1, T2, T3, and T4.

Leaf wax n-alkane distributions in and across modern plants: Implications for paleoecology and chemotaxonomy

NASA Astrophysics Data System (ADS)

Bush, Rosemary T.; McInerney, Francesca A.

2013-09-01

Long chain (C21 to C37) n-alkanes are among the most long-lived and widely utilized terrestrial plant biomarkers. Dozens of studies have examined the range and variation of n-alkane chain-length abundances in modern plants from around the world, and n-alkane distributions have been used for a variety of purposes in paleoclimatology and paleoecology as well as chemotaxonomy. However, most of the paleoecological applications of n-alkane distributions have been based on a narrow set of modern data that cannot address intra- and inter-plant variability. Here, we present the results of a study using trees from near Chicago, IL, USA, as well as a meta-analysis of published data on modern plant n-alkane distributions. First, we test the conformity of n-alkane distributions in mature leaves across the canopy of 38 individual plants from 24 species as well as across a single growing season and find no significant differences for either canopy position or time of leaf collection. Second, we compile 2093 observations from 86 sources, including the new data here, to examine the generalities of n-alkane parameters such as carbon preference index (CPI), average chain length (ACL), and chain-length ratios for different plant groups. We show that angiosperms generally produce more n-alkanes than do gymnosperms, supporting previous observations, and furthermore that CPI values show such variation in modern plants that it is prudent to discard the use of CPI as a quantitative indicator of n-alkane degradation in sediments. We also test the hypotheses that certain n-alkane chain lengths predominate in and therefore can be representative of particular plant groups, namely, C23 and C25 in Sphagnum mosses, C27 and C29 in woody plants, and C31 in graminoids (grasses). We find that chain-length distributions are highly variable within plant groups, such that chemotaxonomic distinctions between grasses and woody plants are difficult to make based on n-alkane abundances. In contrast, Sphagnum mosses are marked by their predominance of C23 and C25, chain lengths which are largely absent in terrestrial vascular plants. The results here support the use of C23 as a robust proxy for Sphagnum mosses in paleoecological studies, but not the use of C27, C29, and C31 to separate graminoids and woody plants from one another, as both groups produce highly variable but significant amounts of all three chain lengths. In Africa, C33 and C35 chain lengths appear to distinguish graminoids from some woody plants, but this may be a reflection of the differences in rainforest and savanna environments. Indeed, variation in the abundances of long n-alkane chain lengths may be responding in part to local environmental conditions, and this calls for a more directed examination of the effects of temperature and aridity on plant n-alkane distributions in natural environments.

High Resolution Measurement of Rhizosphere Priming Effects and Temporal Variability of CO2 Fluxes under Zea Mays

NASA Astrophysics Data System (ADS)

Splettstößer, T.; Pausch, J.

2016-12-01

Plant induced increase of soil organic matter turnover rates contribute to carbon emissions in agricultural land use systems. In order to better understand these rhizosphere priming effects, we conducted an experiment, which enabled us to monitor CO2 fluxes under zea mays plants with high resolution. The experiment was conducted in a climate chamber where the plants were grown in thin, tightly sealed boxes for 40 days and CO2 efflux from soil was measured twice a day. 13C-CO2 was introduced to allow differentiation between plant and soil derived CO2.This enabled us to monitor root respiration and soil organic matter turnover in the early stages of plant growth and to highlight changes in soil CO2 emissions and priming effects between day and night. The measurements were conducted with a PICARRO G2131-I δ13C high-precision isotopic CO2 Analyzer (PICARRO INC.) utilizing an automated valve system governed by a CR1000 data logger (Campbell Scientific). After harvest roots and shoots were analyzed for 13C content. Microbial biomass, root length density and enzymatic activities in soil were measured and linked to soil organic matter turnover rates. In order to visualize the spatial distribution of carbon allocation to the root system a few plants were additionally labeled with 14C and 14C distribution was monitored by 14C imaging of the root systems over 4 days. Based on the 14C distribution a grid was chosen and the soil was sampled from each square of the grid to investigate the impact of carbon allocation hotspots on enzymatic activities and microbial biomass. First initial results show an increase of soil CO2 efflux in the night periods, whereby the contribution of priming is not fully analyzed yet. Additionally, root tips were identified as hotspots of short term carbon allocation via 14C imaging and an in increase in microbial biomass could be measured in this regions. The full results will be shown at AGU 2016.

The Plant Short-Chain Dehydrogenase (SDR) superfamily: genome-wide inventory and diversification patterns

PubMed Central

2012-01-01

Background Short-chain dehydrogenases/reductases (SDRs) form one of the largest and oldest NAD(P)(H) dependent oxidoreductase families. Despite a conserved ‘Rossmann-fold’ structure, members of the SDR superfamily exhibit low sequence similarities, which constituted a bottleneck in terms of identification. Recent classification methods, relying on hidden-Markov models (HMMs), improved identification and enabled the construction of a nomenclature. However, functional annotations of plant SDRs remain scarce. Results Wide-scale analyses were performed on ten plant genomes. The combination of hidden Markov model (HMM) based analyses and similarity searches led to the construction of an exhaustive inventory of plant SDR. With 68 to 315 members found in each analysed genome, the inventory confirmed the over-representation of SDRs in plants compared to animals, fungi and prokaryotes. The plant SDRs were first classified into three major types — ‘classical’, ‘extended’ and ‘divergent’ — but a minority (10% of the predicted SDRs) could not be classified into these general types (‘unknown’ or ‘atypical’ types). In a second step, we could categorize the vast majority of land plant SDRs into a set of 49 families. Out of these 49 families, 35 appeared early during evolution since they are commonly found through all the Green Lineage. Yet, some SDR families — tropinone reductase-like proteins (SDR65C), ‘ABA2-like’-NAD dehydrogenase (SDR110C), ‘salutaridine/menthone-reductase-like’ proteins (SDR114C), ‘dihydroflavonol 4-reductase’-like proteins (SDR108E) and ‘isoflavone-reductase-like’ (SDR460A) proteins — have undergone significant functional diversification within vascular plants since they diverged from Bryophytes. Interestingly, these diversified families are either involved in the secondary metabolism routes (terpenoids, alkaloids, phenolics) or participate in developmental processes (hormone biosynthesis or catabolism, flower development), in opposition to SDR families involved in primary metabolism which are poorly diversified. Conclusion The application of HMMs to plant genomes enabled us to identify 49 families that encompass all Angiosperms (‘higher plants’) SDRs, each family being sufficiently conserved to enable simpler analyses based only on overall sequence similarity. The multiplicity of SDRs in plant kingdom is mainly explained by the diversification of large families involved in different secondary metabolism pathways, suggesting that the chemical diversification that accompanied the emergence of vascular plants acted as a driving force for SDR evolution. PMID:23167570

Below-ground carbon transfer among Betula nana may increase with warming in Arctic tundra.

PubMed

Deslippe, Julie R; Simard, Suzanne W

2011-11-01

• Shrubs are expanding in Arctic tundra, but the role of mycorrhizal fungi in this process is unknown. We tested the hypothesis that mycorrhizal networks are involved in interplant carbon (C) transfer within a tundra plant community. • Here, we installed below-ground treatments to control for C transfer pathways and conducted a (13)CO(2)-pulse-chase labelling experiment to examine C transfer among and within plant species. • We showed that mycorrhizal networks exist in tundra, and facilitate below-ground transfer of C among Betula nana individuals, but not between or within the other tundra species examined. Total C transfer among conspecific B. nana pairs was 10.7 ± 2.4% of photosynthesis, with the majority of C transferred through rhizomes or root grafts (5.2 ± 5.3%) and mycorrhizal network pathways (4.1 ± 3.3%) and very little through soil pathways (1.4 ± 0.35%). • Below-ground C transfer was of sufficient magnitude to potentially alter plant interactions in Arctic tundra, increasing the competitive ability and mono-dominance of B. nana. C transfer was significantly positively related to ambient temperatures, suggesting that it may act as a positive feedback to ecosystem change as climate warms. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Removal of trimethylamine (fishy odor) by C₃ and CAM plants.

PubMed

Boraphech, Phattara; Thiravetyan, Paitip

2015-08-01

From screening 23 plant species, it was found that Pterocarpus indicus (C3) and Sansevieria trifasciata (crassulacean acid metabolism (CAM)) were the most effective in polar gaseous trimethylamine (TMA) uptake, reaching up to 90% uptake of initial TMA (100 ppm) within 8 h, and could remove TMA at cycles 1-4 without affecting photosystem II (PSII) photochemistry. Up to 55 and 45% of TMA was taken up by S. trifasciata stomata and leaf epicuticular wax, respectively. During cycles 1-4, interestingly, S. trifasciata changed its stomata apertures, which was directly induced by gaseous TMA and light treatments. In contrast, for P. indicus the leaf epicuticular wax and stem were the major pathways of TMA removal, followed by stomata; these pathways accounted for 46, 46, and 8%, respectively, of TMA removal percentages. Fatty acids, particularly tetradecanoic (C14) acid and octadecanoic (C18) acid, were found to be the main cuticular wax components in both plants, and were associated with TMA removal ability. Moreover, the plants could degrade TMA via multiple metabolic pathways associated with carbon/nitrogen interactions. In CAM plants, one of the crucial pathways enabled 78% of TMA to be transformed directly to dimethylamine (DMA) and methylamine (MA), which differed from C3 plant pathways. Various metabolites were also produced for further detoxification and mineralization so that TMA was completely degraded by plants.

Kranz and single-cell forms of C4 plants in the subfamily Suaedoideae show kinetic C4 convergence for PEPC and Rubisco with divergent amino acid substitutions

PubMed Central

Rosnow, Josh J.; Evans, Marc A.; Kapralov, Maxim V.; Cousins, Asaph B.; Edwards, Gerald E.; Roalson, Eric H.

2015-01-01

The two carboxylation reactions performed by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are vital in the fixation of inorganic carbon for C4 plants. The abundance of PEPC is substantially elevated in C4 leaves, while the location of Rubisco is restricted to one of two chloroplast types. These differences compared with C3 leaves have been shown to result in convergent enzyme optimization in some C4 species. Investigation into the kinetic properties of PEPC and Rubisco from Kranz C4, single cell C4, and C3 species in Chenopodiaceae s. s. subfamily Suaedoideae showed that these major carboxylases in C4 Suaedoideae species lack the same mutations found in other C4 systems which have been examined; but still have similar convergent kinetic properties. Positive selection analysis on the N-terminus of PEPC identified residues 364 and 368 to be under positive selection with a posterior probability >0.99 using Bayes empirical Bayes. Compared with previous analyses on other C4 species, PEPC from C4 Suaedoideae species have different convergent amino acids that result in a higher K m for PEP and malate tolerance compared with C3 species. Kinetic analysis of Rubisco showed that C4 species have a higher catalytic efficiency of Rubisco (k catc in mol CO2 mol–1 Rubisco active sites s–1), despite lacking convergent substitutions in the rbcL gene. The importance of kinetic changes to the two-carboxylation reactions in C4 leaves related to amino acid selection is discussed. PMID:26417023

Kranz and single-cell forms of C4 plants in the subfamily Suaedoideae show kinetic C4 convergence for PEPC and Rubisco with divergent amino acid substitutions.

PubMed

Rosnow, Josh J; Evans, Marc A; Kapralov, Maxim V; Cousins, Asaph B; Edwards, Gerald E; Roalson, Eric H

2015-12-01

The two carboxylation reactions performed by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are vital in the fixation of inorganic carbon for C4 plants. The abundance of PEPC is substantially elevated in C4 leaves, while the location of Rubisco is restricted to one of two chloroplast types. These differences compared with C3 leaves have been shown to result in convergent enzyme optimization in some C4 species. Investigation into the kinetic properties of PEPC and Rubisco from Kranz C4, single cell C4, and C3 species in Chenopodiaceae s. s. subfamily Suaedoideae showed that these major carboxylases in C4 Suaedoideae species lack the same mutations found in other C4 systems which have been examined; but still have similar convergent kinetic properties. Positive selection analysis on the N-terminus of PEPC identified residues 364 and 368 to be under positive selection with a posterior probability >0.99 using Bayes empirical Bayes. Compared with previous analyses on other C4 species, PEPC from C4 Suaedoideae species have different convergent amino acids that result in a higher K m for PEP and malate tolerance compared with C3 species. Kinetic analysis of Rubisco showed that C4 species have a higher catalytic efficiency of Rubisco (k catc in mol CO2 mol(-1) Rubisco active sites s(-1)), despite lacking convergent substitutions in the rbcL gene. The importance of kinetic changes to the two-carboxylation reactions in C4 leaves related to amino acid selection is discussed. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Optimization of animal manure vermicomposting based on biomass production of earthworms and higher plants.

PubMed

Borges, Yan V; Alves, Luciano; Bianchi, Ivan; Espíndola, Jonas C; Oliveira, Juahil M De; Radetski, Claudemir M; Somensi, Cleder A

2017-11-02

The goal of this study was to optimize the mixture of swine manure (SM) and cattle manure (CM) used in the vermicomposting process, seeking to increase the manure biodegradation rate and enhance the biomass production of both earthworms and higher plants. To achieve this goal, physico-chemical parameters were determined to assess the final compost quality after 50 days of vermicomposting. The different manure ratios used to produce the composts (C) were as follows (SM:CM, % m/m basis): C1 100:0, C2 (75:25), C3 (50:50), C4 (25:75), and C5 (0:100). In addition, the earthworm biomass and the phytoproductivity of lettuce (Lactuca sativa L.) plants grown in mixtures (1:1) of natural soil and the most viable vermicomposts were investigated. The C1 and C2 compost compositions were associated with high earthworm mortality rates. The C3 compost provided the highest mineral concentrations and C5 showed the highest lettuce yield (wet biomass). The results verify that stabilized cattle manure is an excellent substrate for the vermicomposting process and that fresh swine manure must be mixed with pre-stabilized cattle manure to ensure an optimized vermicomposting process, which must be controlled in terms of temperature and ammonia levels. It is concluded that small livestock farmers could add value to swine manure by applying the vermicomposting process, without the need for high investments and with a minimal requirement for management of the biodegradation process. These are important technical aspects to be considered when circular economy principles are applied to small farms.

Phenology and productivity of C3 and C4 grasslands in Hawaii.

PubMed

Pau, Stephanie; Still, Christopher J

2014-01-01

Grasslands account for a large proportion of global terrestrial productivity and play a critical role in carbon and water cycling. Within grasslands, photosynthetic pathway is an important functional trait yielding different rates of productivity along environmental gradients. Recently, C3-C4 sorting along spatial environmental gradients has been reassessed by controlling for confounding traits in phylogenetically structured comparisons. C3 and C4 grasses should sort along temporal environmental gradients as well, resulting in differing phenologies and growing season lengths. Here we use 10 years of satellite data (NDVI) to examine the phenology and greenness (as a proxy for productivity) of C3 and C4 grass habitats, which reflect differences in both environment and plant physiology. We perform phylogenetically structured comparisons based on 3,595 digitized herbarium collections of 152 grass species across the Hawaiian Islands. Our results show that the clade identity of grasses captures differences in their habitats better than photosynthetic pathway. Growing season length (GSL) and associated productivity (GSP) were not significantly different when considering photosynthetic type alone, but were indeed different when considering photosynthetic type nested within clade. The relationship between GSL and GSP differed most strongly between C3 clade habitats, and not between C3-C4 habitats. Our results suggest that accounting for the interaction between phylogeny and photosynthetic pathway can help improve predictions of productivity, as commonly used C3-C4 classifications are very broad and appear to mask important diversity in grassland ecosystem functions.

Precontact vegetation and soil nutrient status in the shadow of Kohala Volcano, Hawaii

NASA Astrophysics Data System (ADS)

Chadwick, Oliver A.; Kelly, Eugene F.; Hotchkiss, Sara C.; Vitousek, Peter M.

2007-09-01

Humans colonized Hawaii about 1200 years ago and have progressively modified vegetation, particularly in mesic to dry tropical forests. We use δ 13C to evaluate the contribution of C 3 and C 4 plants to deep soil organic matter to reconstruct pre-human contact vegetation patterns along a wet to dry climate transect on Kohala Mountain, Hawaii Island. Precontact vegetation assemblages fall into three distinct zones: a wet C 3 dominated closed canopy forest where annual rainfall is > 2000 mm, a dry C 4 dominated grassland with annual rainfall < 500 mm, and a broad transition zone between these communities characterized by either C 3 trees with higher water-use efficiency than the rainforest trees or C 3 trees with a small amount of C 4 grasses intermixed. The likelihood of C 4 grass understory decreases with increasing rainfall. We show that the total concentration of rock-derived nutrients in the < 2-mm soil fraction differs in each of these vegetation zones. Nutrient losses are driven by leaching at high rainfall and by plant cycling and wind erosion at low rainfall. By contrast, nutrients are best preserved in surface soils of the intermediate rainfall zone, where rainfall supports abundant plant growth but does not contribute large amounts of water in excess of evapotranspiration. Polynesian farmers exploited these naturally enriched soils as they intensified their upland agricultural systems during the last three centuries before European contact.

Elevated CO2 shifts the functional structure and metabolic potentials of soil microbial communities in a C4 agroecosystem

PubMed Central

Xiong, Jinbo; He, Zhili; Shi, Shengjing; Kent, Angela; Deng, Ye; Wu, Liyou; Van Nostrand, Joy D.; Zhou, Jizhong

2015-01-01

Atmospheric CO2 concentration is continuously increasing, and previous studies have shown that elevated CO2 (eCO2) significantly impacts C3 plants and their soil microbial communities. However, little is known about effects of eCO2 on the compositional and functional structure, and metabolic potential of soil microbial communities under C4 plants. Here we showed that a C4 maize agroecosystem exposed to eCO2 for eight years shifted the functional and phylogenetic structure of soil microbial communities at both soil depths (0–5 cm and 5–15 cm) using EcoPlate and functional gene array (GeoChip 3.0) analyses. The abundances of key genes involved in carbon (C), nitrogen (N) and phosphorus (P) cycling were significantly stimulated under eCO2 at both soil depths, although some differences in carbon utilization patterns were observed between the two soil depths. Consistently, CO2 was found to be the dominant factor explaining 11.9% of the structural variation of functional genes, while depth and the interaction of depth and CO2 explained 5.2% and 3.8%, respectively. This study implies that eCO2 has profound effects on the functional structure and metabolic potential/activity of soil microbial communities associated with C4 plants, possibly leading to changes in ecosystem functioning and feedbacks to global change in C4 agroecosystems. PMID:25791904

Development of Novel Vaccines and Therapeutics Using Plant-Based Expression Systems

DTIC Science & Technology

2010-04-01

Long L, Bohorova N, Kim D, Pauly M, Velasco J, Whaley K , Zeiltin L, Garger SJ, White E, Bai Y, Haydon H, Bratcher B . Production of pharmaceutical...2009 Nobuyuki Matoba Barnett B , Conway H, Husk A, Pickel M, Arntzen C, Zhang P, Quinnan G, Mooney J, Hanson C, Takahashi A, Tanno K , Tanaka H...Viruses of the Family Coronaviridae Barry R. O’Keefe,1* Barbara Giomarelli,1 Dale L. Barnard,2 Shilpa R. Shenoy,3 Paul K . S. Chan,4 James B . McMahon,1

Increase of cold tolerance in cotton plant (Gossypium hirsutum L.) by mepiquat chloride

NASA Technical Reports Server (NTRS)

Gausman, H. W.; Escobar, D. E.; Rodriguez, R. R. (Principal Investigator); Huang, S. Y.; Rittig, F. R.

1982-01-01

Three mepiquat chloride (MC) concentrations - 40, 70, and 100 g a.i./ha - were used to spray cotton (Gossypium hirsutum L., cultival McNair 220) plants to determine whether or not MC would increase their cold tolerance. Seven to ten days after the spray, the plants were exposed to three different cold treatments. No important difference in cold damage was noticed between the control and the MC-treated plants when they were exposed repeatedly to 4.5 C. No plants died when exposed to 0.5 C for 12 h; however, 90% of the 1st and 2nd leaves of the control plants were damaged. This was three times more damage than those leaves of plants treated with 70 and 100 g a.i./ha MC concentrations; 60% f the control and 10-20% of the MC-treated plants died when the plants were subjected to a cold hardening process with 15.5 C day (12 h) and 1.7 C night (12 h) for 10 days, and then, held at -2.2 C for 24 hours. The electrolyte leakage and reflectance measurement data showed that the cell membranes of the MC-treated plants sustained much less damage than those of the control. Freezing injury was easily assessed by reflectance measurements at the 1.65 micrometer wavelength.

Variation in n-Alkane Distributions of Modern Plants: Questioning Applications of n-Alkanes in Chemotaxonomy and Paleoecology

NASA Astrophysics Data System (ADS)

Bush, R. T.; McInerney, F. A.

2010-12-01

Long chain n-alkanes (n-C21 to n-C37) are synthesized as part of the epicuticular leaf wax of terrestrial plants and are among the most recognizable and widely used plant biomarkers. n-Alkane distributions have been utilized in previous studies on modern plant chemotaxonomy, testing whether taxa can be identified based on characteristic n-alkane profiles. Dominant n-alkanes (e.g. n-C27 or n-C31) have also been ascribed to major plant groups (e.g. trees or grasses respectively) and have been used in paleoecology studies to reconstruct fluctuations in plant functional types. However, many of these studies have been based on relatively few modern plant data; with the wealth of modern n-alkane studies, a more comprehensive analysis of n-alkanes in modern plants is now possible and can inform the usefulness of n-alkane distributions as paleoecological indicators. The work presented here is a combination of measurements made using plant leaves collected from the Chicago Botanic Garden and a compilation of published literature data from six continents. We categorized plants by type: angiosperms, gymnosperms, woody plants, forbs, grasses, ferns and pteridophytes, and mosses. We then quantified n-alkane distribution parameters such as carbon preference index (CPI), average chain length (ACL), and dispersion (a measure of the spread of the profile over multiple chain lengths) and used these to compare plant groups. Among all plants, one of the emergent correlations is a decrease in dispersion with increasing CPI. Within and among plant groups, n-alkane distributions show a very large range of variation, and the results show little or no correspondence between broad plant groups and a single dominant n-alkane or a ratio of n-alkanes. These findings are true both when data from six continents are combined and when plants from a given region are compared (North America). We also compared the n-alkane distributions of woody angiosperms, woody gymnosperms, and grasses with one another in order to test whether n-C27 and n-C29 represent trees and shrubs while n-C31 represents grasses as previously proposed. The average group profiles are not distinguishable from one another due to their large standard deviations. Although n-C31 is the predominant chain length in many (but not all) grasses, other chain lengths such as n-C29 are also abundant. For grasses as a group one chain length does not dominate significantly over the other. In mosses, while the genus Sphagnum appears to be typified by n-C23 and n-C25 alkanes, the same cannot be said for other moss genera which were more dominated by n-C27 and n-C29. Differences in n-alkane distributions may relate more to environmental changes such as temperature and precipitation than to shifts in dominant plant types.

Ecohydrology of the different photosynthetic pathways and implication for sustainable agriculture

NASA Astrophysics Data System (ADS)

Porporato, A. M.; Bartlett, M. S., Jr.; Hartzell, S. R.

2016-12-01

We use a recently proposed model that can simulate the different photosynthetic pathways coupled to the soil-plant-atmosphere continuum (SPAC) to discuss their ecohydrological implications in relation to water use and plant water stress in both natural and agricultural ecosystems. Built around the classical C3 photosynthesis core model (light reactions and Calvin cycle), the model includes a simple CO2-pump parameterization for C4 plants and a circadian rhythm and carbon storage components for the CAM (Crassulacean Acid Metabolism) plants. Its architecture takes advantage of the interesting modularity in which photosynthesis evolved in geological times to provide a relatively simple but comprehensive framework to explore the advantages and tradeoffs in water energy and carbon fluxes of the three photosynthetic pathways under fluctuating environmental forcing. We calibrate the model with reference to a series of C3,C4 and CAM plants, and discuss the trade-offs in water use and plan productivity and the related impact on hydrologic fluxes and soil biogeochemistry. We also consider some important crop species to analyze the implications of choosing crops with different photosynthetic pathways to improve sustainability of agriculture and irrigation in semiarid systems.

Anomalous uptake and circulatory characteristics of the plant-based small RNA MIR2911

USDA-ARS?s Scientific Manuscript database

Inconsistent detection of plant-based dietary small RNAs in circulation has thwarted the use of dietary RNA therapeutics. Here we demonstrate mice consuming diets rich in vegetables displayed enhanced serum levels of the plant specific small RNA MIR2911. Differential centrifugation, size-exclusion c...

Carbon storage potential increases with increasing ratio of C4 to C3 grass cover and soil productivity in restored tallgrass prairies.

PubMed

Spiesman, Brian J; Kummel, Herika; Jackson, Randall D

2018-02-01

Long-term soil carbon (C) storage is essential for reducing CO 2 in the atmosphere. Converting unproductive and environmentally sensitive agricultural lands to grasslands for bioenergy production may enhance C storage. However, a better understanding of the interacting effects of grass functional composition (i.e., relative abundance of C 4 and C 3 grass cover) and soil productivity on C storage will help guide sustainable grassland management. Our objective was to examine the relationship between grass functional composition and potential C storage and how it varies with potential soil productivity. We estimated C inputs from above- and belowground net primary productivity (ANPP and BNPP), and heterotrophic respiration (R H ) to calculate net ecosystem production (NEP), a measure of potential soil C storage, in grassland plots of relatively high- and low-productivity soils spanning a gradient in the ratio of C 4 to C 3 grass cover (C 4 :C 3 ). NEP increased with increasing C 4 :C 3 , but only in potentially productive soils. The positive relationship likely stemmed from increased ANPP, rather than BNPP, which was possibly related to efficient resource-use and physiological/anatomical advantages of C 4 plants. R H was negatively correlated with C 4 :C 3 , possibly because of changes in microclimate or plant-microbe interactions. It is possible that in potentially productive soils, C storage can be enhanced by favoring C 4 over C 3 grasses through increased ANPP and BNPP and reduced R H . Results also suggest that potential C storage gains from C 4 productivity would not be undermined by a corresponding increase in R H .

Spatial distributions ofC3 and C4 grass functional types in the U.S. great plains and their despendency on inter-annual climate variability

USDA-ARS?s Scientific Manuscript database

Grassland ecosystems in North America are primarily composed of C3 and C4 plant functional types (PFTs) with their relative cover varying spatially and temporally. This study used 500-m MODIS surface reflectance products (MOD09A1) from 2000 to 2009 to extract an NDVI time series of C3 and C4 PFTs in...

Mechanism of the effect of pH and biochar on the phytotoxicity of the weak acid herbicides imazethapyr and 2,4-D in soil to rice (Oryza sativa) and estimation by chemical methods.

PubMed

Liu, Kailin; He, Ying; Xu, Shiji; Hu, Lifeng; Luo, Kun; Liu, Xiangying; Liu, Min; Zhou, Xiaomao; Bai, Lianyang

2018-06-18

The existing form of an ionizable organic compound can simultaneously affect its soil adsorption and plant bioactivity. In this experiment, the adsorption and bioactivity of two weak acid herbicides (WAHs), imazethapyr and 2,4-D, were studied to explore the predominant mechanism by which the soil pH and the addition of biochar can influence the phytotoxicity of WAHs in soil. Then, the WAH concentration extracted by hollow fiber-based liquid-phase microextraction (C HF-LPME ), the in situ pore water concentration (C IPW ) and the added concentration (C AC ) were employed to estimate the phytotoxicity. The results showed that with increased pH from 5.5 to 8.5, the phytotoxicity of the WAHs to rice increased about 1-fold in the soil, but decreased in aqueous solutions, the IC 50 values for imazethapyr and 2,4-D at pH 5.0 were 3- and 2-fold higher than that at pH 8.0. In addition, the soil adsorption decreased, indicating that the adsorption process was the dominant factor for the variation of the phytotoxicity of the WAHs in the tested soil instead of the decreasing bioactivity. The concentration that inhibits plant growth by 50% (IC 50 ) calculated by the C AC in different pH and biochar soils ranged from 0.619 to 3.826 mg/kg for imazethapyr and 1.871-72.83 mg/kg for 2,4-D. The coefficient of variation (CV) of the IC 50 values reached 65.61% for imazethapyr and 130.0% for 2,4-D. However, when IC 50 was calculated by C IPW and C HF-LPME , the CVs of the IC 50 values decreased to 23.51% and 36.23% for imazethapyr and 40.21% and 50.93% for 2,4-D, respectively. These results suggested that C IPW and C HF-LPME may be more appropriate than C AC for estimating the phytotoxicity of WAHs. Copyright © 2018 Elsevier Inc. All rights reserved.

[Determination of quercetin and kaempferol in Dysosma plants by RP-HPLC].

PubMed

Luo, Jun; Zhang, Liyan; Wan, Mingxiang; He, Shunzhi; Yang, Yuqin

2010-11-01

To determine quercetin and kaempferol in the plant of genus Dysosma that come from different species, different plant parts or different growing areas, which provide the basis of rational utilization of Dysosma plants. The analysis was performed on a Diamonsil C18 column (4.6 mm x 150 mm, 5 microm) eluted with the mobile phase of methanol-water containing 0.1% phosphoric acid (60:40). The flow rate was 1 mL x min(-1), the detection wavelength was 360 nm; and the column temperature was set at 25 degrees C. The linear ranges of quercetin and kaempferol are 0.22-1.1 microg and 0.42-2.1 microg. The average recoveries of quercetin and kaempferol are 97.1% (RSD 1.4%) and 99.6% (RSD 2.4%); respectively. The contents of flavones in different species of Dysosma are significantly different.

Seasonal variation of bacterial community in biological aerated filter for ammonia removal in drinking water treatment.

PubMed

Liu, Hongyuan; Zhu, Liying; Tian, Xiaohe; Yin, Yeshi

2017-10-15

Biological aerated filter (BAF) is widely used in wastewater treatment plants (WWTPs) and shows potential application of micropolluted drinking water sources with a higher NH 4 + -N removal efficiency during short warm seasons. Here we adopted a pilot lava-based BAF setup as a pretreatment unit of drinking water treatment plant (DWTP) and achieved a great performance of ammonia removal over a two-year operation using natural river water. We respectively observed 92.62% of NH 4 + -N removal efficiency, 97.88% of NO 2 - -N removal efficiency in summer, and 77.52% NH 4 + -N removal efficiency in winter down to 5 °C. Based on DGGE analysis, AOB, NOB, as well as heterotrophic bacteria including genus Flavobacterium and Sphingomonas are responsible for the performance. Nitrosomonas and Nitrospira are found to be the dominant AOB and NOB in the BAF microbiota. The compositions of AOB including Nitrosomonas communis and Nitrosomonas oligotropha are different from the strains previously reported in BAF of WWTPs but similar to the observations in DWPTs. We observed seasonal bacterial shifts between summer and winter groups involved in AOB, NOB and heterotrophic genus Flavobacterium, which may be responsible for the seasonal performance fluctuation. The psychrophilic AOB belonging to Nitrosomonas likely contribute to the recovered NH 4 + -N removal efficiency when temperature is below 7 °C. Lack of nitrification functional psychrophilic or psychrotolerant NOB may be in charge of the severe nitrite accumulation below 7 °C. Our analysis suggests that the colonization of psychrophilic nitrifying bacteria in BAF needs at least two-year of natural acclimatization and is necessary for all-weather BAF in DWTPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

From proto-Kranz to C4 Kranz: building the bridge to C4 photosynthesis.

PubMed

Sage, Rowan F; Khoshravesh, Roxana; Sage, Tammy L

2014-07-01

In this review, we examine how the specialized "Kranz" anatomy of C4 photosynthesis evolved from C3 ancestors. Kranz anatomy refers to the wreath-like structural traits that compartmentalize the biochemistry of C4 photosynthesis and enables the concentration of CO2 around Rubisco. A simplified version of Kranz anatomy is also present in the species that utilize C2 photosynthesis, where a photorespiratory glycine shuttle concentrates CO2 into an inner bundle-sheath-like compartment surrounding the vascular tissue. C2 Kranz is considered to be an intermediate stage in the evolutionary development of C4 Kranz, based on the intermediate branching position of C2 species in 14 evolutionary lineages of C4 photosynthesis. In the best-supported model of C4 evolution, Kranz anatomy in C2 species evolved from C3 ancestors with enlarged bundle sheath cells and high vein density. Four independent lineages have been identified where C3 sister species of C2 plants exhibit an increase in organelle numbers in the bundle sheath and enlarged bundle sheath cells. Notably, in all of these species, there is a pronounced shift of mitochondria to the inner bundle sheath wall, forming an incipient version of the C2 type of Kranz anatomy. This incipient version of C2 Kranz anatomy is termed proto-Kranz, and is proposed to scavenge photorespiratory CO2. By doing so, it may provide fitness benefits in hot environments, and thus represent a critical first stage of the evolution of both the C2 and C4 forms of Kranz anatomy. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Distinct regions of the Pseudomonas syringae coiled-coil effector AvrRps4 are required for activation of immunity

PubMed Central

Sohn, Kee Hoon; Hughes, Richard K.; Piquerez, Sophie J.; Jones, Jonathan D. G.; Banfield, Mark J.

2012-01-01

Gram-negative phytopathogenic bacteria translocate effector proteins into plant cells to subvert host defenses. These effectors can be recognized by plant nucleotide-binding–leucine-rich repeat immune receptors, triggering defense responses that restrict pathogen growth. AvrRps4, an effector protein from Pseudomonas syringae pv. pisi, triggers RPS4-dependent immunity in resistant accessions of Arabidopsis. To better understand the molecular basis of AvrRps4-triggered immunity, we determined the crystal structure of processed AvrRps4 (AvrRps4C, residues 134–221), revealing that it forms an antiparallel α-helical coiled coil. Structure-informed mutagenesis reveals an electronegative surface patch in AvrRps4C required for recognition by RPS4; mutations in this region can also uncouple triggering of the hypersensitive response from disease resistance. This uncoupling may result from a lower level of defense activation, sufficient for avirulence but not for triggering a hypersensitive response. Natural variation in AvrRps4 reveals distinct recognition specificities that involve a surface-exposed residue. Recently, a direct interaction between AvrRps4 and Enhanced Disease Susceptibility 1 has been implicated in activation of immunity. However, we were unable to detect direct interaction between AvrRps4 and Enhanced Disease Susceptibility 1 after coexpression in Nicotiana benthamiana or in yeast cells. How intracellular plant immune receptors activate defense upon effector perception remains an unsolved problem. The structure of AvrRps4C, and identification of functionally important residues for its activation of plant immunity, advances our understanding of these processes in a well-defined model pathosystem. PMID:22988101

Variability in the carbon isotope composition of individual amino acids in plant proteins from different sources: 1 Leaves.

PubMed

Lynch, Anthony H; Kruger, Nicholas J; Hedges, Robert E M; McCullagh, James S O

2016-05-01

The natural carbon isotope composition of individual amino acids from plant leaf proteins has been measured to establish potential sources of variability. The plant leaves studied, taken from a range of plant groups (forbs, trees, grasses, and freshwater aquatic plants), showed no significant influence of either season or environment (water and light availability) on their Δδ(13)C values. Plant groups did, however, differ in carbon isotope composition, although no consistent differences were identified at the species level. A discriminant analysis model was constructed which allowed leaves from (1) nettles, (2) Pooideae, (3) other Poales, (4) trees and (5) freshwater higher plants to be distinguished from each other on the basis of their natural abundance (13)C/(12)C ratios of individual amino acids. Differences in carbon isotope composition are known to be retained, to some extent, in the tissues of their consumers, and hence an understanding of compound-specific variation in (13)C/(12)C fractional abundance in plants has the potential to provide dietary insights of value in archaeological and ecological studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Expression of two functionally distinct plant endo-beta-1,4-glucanases is essential for the compatible interaction between potato cyst nematode and its hosts.

PubMed

Karczmarek, Aneta; Fudali, Sylwia; Lichocka, Malgorzata; Sobczak, Miroslaw; Kurek, Wojciech; Janakowski, Slawomir; Roosien, Jan; Golinowski, Wladyslaw; Bakker, Jaap; Goverse, Aska; Helder, Johannes

2008-06-01

For the proliferation of their feeding sites (syncytia), the potato cyst nematode Globodera rostochiensis is thought to recruit plant endo-beta-1,4-glucanases (EGases, EC. 3.2.1.4). Reverse-transcription polymerase chain reaction experiments on tomato (Solanum lycopersicum) indicated that the expression of two out of the at least eight EGases, namely Sl-cel7 and Sl-cel9C1, is specifically upregulated during syncytium formation. In situ hybridization and immunodetection studies demonstrated that both EGases are specifically expressed inside and adjacent to proliferating syncytia. To assess the importance of Sl-cel7 and Sl-cel9C1 for nematode development, we decided to knock them out individually. Sl-cel9C1 probably is the only class C EGase in tomato, and we were unable to regenerate Sl-cel9C1-silenced plants. Potato (S. tuberosum), a close relative of tomato, harbors at least two class C EGases, and St-cel7-or St-cel9C1-silenced potato plants showed no obvious aberrant phenotype. Infection with potato cyst nematodes resulted in a severe reduction of the number of adult females (up to 60%) and a sharp increase in the fraction of females without eggs (up to 89%). Hence, the recruitment of CEL7, an enzyme that uses xyloglucan and noncrystalline cellulose as natural substrates, and CEL9C1, an enzyme that uses crystalline cellulose, is essential for growth and development of potato cyst nematodes.

Identification and characterization of miRNAs in two closely related C4 and C3 species of Cleome by high-throughput sequencing

PubMed Central

Gao, Shuangcheng; Zhao, Wei; Li, Xiang; You, Qingbo; Shen, Xinjie; Guo, Wei; Wang, Shihua; Shi, Guoan; Liu, Zheng; Jiao, Yongqing

2017-01-01

Cleome gynandra and Cleome hassleriana, which are C4 and C3 plants, respectively, are two species of Cleome. The close genetic relationship between C. gynandra and C. hassleriana provides advantages for discovering the differences in leaf development and physiological processes between C3 and C4 plants. MicroRNAs (miRNAs) are a class of important regulators of various biological processes. In this study, we investigate the differences in the characteristics of miRNAs between C. gynandra and C. hassleriana using high-throughput sequencing technology. In total, 94 and 102 known miRNAs were identified in C. gynandra and C. hassleriana, respectively, of which 3 were specific for C. gynandra and 10 were specific for C. hassleriana. Ninety-one common miRNAs were identified in both species. In addition, 4 novel miRNAs were detected, including three in C. gynandra and three in C. hassleriana. Of these miRNAs, 67 were significantly differentially expressed between these two species and were involved in extensive biological processes, such as glycol-metabolism and photosynthesis. Our study not only provided resources for C. gynandra and C. hassleriana research but also provided useful clues for the understanding of the roles of miRNAs in the alterations of biological processes in leaf tissues during the evolution of the C4 pathway. PMID:28422166

Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi

PubMed Central

Hynson, Nicole A.; Schiebold, Julienne M.-I.; Gebauer, Gerhard

2016-01-01

Background and Aims Mycoheterotrophy entails plants meeting all or a portion of their carbon (C) demands via symbiotic interactions with root-inhabiting mycorrhizal fungi. Ecophysiological traits of mycoheterotrophs, such as their C stable isotope abundances, strongly correlate with the degree of species’ dependency on fungal C gains relative to C gains via photosynthesis. Less explored is the relationship between plant evolutionary history and mycoheterotrophic plant ecophysiology. We hypothesized that the C and nitrogen (N) stable isotope compositions, and N concentrations of fully and partially mycoheterotrophic species differentiate them from autotrophs, and that plant family identity would be an additional and significant explanatory factor for differences in these traits among species. We focused on mycoheterotrophic species that associate with ectomycorrhizal fungi from plant families Ericaceae and Orchidaceae. Methods Published and unpublished data were compiled on the N concentrations, C and N stable isotope abundances (δ13C and δ15N) of fully (n = 18) and partially (n = 22) mycoheterotrophic species from each plant family as well as corresponding autotrophic reference species (n = 156). These data were used to calculate site-independent C and N stable isotope enrichment factors (ε). Then we tested for differences in N concentration, 13C and 15N enrichment among plant families and trophic strategies. Key Results We found that in addition to differentiating partially and fully mycoheterotrophic species from each other and from autotrophs, C and N stable isotope enrichment also differentiates plant species based on familial identity. Differences in N concentrations clustered at the plant family level rather than the degree of dependency on mycoheterotrophy. Conclusions We posit that differences in stable isotope composition and N concentrations are related to plant family-specific physiological interactions with fungi and their environments. PMID:27451987

Light quality affects flavonoid production and related gene expression in Cyclocarya paliurus.

PubMed

Liu, Yang; Fang, Shengzuo; Yang, Wanxia; Shang, Xulan; Fu, Xiangxiang

2018-02-01

Understanding the responses of plant growth and secondary metabolites to differential light conditions is very important to optimize cultivation conditions of medicinal woody plants. As a highly valued and multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medical use. In this study, LED-based light including white light (WL), blue light (BL), red light (RL), and green light (GL) were used to affect leaf biomass production, flavonoid accumulation and related gene expression of one-year C. paliurus seedlings in controlled environments. After the treatments of 60 days, the highest leaf biomass appeared in the treatment of WL, while the lowest leaf biomass was found under GL. Compared to WL, the total flavonoid contents of C. paliurus leaves were significantly higher in BL, RL, and GL, but the highest values of selected flavonoids (kaempferol, isoquercitrin and quercetin) were observed under BL. Furthermore, the greatest yields of total and selected flavonoids in C. paliurus leaves per seedling were also achieved under BL, indicating that blue light was effective for inducing the production of flavonoids in C. paliurus leaves. Pearson's correlation analysis showed that there were significantly positive correlations between leaf flavonoid content and relative gene expression of key enzymes (phenylalanine ammonia lyase, PAL; 4-coumaroyl CoA-ligase, 4CL; and chalcone synthase, CHS) in the upstream, which converting phenylalanine into the flavonoid skeleton of tetrahydroxy chalcone. It is concluded that manipulating light quality may be potential mean to achieve the highest yields of flavonoids in C. paliurus cultivation, however this needs to be further verified by more field trials. Copyright © 2018 Elsevier B.V. All rights reserved.

Substrate lability and plant activity controls greenhouse gas release from Neotropical peatland

NASA Astrophysics Data System (ADS)

Sjogersten, Sofie; Hoyos, Jorge; Lomax, Barry; Turner, Ben; Wright, Emma

2014-05-01

Almost one third of global CO2 emissions resulting from land use change and substantial CH4 emissions originate from tropical peatlands. However, our understanding of the controls of CO2 and CH4 release from tropical peatlands are limited. The aim of this study was to investigate the role of peat lability and the activity of the vegetation on gas release using a combination of field and laboratory experiments. We demonstrated that peat lability constrained CH4 production to the surface peat under anaerobic conditions. The presence of plants shifted the C balance from a C source to a C sink with respect to CO2 while the activity of the root system strongly influenced CH4 emissions through its impact on soil O2 inputs. Both field and laboratory data suggest a coupling between the photosynthetic activity of the vegetation and the release of both CO2 and CH4 following the circadian rhythm of the dominant plant functional types. Forest clearance for agriculture resulted in elevated CH4 release, which we attribute in part to the cessation of root O2 inputs to the peat. We conclude that high emissions of CO2 and CH4 from forested tropical peatlands are likely driven by labile C inputs from the vegetation but that root O2 release may limit CH4 emissions.

Thermotolerance capacities of native and exotic coastal plants will lead to changes in species composition under increased heat waves

PubMed Central

Robinson, Sharon A.; Lia, Jodie

2017-01-01

Abstract With an increase in the frequency and intensity of extreme heat events, plants are likely to reach their thermal limits and show slower growth or increased mortality. We investigated differences amongst coastal native and invasive shrubs and grasses to investigate if particular species might be more at risk in the future. Using an ecologically relevant experimental set of heat waves over a month, we assessed changes in biomass and photosynthetic efficiency in a laboratory setting using 25 coastal Australian species divided into native and exotic shrubs, and native and exotic grasses. We also compared three C3 and three C4 grasses within the native and exotic groups. Overall, native shrubs suffered higher mortality, lower growth and increased photosynthetic stress. There was some evidence that C3 grasses, had lower growth with heat waves, compared to C4 species although, in general, grasses showed evidence of photosynthetic acclimation over the month. Increases in leaf abscission suggest that part of the acclimation process was to develop new, thermally tolerant leaves. Our results indicate that in the future we would expect an increase in exotic shrubs and grasses occupying spaces in coastal plant communities that arise from native mortality following extreme heat events. Management of these coastal communities will need to focus strongly on maintaining a diverse native shrub composition that can resist climate-based disturbances (such as wildfire), as well as controlling the extent and biomass of exotic species, if coastal communities are to remain healthy and diverse in a changing climate. PMID:28491321

Genetic transformation of Bacopa monnieri by wild type strains of Agrobacterium rhizogenes stimulates production of bacopa saponins in transformed calli and plants.

PubMed

Majumdar, Sukanya; Garai, Saraswati; Jha, Sumita

2011-05-01

We have developed an efficient transformation system for Bacopa monnieri, an important Indian medicinal plant, using Agrobacterium rhizogenes strains LBA 9402 and A4. Transformed roots induced by strain LBA 9402 spontaneously dedifferentiated to callus while excised roots induced by strain A4 spontaneously showed induction of shoot buds within 10 days. PCR and RT-PCR analysis revealed the presence and expression of the rolAB and rolC genes at the transcription level in pRi A4 transformed cultures indicating that the TL-DNA was integrated retained and expressed in the A4-Ri transformed shoots. Transformed calli showed the presence of rolAB or rol A, TR and ags genes. Transformed plants showed morphological features typically seen in transgenic plants produced by A. rhizogenes. Growth and biomass accumulation was significantly higher in the transformed shoots (twofold) and roots (fourfold) than in the non-transformed (WT) plants. In pRi A4-transformed plants, the content of bacopasaponin D, bacopasaponin F, bacopaside II and bacopaside V was enhanced significantly as compared to WT plants of similar age while bacoside A3 and bacopasaponin C content was comparable with that of WT plants. Significant increase in content of five bacopa saponins could be detected in pRi 9402-transformed callus cultures. There is an overall stimulatory effect on accumulation of bacopa saponins in transformed plants and cells of B. monnieri establishing the role of endogenous elicitation by Ri T-DNA of A. rhizogenes.

Initial Soil Organic Matter Content Influences the Storage and Turnover of Litter-, Root- and Soil Carbon in Grasslands

NASA Astrophysics Data System (ADS)

Liu, L.; Xu, S.; Li, P.; Sayer, E. J.

2017-12-01

Grassland degradation is a worldwide problem that often leads to substantial loss of soil organic matter (SOM). Understanding how SOM content influences the stabilization of plant carbon (C) to form soil C is important to evaluate the potential of degraded grasslands to sequester additional C. We conducted a greenhouse experiment using C3 soils with six levels of SOM content and planted the C4 grass Cleistogenes squarrosa and/or added its litter to investigate how SOM content regulates the storage of new soil C derived from litter and roots, the decomposition of extant soil C, and the formation of soil aggregates. We found that microbial biomass carbon (MBC) increased with SOM content, and increased the mineralization of litter C. Both litter addition and planted treatments increased the amount of new C inputs to soil. However, litter addition had no significant impacts on the mineralization of extant soil C, but the presence of living roots significantly accelerated it. Thus, by the end of the experiment, soil C content was significantly higher in the litter addition treatments, but was not affected by planted treatments. The soil macroaggregate fraction increased with SOM content and was positively related to MBC. Overall, our study suggests that as SOM content increases, plant growth and soil microbes become more active, which allows microbes to process more plant-derived C and increases new soil C formation. The interactions between SOM content and plant C inputs should be considered when evaluating soil C turnover in degraded grasslands.

[The intensity of phytodetrite decomposition in Larch Forest of the permafrost zone in central Siberia].

PubMed

Prokushkin, S G; Prokushkin, A S; Sorokin, N D

2014-01-01

Based on the results of long-term investigations, quantitative assessment ofphytodetrite mineralization rates is provided. Their role in the biological cycle of larch stands growing in the permafrost zone of Central Evenkia is discussed. It is demonstrated that their destruction in the subshrub-sphagnum and cowberry-green moss larch stands is extremely slow, the plant litter contains the most cecalcitrant organic matter demonstrating the lowest decomposition coefficient of 0.03-0.04 year(-1), whereas fresh components of the plant litter have 3- to 4-fold higher values. An insignificant input of N and C from the analyzed mortmass to the soil has been registered. It has been revealed that the changes in N and C in the decomposition components are closely related to the quantitative dynamics (biomass) of microorganisms, such as hydrolytics and, especially, micromicetes.

Lipid metabolites with free-radical scavenging activity from Euphorbia helioscopia L.

PubMed

Cateni, F; Zilic, J; Altieri, T; Zacchigna, M; Procida, G; Gaggeri, R; Rossi, D; Collina, S

2014-07-01

The methanolic extract of the plant Euphorbia helioscopia L. exhibited an interesting free-radical scavenging activity. From the aerial parts of Euphorbia helioscopia L. (Euphorbiaceae), a complex mixture of seven cerebrosides together with glucoclionasterol, a digalactosyldiacylglycerol and a diacylmonogalactosylglycerol were identified. The structures of the cerebrosides were characterized as 1-O-β-D-glucosides of phytosphingosines, which comprised (2S, 3S, 4E, 8E)-2-amino-4(E),8(E)-octadecadiene-1,3-diol, (2S, 3S, 4E, 8Z)-2-amino-4(E),8(Z)-octadecadiene-1,3-diol, (2S, 3S, 4R, 8Z)-2-amino-8(Z)-octadecene-1,3,4-triol as long chain bases with seven 2-hydroxy fatty acids of varying chain lengths (C16, C24:1, C26:1, C24, C26, C28:1) linked to the amino group. The glycosylglycerides were characterized as (2S)-2,3-O-di-(9,12,15-octadecatrienoyl)-glyceryl-6-O-(α-D-galactopyranosyl)-β-D-galactopyranoside and (2S)-2,3-O-di-(9,12,15-octadecatrienoyl)-glyceryl-1-O-β-D-galactopyranoside. The structures were established on the basis of spectroscopic data and chemical reactions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Expansion of plants with Crassulacean Acid Metabolism under global environment change

NASA Astrophysics Data System (ADS)

Yu, K.; D'Odorico, P.; Collins, S. L.; Carr, D.

2016-12-01

The abundance of plants with Crassulacean Acid Metabolism (CAM) has increased in many drylands worldwide. This is hypothesized to occur because CAM plants store water, take up CO2 at night, exhibit photosynthetic plasticity, and have high water use efficiency. The increased dominance of CAM plants, however, also depends on their competitive relationship with other functional groups, an aspect of CAM plant sensitivity to global environmental change that has remained largely understudied. Here, we investigated the response of CAM plants and their competitive relationships with C3 and C4 plants under global environmental change. We focused on two pairs of CAM and non-CAM species, namely Cylindropuntia imbricata (a constitutive CAM species) and Bouteloua eriopoda (C4 grass), which co-occur in desert grasslands in northern Mexico, and invasive Mesembryanthemum crystallinum (a facultative CAM species) and Bromus mollis (a C3 invasive grass), which coexist in California's coastal grasslands. A set of growth chamber experiments under altered CO2 and water conditions show that C. imbricata outcompeted B. eriopoda under drought conditions, while in well-watered conditions B. eriopoda was a stronger competitor for soil water than C. imbricata. Under drought conditions a more positive response to CO2 enrichment by C. imbricata indirectly disfavored B. eriopoda, which suggests that interspecific competition can outweigh the favorable direct effect of CO2 enrichment on plant growth. A set of greenhouse experiments under water, N, and soil salinity manipulations showed that drought, N deposition, and/or increased soil salinity served as important drivers for success of M. crystallinum invasion, while B. mollis exerted strong competitive effects on M. crystallinum for light and soil nutrients in well-watered conditions. M. crystallinum switched from C3 photosynthesis to CAM photosynthesis as an adaptive strategy in response to moderate intensity of competition from B. mollis, in contrast to the case of the strong competitive effect from B. mollis. Overall, these research improves understanding of mechanisms underlying the expansion of CAM plants with important implications on shifts in dryland vegetation composition, bioenergy production, food security, and adaptation to global environment change.

Difference in light-induced increase in ploidy level and cell size between adaxial and abaxial epidermal pavement cells of Phaseolus vulgaris primary leaves.

PubMed

Kinoshita, Isao; Sanbe, Akiko; Yokomura, E-iti

2008-01-01

Changes in nuclear DNA content and cell size of adaxial and abaxial epidermal pavement cells were investigated using bright light-induced leaf expansion of Phaseolus vulgaris plants. In primary leaves of bean plants grown under high (sunlight) or moderate (ML; photon flux density, 163 micromol m(-2) s(-1)) light, most adaxial epidermal pavement cells had a nucleus with the 4C amount of DNA, whereas most abaxial pavement cells had a 2C nucleus. In contrast, plants grown under low intensity white light (LL; 15 micromol m(-2) s(-1)) for 13 d, when cell proliferation of epidermal pavement cells had already finished, had a 2C nuclear DNA content in most adaxial pavement cells. When these LL-grown plants were transferred to ML, the increase in irradiance raised the frequency of 4C nuclei in adaxial but not in abaxial pavement cells within 4 d. On the other hand, the size of abaxial pavement cells increased by 53% within 4 d of transfer to ML and remained unchanged thereafter, whereas adaxial pavement cells continuously enlarged for 12 d. This suggests that the increase in adaxial cell size after 4 d is supported by the nuclear DNA doubling. The different responses between adaxial and abaxial epidermal cells were not induced by the different light intensity at both surfaces. It was shown that adaxial epidermal cells have a different property than abaxial ones.

Stable Carbon Isotope Enrichment Before Late Miocene and Its Iimplication for Landscape Change in the Amazon Basin

NASA Astrophysics Data System (ADS)

Lee, Y. I.; Kim, D.; Hyeong, K.; Chan Min, Y.

2016-12-01

The appearance and development of C4 plants in the Late Miocene is well-established by various lines of evidence including stable carbon isotope data, yet the stable carbon isotope change before the global vegetation change has not been reported. Prior to the C4 plant expansion, the ecosystem may have been composed of C3 plants. Here we present the content and stable carbon isotope record of black carbon (BC) in a 470-cm-long piston core retrieved from the northeastern equatorial Pacific. Although suitable age dating method is lacking for the studied core, correlation of clay mineral composition, BC content, and stable carbon isotope data with a nearby well-studied core (Kim et al., submitted) at the same latitude suggests that the studied core contains sediment older than 15 Ma (330 cm in depth) and possibly back to 25 Ma, much prior to the major diversification of C4 plants. The older sediment was derived from Southern Hemisphere. The δ13C value of BC in the oldest sediment shows a relatively high value ( -22.7 ‰ on average), similar to that of C4 expansion event, and then decreases with time till reaching normal δ13C value of C3-dominated environment (-25.3 ‰ on average) around 13 Ma. This relatively high δ13C value reflects the presence of specific ecosystem, likely Pebas wetland that dominated western Amazonia before 17 Ma, and decreasing δ13C value suggests subsequent gradual development of closed-forest ecosystem. The BC content shows an abrupt increase around 400 cm, suggesting a significant aridity event in South America. Uplift of the North Andean region at 23 Ma seems to be the likely cause of such aridity event. From these observations, we argue that by comparing with the well-studied core data environmental record provided by BC data can be used for approximate age dating of deep-sea core sediment lacking appropriate dating tools, and that carbon isotope data before C4 development event may also provide information about specific regional ecosystem

Insights into deep-time terrestrial carbon cycle processes from modern plant isotope ecology

NASA Astrophysics Data System (ADS)

Sheldon, N. D.; Smith, S. Y.

2012-12-01

While the terrestrial biosphere and soils contain much of the readily exchangeable carbon on Earth, how those reservoirs function on long time scales and at times of higher atmospheric CO2 and higher temperatures is poorly understood, which limits our ability to make accurate future predictions of their response to anthropogenic change. Recent data compilation efforts have outlined the response of plant carbon isotope compositions to a variety of environmental factors including precipitation amount and timing, elevation, and latitude. The compilations involve numerous types of plants, typically only found at a limited number of climatic conditions. Here, we expand on those efforts by examining the isotopic response of specific plant groups found both globally and across environmental gradients including: 1) ginkgo, 2) conifers, and 3) C4 grasses. Ginkgo is presently widely distributed as a cultivated plant and the ginkgoalean fossil record spans from the Permian to the present, making it an ideal model organism to understand climatic influence on carbon cycling both in modern and ancient settings. Ginkgo leaves have been obtained from a range of precipitation conditions (400-2200 mm yr-1), including dense sampling from individuals and populations in both Mediterranean and temperate climate areas and samples of different organs and developmental stages. Ginkgo carbon isotope results plot on the global C3 plant array, are consistent among trees at single sites, among plant organs, and among development stages, making ginkgo a robust recorder of both climatic conditions and atmospheric δ13C. In contrast, a climate-carbon isotope transect in Arizona highlights that conifers (specifically, pine and juniper) record large variability between organs and have a very different δ13C slope as a function of climate than the global C3 plant array, while C4 plants have a slope with the opposite sign as a function of climate. This has a number of implications for paleo-diet studies. Finally, using these new results we examine terrestrial carbon inputs into the Cretaceous Interior Seaway using plant fossils from the Campanian Pierre Shale, as well as presenting mean annual precipitation (MAP) estimates derived from the relationship between conifer δ13C composition and MAP described above.

Carbon isotopic evidence from paleosols for mixed C 3/C 4 vegetation in the Bogota Basin, Colombia

NASA Astrophysics Data System (ADS)

Mora, Germán; Pratt, Lisa M.

2002-04-01

Pollen reconstructions in the Bogota basin (Colombia) indicate the expansion of tropical high-altitude grassland (paramo) at the expense of Andean forests during glacial intervals. The carbon isotopic composition (δ 13C) of soil organic matter (SOM) can be a useful indicator of changes in vegetation affecting grasslands because it distinguishes between two groups of grasses (C 3 and C 4) adapted to different ecological environments. Values of SOM δ 13C were determined in four weathering profiles containing both modern (Holocene) soils and paleosols formed during the Last Glacial Stage. These profiles are located along an altitudinal transect in the Bogota basin, extending from 2550 to 3100 m. Values of SOM δ 13C in the topsoil horizons reflect those of the native C 3 vegetation that currently dominates the ecosystems in the Colombian Andes. Although C 4 grasses are currently negligible in the basin, elevated SOM δ 13C values indicative of C 4 plants were found in two Holocene soils. Environmental changes or ancient agricultural activities could explain the increased abundance of these plants in the basin during the late Holocene. Isotopic values in the studied paleosols revealed the presence of a mixed C 3/C 4 vegetation in the basin during the Last Glacial Stage, thus indicating the expansion of C 4 grasses. We hypothesized that lowered pCO 2 and possibly reduced rainfall resulted in the colonization of the tropical Andes by lowland C 4 grasses despite of prevailing cooler temperatures.

Azadirachta indica plant-assisted green synthesis of Mn3O4 nanoparticles: Excellent thermal catalytic performance and chemical sensing behavior.

PubMed

Sharma, Jitendra Kumar; Srivastava, Pratibha; Ameen, Sadia; Akhtar, M Shaheer; Singh, Gurdip; Yadava, Sudha

2016-06-15

The leaf extract of Azadirachta indica (Neem) plant was utilized as reducing agent for the green synthesis of Mn3O4 nanoparticles (NPs). The crystalline analysis demonstrated the typical tetragonal hausmannite crystal structure of Mn3O4, which confirmed the formation of Mn3O4 NPs without the existence of other oxides. Green synthesized Mn3O4 NPs were applied for the catalytic thermal decomposition of ammonium perchlorate (AP) and as working electrode for fabricating the chemical sensor. The excellent catalytic effect for the thermal decomposition of AP was observed by decreasing the decomposition temperature by 175 °C with single decomposing step. The fabricated chemical sensor based on green synthesized Mn3O4 NPs displayed high, reliable and reproducible sensitivity of ∼569.2 μA mM(-1) cm(-2) with reasonable limit of detection (LOD) of ∼22.1 μM and the response time of ∼10 s toward the detection of 2-butanone chemical. A relatively good linearity in the ranging from ∼20 to 160 μM was detected for Mn3O4 NPs electrode based 2-butanone chemical sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

Targeted DNA demethylation in human cells by fusion of a plant 5-methylcytosine DNA glycosylase to a sequence-specific DNA binding domain

PubMed Central

Parrilla-Doblas, Jara Teresa; Ariza, Rafael R.; Roldán-Arjona, Teresa

2017-01-01

ABSTRACT DNA methylation is a crucial epigenetic mark associated to gene silencing, and its targeted removal is a major goal of epigenetic editing. In animal cells, DNA demethylation involves iterative 5mC oxidation by TET enzymes followed by replication-dependent dilution and/or replication-independent DNA repair of its oxidized derivatives. In contrast, plants use specific DNA glycosylases that directly excise 5mC and initiate its substitution for unmethylated C in a base excision repair process. In this work, we have fused the catalytic domain of Arabidopsis ROS1 5mC DNA glycosylase (ROS1_CD) to the DNA binding domain of yeast GAL4 (GBD). We show that the resultant GBD-ROS1_CD fusion protein binds specifically a GBD-targeted DNA sequence in vitro. We also found that transient in vivo expression of GBD-ROS1_CD in human cells specifically reactivates transcription of a methylation-silenced reporter gene, and that such reactivation requires both ROS1_CD catalytic activity and GBD binding capacity. Finally, we show that reactivation induced by GBD-ROS1_CD is accompanied by decreased methylation levels at several CpG sites of the targeted promoter. All together, these results show that plant 5mC DNA glycosylases can be used for targeted active DNA demethylation in human cells. PMID:28277978

Bacillus amyloliquefaciens SAY09 Increases Cadmium Resistance in Plants by Activation of Auxin-Mediated Signaling Pathways

PubMed Central

Zhou, Cheng; Zhu, Lin; Ma, Zhongyou; Wang, Jianfei

2017-01-01

Without physical contact with plants, certain plant growth-promoting rhizobacteria (PGPR) can release volatile organic compounds (VOCs) to regulate nutrient acquisition and induce systemic immunity in plants. However, whether the PGPR-emitted VOCs can induce cadmium (Cd) tolerance of plants and the underlying mechanisms remain elusive. In this study, we probed the effects of Bacillus amyloliquefaciens (strain SAY09)-emitted VOCs on the growth of Arabidopsis plants under Cd stress. SAY09 exposure alleviates Cd toxicity in plants with increased auxin biosynthesis. RNA-Seq analyses revealed that SAY09 exposure provoked iron (Fe) uptake- and cell wall-associated pathways in the Cd-treated plants. However, SAY09 exposure failed to increase Cd resistance of plants after treatment with 1-naphthylphthalamic acid (NPA) or 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO). Under Cd stress, SAY09 exposure markedly promoted Fe absorption in plants with the increased hemicellulose 1 (HC1) content and Cd deposition in root cell wall, whereas these effects were almost abrogated by treatment with NPA or c-PTIO. Moreover, exogenous NPA remarkably repressed the accumulation of nitric oxide (NO) in the SAY09-exposed roots under Cd stress. Taken together, the findings indicated that NO acted as downstream signals of SAY09-induced auxin to regulate Fe acquisition and augment Cd fixation in roots, thereby ameliorating Cd toxicity. PMID:28657581

RING-type ubiquitin ligase McCPN1 catalyzes UBC8-dependent protein ubiquitination and interacts with Argonaute 4 in halophyte ice plant.

PubMed

Li, Chang-Hua; Chiang, Chih-Pin; Yang, Jun-Yi; Ma, Chia-Jou; Chen, Yu-Chan; Yen, Hungchen Emilie

2014-07-01

RING-type copines are a small family of plant-specific RING-type ubiquitin ligases. They contain an N-terminal myristoylation site for membrane anchoring, a central copine domain for substrate recognition, and a C-terminal RING domain for E2 docking. RING-type copine McCPN1 (copine1) from halophyte ice plant (Mesembryanthemum crystallinum L.) was previously identified from a salt-induced cDNA library. In this work, we characterize the activity, expression, and localization of McCPN1 in ice plant. An in vitro ubiquitination assay of McCPN1 was performed using two ice plant UBCs, McUBC1 and McUBC2, characterized from the same salt-induced cDNA library. The results showed that McUBC2, a member of the UBC8 family, stimulated the autoubiquitination activity of McCPN1, while McUBC1, a homolog of the UBC35 family, did not. The results indicate that McCPN1 has selective E2-dependent E3 ligase activity. We found that McCPN1 localizes primarily on the plasma membrane and in the nucleus of plant cells. Under salt stress, the accumulation of McCPN1 in the roots increases. A yeast two-hybrid screen was used to search for potential McCPN1-interacting partners using a library constructed from salt-stressed ice plants. Screening with full-length McCPN1 identified several independent clones containing partial Argonaute 4 (AGO4) sequence. Subsequent agro-infiltration, protoplast two-hybrid analysis, and bimolecular fluorescence complementation assay confirmed that McCPN1 and AGO4 interacted in vivo in the nucleus of plant cells. The possible involvement of a catalyzed degradation of AGO4 by McCPN1 in response to salt stress is discussed. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Gulf Coast Deep Water Port Facilities Study. Appendix C. Eastern Gulf Hydrobiological Zones.

DTIC Science & Technology

1973-04-01

MARINE 5IOTA C-22 1. Benthic Plants C-22 2. Plankton C;23 3. Benthic Invertebrates C-27 4. Fish C-33 5. Marine Mammals C-35 6. Marine Birds C-37 7. Rare...56 B. RESIDENT AND TRANSIENT MARINE BIOTA C-56 1. Plankton C-56 2. Benthic Invertebrates C-62 3. Fish C-62 4. Marine Mammals C-684 Artur D Little Inc...TRANSIENT MARINE BIOTA C-78 l.-Plankton C-78 .-2. Benthic Invertebrates C8 3. F ish C-81 4. Marine Mammals C-85 V. ZONAL ANALYSIS C-87 A. ZONE V

Balancing photosynthetic light-harvesting and light-utilization capacities in potato leaf tissue during acclimation to different growth temperatures

NASA Technical Reports Server (NTRS)

Steffen, K. L.; Wheeler, R. M.; Arora, R.; Palta, J. P.; Tibbitts, T. W.

1995-01-01

We investigated the effect of temperature during growth and development on the relationship between light-harvesting capacity, indicated by chlorophyll concentration, and light-utilization potential, indicated by light- and bicarbonate-saturated photosynthetic oxygen evolution, in Solanum tuberosum L. cv. Norland. Clonal plantlets were transplanted and grown at 20 degrees C for 2 weeks before transfer to 12, 16, 20, 24 and 28 degrees C for 6 weeks. After 4 weeks of the temperature treatments, leaf tissue fresh weights per area were one-third higher in plants grown at 12 degrees C vs those grown at 28 degrees C. Conversely, chlorophyll content per area in tissue grown at 12 degrees C was less than one-half of that of tissue grown at 28 degrees C at 4 weeks. Photosynthetic capacity measured at a common temperature of 20 degrees C and expressed on a chlorophyll basis was inversely proportional to growth temperature. Leaf tissue from plants grown at 12 degrees C for 4 weeks had photosynthetic rates that were 3-fold higher on a chlorophyll basis than comparable tissue from plants grown at 28 degrees C. These results suggest that the relationship between light-harvesting capacity and light-utilization potential varies 3-fold in response to the growth temperatures examined. The role of this response in avoidance of photoinhibition is discussed.

Comparative analysis of the ability of Clostridium clariflavum strains and Clostridium thermocellumto utilize hemicellulose and unpretreated plant material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izquierdo, Javier A.; Pattathil, Sivakumar; Guseva, Anna

2014-11-18

Among themophilic consolidated bioprocessing (CBP) candidate organisms, environmental isolates of Clostridium clariflavum have demonstrated the ability to grow on xylan, and the genome of C. clariflavum DSM 19732 has revealed a number of mechanisms that foster solubilization of hemicellulose that are distinctive relative to the model cellulolytic thermophile Clostridium thermocellum. Growth experiments on xylan, xylooligosaccharides, and xylose reveal that C. clariflavum strains are able to completely break down xylan to xylose and that the environmental strain C. clariflavum sp. 4-2a is able to grow on monomeric xylose. C. clariflavum strains were able to utilize a larger proportion of unpretreated switchgrass,more » and solubilize a higher proportion of glucan, xylan, and arabinan, with strain 4-2a reaching the highest extent of solubilization of these components (64.7 to 69.4%) compared to C. thermocellum (29.5 to 42.5%). In addition, glycome immunoanalyses of residual plant biomass reveal differences in the extent of degradation of easily accessible xylans, with C. clariflavum strains having increased solubilization of this fraction of xylans relative to C. thermocellum. In conclusion, C. clariflavum strains exhibit higher activity than C. thermocellum in the breakdown of hemicellulose and are capable of degrading xylan to xylooligomers and xylose. This capability seems to also play a role in the higher levels of utilization of unpretreated plant material.« less

Construction of a high-density genetic map and the X/Y sex-determining gene mapping in spinach based on large-scale markers developed by specific-locus amplified fragment sequencing (SLAF-seq).

PubMed

Qian, Wei; Fan, Guiyan; Liu, Dandan; Zhang, Helong; Wang, Xiaowu; Wu, Jian; Xu, Zhaosheng

2017-04-04

Cultivated spinach (Spinacia oleracea L.) is one of the most widely cultivated types of leafy vegetable in the world, and it has a high nutritional value. Spinach is also an ideal plant for investigating the mechanism of sex determination because it is a dioecious species with separate male and female plants. Some reports on the sex labeling and localization of spinach in the study of molecular markers have surfaced. However, there have only been two reports completed on the genetic map of spinach. The lack of rich and reliable molecular markers and the shortage of high-density linkage maps are important constraints in spinach research work. In this study, a high-density genetic map of spinach based on the Specific-locus Amplified Fragment Sequencing (SLAF-seq) technique was constructed; the sex-determining gene was also finely mapped. Through bio-information analysis, 50.75 Gb of data in total was obtained, including 207.58 million paired-end reads. Finally, 145,456 high-quality SLAF markers were obtained, with 27,800 polymorphic markers and 4080 SLAF markers were finally mapped onto the genetic map after linkage analysis. The map spanned 1,125.97 cM with an average distance of 0.31 cM between the adjacent marker loci. It was divided into 6 linkage groups corresponding to the number of spinach chromosomes. Besides, the combination of Bulked Segregation Analysis (BSA) with SLAF-seq technology(super-BSA) was employed to generate the linkage markers with the sex-determining gene. Combined with the high-density genetic map of spinach, the sex-determining gene X/Y was located at the position of the linkage group (LG) 4 (66.98 cM-69.72 cM and 75.48 cM-92.96 cM), which may be the ideal region for the sex-determining gene. A high-density genetic map of spinach based on the SLAF-seq technique was constructed with a backcross (BC 1 ) population (which is the highest density genetic map of spinach reported at present). At the same time, the sex-determining gene X/Y was mapped to LG4 with super-BSA. This map will offer a suitable basis for further study of spinach, such as gene mapping, map-based cloning of Specific genes, quantitative trait locus (QTL) mapping and marker-assisted selection (MAS). It will also provide an efficient reference for studies on the mechanism of sex determination in other dioecious plants.

Analyses of plant biomarkers in modern ecosystems to improve vegetation reconstructions at hominid sites

NASA Astrophysics Data System (ADS)

Uno, K. T.; Boisserie, J. R.; Cerling, T. E.; Polissar, P. J.

2017-12-01

Reconstructing vegetation at hominid localities in eastern Africa remains a significant challenge for examining the role of climate and environment in human evolution. Plant wax biomarker approaches, particularly carbon isotopes of n-alkyl lipids, have been increasingly used to estimate the proportion of C3 and C4­ vegetation in past environments. Identifying new biomarkers indicative of vegetation type, specifically those that can be used to identify (C3) grasses prior to the late Miocene C4 expansion, will enable vegetation reconstructions during the first half of the Neogene, where much remains to be learned about hominid environments. Here, we begin to look beyond carbon isotopes from n-alkyl lipids by analyzing molecular distributions and screening for new plant biomarkers that can be used to identify plant functional types or possibly, more specific taxonomic information. We evaluate molecular distributions, carbon isotope ratios, and pentacyclic triterpenoid methyl esters (PTMEs) in modern soils from a wide range of ecosystems in Ethiopia and Kenya where vegetation types, fraction woody cover, and climatic conditions are known. Preliminary data suggest PTMEs are associated with grassy ecosystems but absent from forested ones. We also find that woody cover can be estimated using n-alkane molecular distributions. This non-isotopic approach to reconstructing woody cover opens the door to reconstructing Neogene vegetation provided the molecular distributions of C3 grasses in the past are similar to those of modern C4 grasses.

Rhizosphere priming effects in two contrasting soils

NASA Astrophysics Data System (ADS)

Lloyd, Davidson; Kirk, Guy; Ritz, Karl

2015-04-01

Inputs of fresh plant-derived carbon may stimulate the turnover of existing soil organic matter by so-called priming effects. Priming may occur directly, as a result of nutrient 'mining' by existing microbial communities, or indirectly via population adjustments. However the mechanisms are poorly understood. We planted C4 Kikuyu grass (Pennisetum clandestinum) in pots with two contrasting C3 soils (clayey, fertile TB and sandy, acid SH), and followed the soil CO2 efflux and its δ13C. The extent of C deposition in the rhizosphere was altered by intermittently clipping the grass in half the pots; there were also unplanted controls. At intervals, pots were destructively sampled for root and shoot biomass. Total soil CO2 efflux was measured using a gas-tight PVC chamber fitted over bare soil, and connected to an infra-red gas analyser; the δ13C of efflux was measured in air sub-samples withdrawn by syringe. The extent of priming was inferred from the δ13C of efflux and the δ13C of the plant and soil end-members. In unclipped treatments, in both soils, increased total soil respiration and rhizosphere priming effects (RPE) were apparent compared to the unplanted controls. The TB soil had greater RPE overall. The total respiration in clipped TB soil was significantly greater than in the unplanted controls, but in the clipped SH soil it was not significantly different from the controls. Clipping affected plant C partitioning with greater allocation to shoot regrowth from about 4 weeks after planting. Total plant biomass decreased in the order TB unclipped > SH unclipped >TB clipped > SH clipped. The results are consistent with priming driven by microbial activation stimulated by rhizodeposits and by nitrogen demand from the growing plants under N limited conditions. Our data suggest that photosynthesis drives RPE and soil differences may alter the rate and intensity of RPE but not the direction.

Interactive effect of calcium and gibberellin on nickel tolerance in relation to antioxidant systems in Triticum aestivum L.

PubMed

Siddiqui, Manzer H; Al-Whaibi, Mohamed H; Basalah, Mohammed O

2011-07-01

Nickel toxicity affects many metabolic facets of plants and induces anatomical and morphological changes resulting in reduced growth and productivity. To overcome the damaging effects of nickel (Ni) stress, different strategies of the application of nutrients with plant hormones are being adopted. The present experiment was carried out to assess the growth and physiological response of wheat plant (Triticum aestivum L.) cv. Samma to pre-sowing seed treatment with GA(3) alone as well as in combination with Ca(2+) and/or Ni stress. The pre-sowing seed treatment of Ni decreased all the growth characteristics (plant height, root length, fresh, and dry weight) as well as chlorophyll (Chl) content and enzyme carbonic anhydrase (CA: E.C. 4.2.1.1) activity. However, an escalation was recorded in malondialdehyde content and electrolyte leakage in plants raised from seed soaked with Ni alone. Moreover, all the growth parameters and physiological attributes (Chl content, proline (Pro) content, CA, peroxidase (E.C.1.11.1.7), catalase (E.C. 1.11.1.6), superoxide dismutase (E.C. 1.15.1.1), ascorbate peroxidase (E.C. 1.11.1.11), and glutathione reductase (E.C. 1.6.4.2) were enhanced in the plants developed from the seeds soaked with the combination of GA(3) (10(-6) M), Ca(2+), and Ni. The present study showed that pre-sowing seed treatment of GA(3) with Ca(2+) was more capable in mitigation of adverse effect of Ni toxicity by improving the antioxidant system and Pro accumulation.

Carbon stocks quantification in agricultural systems employing succession and rotation of crops in Rio Grande do Sul State, Brazil.

NASA Astrophysics Data System (ADS)

Walter, Michele K. C.; Marinho, Mara de A.; Denardin, José E.; Zullo, Jurandir, Jr.; Paz-González, Antonio

2013-04-01

Soil and vegetation constitute respectively the third and the fourth terrestrial reservoirs of Carbon (C) on Earth. C sequestration in these reservoirs includes the capture of the CO2 from the atmosphere by photosynthesis and its storage as organic C. Consequently, changes in land use and agricultural practices affect directly the emissions of the greenhouse gases and the C sequestration. Several studies have already demonstrated that conservation agriculture, and particularly zero tillage (ZT), has a positive effect on soil C sequestration. The Brazilian federal program ABC (Agriculture of Low Carbon Emission) was conceived to promote agricultural production with environmental protection and represents an instrument to achieve voluntary targets to mitigate emissions or NAMAS (National Appropriated Mitigation Actions). With financial resources of about US 1.0 billion until 2020 the ABC Program has a target of expand ZT in 8 million hectares of land, with reduction of 16 to 20 million of CO2eq. Our objective was to quantify the C stocks in soil, plants and litter of representative grain crops systems under ZT in Rio Grande do Sul State, Brazil. Two treatments of a long term experimental essay (> 20 years) were evaluated: 1) Crop succession with wheat (Triticum aestivum L.)/soybean (Glycine max (L.) Merril); 2) Crop rotation with wheat/soybean (1st year), vetch (Vicia sativa L.)/soybean (2nd year), and white oat (Avena sativa L.)/sorghum (Sorghum bicolor L.) (3rd year). C quantification in plants and in litter was performed using the direct method of biomass quantification. The soil type evaluated was a Humic Rhodic Hapludox, and C quantification was executed employing the method referred by "C mass by unit area". Results showed that soybean plants under crop succession presented greater C stock (4.31MgC ha-1) comparing with soybean plants cultivated under crop rotation (3.59 MgC ha-1). For wheat, however, greater C stock was quantified in plants under rotation comparing with that under succession (4.95 and 4.14 MgC ha-1, respectively). No differences between succession X rotation (1st year) and succession X rotation (3rd year) were found for litter. Differences in C stock in litter were found only comparing succession (2.42 MgC ha-1) X rotation (2nd year) (3.44 MgC ha-1). Average values of soil C stocks at depth 0-30cm under succession (67.79 MgC ha-1) and rotation (64.83 MgC ha-1) don't differ among treatments. These values in comparison with other determined for similar soil-climate conditions for soils under native forest (60.83 MgC ha-1) and under conventional tillage (60.68 MgC ha-1) reveals a beneficial effect of ZT in soil C stock. Finally, the C stocks determined for plants and litter, representing only 4.0% and 6.4% of that determined for soil, confirm the relevance of soil as a terrestrial C reservoir. Acknowledgments: The authors express thanks for the financial support and technical facilities receipt from Embrapa Trigo, CEPAGRI/ UNICAMP, and FAEPEX/ UNICAMP. CAPES/GOV.BRAZIL is also acknowledged by Dr. Michele K. C. Walter for the greeted scholarship.

Numerically Solving a Transient Heat Conduction Problem with Convection and Radiation

DTIC Science & Technology

1993-06-01

AGREE W1 DISAGREE W1 DISAGREE STRONGLY AGREE RESERVATION RESERVATION DISAGREE COMMENT: Synonyms: Antonyms: 91 INDUSTRIAL PLANT EQUIPMENT (IPI) Plant ... Plant equipment acquired by the Government, exceeding an established acquisition cost threshold, used for the purpose of cutting, abrading, grinding...Antonyms: None Survey Results Industrial Plant Equipment First Round 60% 51.X In C 40%0 Q cc 4- 30% -28.2% 0 4-, 0) 20% U 10% 2.6% 2.6s BA A AR DR D

Inflorescences of alpine cushion plants freeze autonomously and may survive subzero temperatures by supercooling

PubMed Central

Hacker, Jürgen; Ladinig, Ursula; Wagner, Johanna; Neuner, Gilbert

2011-01-01

Freezing patterns in the high alpine cushion plants Saxifraga bryoides, Saxifraga caesia, Saxifraga moschata and Silene acaulis were studied by infrared thermography at three reproductive stages (bud, anthesis, fruit development). The single reproductive shoots of a cushion froze independently in all four species at every reproductive stage. Ice formation caused lethal damage to the respective inflorescence. After ice nucleation, which occurred mainly in the stalk or the base of the reproductive shoot, ice propagated throughout that entire shoot, but not into neighboring shoots. However, anatomical ice barriers within cushions were not detected. The naturally occurring temperature gradient within the cushion appeared to interrupt ice propagation thermally. Consequently, every reproductive shoot needed an autonomous ice nucleation event to initiate freezing. Ice nucleation was not only influenced by minimum temperatures but also by the duration of exposure. At moderate subzero exposure temperatures (−4.3 to −7.7 °C) the number of frozen inflorescences increased exponentially. Due to efficient supercooling, single reproductive shoots remained unfrozen down to −17.4 °C (cooling rate 6 K h−1). Hence, the observed freezing pattern may be advantageous for frost survival of individual inflorescences and reproductive success of high alpine cushion plants, when during episodic summer frosts damage can be avoided by supercooling. PMID:21151351

Beta-ketoacyl-acyl carrier protein synthase IV: a key enzyme for regulation of medium-chain fatty acid synthesis in Cuphea lanceolata seeds.

PubMed

Schütt, Burkhardt Siegfried; Abbadi, Amine; Loddenkötter, Brigitte; Brummel, Monika; Spener, Friedrich

2002-09-01

With the aim of elucidating the mechanisms involved in the biosynthesis of medium-chain fatty acids in Cuphea lanceolata Ait., a crop accumulating up to 90% decanoic acid in seed triacylglycerols, cDNA clones of a beta-ketoacyl-acyl carrier protein (ACP) synthase IV (clKAS IV, EC 2.3.1.41) were isolated from C. lanceolata seed embryos. The amino acid sequence deduced from clKAS IV cDNA showed 80% identity to other plant KAS II-type enzymes, 55% identity towards plant KAS I and over 90% towards other Cuphea KAS IV-type sequences. Recombinant clKAS IV was functionally overexpressed in Escherichia coli, and substrate specificity of purified enzyme showed strong preference for elongation of short-chain and medium-chain acyl-ACPs (C4- to C10-ACP) with nearly equal activity. Further elongation steps were catalysed with distinctly less activity. Moreover, short- and medium-chain acyl-ACPs exerted a chain-length-specific and concentration-dependent substrate inhibition of clKAS IV. Based on these findings a regulatory mechanism for medium-chain fatty acid synthesis in C. lanceolata is presented.

Isolation and Identification of Plant Growth Promoting Rhizobacteria from Cucumber Rhizosphere and Their Effect on Plant Growth Promotion and Disease Suppression

PubMed Central

Islam, Shaikhul; Akanda, Abdul M.; Prova, Ananya; Islam, Md. T.; Hossain, Md. M.

2016-01-01

Plant growth promoting rhizobacteria (PGPR) are the rhizosphere bacteria that may be utilized to augment plant growth and suppress plant diseases. The objectives of this study were to identify and characterize PGPR indigenous to cucumber rhizosphere in Bangladesh, and to evaluate their ability to suppress Phytophthora crown rot in cucumber. A total of 66 isolates were isolated, out of which 10 (PPB1, PPB2, PPB3, PPB4, PPB5, PPB8, PPB9, PPB10, PPB11, and PPB12) were selected based on their in vitro plant growth promoting attributes and antagonism of phytopathogens. Phylogenetic analysis of 16S rRNA sequences identified these isolates as new strains of Pseudomonas stutzeri, Bacillus subtilis, Stenotrophomonas maltophilia, and Bacillus amyloliquefaciens. The selected isolates produced high levels (26.78–51.28 μg mL-1) of indole-3-acetic acid, while significant acetylene reduction activities (1.79–4.9 μmole C2H4 mg-1 protein h-1) were observed in eight isolates. Cucumber plants grown from seeds that were treated with these PGPR strains displayed significantly higher levels of germination, seedling vigour, growth, and N content in root and shoot tissue compared to non-treated control plants. All selected isolates were able to successfully colonize the cucumber roots. Moreover, treating cucumber seeds with these isolates significantly suppressed Phytophthora crown rot caused by Phytophthora capsici, and characteristic morphological alterations in P. capsici hyphae that grew toward PGPR colonies were observed. Since these PGPR inoculants exhibited multiple traits beneficial to the host plants, they may be applied in the development of new, safe, and effective seed treatments as an alternative to chemical fungicides. PMID:26869996

Isoleucine 309 acts as a C4 catalytic switch that increases ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) carboxylation rate in Flaveria.

PubMed

Whitney, Spencer M; Sharwood, Robert E; Orr, Douglas; White, Sarah J; Alonso, Hernan; Galmés, Jeroni

2011-08-30

Improving global yields of important agricultural crops is a complex challenge. Enhancing yield and resource use by engineering improvements to photosynthetic carbon assimilation is one potential solution. During the last 40 million years C(4) photosynthesis has evolved multiple times, enabling plants to evade the catalytic inadequacies of the CO(2)-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Compared with their C(3) ancestors, C(4) plants combine a faster rubisco with a biochemical CO(2)-concentrating mechanism, enabling more efficient use of water and nitrogen and enhanced yield. Here we show the versatility of plastome manipulation in tobacco for identifying sequences in C(4)-rubisco that can be transplanted into C(3)-rubisco to improve carboxylation rate (V(C)). Using transplastomic tobacco lines expressing native and mutated rubisco large subunits (L-subunits) from Flaveria pringlei (C(3)), Flaveria floridana (C(3)-C(4)), and Flaveria bidentis (C(4)), we reveal that Met-309-Ile substitutions in the L-subunit act as a catalytic switch between C(4) ((309)Ile; faster V(C), lower CO(2) affinity) and C(3) ((309)Met; slower V(C), higher CO(2) affinity) catalysis. Application of this transplastomic system permits further identification of other structural solutions selected by nature that can increase rubisco V(C) in C(3) crops. Coengineering a catalytically faster C(3) rubisco and a CO(2)-concentrating mechanism within C(3) crop species could enhance their efficiency in resource use and yield.

In vitro inhibition of metabolism but not transport of gliclazide and repaglinide by Cree medicinal plant extracts.

PubMed

Cieniak, Carolina; Liu, Rui; Fottinger, Alexandra; Smiley, Sheila A M; Guerrero-Analco, Jose A; Bennett, Steffany A L; Haddad, Pierre S; Cuerrier, Alain; Saleem, Ammar; Arnason, John T; Foster, Brian C

2013-12-12

Interactions between conventional drug and traditional medicine therapies may potentially affect drug efficacy and increase the potential for adverse reactions. Cree traditional healing is holistic and patients may use medicinal plants simultaneously with the conventional drugs. However, there is limited information that these medicinal plants may interact with drugs and additional mechanistic information is required. In this study, extracts from traditionally used Cree botanicals were assessed for their potential interaction that could alter the disposition of two blood glucose lowering drugs, gliclazide (Diamicron) and repaglinide (Gluconorm) though inhibition of either metabolism or transport across cell membranes. The effect of 17 extracts on metabolism was examined in a human liver microsome assay by HPLC and individual cytochrome P450s 2C9, 2C19, 2C8 and 3A4 in a microplate fluorometric assay. Gliclazide, rhaponticin and its aglycone derivative, rhapontigenin were also examined in the fluorometric assay. The effect on transport was examined with 11 extracts using the intestinal epithelial Caco-2 differentiated cell monolayer model at times up to 180 min. Both blood glucose lowering medications, gliclazide and repaglinide traversed the Caco-2 monolayer in a time-dependent manner that was not affected by the Cree plant extracts. Incubation of the Cree plant extracts inhibited CYP2C9, 2C19, 2C8 and 3A4-mediated metabolism, and the formation of four repaglinide metabolites: M4, m/z 451-A, m/z 451-B and the glucuronide of repaglinide in the human liver microsome assay. Gliclazide caused no significant inhibition. Likewise, rhaponticin had little effect on the enzymes causing changes of less than 10% with an exception of 17% inhibition of CYP2C19. By contrast, the aglycone rhapontigenin showed the greatest effects on all CYP-mediated metabolism. Its inhibition ranged from a mean of 58% CYP3A4 inhibition to 89% inhibition of CYP2C9. While rhaponticin and the aglycone did not show significant effects on repaglinide metabolism, they demonstrated inhibition of gliclazide metabolism. The aglycone significantly affected levels of gliclazide and its metabolites. These studies demonstrate that the Cree plant extracts examined have the potential in vitro to cause drug interactions through effects on key metabolic enzymes. © 2013 Elsevier Ireland Ltd. All rights reserved.

Identification and analysis of CYP450 genes from transcriptome of Lonicera japonica and expression analysis of chlorogenic acid biosynthesis related CYP450s.

PubMed

Qi, Xiwu; Yu, Xu; Xu, Daohua; Fang, Hailing; Dong, Ke; Li, Weilin; Liang, Chengyuan

2017-01-01

Lonicera japonica is an important medicinal plant that has been widely used in traditional Chinese medicine for thousands of years. The pharmacological activities of L. japonica are mainly due to its rich natural active ingredients, most of which are secondary metabolites. CYP450s are a large, complex, and widespread superfamily of proteins that participate in many endogenous and exogenous metabolic reactions, especially secondary metabolism. Here, we identified CYP450s in L. japonica transcriptome and analyzed CYP450s that may be involved in chlorogenic acid (CGA) biosynthesis. The recent availability of L. japonica transcriptome provided opportunity to identify CYP450s in this herb. BLAST based method and HMM based method were used to identify CYP450s in L. japonica transcriptome. Then, phylogenetic analysis, conserved motifs analysis, GO annotation, and KEGG annotation analyses were conducted to characterize the identified CYP450s. qRT-PCR was used to explore expression patterns of five CGA biosynthesis related CYP450s. In this study, 151 putative CYP450s with complete cytochrome P450 domain, which belonged to 10 clans, 45 families and 76 subfamilies, were identified in L. japonica transcriptome. Phylogenetic analysis classified these CYP450s into two major branches, A-type (47%) and non-A type (53%). Both types of CYP450s had conserved motifs in L. japonica . The differences of typical motif sequences between A-type and non-A type CYP450s in L. japonica were similar with other plants. GO classification indicated that non-A type CYP450s participated in more molecular functions and biological processes than A-type. KEGG pathway annotation totally assigned 47 CYP450s to 25 KEGG pathways. From these data, we cloned two LjC3Hs (CYP98A subfamily) and three LjC4Hs (CYP73A subfamily) that may be involved in biosynthesis of CGA, the major ingredient for pharmacological activities of L. japonica . qRT-PCR results indicated that two LjC3Hs exhibited oppositing expression patterns during the flower development and LjC3H2 exhibited a similar expression pattern with CGA concentration measured by HPLC. The expression patterns of three LjC4Hs were quite different and the expression pattern of LjC4H3 was quite similar with that of LjC3H1 . Our results provide a comprehensive identification and characterization of CYP450s in L. japonica . Five CGA biosynthesis related CYP450s were cloned and their expression patterns were explored. The different expression patterns of two LjC3Hs and three LjC4Hs may be due to functional divergence of both substrate and catalytic specificity during plant evolution. The co-expression pattern of LjC3H1 and LjC4H3 strongly suggested that they were under coordinated regulation by the same transcription factors due to same cis elements in their promoters. In conclusion, this study provides insight into CYP450s and will effectively facilitate the research of biosynthesis of CGA in L. japonica .

Effect of temperature post viral vector inoculation on the amount of hemagglutinin transiently expressed in Nicotiana benthamiana leaves.

PubMed

Matsuda, Ryo; Abe, Tatsuki; Fujiuchi, Naomichi; Matoba, Nobuyuki; Fujiwara, Kazuhiro

2017-09-01

Transient gene expression in whole plants by using viral vectors is promising as a rapid, mass production system for biopharmaceutical proteins. Recent studies have indicated that plant growth conditions such as air temperature markedly influence the accumulation levels of target proteins. Here, we investigated time course of the amount of recombinant hemagglutinin (HA), a vaccine antigen of influenza virus, in leaves of Nicotiana benthamiana plants grown at 20°C or 25°C post viral vector inoculation. The HA content per unit of leaf biomass increased and decreased from 4 to 6 days post inoculation at 20°C and 25°C, respectively, irrespective of the subcellular localization of HA. The overall HA contents were higher when HA was targeted to the endoplasmic reticulum (ER) rather than the apoplast. Necrosis of leaf tissues was specifically observed in plants inoculated with the ER-targeting vector and grown at 25°C. With the ER-targeting vector, the maximum HA contents at 20°C and 25°C were recorded at 6 and 4 days post inoculation, respectively, and were comparable to each other. HA contents thereafter decreased at both temperatures; the rate of reduction appeared faster at 25°C than at 20°C. From a practical point of view, our results indicate that the strategy of targeting HA to the ER, growing plants at a lower temperature of 20°C, and harvesting leaves at around a week after vector inoculation should be implemented to obtain a high HA yield stably and efficiently. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The in vitro antimicrobial activity of natural infant fluoride-free toothpastes on oral micro-organisms.

PubMed

Carvalho, Fabíola G; Negrini, Thais De Cássia; Sacramento, Luis Victor S; Hebling, Josimeri; Spolidorio, Denise M P; Duque, Cristiane

2011-01-01

The objective of this study was to evaluate the antimicrobial activity of six toothpastes for infants: 3 fluoride-free experimental toothpastes--cashew-based, mango-based and without plant extract and fluoride compared with 2 commercially fluoride-free toothpastes and 1 fluoridated toothpastes. Six toothpastes for infants were evaluated in this study: (1) experimental cashew-based toothpaste; (2) experimental mango-based toothpaste; (3) experimental toothpaste without plant extract and fluoride (negative control); (4) First Teeth brand toothpaste; (5) Weleda brand toothpaste; and (6) Tandy brand toothpaste (positive control). The antimicrobial activity was recorded against Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, and Candida albicans using the agar plate diffusion test. First Teeth, Weleda, mango-based toothpaste, and toothpaste without plant extract presented no antimicrobial effect against any of the tested micro-organisms. Cashew toothpaste had antimicrobial activity against S mutans, S sobrinus, and L acidophilus, but it showed no antimicrobial activity against C albicans. There was no statistical difference between the inhibition halo of cashew and Tandy toothpastes against S mutans and L acidophilus. Cashew fluoride-free toothpaste had inhibitory activity against Streptococcus mutans and Lactobacillus acidophilus, and these results were similar to those obtained for fluoridated toothpaste.

PhytoBeta imager: a positron imager for plant biology

NASA Astrophysics Data System (ADS)

Weisenberger, Andrew G.; Kross, Brian; Lee, Seungjoon; McKisson, John; McKisson, J. E.; Xi, Wenze; Zorn, Carl; Reid, Chantal D.; Howell, Calvin R.; Crowell, Alexander S.; Cumberbatch, Laurie; Fallin, Brent; Stolin, Alexander; Smith, Mark F.

2012-07-01

Several positron emitting radioisotopes such as 11C and 13N can be used in plant biology research. The 11CO2 tracer is used to facilitate plant biology research toward optimization of plant productivity, biofuel development and carbon sequestration in biomass. Positron emission tomography (PET) imaging has been used to study carbon transport in live plants using 11CO2. Because plants typically have very thin leaves, little medium is present for the emitted positrons to undergo an annihilation event. The emitted positrons from 11C (maximum energy 960 keV) could require up to approximately 4 mm of water equivalent material for positron annihilation. Thus many of the positrons do not annihilate inside the leaf, resulting in limited sensitivity for PET imaging. To address this problem we have developed a compact beta-positive, beta-minus particle imager (PhytoBeta imager) for 11CO2 leaf imaging. The detector is based on a Hamamatsu H8500 position sensitive photomultiplier tube optically coupled via optical grease to a 0.5 mm thick Eljen EJ-212 plastic scintillator. The detector is equipped with a flexible arm to allow its placement and orientation over or under the leaf to be studied while maintaining the leaf's original orientation. To test the utility of the system the detector was used to measure carbon translocation in a leaf of the spicebush (Lindera benzoin) under two transient light conditions.

PhytoBeta imager: a positron imager for plant biology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisenberger, Andrew G; Lee, Seungjoon; McKisson, John

2012-06-01

Several positron emitting radioisotopes such as 11C and 13N can be used in plant biology research. The 11CO2 tracer is used to facilitate plant biology research toward optimization of plant productivity, biofuel development and carbon sequestration in biomass. Positron emission tomography (PET) imaging has been used to study carbon transport in live plants using 11CO2. Because plants typically have very thin leaves, little medium is present for the emitted positrons to undergo an annihilation event. The emitted positrons from 11C (maximum energy 960 keV) could require up to approximately 4 mm of water equivalent material for positron annihilation. Thus manymore » of the positrons do not annihilate inside the leaf, resulting in limited sensitivity for PET imaging. To address this problem we have developed a compact beta-positive, beta-minus particle imager (PhytoBeta imager) for 11CO2 leaf imaging. The detector is based on a Hamamatsu H8500 position sensitive photomultiplier tube optically coupled via optical grease to a 0.5 mm thick Eljen EJ-212 plastic scintillator. The detector is equipped with a flexible arm to allow its placement and orientation over or under the leaf to be studied while maintaining the leaf's original orientation. To test the utility of the system the detector was used to measure carbon translocation in a leaf of the spicebush (Lindera benzoin) under two transient light conditions.« less

Structural basis for the glucan phosphatase activity of Starch Excess4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vander Kooi, Craig W.; Taylor, Adam O.; Pace, Rachel M.

Living organisms utilize carbohydrates as essential energy storage molecules. Starch is the predominant carbohydrate storage molecule in plants while glycogen is utilized in animals. Starch is a water-insoluble polymer that requires the concerted activity of kinases and phosphatases to solubilize the outer surface of the glucan and mediate starch catabolism. All known plant genomes encode the glucan phosphatase Starch Excess4 (SEX4). SEX4 can dephosphorylate both the starch granule surface and soluble phosphoglucans and is necessary for processive starch metabolism. The physical basis for the function of SEX4 as a glucan phosphatase is currently unclear. Herein, we report the crystal structuremore » of SEX4, containing phosphatase, carbohydrate-binding, and C-terminal domains. The three domains of SEX4 fold into a compact structure with extensive interdomain interactions. The C-terminal domain of SEX4 integrally folds into the core of the phosphatase domain and is essential for its stability. The phosphatase and carbohydrate-binding domains directly interact and position the phosphatase active site toward the carbohydrate-binding site in a single continuous pocket. Mutagenesis of the phosphatase domain residue F167, which forms the base of this pocket and bridges the two domains, selectively affects the ability of SEX4 to function as a glucan phosphatase. Together, these results reveal the unique tertiary architecture of SEX4 that provides the physical basis for its function as a glucan phosphatase.« less

Greater soil carbon accumulation in deeper soils in native- than in exotic-dominated grassland plantings in the southern Plains

NASA Astrophysics Data System (ADS)

Wilsey, B. J.; Xu, X.; Polley, H. W.; Hofmockel, K. S.

2017-12-01

Global change includes invasion by non-native plant species, and invasion may affect carbon cycling and storage. We tested predictions in central Texas in an experiment that compares mixtures of all exotic or all native species under two summer irrigation treatments (128 or 0 mm) that varies the amount of summer drought stress. At the end of the eighth growing season after establishment, soils were sampled in 10 cm increments to 100 cm depth to determine if soil C differed among treatments, and if treatments differentially affected soil C in deeper soils. Soil C content was significantly (5%) higher under native plantings than under exotic species plantings (P < 0.001). The difference between native and exotic plantings increased with depth, and native plantings had higher soil C in deeper soil layers than in surface layers (native-exotic x depth, P < 0.001). Exotic plantings had decreasing soil C with depth. Soil C:N ratio and δ13C/12C were also significantly affected by native-exotic status, with soils in exotic plots having a significantly greater C4 contribution than native soils. Soil C was unaffected by summer irrigation treatments. Our results suggest that a significant amount of carbon could be sequestered by replacing exotic plant species with native species in the southern Plains, and that more work should be conducted at deeper soil depths. If we had restricted our analyses to surface soil layers (e.g. top 30 cm), we would have failed to detect depth differences between natives and exotics.

Assessing plant residue decomposition in soil using DRIFT spectroscopy

NASA Astrophysics Data System (ADS)

Ouellette, Lance; Van Eerd, Laura; Voroney, Paul

2016-04-01

Assessment of the decomposition of plant residues typically involves the use of tracer techniques combined with measurements of soil respiration. This laboratory study evaluated use of Diffuse Reflectance Fourier Transform (DRIFT) spectroscopy for its potential to assess plant residue decomposition in soil. A sandy loam soil (Orthic Humic Gleysol) obtained from a field research plot was passed through a 4.75 mm sieve moist (~70% of field capacity) to remove larger crop residues. The experimental design consisted of a randomized complete block with four replicates of ten above-ground cover crop residue-corn stover combinations, where sampling time was blocked. Two incubations were set up for 1) Drift analysis: field moist soil (250 g ODW) was placed in 500 mL glass jars, and 2) CO2 evolution: 100 g (ODW) was placed in 2 L jars. Soils were amended with the plant residues (oven-dried at 60°C and ground to <2 mm) at rates equivalent to field mean above-ground biomass yields, then moistened to 60% water holding capacity and incubated in the dark at 22±3°C. Measurements for DRIFT and CO2-C evolved were taken after 0.5, 2, 4, 7, 10, 15, 22, 29, 36, 43, 50 64 and 72 d. DRIFT spectral data (100co-added scans per sample) were recorded with a Varian Cary 660 FT-IR Spectrometer equipped with an EasiDiff Diffuse Reflectance accessory operated at a resolution of 4 cm-1 over the mid-infrared spectrum from 4000 to 400 cm-1. DRIFT spectra of amended soils indicated peak areas of aliphatics at 2930 cm-1, of aromatics at 1620, and 1530 cm-1 and of polysaccharides at 1106 and 1036 cm-1. Evolved CO2 was measured by the alkali trap method (1 M NaOH); the amount of plant residue-C remaining in soil was calculated from the difference in the quantity of plant residue C added and the additional CO2-C evolved from the amended soil. First-order model parameters of the change in polysaccharide peak area over the incubation were related to those generated from the plant residue C decay curves obtained from respiration measurements. The DRIFT method demonstrated that spectral areas consistent with labile aliphatic-C bands (2930 cm-1) can also be used to describe residue C decomposition. This is the first study to demonstrate the usefulness of DRIFT spectroscopy to characterize plant decomposition in soil.

Modeled hydraulic redistribution in tree-grass, CAM-grass, and tree-CAM associations: the implications of crassulacean acid metabolism (CAM).

PubMed

Yu, Kailiang; Foster, Adrianna

2016-04-01

Past studies have largely focused on hydraulic redistribution (HR) in trees, shrubs, and grasses, and recognized its role in interspecies interactions. HR in plants that conduct crassulacean acid metabolism (CAM), however, remains poorly investigated, as does the effect of HR on transpiration in different vegetation associations (i.e., tree-grass, CAM-grass, and tree-CAM associations). We have developed a mechanistic model to investigate the net direction and magnitude of HR at the patch scale for tree-grass, CAM-grass, and tree-CAM associations at the growing season to yearly timescale. The modeling results show that deep-rooted CAM plants in CAM-grass associations could perform hydraulic lift at a higher rate than trees in tree-grass associations in a relatively wet environment, as explained by a significant increase in grass transpiration rate in the shallow soil layer, balancing a lower transpiration rate by CAM plants. By comparison, trees in tree-CAM associations may perform hydraulic descent at a higher rate than those in tree-grass associations in a dry environment. Model simulations also show that hydraulic lift increases the transpiration of shallow-rooted plants, while hydraulic descent increases that of deep-rooted plants. CAM plants transpire during the night and thus perform HR during the day. Based on these model simulations, we suggest that the ability of CAM plants to perform HR at a higher rate may have different effects on the surrounding plant community than those of plants with C3 or C4 photosynthetic pathways (i.e., diurnal transpiration).

Diet and environment of a mid-Pliocene fauna from southwestern Himalaya: Paleo-elevation implications

NASA Astrophysics Data System (ADS)

Wang, Yang; Xu, Yingfeng; Khawaja, Sofia; Passey, Benjamin H.; Zhang, Chunfu; Wang, Xiaoming; Li, Qiang; Tseng, Zhijie J.; Takeuchi, Gary T.; Deng, Tao; Xie, Guangpu

2013-08-01

A mid-Pliocene fauna (4.2-3.1 Ma) was recently uncovered in the Zanda (Zhada) Basin in the southwestern Himalaya, at an elevation of about 4200 m above sea level. These fossil materials provide a unique window for examining the linkage among tectonic, climatic and biotic changes. Here we report the results from isotopic analyses of this fauna and of modern herbivores and waters as well as paleo-temperature estimates from the Zanda Basin. The δ13C values of enamel samples from modern wild Tibetan asses, and domesticated horses, cows and goats in the area are -9.4±1.8‰, which indicate a diet comprising predominantly of C3 plants and are consistent with the current dominance of C3 vegetation in the region. The enamel-δ13C values of the fossil horses, rhinos, deer, and bovids are -9.6±0.8‰, indicating that these ancient mammals, like modern herbivores in the area, also fed primarily on C3 vegetation and lived in an environment dominated by C3 plants. The lack of significant C4 plants in the basin suggests that the area had reached high elevations (>2.5 km) by at least the mid-Pliocene. Taking into account the changes in the δ13C of atmospheric CO2 in the past, the enamel-δ13C values suggest that the average modern-equivalent δ13C value of C3 vegetation in the Zanda Basin in the mid-Pliocene was ∼1-2‰ lower than that of the C3 biomass in the basin today. This would imply a reduction in annual precipitation by about 200-400 mm in the area since then (assuming that the modern C3 δ13C-precipitation relationship applied to the past). Consistent with this inference from the δ13C data, the enamel-δ18O data show a significant shift to higher values after the mid-Pliocene, which also suggests a shift in climate to much drier conditions after ∼4-3 Ma. Paleo-temperature estimates derived from a fossil bone-based oxygen isotope temperature proxy as well as the carbonate clumped isotope thermometer for the mid-Pliocene Zanda Basin are higher than the present-day mean annual temperature in the area. After accounting for late Cenozoic global cooling, these paleo-temperature estimates suggest that the paleo-elevation of the Zanda Basin in the mid-Pliocene was similar to or slightly (less than ∼1 km) lower than its present-day elevation, which is consistent with the inference from the δ13C data.

Diversity of sulfate-reducing bacteria in a plant using deep geothermal energy

NASA Astrophysics Data System (ADS)

Alawi, Mashal; Lerm, Stephanie; Vetter, Alexandra; Wolfgramm, Markus; Seibt, Andrea; Würdemann, Hilke

2011-06-01

Enhanced process understanding of engineered geothermal systems is a prerequisite to optimize plant reliability and economy. We investigated microbial, geochemical and mineralogical aspects of a geothermal groundwater system located in the Molasse Basin by fluid analysis. Fluids are characterized by temperatures ranging from 61°C to 103°C, salinities from 600 to 900 mg/l and a dissolved organic carbon content (DOC) between 6.4 to 19.3 mg C/l. The microbial population of fluid samples was analyzed by genetic fingerprinting techniques based on PCR-amplified 16S rRNA- and dissimilatory sulfite reductase genes. Despite of the high temperatures, microbes were detected in all investigated fluids. Fingerprinting and DNA sequencing enabled a correlation to metabolic classes and biogeochemical processes. The analysis revealed a broad diversity of sulfate-reducing bacteria. Overall, the detection of microbes known to be involved in biocorrosion and mineral precipitation indicates that microorganisms could play an important role for the understanding of processes in engineered geothermal systems.

Dynamic Simulation of a Helium Liquefier

NASA Astrophysics Data System (ADS)

Maekawa, R.; Ooba, K.; Nobutoki, M.; Mito, T.

2004-06-01

Dynamic behavior of a helium liquefier has been studied in detail with a Cryogenic Process REal-time SimulaTor (C-PREST) at the National Institute for Fusion Science (NIFS). The C-PREST is being developed to integrate large-scale helium cryogenic plant design, operation and maintenance for optimum process establishment. As a first step of simulations of cooldown to 4.5 K with the helium liquefier model is conducted, which provides a plant-process validation platform. The helium liquefier consists of seven heat exchangers, a liquid-nitrogen (LN2) precooler, two expansion turbines and a liquid-helium (LHe) reservoir. Process simulations are fulfilled with sequence programs, which were implemented with C-PREST based on an existing liquefier operation. The interactions of a JT valve, a JT-bypass valve and a reservoir-return valve have been dynamically simulated. The paper discusses various aspects of refrigeration process simulation, including its difficulties such as a balance between complexity of the adopted models and CPU time.

Leaf oxygen and Carbon Isotopic Signatures Reflect Drought Resistance and Water Use Efficiency in the C4 Grass, Setaria viridis

NASA Astrophysics Data System (ADS)

Ellsworth, P.; Cousins, A. B.

2014-12-01

Low water availability is a major constraint in crop production, especially as agriculture is pushed to marginal lands. Therefore, improving drought resistance such as increasing water use efficiency (WUE) through plant breeding is needed to expand the range of soil water availability adequate for food production. With the goal of finding the genomic basis for WUE in C4 grasses, Setaria viridis makes an ideal model species because of its small size, short lifespan, and sequenced genome. Also it is part of the panicoid grass clade, which is one of the most important clades for food and biofuel production. In plant breeding programs, large numbers of genotypes must be quickly screened for drought resistance traits, but there is no well-defined method of screening for WUE in C4 grasses. However, bulk leaf oxygen (Δ18OBL) and carbon (δ13C) isotopic signatures have shown potential as recorders of transpiration rate (E) and stomatal conductance (gs), and combined with biomass production potentially serve as a measure of WUE. Values of Δ18OBL record differences in transpiration rate because leaf water becomes more enriched as transpiration rate decreases, and leaf tissue records the isotopic composition of leaf water in which it is synthesized. Additionally, in C4 plants δ13C values decrease as gs decreases but the change in δ13C in response to gs may not be adequate to tease apart differences in WUE. In this study, we grew S. viridis plants under well-watered and water-limited conditions to determine if Δ18OBL and δ13C could be used as proxies for E and gs, and be used to screen S. viridis for differences in WUE in breeding programs. The Δ18OBL and δ13C were significantly different between well-watered and water-limited plants and correlated with each other and with E, gs, and instantaneous water use efficiency (Anet/gs). Therefore, Δ18OBL and δ13C can be useful proxies to screen genotypes for drought resistance by recording differences in E, gs, and WUE. Measuring Δ18OBL and δ13C are relatively simple and quick, requiring the collection of a single leaf sample from each genotype instead of making laborious gas exchange measurements of E and gs.

Morphology, nurse plants, and minimum apical temperatures for young Carnegiea gigantea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobel, P.S.

1980-06-01

The northern limit of Carnegiea gigantea (Engelm.) Britton and Rose apparently depends on minimum apical temperatures. Diameters, apical spine coverage, and effects of nurse plants on incoming long-wave (infrared (ir)) radiation, all of which affect apical temperatures, were therefore determined for stems of C. gigantea up to 4 m tall at four sites along a north-south transect in Arizona. A simulation model indicated that the increase in diameter accompanying stem growth raised the minimum apical temperature more than 3 C. Thus, plants with the shortest stems would be expected to be the most vulnerable to freezing damage; indeed, freezing damagemore » on stems <0.5 m tall without nurse plants was fairly common at the colder sites. Nurse plants obstructed a greater portion of the sky for C. gigantea at the colder sites; e.g., the effective environmental temperature for ir radiation at such locations was raised more than 10 C for stems under 1 m tall. If the northern limit of C. gigantea reflects wintertime survival of juveniles, nurse plants could extend the range by offering some protection against freezing.« less

Leaf water use efficiency of C{sub 4} plants grown at glacial to elevated CO{sub 2} concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polley, H.W.; Johnson, H.B.; Mayeux, H.S.

1995-09-01

Leaf gas exchange and stable carbon isotope compositions were measured on C{sub 4} species grown from near glacial to current CO{sub 2} concentrations (200 to 350 {mu}mol/mol) and from the current concentration to levels possible in the future (700 and 1000 {mu}mol/mol) to determine effects of rising CO{sub 2} on intrinsic water use efficiency (CO{sub 2} assimilation, A/stomatal conductance to water, g) of C{sub 4} plants. The increase in A/g was proportionally greater than that in CO{sub 2} from near glacial to present concentrations in the perennial grass Schizachyrium scoparium and, in one of two years, in the annual grassmore » Zea mays, because of a corresponding decrease in the ratio of leaf intercellular (c{sub i}) to external CO{sub 2} concentration (c{sub a}). Leaf A/g increased 66% in S. scoparium and 80% in the perennial shrub Atriplex canescens from 350 to 700 {mu}mol/mol CO{sub 2}, but averaged across species declined 15% from 700 to 1000 {mu}mol/mol because of an accompanying increase in c{sub i}/c{sub a}. At each CO{sub 2} level, A/g was higher in the grass than shrub. There were substantial differences in A/g at a given CO{sub 2} concentration and in the response of A/g to CO{sub 2} among the species examined. Because much of the positive response of C{sub 4} plants to CO{sub 2} derives from higher water use efficiency, these differences could influence the relative productivities of C{sub 4} species.« less

Low night temperature effect on photosynthate translocation of two C4 grasses.

PubMed

Potvin, C; Strain, B R; Goeschl, J D

1985-10-01

Translocation of assimilates in plants of Echinochloa crus-galli, from Quebec and Mississippi, and of Eleusine indica from Mississippi was monitored, before and after night chilling, using radioactive tracing with the short-life isotope 11 C. Plants were grown at 28°/22°C (day/night temperatures) under either 350 or 675 μl·l -1 CO 2 . Low night temperature reduced translocation mainly by increasing the turn-over times of the export pool. E. crus-galli plants from Mississippi were the most susceptible to chilling; translocation being completely inhibited by exposure for one night to 7°C at 350 μl·l -1 CO 2 . Overall, plants from Quebec were the most tolerant to chilling-stress. For plants of all three populations, growth under CO 2 enrichment resulted in higher 11 C activity in the leaf phloem. High CO 2 concentrations also seemed to buffer the transport system against chilling injuries.

76 FR 38503 - Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List a Distinct...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-30

... U.S.C. 1531 et seq.) requires that, for any petition to revise the Federal Lists of Endangered and... this finding, we will determine that the petitioned action is: (a) Not warranted, (b) warranted, or (c... Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we treat a petition for which the...

Microsporols A-C from the Plant Endophytic Fungus Pestalotiopsis microspore.

PubMed

Wu, Xianfu; Wang, Yadan; Liu, Shuchun; Liu, Xinzhong; Guo, Liangdong

2015-10-01

Three new ambuic acid derivatives, microsporols A-C (1-3) and the known compound ambuic acid (4), were isolated from the solid-substrate fermentation cultures of the plant endophytic fungus Pestalotiopsis microspora. Their structures were elucidated primarily by NMR experiments. The absolute configurations of the 6,7-diol moiety in 1 and 2 were assigned using the Snatzke's method, whereas that of 3 was deduced by circular dichroism (CD) exciton chirality method. Compounds 1, 3, and 4 showed moderate 5-lipoxygenase (5-LOX) inhibitory effects.

The carbon isotope biogeochemistry of the individual hydrocarbons in bat guano and the ecology of insectivorous bats in the region of Carlsbad, New Mexico

NASA Technical Reports Server (NTRS)

Desmarais, D. J.; Mitchell, J. M.; Meinschein, W. G.; Hayes, J. M.

1980-01-01

The structures and C-13 contents of individual alkanes extracted from bat guano found in the Carlsbad region of New Mexico can be related to both the photosynthetic pathways of the local plants and the feeding habits of the insects that support the bats. Carbon isotopic analyses of the 62 most important plant species in the Pecos River Valley, the most significant feeding area for the Carlsbad bats, reveal the presence of 29 species with C3 photosynthesis and 33 species, mostly grasses, with C4 photosynthesis. Although the abundances of nonagricultural C3 and C4 plants are similar, alfalfa and cotton, both C3 plants, constitute over 95 per cent of the crop biomass. The molecular composition of the bat guano hydrocarbons is fully consistent with an insect origin. Two isotopically distinct groups of insect branched alkanes were discerned. These two groups of alkanes derived from two chemotaxonomically distinct populations of insects possessing distinctly different feeding habits. It is likely that one population grazes predominantly on crops whereas the other population prefers native vegetation. This and other isotopic evidence supports the notion that crop pests constitute a major percentage of the bats' diet.

Effects of Disinfectants in Water on Mir- and Earth-Grown Wheat

NASA Technical Reports Server (NTRS)

Campbell, William .F.; Bubenheim, D. L.; Bugbee, B.; Salisbury, F. B.; Bingham, G. E.; Levinskikh, M.; Sytchev, V. N.; Ivanova, I.; Chernova, L.; Podolsky, I.

2002-01-01

Iodine and silver fluoride are used to purify water onboard U. S. Shuttles and the Russian Space Station, Mir, respectively. In 1995, iodine-treated water, which ranged from 1.0-4.0 mg x kg(exp -1) with a mean of 2.9 mg x kg(exp -1), was applied to Super Dwarf wheat (Triticum aestivum L.) plants when Mir water (grey or tech grade) became scarce. The potential phytotoxicity of iodine on Super Dwarf wheat is an unknown. Since use of iodine-treated water was not part of the experiment, we sought to determine whether it accounted for the subsequent poor wheat seedling growth and floral development onboard the Mir. Super Dwarf wheat seeds were imbibed in iodine or silver fluoride concentrations of 0.0, 1.0, 2.0, 4.0, 8.0 or 16.0 mg x kg(exp -1) for 96 h at 4 C. Five seeds were then planted per 13.3 cm x 13.3 cm pots containing a granular clinoptilolite (Cp) zeolite (1 -2 mm dia.) and placed in Percival(TM) growth chambers programmed for 20/15 C and 18/6 h d/n regime. Plants were irrigated with distilled water, and Iodine- or silver fluoride-treated distilled water. In separate experiments, seeds were treated as above and germination and early seedling growth were determined by examining seedling responses to disinfectants in rolled paper towels. Silver fluoride had very little effect on wheat seed germination. By contrast, iodine reduced germination at all treatment levels. Seedlings exposed to 1.0, 2.0, and 4.0 mg x kg(exp -1) of iodine or silver fluoride levels exhibited a slight stimulation in shoot and root growth. Both disinfectants at 8 and 16 mg x kg(exp -1) showed significantly (p is less than or equal to 0.01) reduced seedling shoot and root lengths and fresh biomasses compared to the control and lower disinfectant levels. The number of spikelets per spike, florets per spikelet, seeds per spike and seed weight were also significantly reduced at the 8 and 16 mg x kg(exp -1) compared to the control and lower levels of disinfectant. Based on these ground-based post-flight analyses, the levels of iodine- and/or silver fluoride-treated water used on Mir-grown plants onboard the Mir did not cause the poor growth and development of the wheat plants.

Animal protein production modules in biological life support systems: Novel combined aquaculture techniques based on the closed equilibrated biological aquatic system (C.E.B.A.S.)

NASA Astrophysics Data System (ADS)

Blüm, V.; Andriske, M.; Kreuzberg, K.; Schreibman, M. P.

Based on the experiences made with the Closed Equilibrated Biological Aquatic System (C.E.B.A.S.) which was primarily deveoloped for long-term and multi-generation experiments with aquatic animals and plants in a space station highly effective fresh water recycling modules were elaborated utilizing a combination of ammonia oxidizing bacteria filters and higher plants. These exhibit a high effectivity to eliminate phosphate and anorganic nitrogen compounds and arc. in addidition. able to contribute to the oxygen supply of the aquatic animals. The C.E.B.A.S. filter system is able to keep a closed artificial aquatic ecosystem containing teleost fishes and water snails biologically stable for several month and to eliminate waste products deriving from degraded dead fishes without a decrease of the oxygen concentration down to less than 3.5 mg/l at 25 °C. More advanced C.E.B.A.S. filter systems, the BIOCURE filters, were also developed for utilization in semiintensive and intensive aquaculture systems for fishes. In fact such combined animal-plant aquaculture systems represent highly effective productions sites for human food if proper plant and fish species are selected The present papers elucidates ways to novel aquaculture systems in which herbivorous fishes are raised by feeding them with plant biomass produced in the BIOCURE filters and presents the scheme of a modification which utilizes a plant species suitable also for human nutrition. Special attention is paid to the benefits of closed aquaculture system modules which may be integrated into bioregenerative life support systems of a higher complexity for, e. g.. lunar or planetary bases including some psychologiccal aspects of the introduction of animal protein production into plant-based life support systems. Moreover, the basic reproductive biological problems of aquatic animal breeding under reduced gravity are explained leading to a disposition of essential research programs in this context.

Effect of ammonium sulfate, ammonium chloride and root-zone acidity on inorganic ion content of tobacco

NASA Technical Reports Server (NTRS)

Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

1990-01-01

Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH4)2SO4 or NH4Cl at root-zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH4+ source or root-zone pH. Plants supplied with NH4Cl accumulated up to 1.2 mM Cl g DW-1, but accumulated 37% less inorganic H2PO4- and 47% less SO4(2-) than plants supplied with (NH4)2SO4. The large Cl- accumulation resulted in NH4Cl- supplied plants having a 31% higher inorganic anion (NO3-, H2, PO4-, SO4(2-), and Cl-) charge. This higher inorganic anion charge in the NH4Cl-supplied plants was balanced by a similar increase in K+ charge. Plants supplied with NH4Cl accumulated greater concentrations of Cl- in leaves (up to 5.1% of DW) than plants supplied with (NH4)2SO4 (less than -% DW). Despite the high Cl- concentration of leaves in NH4Cl supplied plants, these plants showed no symptoms of Cl- toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl- concentration in tissue and NH4+ nutrition. The increase in root-zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.

Evolution of RLSB, a nuclear-encoded S1 domain RNA binding protein associated with post-transcriptional regulation of plastid-encoded rbcL mRNA in vascular plants.

PubMed

Yerramsetty, Pradeep; Stata, Matt; Siford, Rebecca; Sage, Tammy L; Sage, Rowan F; Wong, Gane Ka-Shu; Albert, Victor A; Berry, James O

2016-06-29

RLSB, an S-1 domain RNA binding protein of Arabidopsis, selectively binds rbcL mRNA and co-localizes with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) within chloroplasts of C3 and C4 plants. Previous studies using both Arabidopsis (C3) and maize (C4) suggest RLSB homologs are post-transcriptional regulators of plastid-encoded rbcL mRNA. While RLSB accumulates in all Arabidopsis leaf chlorenchyma cells, in C4 leaves RLSB-like proteins accumulate only within Rubisco-containing bundle sheath chloroplasts of Kranz-type species, and only within central compartment chloroplasts in the single cell C4 plant Bienertia. Our recent evidence implicates this mRNA binding protein as a primary determinant of rbcL expression, cellular localization/compartmentalization, and photosynthetic function in all multicellular green plants. This study addresses the hypothesis that RLSB is a highly conserved Rubisco regulatory factor that occurs in the chloroplasts all higher plants. Phylogenetic analysis has identified RLSB orthologs and paralogs in all major plant groups, from ancient liverworts to recent angiosperms. RLSB homologs were also identified in algae of the division Charophyta, a lineage closely related to land plants. RLSB-like sequences were not identified in any other algae, suggesting that it may be specific to the evolutionary line leading to land plants. The RLSB family occurs in single copy across most angiosperms, although a few species with two copies were identified, seemingly randomly distributed throughout the various taxa, although perhaps correlating in some cases with known ancient whole genome duplications. Monocots of the order Poales (Poaceae and Cyperaceae) were found to contain two copies, designated here as RLSB-a and RLSB-b, with only RLSB-a implicated in the regulation of rbcL across the maize developmental gradient. Analysis of microsynteny in angiosperms revealed high levels of conservation across eudicot species and for both paralogs in grasses, highlighting the possible importance of maintaining this gene and its surrounding genomic regions. Findings presented here indicate that the RLSB family originated as a unique gene in land plant evolution, perhaps in the common ancestor of charophytes and higher plants. Purifying selection has maintained this as a highly conserved single- or two-copy gene across most extant species, with several conserved gene duplications. Together with previous findings, this study suggests that RLSB has been sustained as an important regulatory protein throughout the course of land plant evolution. While only RLSB-a has been directly implicated in rbcL regulation in maize, RLSB-b could have an overlapping function in the co-regulation of rbcL, or may have diverged as a regulator of one or more other plastid-encoded mRNAs. This analysis confirms that RLSB is an important and unique photosynthetic regulatory protein that has been continuously expressed in land plants as they emerged and diversified from their ancient common ancestor.

Structural and metabolic transitions of C4 leaf development and differentiation defined by microscopy and quantitative proteomics in maize.

PubMed

Majeran, Wojciech; Friso, Giulia; Ponnala, Lalit; Connolly, Brian; Huang, Mingshu; Reidel, Edwin; Zhang, Cankui; Asakura, Yukari; Bhuiyan, Nazmul H; Sun, Qi; Turgeon, Robert; van Wijk, Klaas J

2010-11-01

C(4) grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations. C(4) photosynthesis is established along the developmental axis of the leaf blade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C(4) differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C(4) specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the Plant Proteome Database.

Investigations of microbial degradation of polycyclic aromatic hydrocarbons based on 13C-labeled phenanthrene in a soil co-contaminated with trace elements using a plant assisted approach.

PubMed

Wawra, Anna; Friesl-Hanl, Wolfgang; Jäger, Anna; Puschenreiter, Markus; Soja, Gerhard; Reichenauer, Thomas; Watzinger, Andrea

2018-03-01

Co-contaminations of soils with organic and inorganic pollutants are a frequent environmental problem. Due to their toxicity and recalcitrance, the heterogeneous pollutants may persist in soil. The hypothesis of this study was that degradation of polycyclic aromatic hydrocarbons (PAHs) is enhanced if heavy metals in soil are immobilized and their bioavailability reduced. For metal immobilization and enhanced biodegradation, distinct mineral and organic soil amendments (iron oxides, gravel sludge, biochar) were deployed in an incubation batch experiment. The second part of the experiment consisted of a greenhouse pot experiment applying fast-growing and pollution-tolerant woody plants (willow and black locust). Soil amendments initially immobilized NH 4 NO 3 -extractable zinc, cadmium, and lead; after 100 days of incubation, soil amendments showed reductions only for cadmium and a tendency to enhance arsenic mobility. In order to monitor the remediation success, a 13 C-phenanthrene (PHE) label was applied. 13 C-phospholipid fatty acid analysis ( 13 C-PLFA) further enabled the identification of PHE-degrading soil microorganisms. Both experiments exhibited a similar PLFA profile. Gram-negative bacteria (esp. cy17:0, 16:1ω7 + 6, 18:1ω7c) were the most significant microbial group taking up 13 C-PHE. Plants effectively increased the label uptake by gram-positive bacteria and increased the biomass of the fungal biomarker, although their contribution to the degradation process was minor. Plants tended to prolong PAH dissipation in soil; at the end of the experiment, however, all treatments showed equally low total PAH concentrations in soil. While black locust plants tended not to take up potentially toxic trace elements, willows accumulated them in their leaves. The results of this study show that the chosen treatments did not enhance the remediation of the experimental soil.

An rbcL mRNA-binding protein is associated with C3 to C4 evolution and light-induced production of Rubisco in Flaveria.

PubMed

Yerramsetty, Pradeep; Agar, Erin M; Yim, Won C; Cushman, John C; Berry, James O

2017-07-20

Nuclear-encoded RLSB protein binds chloroplastic rbcL mRNA encoding the Rubisco large subunit. RLSB is highly conserved across all groups of land plants and is associated with positive post-transcriptional regulation of rbcL expression. In C3 leaves, RLSB and Rubisco occur in all chlorenchyma cell chloroplasts, while in C4 leaves these accumulate only within bundle sheath (BS) chloroplasts. RLSB's role in rbcL expression makes modification of its localization a likely prerequisite for the evolutionary restriction of Rubisco to BS cells. Taking advantage of evolutionarily conserved RLSB orthologs in several C3, C3-C4, C4-like, and C4 photosynthetic types within the genus Flaveria, we show that low level RLSB sequence divergence and modification to BS specificity coincided with ontogeny of Rubisco specificity and Kranz anatomy during C3 to C4 evolution. In both C3 and C4 species, Rubisco production reflected RLSB production in all cell types, tissues, and conditions examined. Co-localization occurred only in photosynthetic tissues, and both proteins were co-ordinately induced by light at post-transcriptional levels. RLSB is currently the only mRNA-binding protein to be associated with rbcL gene regulation in any plant, with variations in sequence and acquisition of cell type specificity reflecting the progression of C4 evolution within the genus Flaveria. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Factors affecting seawater-based pretreatment of lignocellulosic date palm residues.

PubMed

Fang, Chuanji; Thomsen, Mette Hedegaard; Frankær, Christian Grundahl; Bastidas-Oyanedel, Juan-Rodrigo; Brudecki, Grzegorz P; Schmidt, Jens Ejbye

2017-12-01

Seawater-based pretreatment of lignocellulosic biomass is an innovative process at research stage. With respect to process optimization, factors affecting seawater-based pretreatment of lignocellulosic date palm residues were studied for the first time in this paper. Pretreatment temperature (180°C-210°C), salinity of seawater (0ppt-50ppt), and catalysts (H 2 SO 4 , Na 2 CO 3 , and NaOH) were investigated. The results showed that pretreatment temperature exerted the largest influence on seawater-based pretreatment in terms of the enzymatic digestibility and fermentability of pretreated solids, and the inhibition of pretreatment liquids to Saccharomyces cerevisiae. Salinity showed the least impact to seawater-based pretreatment, which widens the application spectrum of saline water sources such as brines discharged in desalination plant. Sulfuric acid was the most effective catalyst for seawater-based pretreatment compared with Na 2 CO 3 and NaOH. Copyright © 2017 Elsevier Ltd. All rights reserved.