Controlled Ecological Life Support System: Use of Higher Plants

NASA Technical Reports Server (NTRS)

Tibbits, T. W.; Alford, D. K.

1982-01-01

Results of two workshops concerning the use of higher plants in Controlled Ecological Life Support Systems (CELSS) are summarized. Criteria for plant selection were identified from these categories: food production, nutrition, oxygen production and carbon dioxide utilization, water recycling, waste recycling, and other morphological and physiological considerations. Types of plant species suitable for use in CELSS, growing procedures, and research priorities were recommended. Also included are productivity values for selected plant species.

A Causality Analysis of the Link between Higher Education and Economic Development.

ERIC Educational Resources Information Center

De Meulemeester, Jean-Luc; Rochat, Denis

1995-01-01

Summarizes a study exploring the relationship between higher education and economic development, using cointegration and Granger-causality tests. Results show a significant causality from higher education efforts in Sweden, United Kingdom, Japan, and France. However, a similar causality link has not been found for Italy or Australia. (68…

Linking plant and ecosystem functional biogeography

PubMed Central

Reichstein, Markus; Bahn, Michael; Mahecha, Miguel D.; Kattge, Jens; Baldocchi, Dennis D.

2014-01-01

Classical biogeographical observations suggest that ecosystems are strongly shaped by climatic constraints in terms of their structure and function. On the other hand, vegetation function feeds back on the climate system via biosphere–atmosphere exchange of matter and energy. Ecosystem-level observations of this exchange reveal very large functional biogeographical variation of climate-relevant ecosystem functional properties related to carbon and water cycles. This variation is explained insufficiently by climate control and a classical plant functional type classification approach. For example, correlations between seasonal carbon-use efficiency and climate or environmental variables remain below 0.6, leaving almost 70% of variance unexplained. We suggest that a substantial part of this unexplained variation of ecosystem functional properties is related to variations in plant and microbial traits. Therefore, to progress with global functional biogeography, we should seek to understand the link between organismic traits and flux-derived ecosystem properties at ecosystem observation sites and the spatial variation of vegetation traits given geoecological covariates. This understanding can be fostered by synergistic use of both data-driven and theory-driven ecological as well as biophysical approaches. PMID:25225392

Controlled ecological life support system higher plant flight experiments

NASA Technical Reports Server (NTRS)

Tibbitts, T. W.; Wheeler, R. M.

1984-01-01

Requirements for spaceflight experments which involve higher plants were determined. The plants are studied for use in controlled ecological life support systems (CELSS). Two categories of research requirements are discussed: (1) the physical needs which include nutrient, water and gas exchange requirements; (2) the biological and physiological functions which affect plants in zero gravity environments. Physical problems studies are given the priority since they affect all biological experiments.

Are the metabolomic responses to folivory of closely related plant species linked to macroevolutionary and plant-folivore coevolutionary processes?

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

Rivas-Ubach, Albert; Hódar, José A.; Sardans, Jordi

The debate whether the coevolution of plants and insects or macroevolutionary processes (phylogeny) is the main driver determining the arsenal of molecular defensive compounds of plants remains unresolved. Attacks by herbivorous insects affect not only the composition of defensive compounds in plants but the entire metabolome (the set of molecular metabolites), including defensive compounds. Metabolomes are the final products of genotypes and are directly affected by macroevolutionary processes, so closely related species should have similar metabolomic compositions and may respond in similar ways to attacks by folivores. We analyzed the elemental compositions and metabolomes of needles from Pinus pinaster, P.more » nigra and P. sylvestris to determine if these closely related Pinus species with different coevolutionary histories with the caterpillars of the processionary moth respond similarly to attacks by this lepidopteran. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the pine species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of phenolic metabolites were generally not higher in the attacked trees, which had lower concentrations of terpenes, suggesting that herbivores avoid individuals with high concentrations of terpenes. Our results suggest that macroevolutionary history plays important roles in the metabolomic responses of these pine species to folivory, but plant-insect coevolution probably constrains those responses. Combinations of different evolutionary factors and trade-offs are likely responsible for the different responses of each species to folivory, which is not necessarily exclusively linked to plant-insect coevolution.« less

Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment.

PubMed

Wolff, Silje A; Coelho, Liz H; Karoliussen, Irene; Jost, Ann-Iren Kittang

2014-05-05

Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA) has developed the Micro-Ecological Life Support System Alternative (MELiSSA) program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space.

Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment

PubMed Central

Wolff, Silje A.; Coelho, Liz H.; Karoliussen, Irene; Jost, Ann-Iren Kittang

2014-01-01

Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA) has developed the Micro-Ecological Life Support System Alternative (MELiSSA) program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space. PMID:25370192

Higher plant modelling for life support applications: first results of a simple mechanistic model

NASA Astrophysics Data System (ADS)

Hezard, Pauline; Dussap, Claude-Gilles; Sasidharan L, Swathy

2012-07-01

In the case of closed ecological life support systems, the air and water regeneration and food production are performed using microorganisms and higher plants. Wheat, rice, soybean, lettuce, tomato or other types of eatable annual plants produce fresh food while recycling CO2 into breathable oxygen. Additionally, they evaporate a large quantity of water, which can be condensed and used as potable water. This shows that recycling functions of air revitalization and food production are completely linked. Consequently, the control of a growth chamber for higher plant production has to be performed with efficient mechanistic models, in order to ensure a realistic prediction of plant behaviour, water and gas recycling whatever the environmental conditions. Purely mechanistic models of plant production in controlled environments are not available yet. This is the reason why new models must be developed and validated. This work concerns the design and test of a simplified version of a mathematical model coupling plant architecture and mass balance purposes in order to compare its results with available data of lettuce grown in closed and controlled chambers. The carbon exchange rate, water absorption and evaporation rate, biomass fresh weight as well as leaf surface are modelled and compared with available data. The model consists of four modules. The first one evaluates plant architecture, like total leaf surface, leaf area index and stem length data. The second one calculates the rate of matter and energy exchange depending on architectural and environmental data: light absorption in the canopy, CO2 uptake or release, water uptake and evapotranspiration. The third module evaluates which of the previous rates is limiting overall biomass growth; and the last one calculates biomass growth rate depending on matter exchange rates, using a global stoichiometric equation. All these rates are a set of differential equations, which are integrated with time in order to provide

Milkweed butterfly resistance to plant toxins is linked to sequestration, not coping with a toxic diet.

PubMed

Petschenka, Georg; Agrawal, Anurag A

2015-11-07

Insect resistance to plant toxins is widely assumed to have evolved in response to using defended plants as a dietary resource. We tested this hypothesis in the milkweed butterflies (Danaini) which have progressively evolved higher levels of resistance to cardenolide toxins based on amino acid substitutions of their cellular sodium-potassium pump (Na(+)/K(+)-ATPase). Using chemical, physiological and caterpillar growth assays on diverse milkweeds (Asclepias spp.) and isolated cardenolides, we show that resistant Na(+)/K(+)-ATPases are not necessary to cope with dietary cardenolides. By contrast, sequestration of cardenolides in the body (as a defence against predators) is associated with the three levels of Na(+)/K(+)-ATPase resistance. To estimate the potential physiological burden of cardenolide sequestration without Na(+)/K(+)-ATPase adaptations, we applied haemolymph of sequestering species on isolated Na(+)/K(+)-ATPase of sequestering and non-sequestering species. Haemolymph cardenolides dramatically impair non-adapted Na(+)/K(+)-ATPase, but had systematically reduced effects on Na(+)/K(+)-ATPase of sequestering species. Our data indicate that major adaptations to plant toxins may be evolutionarily linked to sequestration, and may not necessarily be a means to eat toxic plants. Na(+)/K(+)-ATPase adaptations thus were a potential mechanism through which predators spurred the coevolutionary arms race between plants and insects. © 2015 The Author(s).

Milkweed butterfly resistance to plant toxins is linked to sequestration, not coping with a toxic diet

PubMed Central

Petschenka, Georg; Agrawal, Anurag A.

2015-01-01

Insect resistance to plant toxins is widely assumed to have evolved in response to using defended plants as a dietary resource. We tested this hypothesis in the milkweed butterflies (Danaini) which have progressively evolved higher levels of resistance to cardenolide toxins based on amino acid substitutions of their cellular sodium–potassium pump (Na+/K+-ATPase). Using chemical, physiological and caterpillar growth assays on diverse milkweeds (Asclepias spp.) and isolated cardenolides, we show that resistant Na+/K+-ATPases are not necessary to cope with dietary cardenolides. By contrast, sequestration of cardenolides in the body (as a defence against predators) is associated with the three levels of Na+/K+-ATPase resistance. To estimate the potential physiological burden of cardenolide sequestration without Na+/K+-ATPase adaptations, we applied haemolymph of sequestering species on isolated Na+/K+-ATPase of sequestering and non-sequestering species. Haemolymph cardenolides dramatically impair non-adapted Na+/K+-ATPase, but had systematically reduced effects on Na+/K+-ATPase of sequestering species. Our data indicate that major adaptations to plant toxins may be evolutionarily linked to sequestration, and may not necessarily be a means to eat toxic plants. Na+/K+-ATPase adaptations thus were a potential mechanism through which predators spurred the coevolutionary arms race between plants and insects. PMID:26538594

The complete mitochondrial genome of Gossypium hirsutum and evolutionary analysis of higher plant mitochondrial genomes.

PubMed

Liu, Guozheng; Cao, Dandan; Li, Shuangshuang; Su, Aiguo; Geng, Jianing; Grover, Corrinne E; Hu, Songnian; Hua, Jinping

2013-01-01

Mitochondria are the main manufacturers of cellular ATP in eukaryotes. The plant mitochondrial genome contains large number of foreign DNA and repeated sequences undergone frequently intramolecular recombination. Upland Cotton (Gossypium hirsutum L.) is one of the main natural fiber crops and also an important oil-producing plant in the world. Sequencing of the cotton mitochondrial (mt) genome could be helpful for the evolution research of plant mt genomes. We utilized 454 technology for sequencing and combined with Fosmid library of the Gossypium hirsutum mt genome screening and positive clones sequencing and conducted a series of evolutionary analysis on Cycas taitungensis and 24 angiosperms mt genomes. After data assembling and contigs joining, the complete mitochondrial genome sequence of G. hirsutum was obtained. The completed G.hirsutum mt genome is 621,884 bp in length, and contained 68 genes, including 35 protein genes, four rRNA genes and 29 tRNA genes. Five gene clusters are found conserved in all plant mt genomes; one and four clusters are specifically conserved in monocots and dicots, respectively. Homologous sequences are distributed along the plant mt genomes and species closely related share the most homologous sequences. For species that have both mt and chloroplast genome sequences available, we checked the location of cp-like migration and found several fragments closely linked with mitochondrial genes. The G. hirsutum mt genome possesses most of the common characters of higher plant mt genomes. The existence of syntenic gene clusters, as well as the conservation of some intergenic sequences and genic content among the plant mt genomes suggest that evolution of mt genomes is consistent with plant taxonomy but independent among different species.

Design of components for growing higher plants in space

NASA Technical Reports Server (NTRS)

1988-01-01

The overall goal of this project is to design unique systems and components for growing higher plants in microgravity during long-term space missions (Mars and beyond). Specific design tasks were chosen to contribute to and supplement NASA's Controlled Ecological Life Support System (CELSS) project. Selected tasks were automated seeding of plants, plant health sensing, and food processing. Prototype systems for planting both germinated and nongerminated seeds were fabricated and tested. Water and air pressure differences and electrostatic fields were used to trap seeds for separation and transport for planting. An absorption spectrometer was developed to measure chlorophyll levels in plants as an early warning of plant health problems. In the area of food processing, a milling system was created using high-speed rotating blades which were aerodynamically configured to produce circulation and retractable to prevent leakage. The project produced significant results having substantial benefit to NASA. It also provided an outstanding learning experience for the students involved.

Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

PubMed Central

Igamberdiev, Abir U.; Eprintsev, Alexander T.

2016-01-01

Organic acids are synthesized in plants as a result of the incomplete oxidation of photosynthetic products and represent the stored pools of fixed carbon accumulated due to different transient times of conversion of carbon compounds in metabolic pathways. When redox level in the cell increases, e.g., in conditions of active photosynthesis, the tricarboxylic acid (TCA) cycle in mitochondria is transformed to a partial cycle supplying citrate for the synthesis of 2-oxoglutarate and glutamate (citrate valve), while malate is accumulated and participates in the redox balance in different cell compartments (via malate valve). This results in malate and citrate frequently being the most accumulated acids in plants. However, the intensity of reactions linked to the conversion of these compounds can cause preferential accumulation of other organic acids, e.g., fumarate or isocitrate, in higher concentrations than malate and citrate. The secondary reactions, associated with the central metabolic pathways, in particularly with the TCA cycle, result in accumulation of other organic acids that are derived from the intermediates of the cycle. They form the additional pools of fixed carbon and stabilize the TCA cycle. Trans-aconitate is formed from citrate or cis-aconitate, accumulation of hydroxycitrate can be linked to metabolism of 2-oxoglutarate, while 4-hydroxy-2-oxoglutarate can be formed from pyruvate and glyoxylate. Glyoxylate, a product of either glycolate oxidase or isocitrate lyase, can be converted to oxalate. Malonate is accumulated at high concentrations in legume plants. Organic acids play a role in plants in providing redox equilibrium, supporting ionic gradients on membranes, and acidification of the extracellular medium. PMID:27471516

Novel Occurrence of Uncommon Polyamines in Higher Plants 1

PubMed Central

Kuehn, Glenn D.; Rodriguez-Garay, Benjamin; Bagga, Suman; Phillips, Gregory C.

1990-01-01

Diamines and polyamines are ubiquitous components of living cells, and apparently are involved in numerous cellular and physiological processes. Certain “uncommon” polyamines have limited distribution in nature and have been associated primarily with organisms adapted to extreme environments, although the precise function of these polyamines in such organisms is unknown. This article summarizes current knowledge regarding the occurrence in higher plants of the uncommon polyamines related to and including norspermidine and norspermine. A putative biosynthetic pathway to account for the occurrences of these uncommon polyamines in higher plants is presented, with a summary of the supporting evidence indicating the existence of the requisite enzymatic activities in alfalfa, Medicago sativa L. PMID:16667862

Linking Soil Moisture Variation and Abundance of Plants to Geomorphic Processes: A Generalized Model for Erosion-Uplifting Landscapes

NASA Astrophysics Data System (ADS)

Ding, Junyan; Johnson, Edward A.; Martin, Yvonne E.

2018-03-01

The diffusive and advective erosion-created landscapes have similar structure (hillslopes and channels) across different scales regardless of variations in drivers and controls. The relative magnitude of diffusive erosion to advective erosion (D/K ratio) in a landscape development model controls hillslope length, shape, and drainage density, which regulate soil moisture variation, one of the critical resources of plants, through the contributing area (A) and local slope (S) represented by a topographic index (TI). Here we explore the theoretical relation between geomorphic processes, TI, and the abundance and distribution of plants. We derived an analytical model that expresses the TI with D, K, and A. This gives us the relation between soil moisture variation and geomorphic processes. Plant tolerance curves are used to link plant performance to soil moisture. Using the hypothetical tolerance curves of three plants, we show that the abundance and distribution of xeric, mesic, and hydric plants on the landscape are regulated by the D/K ratio. Where diffusive erosion is the major erosion process (large D/K ratio), mesic plants have higher abundance relative to xeric and hydric plants and the landscape has longer and convex-upward hillslope and low channel density. Increasing the dominance of advective erosion increases relative abundance of xeric and hydric plants dominance, and the landscape has short and concave hillslope and high channel density.

Higher Plants in life support systems: design of a model and plant experimental compartment

NASA Astrophysics Data System (ADS)

Hezard, Pauline; Farges, Berangere; Sasidharan L, Swathy; Dussap, Claude-Gilles

The development of closed ecological life support systems (CELSS) requires full control and efficient engineering for fulfilling the common objectives of water and oxygen regeneration, CO2 elimination and food production. Most of the proposed CELSS contain higher plants, for which a growth chamber and a control system are needed. Inside the compartment the development of higher plants must be understood and modeled in order to be able to design and control the compartment as a function of operating variables. The plant behavior must be analyzed at different sub-process scales : (i) architecture and morphology describe the plant shape and lead to calculate the morphological parameters (leaf area, stem length, number of meristems. . . ) characteristic of life cycle stages; (ii) physiology and metabolism of the different organs permit to assess the plant composition depending on the plant input and output rates (oxygen, carbon dioxide, water and nutrients); (iii) finally, the physical processes are light interception, gas exchange, sap conduction and root uptake: they control the available energy from photosynthesis and the input and output rates. These three different sub-processes are modeled as a system of equations using environmental and plant parameters such as light intensity, temperature, pressure, humidity, CO2 and oxygen partial pressures, nutrient solution composition, total leaf surface and leaf area index, chlorophyll content, stomatal conductance, water potential, organ biomass distribution and composition, etc. The most challenging issue is to develop a comprehensive and operative mathematical model that assembles these different sub-processes in a unique framework. In order to assess the parameters for testing a model, a polyvalent growth chamber is necessary. It should permit a controlled environment in order to test and understand the physiological response and determine the control strategy. The final aim of this model is to have an envi

The Complete Mitochondrial Genome of Gossypium hirsutum and Evolutionary Analysis of Higher Plant Mitochondrial Genomes

PubMed Central

Su, Aiguo; Geng, Jianing; Grover, Corrinne E.; Hu, Songnian; Hua, Jinping

2013-01-01

Background Mitochondria are the main manufacturers of cellular ATP in eukaryotes. The plant mitochondrial genome contains large number of foreign DNA and repeated sequences undergone frequently intramolecular recombination. Upland Cotton (Gossypium hirsutum L.) is one of the main natural fiber crops and also an important oil-producing plant in the world. Sequencing of the cotton mitochondrial (mt) genome could be helpful for the evolution research of plant mt genomes. Methodology/Principal Findings We utilized 454 technology for sequencing and combined with Fosmid library of the Gossypium hirsutum mt genome screening and positive clones sequencing and conducted a series of evolutionary analysis on Cycas taitungensis and 24 angiosperms mt genomes. After data assembling and contigs joining, the complete mitochondrial genome sequence of G. hirsutum was obtained. The completed G.hirsutum mt genome is 621,884 bp in length, and contained 68 genes, including 35 protein genes, four rRNA genes and 29 tRNA genes. Five gene clusters are found conserved in all plant mt genomes; one and four clusters are specifically conserved in monocots and dicots, respectively. Homologous sequences are distributed along the plant mt genomes and species closely related share the most homologous sequences. For species that have both mt and chloroplast genome sequences available, we checked the location of cp-like migration and found several fragments closely linked with mitochondrial genes. Conclusion The G. hirsutum mt genome possesses most of the common characters of higher plant mt genomes. The existence of syntenic gene clusters, as well as the conservation of some intergenic sequences and genic content among the plant mt genomes suggest that evolution of mt genomes is consistent with plant taxonomy but independent among different species. PMID:23940520

Selection of root-zone media for higher plant cultivation in space.

PubMed

Guo, Shuang-sheng; Ai, Wei-dang; Zhao, Cheng-jian; Han, Li-jun; Wang, Jian-xiao

2004-04-01

To investigate the cultivating effects of several mineral matters used as root-zone media for higher plant growth in space. Four kinds of artificial and natural mineral matters were used as plant root-zone media based on lots of investigation and analysis. Nutrient liquid was delivered into the media by a long capillary material, and roots of plants obtained nutrition and water from the media. The related parameters such as plant height and photosynthetic efficiency were measured and analyzed. The growing effect in a mixture of coarse and fine ceramic particles with equal quantity proportion was the best, that in fine ceramic particles was the second best, that in clinoptilolite particles was the third and that in diorite particles was the last. The mixture of coarse and fine ceramic particles with equal quantity possesses not only fine capillary action, but also good aerating ability, and therefore is capable of being utilized as an effective root-zone media for higher plants intended to be grown in space.

Water-Wisteria as an ideal plant to study heterophylly in higher aquatic plants.

PubMed

Li, Gaojie; Hu, Shiqi; Yang, Jingjing; Schultz, Elizabeth A; Clarke, Kurtis; Hou, Hongwei

2017-08-01

The semi-aquatic plant Water-Wisteria is suggested as a new model to study heterophylly due to its many advantages and typical leaf phenotypic plasticity in response to environmental factors and phytohormones. Water-Wisteria, Hygrophila difformis (Acanthaceae), is a fast growing semi-aquatic plant that exhibits a variety of leaf shapes, from simple leaves to highly branched compound leaves, depending on the environment. The phenomenon by which leaves change their morphology in response to environmental conditions is called heterophylly. In order to investigate the characteristics of heterophylly, we assessed the morphology and anatomy of Hygrophila difformis in different conditions. Subsequently, we verified that phytohormones and environmental factors can induce heterophylly and found that Hygrophila difformis is easily propagated vegetatively through either leaf cuttings or callus induction, and the callus can be easily transformed by Agrobacterium tumefaciens. These results suggested that Hygrophila difformis is a good model plant to study heterophylly in higher aquatic plants.

The Glycerate and Phosphorylated Pathways of Serine Synthesis in Plants: The Branches of Plant Glycolysis Linking Carbon and Nitrogen Metabolism.

PubMed

Igamberdiev, Abir U; Kleczkowski, Leszek A

2018-01-01

Serine metabolism in plants has been studied mostly in relation to photorespiration where serine is formed from two molecules of glycine. However, two other pathways of serine formation operate in plants and represent the branches of glycolysis diverging at the level of 3-phosphoglyceric acid. One branch (the glycerate - serine pathway) is initiated in the cytosol and involves glycerate formation from 3-phosphoglycerate, while the other (the phosphorylated serine pathway) operates in plastids and forms phosphohydroxypyruvate as an intermediate. Serine formed in these pathways becomes a precursor of glycine, formate and glycolate accumulating in stress conditions. The pathways can be linked to GABA shunt via transamination reactions and via participation of the same reductase for both glyoxylate and succinic semialdehyde. In this review paper we present a hypothesis of the regulation of redox balance in stressed plant cells via participation of the reactions associated with glycerate and phosphorylated serine pathways. We consider these pathways as important processes linking carbon and nitrogen metabolism and maintaining cellular redox and energy levels in stress conditions.

Microorganism and filamentous fungi drive evolution of plant synapses.

PubMed

Baluška, František; Mancuso, Stefano

2013-01-01

In the course of plant evolution, there is an obvious trend toward an increased complexity of plant bodies, as well as an increased sophistication of plant behavior and communication. Phenotypic plasticity of plants is based on the polar auxin transport machinery that is directly linked with plant sensory systems impinging on plant behavior and adaptive responses. Similar to the emergence and evolution of eukaryotic cells, evolution of land plants was also shaped and driven by infective and symbiotic microorganisms. These microorganisms are the driving force behind the evolution of plant synapses and other neuronal aspects of higher plants; this is especially pronounced in the root apices. Plant synapses allow synaptic cell-cell communication and coordination in plants, as well as sensory-motor integration in root apices searching for water and mineral nutrition. These neuronal aspects of higher plants are closely linked with their unique ability to adapt to environmental changes.

Cellular Mechanisms of Gravitropic Response in Higher Plants

NASA Astrophysics Data System (ADS)

Medvedev, Sergei; Smolikova, Galina; Pozhvanov, Gregory; Suslov, Dmitry

The evolutionary success of land plants in adaptation to the vectorial environmental factors was based mainly on the development of polarity systems. In result, normal plant ontogenesis is based on the positional information. Polarity is a tool by which the developing plant organs and tissues are mapped and the specific three-dimensional structure of the organism is created. It is due to their polar organization plants are able to orient themselves relative to the gravity vector and different vectorial cues, and to respond adequately to various stimuli. Gravitation is one of the most important polarized environmental factor that guides the development of plant organisms in space. Every plant can "estimate" its position relative to the gravity vector and correct it, if necessary, by means of polarized growth. The direction and the magnitude of gravitational stimulus are constant during the whole plant ontogenesis. The key plant response to the action of gravity is gravitropism, i.e. the directed growth of organs with respect to the gravity vector. This response is a very convenient model to study the mechanisms of plant orientation in space. The present report is focused on the main cellular mechanisms responsible for graviropic bending in higher plants. These mechanisms and structures include electric polarization of plant cells, Ca ({2+) }gradients, cytoskeleton, G-proteins, phosphoinositides and the machinery responsible for asymmetric auxin distribution. Those mechanisms tightly interact demonstrating some hierarchy and multiple feedbacks. The Ca (2+) gradients provide the primary physiological basis of polarity in plant cells. Calcium ions influence on the bioelectric potentials, the organization of actin cytoskeleton, the activity of Ca (2+) -binding proteins and Ca (2+) -dependent protein kinases. Protein kinases modulate transcription factors activity thereby regulating the gene expression and switching the developmental programs. Actin cytoskeleton affects

Interaction of metal oxide nanoparticles with higher terrestrial plants: Physiological and biochemical aspects.

PubMed

Du, Wenchao; Tan, Wenjuan; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L; Ji, Rong; Yin, Ying; Guo, Hongyan

2017-01-01

Multiple applications of metal oxide nanoparticles (MONPs) could result in their accumulation in soil, threatening higher terrestrial plants. Several reports have shown the effects of MONPs on plants. In this review, we analyze the most recent reports about the physiological and biochemical responses of plants to stress imposed by MONPs. Findings demonstrate that MONPs may be taken up and accumulated in plant tissues causing adverse or beneficial effects on seed germination, seedling elongation, photosynthesis, antioxidative stress response, agronomic, and yield characteristics. Given the importance of determining the potential risks of MONPs on crops and other terrestrial higher plants, research questions about field long-term conditions, transgenernational phytotoxicity, genotype specific sensitivity, and combined pollution problems should be considered. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A Comparison of Selective Pressures in Plant X-Linked and Autosomal Genes

PubMed Central

Krasovec, Marc; Filatov, Dmitry A.

2018-01-01

Selection is expected to work differently in autosomal and X-linked genes because of their ploidy difference and the exposure of recessive X-linked mutations to haploid selection in males. However, it is not clear whether these expectations apply to recently evolved sex chromosomes, where many genes retain functional X- and Y-linked gametologs. We took advantage of the recently evolved sex chromosomes in the plant Silene latifolia and its closely related species to compare the selective pressures between hemizygous and non-hemizygous X-linked genes as well as between X-linked genes and autosomal genes. Our analysis, based on over 1000 genes, demonstrated that, similar to animals, X-linked genes in Silene evolve significantly faster than autosomal genes—the so-called faster-X effect. Contrary to expectations, faster-X divergence was detectable only for non-hemizygous X-linked genes. Our phylogeny-based analyses of selection revealed no evidence for faster adaptation in X-linked genes compared to autosomal genes. On the other hand, partial relaxation of purifying selection was apparent on the X-chromosome compared to the autosomes, consistent with a smaller genetic diversity in S. latifolia X-linked genes (πx = 0.016; πaut = 0.023). Thus, the faster-X divergence in S. latifolia appears to be a consequence of the smaller effective population size rather than of a faster adaptive evolution on the X-chromosome. We argue that this may be a general feature of “young” sex chromosomes, where the majority of X-linked genes are not hemizygous, preventing haploid selection in heterogametic sex. PMID:29751495

A Comparison of Selective Pressures in Plant X-Linked and Autosomal Genes.

PubMed

Krasovec, Marc; Nevado, Bruno; Filatov, Dmitry A

2018-05-03

Selection is expected to work differently in autosomal and X-linked genes because of their ploidy difference and the exposure of recessive X-linked mutations to haploid selection in males. However, it is not clear whether these expectations apply to recently evolved sex chromosomes, where many genes retain functional X- and Y-linked gametologs. We took advantage of the recently evolved sex chromosomes in the plant Silene latifolia and its closely related species to compare the selective pressures between hemizygous and non-hemizygous X-linked genes as well as between X-linked genes and autosomal genes. Our analysis, based on over 1000 genes, demonstrated that, similar to animals, X-linked genes in Silene evolve significantly faster than autosomal genes—the so-called faster-X effect. Contrary to expectations, faster-X divergence was detectable only for non-hemizygous X-linked genes. Our phylogeny-based analyses of selection revealed no evidence for faster adaptation in X-linked genes compared to autosomal genes. On the other hand, partial relaxation of purifying selection was apparent on the X-chromosome compared to the autosomes, consistent with a smaller genetic diversity in S. latifolia X-linked genes (π x = 0.016; π aut = 0.023). Thus, the faster-X divergence in S. latifolia appears to be a consequence of the smaller effective population size rather than of a faster adaptive evolution on the X-chromosome. We argue that this may be a general feature of “young” sex chromosomes, where the majority of X-linked genes are not hemizygous, preventing haploid selection in heterogametic sex.

Microorganism and filamentous fungi drive evolution of plant synapses

PubMed Central

Baluška, František; Mancuso, Stefano

2013-01-01

In the course of plant evolution, there is an obvious trend toward an increased complexity of plant bodies, as well as an increased sophistication of plant behavior and communication. Phenotypic plasticity of plants is based on the polar auxin transport machinery that is directly linked with plant sensory systems impinging on plant behavior and adaptive responses. Similar to the emergence and evolution of eukaryotic cells, evolution of land plants was also shaped and driven by infective and symbiotic microorganisms. These microorganisms are the driving force behind the evolution of plant synapses and other neuronal aspects of higher plants; this is especially pronounced in the root apices. Plant synapses allow synaptic cell–cell communication and coordination in plants, as well as sensory-motor integration in root apices searching for water and mineral nutrition. These neuronal aspects of higher plants are closely linked with their unique ability to adapt to environmental changes. PMID:23967407

Aquatic food production modules in bioregenerative life support systems based on higher plants

NASA Astrophysics Data System (ADS)

Bluem, V.; Paris, F.

Most bioregenerative life support systems (BLSS) are based on gravitropic higher plants which exhibit growth and seed generation disturbances in microgravity. Even when used for a lunar or martian base the reduced gravity may induce a decreased productivity in comparison to Earth. Therefore, the implementation of aquatic biomass production modules in higher plant and/or hybrid BLSS may compensate for this and offer, in addition, the possibility to produce animal protein for human nutrition. It was shown on the SLS-89 and SLS-90 space shuttle missions with the C.E.B.A.S.-MINI MODULE that the edible non gravitropic rootless higher aquatic plant Ceratophyllum demeresum exhibits an undisturbed high biomass production rate in space and that the teleost fish species, Xiphophorus helleri, adapts rapidly to space conditions without loss of its normal reproductive functions. Based on these findings a series of ground-based aquatic food production systems were developed which are disposed for utilization in space. These are plant production bioreactors for the species mentioned above and another suitable candidate, the lemnacean (duckweed) species, Wolffia arrhiza. Moreover, combined intensive aquaculture systems with a closed food loop between herbivorous fishes and aquatic and land plants are being developed which may be suitable for integration into a BLSS of higher complexity.

Diurnal adjustment in ultraviolet sunscreen protection is widespread among higher plants.

PubMed

Barnes, Paul W; Flint, Stephan D; Tobler, Mark A; Ryel, Ronald J

2016-05-01

The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) in the epidermis of higher plants reduces the penetration of solar UV radiation to underlying tissues and is a primary mechanism of acclimation to changing UV conditions resulting from ozone depletion and climate change. Previously we reported that several herbaceous plant species were capable of rapid, diurnal adjustments in epidermal UV transmittance (T UV), but how widespread this phenomenon is among plants has been unknown. In the present study, we tested the generality of this response by screening 37 species of various cultivated and wild plants growing in four locations spanning a gradient of ambient solar UV and climate (Hawaii, Utah, Idaho and Louisiana). Non-destructive measurements of adaxial T UV indicated that statistically significant midday decreases in T UV occurred in 49 % of the species tested, including both herbaceous and woody growth forms, and there was substantial interspecific variation in the magnitude of these changes. In general, plants in Louisiana exhibited larger diurnal changes in T UV than those in the other locations. Moreover, across all taxa, the magnitude of these changes was positively correlated with minimum daily air temperatures but not daily UV irradiances. Results indicate that diurnal changes in UV shielding are widespread among higher plants, vary both within and among species and tend to be greatest in herbaceous plants growing in warm environments. These findings suggest that plant species differ in their UV protection "strategies" though the functional and ecological significance of this variation in UV sunscreen protection remains unclear at present.

Links between plant and fungal communities across a deforestation chronosequence in the Amazon rainforest.

PubMed

Mueller, Rebecca C; Paula, Fabiana S; Mirza, Babur S; Rodrigues, Jorge L M; Nüsslein, Klaus; Bohannan, Brendan J M

2014-07-01

Understanding the interactions among microbial communities, plant communities and soil properties following deforestation could provide insights into the long-term effects of land-use change on ecosystem functions, and may help identify approaches that promote the recovery of degraded sites. We combined high-throughput sequencing of fungal rDNA and molecular barcoding of plant roots to estimate fungal and plant community composition in soil sampled across a chronosequence of deforestation. We found significant effects of land-use change on fungal community composition, which was more closely correlated to plant community composition than to changes in soil properties or geographic distance, providing evidence for strong links between above- and below-ground communities in tropical forests.

Higher plant diversity promotes higher diversity of fungal pathogens, while it decreases pathogen infection per plant.

PubMed

Rottstock, Tanja; Joshi, Jasmin; Kummer, Volker; Fischer, Markus

2014-07-01

Fungal plant pathogens are common in natural communities where they affect plant physiology, plant survival, and biomass production. Conversely, pathogen transmission and infection may be regulated by plant community characteristics such as plant species diversity and functional composition that favor pathogen diversity through increases in host diversity while simultaneously reducing pathogen infection via increased variability in host density and spatial heterogeneity. Therefore, a comprehensive understanding of multi-host multi-pathogen interactions is of high significance in the context of biodiversity-ecosystem functioning. We investigated the relationship between plant diversity and aboveground obligate parasitic fungal pathogen ("pathogens" hereafter) diversity and infection in grasslands of a long-term, large-scale, biodiversity experiment with varying plant species (1-60 species) and plant functional group diversity (1-4 groups). To estimate pathogen infection of the plant communities, we visually assessed pathogen-group presence (i.e., rusts, powdery mildews, downy mildews, smuts, and leaf-spot diseases) and overall infection levels (combining incidence and severity of each pathogen group) in 82 experimental plots on all aboveground organs of all plant species per plot during four surveys in 2006. Pathogen diversity, assessed as the cumulative number of pathogen groups on all plant species per plot, increased log-linearly with plant species diversity. However, pathogen incidence and severity, and hence overall infection, decreased with increasing plant species diversity. In addition, co-infection of plant individuals by two or more pathogen groups was less likely with increasing plant community diversity. We conclude that plant community diversity promotes pathogen-community diversity while at the same time reducing pathogen infection levels of plant individuals.

Linking the development and functioning of a carnivorous pitcher plant's microbial digestive community.

PubMed

Armitage, David W

2017-11-01

Ecosystem development theory predicts that successional turnover in community composition can influence ecosystem functioning. However, tests of this theory in natural systems are made difficult by a lack of replicable and tractable model systems. Using the microbial digestive associates of a carnivorous pitcher plant, I tested hypotheses linking host age-driven microbial community development to host functioning. Monitoring the yearlong development of independent microbial digestive communities in two pitcher plant populations revealed a number of trends in community succession matching theoretical predictions. These included mid-successional peaks in bacterial diversity and metabolic substrate use, predictable and parallel successional trajectories among microbial communities, and convergence giving way to divergence in community composition and carbon substrate use. Bacterial composition, biomass, and diversity positively influenced the rate of prey decomposition, which was in turn positively associated with a host leaf's nitrogen uptake efficiency. Overall digestive performance was greatest during late summer. These results highlight links between community succession and ecosystem functioning and extend succession theory to host-associated microbial communities.

Plants as green phones

PubMed Central

Harvey, Jeffrey A; Bezemer, T Martijn; Stuefer, Josef F

2008-01-01

Plants can act as vertical communication channels or ‘green phones’ linking soil-dwelling insects and insects in the aboveground ecosystem. When root-feeding insects attack a plant, the direct defense system of the shoot is activated, leading to an accumulation of phytotoxins in the leaves. The protection of the plant shoot elicited by root damage can impair the survival, growth and development of aboveground insect herbivores, thereby creating plant-based functional links between soil-dwelling insects and insects that develop in the aboveground ecosystem. The interactions between spatially separated insects below- and aboveground are not restricted to root and foliar plant-feeding insects, but can be extended to higher trophic levels such as insect parasitoids. Here we discuss some implications of plants acting as communication channels or ‘green phones’ between root and foliar-feeding insects and their parasitoids, focusing on recent findings that plants attacked by root-feeding insects are significantly less attractive for the parasitoids of foliar-feeding insects. PMID:19513244

Bioinformatics analysis of the predicted polyprenol reductase genes in higher plants

NASA Astrophysics Data System (ADS)

Basyuni, M.; Wati, R.

2018-03-01

The present study evaluates the bioinformatics methods to analyze twenty-four predicted polyprenol reductase genes from higher plants on GenBank as well as predicted the structure, composition, similarity, subcellular localization, and phylogenetic. The physicochemical properties of plant polyprenol showed diversity among the observed genes. The percentage of the secondary structure of plant polyprenol genes followed the ratio order of α helix > random coil > extended chain structure. The values of chloroplast but not signal peptide were too low, indicated that few chloroplast transit peptide in plant polyprenol reductase genes. The possibility of the potential transit peptide showed variation among the plant polyprenol reductase, suggested the importance of understanding the variety of peptide components of plant polyprenol genes. To clarify this finding, a phylogenetic tree was drawn. The phylogenetic tree shows several branches in the tree, suggested that plant polyprenol reductase genes grouped into divergent clusters in the tree.

Voltage-dependent calcium-permeable channels in the plasma membrane of a higher plant cell.

PubMed

Thuleau, P; Ward, J M; Ranjeva, R; Schroeder, J I

1994-07-01

Numerous biological assays and pharmacological studies on various higher plant tissues have led to the suggestion that voltage-dependent plasma membrane Ca2+ channels play prominent roles in initiating signal transduction processes during plant growth and development. However, to date no direct evidence has been obtained for the existence of such depolarization-activated Ca2+ channels in the plasma membrane of higher plant cells. Carrot suspension cells (Daucus carota L.) provide a well-suited system to determine whether voltage-dependent Ca2+ channels are present in the plasma membrane of higher plants and to characterize the properties of putative Ca2+ channels. It is known that both depolarization, caused by raising extracellular K+, and exposure to fungal toxins or oligogalacturonides induce Ca2+ influx into carrot cells. By direct application of patch-clamp techniques to isolated carrot protoplasts, we show here that depolarization of the plasma membrane positive to -135 mV activates Ca(2+)-permeable channels. These voltage-dependent ion channels were more permeable to Ca2+ than K+, while displaying large permeabilities to Ba2+ and Mg2+ ions. Ca(2+)-permeable channels showed slow and reversible inactivation. The single-channel conductance was 13 pS in 40 mM CaCl2. These data provide direct evidence for the existence of voltage-dependent Ca2+ channels in the plasma membrane of a higher plant cell and point to physiological mechanisms for plant Ca2+ channel regulation. The depolarization-activated Ca(2+)-permeable channels identified here could constitute a regulated pathway for Ca2+ influx in response to physiologically occurring stimulus-induced depolarizations in higher plant cells.

The Relevance of Higher Plants in Lead Compound Discovery Programs⊥

PubMed Central

Kinghorn, A. Douglas; Pan, Li; Fletcher, Joshua N.; Chai, Heebyung

2011-01-01

Along with compounds from terrestrial microorganisms, the constituents of higher plants have provided a substantial number of the natural product-derived drugs used currently in western medicine. Interest in the elucidation of new structures of the secondary metabolite constituents of plants has remained high among the natural products community over the first decade of the 21st century, particularly of species that are used in systems of traditional medicine or are utilized as botanical dietary supplements. In this review, progress made in the senior author’s laboratory in research work on naturally occurring sweeteners and other taste-modifying substances and on potential anticancer agents from tropical plants will be described. PMID:21650152

Growth and development in inert non-aqueous liquids. [of higher plants

NASA Technical Reports Server (NTRS)

Siegel, S. M.

1974-01-01

A preview is presented of the survival and growth capabilities of higher plants in non-aqueous, inert liquids. The two media which were used are mineral (white) oil and fluorochemical inert liquid FC-75. Both liquids dissolve oxygen and carbon dioxide readily, but are insoluble in water. Consequently, plants submerged in these liquids are capable of gas exchange with the atmosphere, but possess a water impermeable coating the dimensions of which are determined by the size of the liquid holding container. In a sense, growing plants in a tank of mineral oil imparts on them a cuticle. Plants plus prescribed volumes of water were innoculated into mineral oil. Organisms with minimal water supplied could then be observed. Also, submersed plants covered with an oil slick were shown to be capable of growth in dessicating atmospheres.

Aquatic food production modules in bioregenerative life support systems based on higher plants.

PubMed

Bluem, V; Paris, F

2001-01-01

Most bioregenerative life support systems (BLSS) are based on gravitropic higher plants which exhibit growth and seed generation disturbances in microgravity. Even when used for a lunar or martian base the reduced gravity may induce a decreased productivity in comparison to Earth. Therefore, the implementation of aquatic biomass production modules in higher plant and/or hybrid BLSS may compensate for this and offer, in addition, the possibility to produce animal protein for human nutrition. It was shown on the SLS-89 and SLS-90 space shuttle missions with the C.E.B.A.S.-MINI MODULE that the edible non gravitropic rootless higher aquatic plant Ceratophyllum demeresum exhibits an undisturbed high biomass production rate in space and that the teleost fish species, Xiphophorus helleri, adapts rapidly to space conditions without loss of its normal reproductive functions. Based on these findings a series of ground-based aquatic food production systems were developed which are disposed for utilization in space. These are plant production bioreactors for the species mentioned above and another suitable candidate, the lemnacean (duckweed) species, Wolffia arrhiza. Moreover, combined intensive aquaculture systems with a closed food loop between herbivorous fishes and aquatic and land plants are being developed which may be suitable for integration into a BLSS of higher complexity. Grant numbers: WS50WB9319-3, IVA1216-00588. c 2001. COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Is polyploidy necessary for tissue differentiation in higher plants. [Triticum, helianthus

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

Evans, L.S.; Hof, J.V.

1975-01-01

Measurements of relative DNA per nucleus of cells from various tissues show that cell differentiation can occur in the absence of polyploidy in higher plants. In Pisum polyploidy was present in roots, sepals, pods, pistils, and stamens but not in petals or leaves. In Triticum cells of leaves exhibited some polyploidy, but no polyploid cells were present in mature roots. No polyploid cells were found in any tissue of Helianthus examined (roots, cotyledons, stems, sepals, petals, pistils, and stamens). Therefore, as a general rule, polyploidy should not be considered essential in tissue or organ differentiation of higher plants. In Helianthusmore » polyploidy is unnecessary for the completion of the life cycle. (auth)« less

Searching for links in the biotic characteristics and abiotic parameters of nine different biogas plants

PubMed Central

Walter, Andreas; Knapp, Brigitte A.; Farbmacher, Theresa; Ebner, Christian; Insam, Heribert; Franke‐Whittle, Ingrid H.

2012-01-01

Summary To find links between the biotic characteristics and abiotic process parameters in anaerobic digestion systems, the microbial communities of nine full‐scale biogas plants in South Tyrol (Italy) and Vorarlberg (Austria) were investigated using molecular techniques and the physical and chemical properties were monitored. DNA from sludge samples was subjected to microarray hybridization with the ANAEROCHIP microarray and results indicated that sludge samples grouped into two main clusters, dominated either by Methanosarcina or by Methanosaeta, both aceticlastic methanogens. Hydrogenotrophic methanogens were hardly detected or if detected, gave low hybridization signals. Results obtained using denaturing gradient gel electrophoresis (DGGE) supported the findings of microarray hybridization. Real‐time PCR targeting Methanosarcina and Methanosaeta was conducted to provide quantitative data on the dominating methanogens. Correlation analysis to determine any links between the microbial communities found by microarray analysis, and the physicochemical parameters investigated was conducted. It was shown that the sludge samples dominated by the genus Methanosarcina were positively correlated with higher concentrations of acetate, whereas sludge samples dominated by representatives of the genus Methanosaeta had lower acetate concentrations. No other correlations between biotic characteristics and abiotic parameters were found. Methanogenic communities in each reactor were highly stable and resilient over the whole year. PMID:22950603

Progress of targeted genome modification approaches in higher plants.

PubMed

Cardi, Teodoro; Neal Stewart, C

2016-07-01

Transgene integration in plants is based on illegitimate recombination between non-homologous sequences. The low control of integration site and number of (trans/cis)gene copies might have negative consequences on the expression of transferred genes and their insertion within endogenous coding sequences. The first experiments conducted to use precise homologous recombination for gene integration commenced soon after the first demonstration that transgenic plants could be produced. Modern transgene targeting categories used in plant biology are: (a) homologous recombination-dependent gene targeting; (b) recombinase-mediated site-specific gene integration; (c) oligonucleotide-directed mutagenesis; (d) nuclease-mediated site-specific genome modifications. New tools enable precise gene replacement or stacking with exogenous sequences and targeted mutagenesis of endogeneous sequences. The possibility to engineer chimeric designer nucleases, which are able to target virtually any genomic site, and use them for inducing double-strand breaks in host DNA create new opportunities for both applied plant breeding and functional genomics. CRISPR is the most recent technology available for precise genome editing. Its rapid adoption in biological research is based on its inherent simplicity and efficacy. Its utilization, however, depends on available sequence information, especially for genome-wide analysis. We will review the approaches used for genome modification, specifically those for affecting gene integration and modification in higher plants. For each approach, the advantages and limitations will be noted. We also will speculate on how their actual commercial development and implementation in plant breeding will be affected by governmental regulations.

The Robustness of Plant-Pollinator Assemblages: Linking Plant Interaction Patterns and Sensitivity to Pollinator Loss

PubMed Central

Astegiano, Julia; Massol, François; Vidal, Mariana Morais; Cheptou, Pierre-Olivier; Guimarães, Paulo R.

2015-01-01

Most flowering plants depend on pollinators to reproduce. Thus, evaluating the robustness of plant-pollinator assemblages to species loss is a major concern. How species interaction patterns are related to species sensitivity to partner loss may influence the robustness of plant-pollinator assemblages. In plants, both reproductive dependence on pollinators (breeding system) and dispersal ability may modulate plant sensitivity to pollinator loss. For instance, species with strong dependence (e.g. dioecious species) and low dispersal (e.g. seeds dispersed by gravity) may be the most sensitive to pollinator loss. We compared the interaction patterns of plants differing in dependence on pollinators and dispersal ability in a meta-dataset comprising 192 plant species from 13 plant-pollinator networks. In addition, network robustness was compared under different scenarios representing sequences of plant extinctions associated with plant sensitivity to pollinator loss. Species with different dependence on pollinators and dispersal ability showed similar levels of generalization. Although plants with low dispersal ability interacted with more generalized pollinators, low-dispersal plants with strong dependence on pollinators (i.e. the most sensitive to pollinator loss) interacted with more particular sets of pollinators (i.e. shared a low proportion of pollinators with other plants). Only two assemblages showed lower robustness under the scenario considering plant generalization, dependence on pollinators and dispersal ability than under the scenario where extinction sequences only depended on plant generalization (i.e. where higher generalization level was associated with lower probability of extinction). Overall, our results support the idea that species generalization and network topology may be good predictors of assemblage robustness to species loss, independently of plant dispersal ability and breeding system. In contrast, since ecological specialization among

A global database of sap flow measurements (SAPFLUXNET) to link plant and ecosystem physiology

NASA Astrophysics Data System (ADS)

Poyatos, Rafael; Granda, Víctor; Flo, Víctor; Molowny-Horas, Roberto; Mencuccini, Maurizio; Oren, Ram; Katul, Gabriel; Mahecha, Miguel; Steppe, Kathy; Martínez-Vilalta, Jordi

2017-04-01

Regional and global networks of ecosystem CO2 and water flux monitoring have dramatically increased our understanding of ecosystem functioning in the last 20 years. More recently, analyses of ecosystem-level fluxes have successfully incorporated data streams at coarser (remote sensing) and finer (plant traits) organisational scales. However, there are few data sources that capture the diel to seasonal dynamics of whole-plant physiology and that can provide a link between organism- and ecosystem-level function. Sap flow measured in plant stems reveals the temporal patterns in plant water transport, as mediated by stomatal regulation and hydraulic architecture. The widespread use of thermometric methods of sap flow measurement since the 1990s has resulted in numerous data sets for hundreds of species and sites worldwide, but these data have remained fragmentary and generally unavailable for syntheses of regional to global scope. We are compiling the first global database of sub-daily sap flow measurements in individual plants (SAPFLUXNET), aimed at unravelling the environmental and biotic drivers of plant transpiration regulation globally. I will present the SAPFLUXNET data infrastructure and workflow, which is built upon flexible, open-source computing tools within the R environment (dedicated R packages and classes, interactive documents and apps with Rmarkdown and Shiny). Data collection started in mid-2016, we have already incorporated > 50 datasets representing > 40 species and > 350 individual plants, globally distributed, and the number of contributed data sets is increasing rapidly. I will provide a general overview of the distribution of available data sets according to climate, measurement method, species, functional groups and plant size attributes. In parallel to the sap flow data compilation, we have also collated published results from calibrations of sap flow methods, to provide a first quantification on the variability associated with different sap

Are litter decomposition and fire linked through plant species traits?

PubMed

Cornelissen, Johannes H C; Grootemaat, Saskia; Verheijen, Lieneke M; Cornwell, William K; van Bodegom, Peter M; van der Wal, René; Aerts, Rien

2017-11-01

Contents 653 I. 654 II. 657 III. 659 IV. 661 V. 662 VI. 663 VII. 665 665 References 665 SUMMARY: Biological decomposition and wildfire are connected carbon release pathways for dead plant material: slower litter decomposition leads to fuel accumulation. Are decomposition and surface fires also connected through plant community composition, via the species' traits? Our central concept involves two axes of trait variation related to decomposition and fire. The 'plant economics spectrum' (PES) links biochemistry traits to the litter decomposability of different fine organs. The 'size and shape spectrum' (SSS) includes litter particle size and shape and their consequent effect on fuel bed structure, ventilation and flammability. Our literature synthesis revealed that PES-driven decomposability is largely decoupled from predominantly SSS-driven surface litter flammability across species; this finding needs empirical testing in various environmental settings. Under certain conditions, carbon release will be dominated by decomposition, while under other conditions litter fuel will accumulate and fire may dominate carbon release. Ecosystem-level feedbacks between decomposition and fire, for example via litter amounts, litter decomposition stage, community-level biotic interactions and altered environment, will influence the trait-driven effects on decomposition and fire. Yet, our conceptual framework, explicitly comparing the effects of two plant trait spectra on litter decomposition vs fire, provides a promising new research direction for better understanding and predicting Earth surface carbon dynamics. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Linking Plant Nutritional Status to Plant-Microbe Interactions

PubMed Central

Carvalhais, Lilia C.; Dennis, Paul G.; Fan, Ben; Fedoseyenko, Dmitri; Kierul, Kinga; Becker, Anke; von Wiren, Nicolaus; Borriss, Rainer

2013-01-01

Plants have developed a wide-range of adaptations to overcome nutrient limitation, including changes to the quantity and composition of carbon-containing compounds released by roots. Root-associated bacteria are largely influenced by these compounds which can be perceived as signals or substrates. Here, we evaluate the effect of root exudates collected from maize plants grown under nitrogen (N), phosphate (P), iron (Fe) and potassium (K) deficiencies on the transcriptome of the plant growth promoting rhizobacterium (PGPR) Bacillus amyloliquefaciens FZB42. The largest shifts in gene expression patterns were observed in cells exposed to exudates from N-, followed by P-deficient plants. Exudates from N-deprived maize triggered a general stress response in FZB42 in the exponential growth phase, which was evidenced by the suppression of numerous genes involved in protein synthesis. Exudates from P-deficient plants induced bacterial genes involved in chemotaxis and motility whilst exudates released by Fe and K deficient plants did not cause dramatic changes in the bacterial transcriptome during exponential growth phase. Global transcriptional changes in bacteria elicited by nutrient deficient maize exudates were significantly correlated with concentrations of the amino acids aspartate, valine and glutamate in root exudates suggesting that transcriptional profiling of FZB42 associated with metabolomics of N, P, Fe and K-deficient maize root exudates is a powerful approach to better understand plant-microbe interactions under conditions of nutritional stress. PMID:23874669

Linking Wildfire and Climate as Drivers of Plant Species and Community-level Change

NASA Astrophysics Data System (ADS)

Newingham, B. A.; Hudak, A. T.; Bright, B. C.

2015-12-01

Plant species distributions and community shifts after fire are affected by burn severity, elevation, aspect, and climate. However, little empirical data exists on long-term (decadal) recovery after fire across these interacting factors, limiting understanding of fire regime characteristics and climate in post-fire community trajectories. We examined plant species and community responses a decade after fire across five fires in ponderosa pine, dry mixed coniferous, and moist mixed coniferous forests across the western USA. Using field data, we determined changes in plant communities one and ten years post-fire across gradients of burn severity, elevation, and aspect. Existing published work has shown that plant species distributions can be accurately predicted from physiologically relevant climate variables using non-parametric Random Forests models; such models have also been linked to projected climate profiles in 2030, 2060, and 2090 generated from three commonly used general circulation models (GCMs). We explore the possibility that fire and climate are coupled drivers affecting plant species distributions. Climate change may not manifest as a slow shift in plant species distributions, but as sudden, localized events tied to changing fire and other disturbance regimes.

Enigma Variations for Peptides and Their Transporters in Higher Plants

PubMed Central

WATERWORTH, WANDA M.; BRAY, CLIFFORD M.

2006-01-01

• Background. Two families of proteins that transport small peptides, the oligopeptide transporters (OPTs) and the peptide transporters (PTRs), have been recognized in eukaryotes. Higher plants contain a far greater number of genes for these transporters than do other eukaryotes. This may be indicative of the relative importance of (oligo)peptides and their transport to plant growth and metabolism. • Recent progress. Recent studies are now allowing us to assign functions to these transporters and are starting to identify their in-planta substrates, revealing unexpected and important contributions of the transporters to plant growth and developmental processes. This Botanical Briefing appraises recent findings that PTRs and OPTs have key roles to play in the control of plant cell growth and development. Evidence is presented that some of these transporters have functions outside that of nitrogen nutrition and that these carriers can also surprise us with their totally unexpected choice of substrates. PMID:16735405

High CO2 Primes Plant Biotic Stress Defences through Redox-Linked Pathways.

PubMed

Mhamdi, Amna; Noctor, Graham

2016-10-01

Industrial activities have caused tropospheric CO 2 concentrations to increase over the last two centuries, a trend that is predicted to continue for at least the next several decades. Here, we report that growth of plants in a CO 2 -enriched environment activates responses that are central to defense against pathogenic attack. Salicylic acid accumulation was triggered by high-growth CO 2 in Arabidopsis (Arabidopsis thaliana) and other plants such as bean (Phaseolus vulgaris). A detailed analysis in Arabidopsis revealed that elevated CO 2 primes multiple defense pathways, leading to increased resistance to bacterial and fungal challenge. Analysis of gene-specific mutants provided no evidence that activation of plant defense pathways by high CO 2 was caused by stomatal closure. Rather, the activation is partly linked to metabolic effects involving redox signaling. In support of this, genetic modification of redox components (glutathione contents and NADPH-generating enzymes) prevents full priming of the salicylic acid pathway and associated resistance by high CO 2 The data point to a particularly influential role for the nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase, a cytosolic enzyme whose role in plants remains unclear. Our observations add new information on relationships between high CO 2 and oxidative signaling and provide novel insight into plant stress responses in conditions of increased CO 2 . © 2016 American Society of Plant Biologists. All Rights Reserved.

Impact of common cytostatic drugs on pollen fertility in higher plants.

PubMed

Mišík, Miroslav; Kundi, Michael; Pichler, Clemens; Filipic, Metka; Rainer, Bernhard; Mišíková, Katarina; Nersesyan, Armen; Knasmueller, Siegfried

2016-08-01

Cytostatic drugs are among the most toxic chemicals which are produced. Many of them cause damage of the genetic material which may affect the fertility of higher organisms. To study the impact of the widely used anticancer drugs [cisplatin (CisPt), etoposide (Et), and 5-fluorouracil (5-FU)] on the reproduction of higher plants, pollen abortion experiments were conducted with species which belong to major plant families, namely with Tradescantia paludosa (Commelinaceae), Arabidopsis thaliana (Brassicaceae), Chelidonium majus (Papaveraceae), and Alisma plantago-aquatica (Alismataceae). All compounds increased the frequencies of abortive grains. The lowest effective doses were in general in a narrow range (i.e., 1 and 10 mg/kg of dry soil). The effects of the individual drugs were similar in T. paludosa, A. plantago-aquatica, and Ch. majus, while A. thaliana was consistently less sensitive. The highest abortion rate was obtained in most experiments with CisPt, followed by 5-FU and Et. Comparisons of the doses which caused effects in the present experiments in the different species with the predicted environment concentrations and with the levels of the cytostatics which were detected in hospital wastewaters show that the realistic environmental concentrations of the drugs are 4-6 orders of magnitude lower. Therefore, it is unlikely that these drugs affect the fertility of higher plants in aquatic and terrestrial ecosystems.

Chemical antipredator defence is linked to higher extinction risk

PubMed Central

2016-01-01

Many attributes of species may be linked to contemporary extinction risk, though some such traits remain untested despite suggestions that they may be important. Here, I test whether a trait associated with higher background extinction rates, chemical antipredator defence, is also associated with current extinction risk, using amphibians as a model system—a group facing global population declines. I find that chemically defended species are approximately 60% more likely to be threatened than species without chemical defence, although the severity of the contemporary extinction risk may not relate to chemical defence. The results confirm that background and contemporary extinction rates can be predicted from the same traits, at least in certain cases. This suggests that associations between extinction risk and phenotypic traits can be temporally stable over long periods. The results also provide novel insights into the relevance of antipredator defences for species subject to conservation concerns. PMID:28018657

Leaf Optical Properties in Higher Plants: Linking Spectral Characteristics to Stress and Chlorophyll Concentration

NASA Technical Reports Server (NTRS)

Carter, Gregory A.; Knapp, Alan K.

2000-01-01

A number of studies have linked responses in leaf spectral reflectance, transmittance or absorptance to physiological stress. A variety of stressors including dehydration, flooding,freezing, ozone, herbicides, competition, disease, insects and deficiencies in ectomycorrhizal development and N fertilization have been imposed on species ranging from grasses to conifers and deciduous trees. In this cases, the maximum difference in reflectance within the 400 - 850 nm wavelength range between control and stressed states occurred as a reflectance increase at wavelength near 700 nm. In studies that included transmittance and absorptance as well as reflectance, maximum differences occurred as increases and decreases, respectively, near 700 nm. This common optical response to stress could be simulated closely by varying the chlorophyll concentrations in senescent leaves of five species. The optical response to stress near 700 nm, as well as corresponding changes in reflectance that occur in the green-yellow spectrum, can be explained by the general tendency of stress to reduce leaf chlorophyll concentration.

Use of higher plants as screens for toxicity assessment.

PubMed

Kristen, U

1997-01-01

This review deals with the use of entire plants, seedlings, cell suspension cultures and pollen tubes for the estimation of potential toxicity in the environment, and for risk assessment of chemicals and formulations of human relevance. It is shown that the roots of onions and various crop seedlings, as well as in vitro growing pollen tubes of some mono- and dicotyledonous plants, are most frequently used to obtain toxicity data by determination of root and tube growth inhibition. Both roots and pollen tubes are chloroplast free, non-photosynthetic systems and, therefore, with regard to their cytotoxic reactions are closer to vertebrate tissues and cells than are chloroplast-containing plant organs. Root tips and anthers of flower buds are shown to be applicable to genotoxicity screening by microscopic analysis of mitotic or meiotic aberrations during cell division or microspore development, respectively. The processes of mitosis and meiosis are similar in plants and animals. Therefore, meristematic and sporogenic tissues of plants generally show patterns of cytotoxic response similar to those of embryogenic and spermatogenic tissues of vertebrates. The suitability of root tips, cell suspensions and pollen tubes for the investigation of mechanisms of toxic action and for the analysis of structure-activity relationships is also demonstrated. Two plant-based assays, the Allium test and the pollen tube growth test, both currently being evaluated alongside with established mammalian in vivo and in vitro protocols, are emphasized with regard to their potential use as alternatives to animal in vivo toxicity tests. For both assays, preliminary results indicate that the tips of growing roots and the rapidly elongating pollen tubes of certain higher plant species are as reliable as mammalian cell lines for detecting basal cytotoxicity. It is suggested that seeds and pollen grains, in particular, provide easily storable and convenient systems for inexpensive, relatively

97. Catalog B, Higher Plants, 200 2 American Chestnut Tree, ...

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

97. Catalog B, Higher Plants, 200 2 American Chestnut Tree, Negative No. 6032 (Photographer and date unknown) THIS GHOST FOREST OF BLIGHTED CHESTNUTS ONCE STOOD APPROXIMATELY AT THE LOCATION OF THE BYRD VISITOR CENTER. - Skyline Drive, From Front Royal, VA to Rockfish Gap, VA , Luray, Page County, VA

Plants as green phones: Novel insights into plant-mediated communication between below- and above-ground insects.

PubMed

Soler, Roxina; Harvey, Jeffrey A; Bezemer, T Martijn; Stuefer, Josef F

2008-08-01

Plants can act as vertical communication channels or 'green phones' linking soil-dwelling insects and insects in the aboveground ecosystem. When root-feeding insects attack a plant, the direct defense system of the shoot is activated, leading to an accumulation of phytotoxins in the leaves. The protection of the plant shoot elicited by root damage can impair the survival, growth and development of aboveground insect herbivores, thereby creating plant-based functional links between soil-dwelling insects and insects that develop in the aboveground ecosystem. The interactions between spatially separated insects below- and aboveground are not restricted to root and foliar plant-feeding insects, but can be extended to higher trophic levels such as insect parasitoids. Here we discuss some implications of plants acting as communication channels or 'green phones' between root and foliar-feeding insects and their parasitoids, focusing on recent findings that plants attacked by root-feeding insects are significantly less attractive for the parasitoids of foliar-feeding insects.

Physiology and toxicology of hormone-disrupting chemicals in higher plants.

PubMed

Couée, Ivan; Serra, Anne-Antonella; Ramel, Fanny; Gouesbet, Gwenola; Sulmon, Cécile

2013-06-01

Higher plants are exposed to natural environmental organic chemicals, associated with plant-environment interactions, and xenobiotic environmental organic chemicals, associated with anthropogenic activities. The effects of these chemicals result not only from interaction with metabolic targets, but also from interaction with the complex regulatory networks of hormone signaling. Purpose-designed plant hormone analogues thus show extensive signaling effects on gene regulation and are as such important for understanding plant hormone mechanisms and for manipulating plant growth and development. Some natural environmental chemicals also act on plants through interference with the perception and transduction of endogenous hormone signals. In a number of cases, bioactive xenobiotics, including herbicides that have been designed to affect specific metabolic targets, show extensive gene regulation effects, which are more in accordance with signaling effects than with consequences of metabolic effects. Some of these effects could be due to structural analogies with plant hormones or to interference with hormone metabolism, thus resulting in situations of hormone disruption similar to animal cell endocrine disruption by xenobiotics. These hormone-disrupting effects can be superimposed on parallel metabolic effects, thus indicating that toxicological characterisation of xenobiotics must take into consideration the whole range of signaling and metabolic effects. Hormone-disruptive signaling effects probably predominate when xenobiotic concentrations are low, as occurs in situations of residual low-level pollutions. These hormone-disruptive effects in plants may thus be of importance for understanding cryptic effects of low-dosage xenobiotics, as well as the interactive effects of mixtures of xenobiotic pollutants.

Design and optimization of an experimental bioregenerative life support system with higher plants and silkworms

NASA Astrophysics Data System (ADS)

Hu, Enzhu; Bartsev, Sergey I.; Zhao, Ming; Liu, Professor Hong

The conceptual scheme of an experimental bioregenerative life support system (BLSS) for planetary exploration was designed, which consisted of four elements - human metabolism, higher plants, silkworms and waste treatment. 15 kinds of higher plants, such as wheat, rice, soybean, lettuce, mulberry, et al., were selected as regenerative component of BLSS providing the crew with air, water, and vegetable food. Silkworms, which producing animal nutrition for crews, were fed by mulberry-leaves during the first three instars, and lettuce leaves last two instars. The inedible biomass of higher plants, human wastes and silkworm feces were composted into soil like substrate, which can be reused by higher plants cultivation. Salt, sugar and some household material such as soap, shampoo would be provided from outside. To support the steady state of BLSS the same amount and elementary composition of dehydrated wastes were removed periodically. The balance of matter flows between BLSS components was described by the system of algebraic equations. The mass flows between the components were optimized by EXCEL spreadsheets and using Solver. The numerical method used in this study was Newton's method.

Calcium delivery and storage in plant leaves: exploring the link with water flow.

PubMed

Gilliham, Matthew; Dayod, Maclin; Hocking, Bradleigh J; Xu, Bo; Conn, Simon J; Kaiser, Brent N; Leigh, Roger A; Tyerman, Stephen D

2011-04-01

Calcium (Ca) is a unique macronutrient with diverse but fundamental physiological roles in plant structure and signalling. In the majority of crops the largest proportion of long-distance calcium ion (Ca(2+)) transport through plant tissues has been demonstrated to follow apoplastic pathways, although this paradigm is being increasingly challenged. Similarly, under certain conditions, apoplastic pathways can dominate the proportion of water flow through plants. Therefore, tissue Ca supply is often found to be tightly linked to transpiration. Once Ca is deposited in vacuoles it is rarely redistributed, which results in highly transpiring organs amassing large concentrations of Ca ([Ca]). Meanwhile, the nutritional flow of Ca(2+) must be regulated so it does not interfere with signalling events. However, water flow through plants is itself regulated by Ca(2+), both in the apoplast via effects on cell wall structure and stomatal aperture, and within the symplast via Ca(2+)-mediated gating of aquaporins which regulates flow across membranes. In this review, an integrated model of water and Ca(2+) movement through plants is developed and how this affects [Ca] distribution and water flow within tissues is discussed, with particular emphasis on the role of aquaporins.

Formation of higher plant component microbial community in closed ecological system

NASA Astrophysics Data System (ADS)

Tirranen, L. S.

2001-07-01

Closed ecological systems (CES) place at the disposal of a researcher unique possibilities to study the role of microbial communities in individual components and of the entire system. The microbial community of the higher plant component has been found to form depending on specific conditions of the closed ecosystem: length of time the solution is reused, introduction of intrasystem waste water into the nutrient medium, effect of other component of the system, and system closure in terms of gas exchange. The higher plant component formed its own microbial complex different from that formed prior to closure. The microbial complex of vegetable polyculture is more diverse and stable than the monoculture of wheat. The composition of the components' microflora changed, species diversity decreased, individual species of bacteria and fungi whose numbers were not so great before the closure prevailed. Special attention should be paid to phytopathogenic and conditionally pathogenic species of microorganisms potentially hazardous to man or plants and the least controlled in CES. This situation can endanger creation of CES and make conjectural existence of preplanned components, man, specifically, and consequently, of CES as it is.

Advancements in mass spectrometry for biological samples: Protein chemical cross-linking and metabolite analysis of plant tissues

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

Klein, Adam

2015-01-01

This thesis presents work on advancements and applications of methodology for the analysis of biological samples using mass spectrometry. Included in this work are improvements to chemical cross-linking mass spectrometry (CXMS) for the study of protein structures and mass spectrometry imaging and quantitative analysis to study plant metabolites. Applications include using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to further explore metabolic heterogeneity in plant tissues and chemical interactions at the interface between plants and pests. Additional work was focused on developing liquid chromatography-mass spectrometry (LC-MS) methods to investigate metabolites associated with plant-pest interactions.

Distribution, congruence, and hotspots of higher plants in China

PubMed Central

Zhao, Lina; Li, Jinya; Liu, Huiyuan; Qin, Haining

2016-01-01

Identifying biodiversity hotspots has become a central issue in setting up priority protection areas, especially as financial resources for biological diversity conservation are limited. Taking China’s Higher Plants Red List (CHPRL), including Bryophytes, Ferns, Gymnosperms, Angiosperms, as the data source, we analyzed the geographic patterns of species richness, endemism, and endangerment via data processing at a fine grid-scale with an average edge length of 30 km based on three aspects of richness information: species richness, endemic species richness, and threatened species richness. We sought to test the accuracy of hotspots used in identifying conservation priorities with regard to higher plants. Next, we tested the congruence of the three aspects and made a comparison of the similarities and differences between the hotspots described in this paper and those in previous studies. We found that over 90% of threatened species in China are concentrated. While a high spatial congruence is observed among the three measures, there is a low congruence between two different sets of hotspots. Our results suggest that biodiversity information should be considered when identifying biological hotspots. Other factors, such as scales, should be included as well to develop biodiversity conservation plans in accordance with the region’s specific conditions. PMID:26750244

Distribution, congruence, and hotspots of higher plants in China.

PubMed

Zhao, Lina; Li, Jinya; Liu, Huiyuan; Qin, Haining

2016-01-11

Identifying biodiversity hotspots has become a central issue in setting up priority protection areas, especially as financial resources for biological diversity conservation are limited. Taking China's Higher Plants Red List (CHPRL), including Bryophytes, Ferns, Gymnosperms, Angiosperms, as the data source, we analyzed the geographic patterns of species richness, endemism, and endangerment via data processing at a fine grid-scale with an average edge length of 30 km based on three aspects of richness information: species richness, endemic species richness, and threatened species richness. We sought to test the accuracy of hotspots used in identifying conservation priorities with regard to higher plants. Next, we tested the congruence of the three aspects and made a comparison of the similarities and differences between the hotspots described in this paper and those in previous studies. We found that over 90% of threatened species in China are concentrated. While a high spatial congruence is observed among the three measures, there is a low congruence between two different sets of hotspots. Our results suggest that biodiversity information should be considered when identifying biological hotspots. Other factors, such as scales, should be included as well to develop biodiversity conservation plans in accordance with the region's specific conditions.

Shoot phototropism in higher plants: new light through old concepts.

PubMed

Christie, John M; Murphy, Angus S

2013-01-01

Light is a key environmental factor that drives many aspects of plant growth and development. Phototropism, the reorientation of growth toward or away from light, represents one of these important adaptive processes. Modern studies of phototropism began with experiments conducted by Charles Darwin demonstrating that light perception at the shoot apex of grass coleoptiles induces differential elongation in the lower epidermal cells. This led to the discovery of the plant growth hormone auxin and the Cholodny-Went hypothesis attributing differential tropic bending to lateral auxin relocalization. In the past two decades, molecular-genetic analyses in the model flowering plant Arabidopsis thaliana has identified the principal photoreceptors for phototropism and their mechanism of activation. In addition, several protein families of auxin transporters have been identified. Despite extensive efforts, however, it still remains unclear as to how photoreceptor activation regulates lateral auxin transport to establish phototropic growth. This review aims to summarize major developments from over the last century and how these advances shape our current understanding of higher plant phototropism. Recent progress in phototropism research and the way in which this research is shedding new light on old concepts, including the Cholodny-Went hypothesis, is also highlighted.

Sex-linked inheritance of host-plant specialization in a polyphagous butterfly

PubMed Central

Janz, N.

1998-01-01

I investigated the genetic background of intraspecific variation in oviposition specificity in the generalist butterfly Polygonia c-album. Using reciprocal crosses between two populations that differ in their degree of specialization, I show that specificity is strongly sex-linked. This indicates that genes determining this difference are located primarily on the paternally inherited X-chromosome. The results suggest that intraspecific differences in specificity are caused by the same genetic mechanisms that have been shown to determine interspecific differences in host-plant ranking in other butterflies. Accordingly, the common assumption that specialization and ranking are determined by fundamentally different mechanisms was not supported.

Links between Plant Invasion, Anthropogenic Nitrogen Enrichment, and Wildfires: A Systematic Review

NASA Astrophysics Data System (ADS)

Felker-Quinn, E.; Gooding Lassiter, M.; Maxwell, A.; Housego, R.; Young, B.

2014-12-01

Wildfires can become positive feedbacks in climate change scenarios, because wildfires release large amounts of carbon sequestered in plants and soil to the atmosphere, and because their frequency increases with increasing temperatures. Invasive plants represent an important biotic link between anthropogenic activity and wildfire, as many of these species benefit from human disturbance while increasing fire frequency and severity. A robust body of literature addresses the response of invasive species to nitrogen enrichment, and a separate body of research assesses the feedbacks between invasive plant species and wildfire. We have undertaken a systematic review of these fields in order to evaluate the hypothesis that anthropogenic nitrogen loading contributes to increasing wildfires by promoting the growth and spread of fire-adapted invasive plant species. We identified invasive plant species using the Fire Effects Information System (FEIS), a Forest Service database that evaluates fire ecology of species identified as being of concern by land managers. We used information contained in the FEIS as well as more recent studies to characterize species on a continuum from fire-adapted to fire-intolerant based on traits related to interactions of fire with survival, reproduction, and spread. Of the 107 invasive plant species with fire ecology reports in the FEIS, we have initially classified 18 as fire-adapted, possessing traits that intensify fire regimes. Additionally, 33 species are fire-tolerant, benefiting from fire primarily because it creates a high-resource, low-competition environment. In continuing work, we are evaluating the responses of the invasive plant species to increased anthropogenic nitrogen with a focus on traits such as germination, productivity, and survival, as these traits contribute to wildfire frequency and severity. The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U

Linking the community structure of arbuscular mycorrhizal fungi and plants: a story of interdependence?

PubMed Central

Horn, Sebastian; Hempel, Stefan; Verbruggen, Erik; Rillig, Matthias C; Caruso, Tancredi

2017-01-01

Arbuscular mycorrhizal fungi (AMF) are crucial to plants and vice versa, but little is known about the factors linking the community structure of the two groups. We investigated the association between AMF and the plant community structure in the nearest neighborhood of Festuca brevipila in a semiarid grassland with steep environmental gradients, using high-throughput sequencing of the Glomeromycotina (former Glomeromycota). We focused on the Passenger, Driver and Habitat hypotheses: (i) plant communities drive AMF (passenger); (ii) AMF communities drive the plants (driver); (iii) the environment shapes both communities causing covariation. The null hypothesis is that the two assemblages are independent and this study offers a spatially explicit novel test of it in the field at multiple, small scales. The AMF community consisted of 71 operational taxonomic units, the plant community of 47 species. Spatial distance and spatial variation in the environment were the main determinants of the AMF community. The structure of the plant community around the focal plant was a poor predictor of AMF communities, also in terms of phylogenetic community structure. Some evidence supports the passenger hypothesis, but the relative roles of the factors structuring the two groups clearly differed, leading to an apparent decoupling of the two assemblages at the relatively small scale of this study. Community phylogenetic structure in AMF suggests an important role of within-assemblage interactions. PMID:28244977

Linking the community structure of arbuscular mycorrhizal fungi and plants: a story of interdependence?

PubMed

Horn, Sebastian; Hempel, Stefan; Verbruggen, Erik; Rillig, Matthias C; Caruso, Tancredi

2017-06-01

Arbuscular mycorrhizal fungi (AMF) are crucial to plants and vice versa, but little is known about the factors linking the community structure of the two groups. We investigated the association between AMF and the plant community structure in the nearest neighborhood of Festuca brevipila in a semiarid grassland with steep environmental gradients, using high-throughput sequencing of the Glomeromycotina (former Glomeromycota). We focused on the Passenger, Driver and Habitat hypotheses: (i) plant communities drive AMF (passenger); (ii) AMF communities drive the plants (driver); (iii) the environment shapes both communities causing covariation. The null hypothesis is that the two assemblages are independent and this study offers a spatially explicit novel test of it in the field at multiple, small scales. The AMF community consisted of 71 operational taxonomic units, the plant community of 47 species. Spatial distance and spatial variation in the environment were the main determinants of the AMF community. The structure of the plant community around the focal plant was a poor predictor of AMF communities, also in terms of phylogenetic community structure. Some evidence supports the passenger hypothesis, but the relative roles of the factors structuring the two groups clearly differed, leading to an apparent decoupling of the two assemblages at the relatively small scale of this study. Community phylogenetic structure in AMF suggests an important role of within-assemblage interactions.

A novel histone variant localized in nucleoli of higher plant cells.

PubMed

Tanaka, I; Akahori, Y; Gomi, K; Suzuki, T; Ueda, K

1999-07-01

Immunofluorescence staining with antisera raised against p35, a basic nuclear protein that accumulates in the pollen nuclei of Lilium longiflorum, specifically stained the nucleoli in interphase nuclei of somatic tissues, including root and leaf, and in pachytene nuclei during meiotic division, whereas antisera raised against histone H1 uniformly stained the entire chromatin domain with the exception of the nucleoli in these nuclei. Further, p35-specific antisera stained the nucleoli in root and leaf nuclei of the monocotyledonous plants Tulipa gesneriana, Allium cepa and Triticum aestivum and of the dicotyledonous plants Vicia faba and Nicotiana tabacum. Thus, these novel antisera stained the nucleoli in cells of all higher plants examined, although the staining patterns within nucleoli were somewhat different among plant species and tissues. The full-length cDNA of p35 was cloned on the basis of the partial amino acid sequence. The deduced amino acid composition and amino acid sequence of p35 indicate that this nucleolar protein is a novel variant of histone Hl. Further, p35 was strongly bound to ribosomal DNA in vitro. The results of immunoblotting of histones extracted from each tissue of the various plant species with the nucleolus-specific antibodies also suggested the conservation of similar epitope(s) in both mono- and dicotyledonous plants. From these results, it is suggested that similar variants of histone Hl are specifically distributed in the nucleoli of all plant species and help to organize the nucleolar chromatin.

Advanced life support systems in lunar and Martian environments utilizing a higher plant based engineering paradigm

NASA Technical Reports Server (NTRS)

Chamberland, Dennis

1992-01-01

The paper describes a higher-plant-based engineering paradigm for advanced life support in a Controlled Ecological Life Support System (CELSS) on the surface of the moon or Mars, called the CELSS Breadboard Project, designed at John F. Kennedy Space Center. Such a higher-plant-based system would use the plants for a direct food source, gas exchange, water reclamation, and plant residuals in a complex biological resource recovery scheme. The CELSS Breadboard Project utilizes a 'breadboard' approach of developing independent systems that are evaluated autonomously and are later interconnected. Such a scheme will enable evaluation of life support system methodologies tested for their efficiency in a life support system for habitats on the moon or Mars.

Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

PubMed Central

Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

2013-01-01

Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed. PMID:23509687

Cloning higher plants from aseptically cultured tissues and cells

NASA Technical Reports Server (NTRS)

Krikorian, A. D.

1982-01-01

A review of aseptic culture methods for higher plants is presented, which focuses on the existing problems that limit or prevent the full realization of cloning plants from free cells. It is shown that substantial progress in clonal multiplication has been made with explanted stem tips or lateral buds which can be stimulated to produce numerous precocious axillary branches. These branches can then be separated or subdivided and induced to root in order to yield populations of genetically and phenotypically uniorm plantlets. Similarly, undifferentiated calluses can sometimes be induced to form shoots and/or roots adventitiously. Although the cell culture techniques required to produce somatic embryos are presently rudimentary, steady advances are being made in learning how to stimulate formation of somatic or adventive embryos from totipotent cells grown in suspension cultures. It is concluded that many problems exist in the producing and growing of totipotent or morphogenetically competent cell suspensions, but the potential benefits are great.

Lessons from natural and artificial polyploids in higher plants.

PubMed

Hegarty, M; Coate, J; Sherman-Broyles, S; Abbott, R; Hiscock, S; Doyle, J

2013-01-01

Polyploidy in higher plants is a major source of genetic novelty upon which selection may act to drive evolution, as evidenced by the widespread success of polyploid species in the wild. However, research into the effects of polyploidy can be confounded by the entanglement of several processes: genome duplication, hybridisation (allopolyploidy is frequent in plants) and subsequent evolution. The discovery of the chemical agent colchicine, which can be used to produce artificial polyploids on demand, has enabled scientists to unravel these threads and understand the complex genomic changes involved in each. We present here an overview of lessons learnt from studies of natural and artificial polyploids, and from comparisons between the 2, covering basic cellular and metabolic consequences through to alterations in epigenetic gene regulation, together with 2 in-depth case studies in Senecio and Glycine. See also the sister article focusing on animals by Arai and Fujimoto in this themed issue. Copyright © 2013 S. Karger AG, Basel.

Soil stabilization linked to plant diversity and environmental context in coastal wetlands.

PubMed

Ford, Hilary; Garbutt, Angus; Ladd, Cai; Malarkey, Jonathan; Skov, Martin W

2016-03-01

Plants play a pivotal role in soil stabilization, with above-ground vegetation and roots combining to physically protect soil against erosion. It is possible that diverse plant communities boost root biomass, with knock-on positive effects for soil stability, but these relationships are yet to be disentangled. We hypothesize that soil erosion rates fall with increased plant species richness, and test explicitly how closely root biomass is associated with plant diversity. We tested this hypothesis in salt marsh grasslands, dynamic ecosystems with a key role in flood protection. Using step-wise regression, the influences of biotic (e.g. plant diversity) and abiotic variables on root biomass and soil stability were determined for salt marshes with two contrasting soil types: erosion-resistant clay (Essex, southeast UK) and erosion-prone sand (Morecambe Bay, northwest UK). A total of 132 (30-cm depth) cores of natural marsh were extracted and exposed to lateral erosion by water in a re-circulating flume. Soil erosion rates fell with increased plant species richness ( R 2  = 0.55), when richness was modelled as a single explanatory variable, but was more important in erosion-prone ( R 2  = 0.44) than erosion-resistant ( R 2  = 0.18) regions. As plant species richness increased from two to nine species·m -2 , the coefficient of variation in soil erosion rate decreased significantly ( R 2  = 0.92). Plant species richness was a significant predictor of root biomass ( R 2  = 0.22). Step-wise regression showed that five key variables accounted for 80% of variation in soil erosion rate across regions. Clay-silt fraction and soil carbon stock were linked to lower rates, contributing 24% and 31%, respectively, to variation in erosion rate. In regional analysis, abiotic factors declined in importance, with root biomass explaining 25% of variation. Plant diversity explained 12% of variation in the erosion-prone sandy region. Our study indicates that soil stabilization

Links between Soil Fungal Diversity and Plant and Soil Properties on the Loess Plateau.

PubMed

Yang, Yang; Dou, Yanxing; Huang, Yimei; An, Shaoshan

2017-01-01

Previous studies have revealed inconsistent correlations between fungal diversity and plant/soil properties from local to global scales. Here, we investigated the internal relationships between soil fungal diversity and plant/soil properties on the Loess Plateau following vegetation restoration, using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region for fungal identification. We found significant effects of land use types (Af, Artificial forest; Ns, Natural shrub; Ag, Artificial grassland; Ng, Natural grassland; Sc, slope cropland) on soil fungal communities composition, and the dominant phyla were Ascomycota, Basidiomycota , and Zygomycota , which transitioned from Basidiomycota -dominant to Ascomycota -dominant community due to vegetation restoration. The Chao1 richness, Shannon's diversity and ACE indices were significantly influenced by land use types with the order of Ns > Af > Ng > Ag > Sc, and the total number of OTUs varied widely. In contrast, Good's coverage and Simpson's diversity indicated no significant difference among land use types ( p > 0.05). Correlation analysis showed that plant and soil properties were closely related to fungal diversity regardless of land use types. In addition, soil organic carbon (SOC) and H plant (plant richness, Shannon-Wiener index) were strong driving factors that explained fungal diversity. As revealed by the structural equation model (SEM) and generalized additive models (GAMs), fungal diversity was directly and indirectly affected by soil and plant properties, respectively, providing evidence for strong links between soil fungal diversity and plant and soil properties on the Loess Plateau.

Characterization of a Chlamydomonas Transposon, Gulliver, Resembling Those in Higher Plants

PubMed Central

Ferris, P. J.

1989-01-01

While pursuing a chromosomal walk through the mt(+) locus of linkage group VI of Chlamydomonas reinhardtii, I encountered a 12-kb sequence that was found to be present in approximately 12 copies in the nuclear genome. Comparison of various C. reinhardtii laboratory strains provided evidence that the sequence was mobile and therefore a transposon. One of two separate natural isolates interfertile with C. reinhardtii, C. smithii (CC-1373), contained the transposon, but at completely different locations in its nuclear genome than C. reinhardtii; and a second, CC-1952 (S1-C5), lacked the transposon altogether. Genetic analysis indicated that the transposon was found at dispersed sites throughout the genome, but had a conserved structure at each location. Sequence homology between the termini was limited to an imperfect 15-bp inverted repeat. An 8-bp target site duplication was created by insertion; transposon sequences were completely removed upon excision leaving behind both copies of the target site duplication, with minor base changes. The transposon contained an internal region of unique repetitive sequence responsible for restriction fragment length heterogeneity among the various copies of the transposon. In several cases it was possible to identify which of the dozen transposons in a given strain served as the donor when a transposition event occurred. The transposon often moved into a site genetically linked to the donor, and transposition appeared to be nonreplicative. Thus the mechanism of transposition and excision of the transposon, which I have named Gulliver, resembles that of certain higher plant transposons, like the Ac transposon of maize. PMID:2570007

Lead stress effects on physiobiochemical activities of higher plants.

PubMed

Sengar, Rakesh Singh; Gautam, Madhu; Sengar, Rajesh Singh; Garg, Sanjay Kumar; Sengar, Kalpana; Chaudhary, Reshu

2008-01-01

Lead is a metallic pollutant emanating from various environmental sources including industrial wastes, combustion of fossil fuels, and use of agrochemicals. Lead may exist in the atmosphere as dusts, fumes, mists, and vapors, and in soil as a mineral. Soils along roadsides are rich in lead because vehicles burn leaded gasoline, which contributes to environmental lead pollution. Other important sources of lead pollution are geological weathering, industrial processing of ores and minerals, leaching of lead from solid wastes, and animal and human excreta. Lead is nondegradable, readily enters the food chain, and can subsequently endanger human and animal health. Lead is one of the most important environment pollutants and deserves the increasing attention it has received in recent decades. The present effort was undertaken to review lead stress effects on the physiobiochemical activity of higher plants. Lead has gained considerable attention as a potent heavy metal pollutant because of growing anthropogenic pressure on the environment. Lead-contaminated soils show a sharp decline in crop productivity. Lead is absorbed by plants mainly through the root system and in minor amounts through the leaves. Within the plants, lead accumulates primarily in roots, but some is translocated to aerial plant parts. Soil pH, soil particle size, cation-exchange capacity, as well as root surface area, root exudation, and mycorrhizal transpiration rate affect the availability and uptake of lead by plants. Only a limited amount of lead is translocated from roots to other organs because there are natural plant barriers in the root endodermis. At lethal concentrations, this barrier is broken and lead may enter vascular tissues. Lead in plants may form deposits of various sizes, present mainly in intercellular spaces, cell walls, and vacuoles. Small deposits of this metal are also seen in the endoplasmic reticulum, dictyosome, and dictyosome-derived vesicles. After entering the cells, lead

Linking plants, fungi and soil mechanics

NASA Astrophysics Data System (ADS)

Yildiz, Anil; Graf, Frank

2017-04-01

Plants provide important functions in respect soil strength and are increasingly considered for slope stabilisation within eco-engineering methods, particularly to prevent superficial soil failure. The protective functions include hydrological regulation through interception and evapo-transpiration as well as mechanical stabilisation through root reinforcement and, to a certain extent, chemical stabilisation through sticky metabolites. The ever-growing application of plants in slope stabilisation demanded more precise information of the vegetation effects and, concomitant, led the models for quantifying the reinforcement shoot up like mushrooms. However, so far, the framework and interrelationships for both the role of plants and the quantification concepts have not been thoroughly analysed and comprehensively considered, respectively, often resulting in unsatisfactory results. Although it seems obvious and is implicitly presupposed that the plant specific functions related to slope stability require growth and development, this is anything but given, particularly under the often hostile conditions dominating on bare and steep slopes. There, the superficial soil layer is often characterised by a lack of fines and missing medium-sized and fine pores due to an unstable soil matrix, predominantly formed by coarse grains. Low water retention capacity and substantial leaching of nutrients are the adverse consequences. Given this general set-up, sustainable plant growth and, particularly, root development is virtually unachievable. At exactly this point mycorrhizal fungi, the symbiotic partners of almost all plants used in eco-engineering, come into play. Though, they are probably well-known within the eco-engineering community, mycorrhizal fungi lead a humble existence. This is in spite of the fact that they supply their hosts with water and nutrients, improving the plant's ability to master otherwise unbridgeable environmental conditions. However, in order to support

Cross-linking measurements of the Potato leafroll virus reveal protein interaction topologies required for virion stability, aphid transmission, and virus-plant interactions.

PubMed

Chavez, Juan D; Cilia, Michelle; Weisbrod, Chad R; Ju, Ho-Jong; Eng, Jimmy K; Gray, Stewart M; Bruce, James E

2012-05-04

Protein interactions are critical determinants of insect transmission for viruses in the family Luteoviridae. Two luteovirid structural proteins, the capsid protein (CP) and the readthrough protein (RTP), contain multiple functional domains that regulate virus transmission. There is no structural information available for these economically important viruses. We used Protein Interaction Reporter (PIR) technology, a strategy that uses chemical cross-linking and high resolution mass spectrometry, to discover topological features of the Potato leafroll virus (PLRV) CP and RTP that are required for the diverse biological functions of PLRV virions. Four cross-linked sites were repeatedly detected, one linking CP monomers, two within the RTP, and one linking the RTP and CP. Virus mutants with triple amino acid deletions immediately adjacent to or encompassing the cross-linked sites were defective in virion stability, RTP incorporation into the capsid, and aphid transmission. Plants infected with a new, infectious PLRV mutant lacking 26 amino acids encompassing a cross-linked site in the RTP exhibited a delay in the appearance of systemic infection symptoms. PIR technology provided the first structural insights into luteoviruses which are crucially lacking and are involved in vector-virus and plant-virus interactions. These are the first cross-linking measurements on any infectious, insect-transmitted virus.

Cross-linking measurements of the Potato leafroll virus reveal protein interaction topologies required for virion stability, aphid transmission, and virus-plant interactions

PubMed Central

Chavez, Juan D.; Cilia, Michelle; Weisbrod, Chad R.; Ju, Ho-Jong; Eng, Jimmy K.; Gray, Stewart M.; Bruce, James E.

2012-01-01

Protein interactions are critical determinants of insect-transmission for viruses in the family Luteoviridae. Two luteovirid structural proteins, the capsid protein (CP) and the readthrough protein (RTP), contain multiple functional domains that regulate virus transmission. There is no structural information available for these economically important viruses. We used Protein Interaction Reporter (PIR) technology, a strategy that uses chemical cross-linking and high resolution mass spectrometry, to discover topological features of the Potato leafroll virus (PLRV) CP and RTP that are required for the diverse biological functions of PLRV virions. Four cross-linked sites were repeatedly detected, one linking CP monomers, two within the RTP, and one linking the RTP and CP. Virus mutants with triple amino acid deletions immediately adjacent to or encompassing the cross-linked sites were defective in virion stability, RTP incorporation into the capsid, and aphid transmission. Plants infected with a new, infectious PLRV mutant lacking 26 amino acids encompassing a cross-linked site in the RTP exhibited a delay in the appearance of systemic infection symptoms. PIR technology provided the first structural insights into luteoviruses which are crucially lacking and that are involved in vector-virus and plant-virus interactions. These are the first cross-linking measurements on any infectious, insect-transmitted virus. PMID:22390342

[Studies on the role of silicic acid in the development of higher plants].

PubMed

Werner, D

1967-03-01

Germanium acid, a specific inhibitor of the silicic acid metabolism in diatoms, inhibits the growth of Sinapis alba, Lemna minor, Wolffia arrhiza, Nicotiana tabacum, Tradescantia spec, Zinnia elegans, and Secale cereale when applied in the same concentrations as those used in the case of diatoms (15-75 μg GeO2/ml medium). The growth of Aspergillus niger, Phycomyces blakesleanus, Escherichia coli K 12, Euglena gracilis and Pandorina morum is not influenced by these and higher concentrations of Germanium acid. By application of high concentrations of silicic acid, the growth inhibition produced by germanium acid in Lemna minor is partially reduced. Plants of Lemna minor which have been inhibited by germanium acid are essentially smaller than plants grown in a normal medium; their chlorophyll content is significantly decreased. The growth of the roots in Lemna is particularly inhibited. Isolated growing roots of Lycopersicon pimpinellifolium MILL. are inhibited by small concentrations of Ge(OH)4 (ca. 1,5×10(-4) M/l). In contrast to the growth of older plants, the germination of Secale cereale and Sinapis alba is not influenced by Ge(OH)4. The effects of germanium acid are discussed in relation to the physiological role of silicic acid. The results suggest that the element silicon, in the form of silicic acid, is generally essential for the normal development of higher plants.

Links between Soil Fungal Diversity and Plant and Soil Properties on the Loess Plateau

PubMed Central

Yang, Yang; Dou, Yanxing; Huang, Yimei; An, Shaoshan

2017-01-01

Previous studies have revealed inconsistent correlations between fungal diversity and plant/soil properties from local to global scales. Here, we investigated the internal relationships between soil fungal diversity and plant/soil properties on the Loess Plateau following vegetation restoration, using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region for fungal identification. We found significant effects of land use types (Af, Artificial forest; Ns, Natural shrub; Ag, Artificial grassland; Ng, Natural grassland; Sc, slope cropland) on soil fungal communities composition, and the dominant phyla were Ascomycota, Basidiomycota, and Zygomycota, which transitioned from Basidiomycota-dominant to Ascomycota-dominant community due to vegetation restoration. The Chao1 richness, Shannon’s diversity and ACE indices were significantly influenced by land use types with the order of Ns > Af > Ng > Ag > Sc, and the total number of OTUs varied widely. In contrast, Good’s coverage and Simpson’s diversity indicated no significant difference among land use types (p > 0.05). Correlation analysis showed that plant and soil properties were closely related to fungal diversity regardless of land use types. In addition, soil organic carbon (SOC) and Hplant (plant richness, Shannon-Wiener index) were strong driving factors that explained fungal diversity. As revealed by the structural equation model (SEM) and generalized additive models (GAMs), fungal diversity was directly and indirectly affected by soil and plant properties, respectively, providing evidence for strong links between soil fungal diversity and plant and soil properties on the Loess Plateau. PMID:29163460

Plant phenology in western Canada: trends and links to the view from space.

PubMed

Beaubien, Elisabeth G; Hall-Beyer, Mryka

2003-01-01

One feature of climate change is the trends to earlier spring onset in many north temperate areas of the world. The timing of spring flowering and leafing of perennial plants is largely controlled by temperature accumulation; both temperature and phenological records illustrate changes in recent decades. Phenology studies date back over a century, with extensive databases existing for western Canada. Earlier spring flowering has been noted for many woody plants, with larger trends seen for species that develop at spring's start. Implications for ecosystems of trends to earlier spring arrival include changes in plant species composition, changes in timing and distribution of pests and disease, and potentially disrupted ecological interactions. While Alberta has extensive phenology databases (for species, years, and geographic coverage) for recent decades, these data cannot provide continuous ground coverage. There is great potential for phenological data to provide ground validation for satellite imagery interpretation, especially as new remote sensors are becoming available. Phenological networks are experiencing a resurgence of interest in Canada (www.plantwatch.ca) and globally, and linking these ground-based observations with the view from space will greatly enhance our capacity to track the biotic response to climate changes.

High CO2 Primes Plant Biotic Stress Defences through Redox-Linked Pathways1[OPEN

PubMed Central

2016-01-01

Industrial activities have caused tropospheric CO2 concentrations to increase over the last two centuries, a trend that is predicted to continue for at least the next several decades. Here, we report that growth of plants in a CO2-enriched environment activates responses that are central to defense against pathogenic attack. Salicylic acid accumulation was triggered by high-growth CO2 in Arabidopsis (Arabidopsis thaliana) and other plants such as bean (Phaseolus vulgaris). A detailed analysis in Arabidopsis revealed that elevated CO2 primes multiple defense pathways, leading to increased resistance to bacterial and fungal challenge. Analysis of gene-specific mutants provided no evidence that activation of plant defense pathways by high CO2 was caused by stomatal closure. Rather, the activation is partly linked to metabolic effects involving redox signaling. In support of this, genetic modification of redox components (glutathione contents and NADPH-generating enzymes) prevents full priming of the salicylic acid pathway and associated resistance by high CO2. The data point to a particularly influential role for the nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase, a cytosolic enzyme whose role in plants remains unclear. Our observations add new information on relationships between high CO2 and oxidative signaling and provide novel insight into plant stress responses in conditions of increased CO2. PMID:27578552

Solution NMR and molecular dynamics reveal a persistent alpha helix within the dynamic region of PsbQ from photosystem II of higher plants.

PubMed

Rathner, Petr; Rathner, Adriana; Horničáková, Michaela; Wohlschlager, Christian; Chandra, Kousik; Kohoutová, Jaroslava; Ettrich, Rüdiger; Wimmer, Reinhard; Müller, Norbert

2015-09-01

The extrinsic proteins of photosystem II of higher plants and green algae PsbO, PsbP, PsbQ, and PsbR are essential for stable oxygen production in the oxygen evolving center. In the available X-ray crystallographic structure of higher plant PsbQ residues S14-Y33 are missing. Building on the backbone NMR assignment of PsbQ, which includes this "missing link", we report the extended resonance assignment including side chain atoms. Based on nuclear Overhauser effect spectra a high resolution solution structure of PsbQ with a backbone RMSD of 0.81 Å was obtained from torsion angle dynamics. Within the N-terminal residues 1-45 the solution structure deviates significantly from the X-ray crystallographic one, while the four-helix bundle core found previously is confirmed. A short α-helix is observed in the solution structure at the location where a β-strand had been proposed in the earlier crystallographic study. NMR relaxation data and unrestrained molecular dynamics simulations corroborate that the N-terminal region behaves as a flexible tail with a persistent short local helical secondary structure, while no indications of forming a β-strand are found. © 2015 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.

Effect of free fall on higher plants.

NASA Technical Reports Server (NTRS)

Gordon, S. A.

1973-01-01

The influence of exposure to the free-fall state on the orientation, morphogenesis, physiology, and radiation response of higher plants is briefly summarized. It is proposed that the duration of the space-flight experiments has been to brief to permit meaningful effects of free fall on general biochemistry, growth, and development to appear. However, two types of significant effect did occur. The first is on differential growth - i.e., tropism and epinasty - resulting from the absence of a normal geostimulus. For these phenomena it is suggested that ground-based experiments with the clinostat would suffice to mimic the effect of the free-fall state. The second is an apparent interaction between the radiation response and some flight condition, yielding an enhanced microspore abortion, a disturbed spindle function, and a stunting of stamen hairs. It is suggested that this apparent interaction may be derived from a shift in the rhythm of the cell cycle, induced by the free fall.

The Maternal-to-Zygotic Transition in Higher Plants: Available Approaches, Critical Limitations, and Technical Requirements.

PubMed

Zhao, Peng; Sun, Meng-Xiang

2015-01-01

Fertilization marks the turnover from the gametophyte to sporophyte generation in higher plants. After fertilization, sporophytic development undergoes genetic turnover from maternal to zygotic control: the maternal-to-zygotic transition (MZT). The MZT is thought to be critical for early embryogenesis; however, little is known about the time course or developmental impact of the MZT in higher plants. Here, we discuss what is known in the field and focus on techniques used in relevant studies and their limitations. Some significant questions and technical requirements for further investigations are also discussed. © 2015 Elsevier Inc. All rights reserved.

Beyond neutral and forbidden links: morphological matches and the assembly of mutualistic hawkmoth-plant networks.

PubMed

Sazatornil, Federico D; Moré, Marcela; Benitez-Vieyra, Santiago; Cocucci, Andrea A; Kitching, Ian J; Schlumpberger, Boris O; Oliveira, Paulo E; Sazima, Marlies; Amorim, Felipe W

2016-11-01

A major challenge in evolutionary ecology is to understand how co-evolutionary processes shape patterns of interactions between species at community level. Pollination of flowers with long corolla tubes by long-tongued hawkmoths has been invoked as a showcase model of co-evolution. Recently, optimal foraging models have predicted that there might be a close association between mouthparts' length and the corolla depth of the visited flowers, thus favouring trait convergence and specialization at community level. Here, we assessed whether hawkmoths more frequently pollinate plants with floral tube lengths similar to their proboscis lengths (morphological match hypothesis) against abundance-based processes (neutral hypothesis) and ecological trait mismatches constraints (forbidden links hypothesis), and how these processes structure hawkmoth-plant mutualistic networks from five communities in four biogeographical regions of South America. We found convergence in morphological traits across the five communities and that the distribution of morphological differences between hawkmoths and plants is consistent with expectations under the morphological match hypothesis in three of the five communities. In the two remaining communities, which are ecotones between two distinct biogeographical areas, interactions are better predicted by the neutral hypothesis. Our findings are consistent with the idea that diffuse co-evolution drives the evolution of extremely long proboscises and flower tubes, and highlight the importance of morphological traits, beyond the forbidden links hypothesis, in structuring interactions between mutualistic partners, revealing that the role of niche-based processes can be much more complex than previously known. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Extinction Risk and Diversification Are Linked in a Plant Biodiversity Hotspot

PubMed Central

Davies, T. Jonathan; Smith, Gideon F.; Bellstedt, Dirk U.; Boatwright, James S.; Bytebier, Benny; Cowling, Richard M.; Forest, Félix; Harmon, Luke J.; Muasya, A. Muthama; Schrire, Brian D.; Steenkamp, Yolande; van der Bank, Michelle; Savolainen, Vincent

2011-01-01

It is widely recognized that we are entering an extinction event on a scale approaching the mass extinctions seen in the fossil record. Present-day rates of extinction are estimated to be several orders of magnitude greater than background rates and are projected to increase further if current trends continue. In vertebrates, species traits, such as body size, fecundity, and geographic range, are important predictors of vulnerability. Although plants are the basis for life on Earth, our knowledge of plant extinctions and vulnerabilities is lagging. Here, we disentangle the underlying drivers of extinction risk in plants, focusing on the Cape of South Africa, a global biodiversity hotspot. By comparing Red List data for the British and South African floras, we demonstrate that the taxonomic distribution of extinction risk differs significantly between regions, inconsistent with a simple, trait-based model of extinction. Using a comprehensive phylogenetic tree for the Cape, we reveal a phylogenetic signal in the distribution of plant extinction risks but show that the most threatened species cluster within short branches at the tips of the phylogeny—opposite to trends in mammals. From analyzing the distribution of threatened species across 11 exemplar clades, we suggest that mode of speciation best explains the unusual phylogenetic structure of extinction risks in plants of the Cape. Our results demonstrate that explanations for elevated extinction risk in plants of the Cape flora differ dramatically from those recognized for vertebrates. In the Cape, extinction risk is higher for young and fast-evolving plant lineages and cannot be explained by correlations with simple biological traits. Critically, we find that the most vulnerable plant species are nonetheless marching towards extinction at a more rapid pace but, surprisingly, independently from anthropogenic effects. Our results have important implications for conservation priorities and cast doubts on the

Higher photosynthesis, nutrient- and energy-use efficiencies contribute to invasiveness of exotic plants in a nutrient poor habitat in northeast China.

PubMed

Liu, Ming-Chao; Kong, De-Liang; Lu, Xiu-Rong; Huang, Kai; Wang, Shuo; Wang, Wei-Bin; Qu, Bo; Feng, Yu-Long

2017-08-01

The roles of photosynthesis-related traits in invasiveness of introduced plant species are still not well elucidated, especially in nutrient-poor habitats. In addition, little effort has been made to determine the physiological causes and consequences of the difference in these traits between invasive and native plants. To address these problems, we compared the differences in 16 leaf functional traits related to light-saturated photosynthetic rate (P max ) between 22 invasive and native plants in a nutrient-poor habitat in northeast China. The invasive plants had significantly higher P max , photosynthetic nitrogen- (PNUE), phosphorus- (PPUE), potassium- (PKUE) and energy-use efficiencies (PEUE) than the co-occurring natives, while leaf nutrient concentrations, construction cost (CC) and specific leaf area were not significantly different between the invasive and native plants. The higher PNUE contributed to higher P max for the invasive plants, which in turn contributed to higher PPUE, PKUE and PEUE. CC changed independently with other traits such as P max , PNUE, PPUE, PKUE and PEUE, showing two trait dimensions, which may facilitate acclimation to multifarious niche dimensions. Our results indicate that the invasive plants have a superior resource-use strategy, i.e. higher photosynthesis under similar resource investments, contributing to invasion success in the barren habitat. © 2017 Scandinavian Plant Physiology Society.

Gravitropism in higher plant shoots. IV - Further studies on participation of ethylene

NASA Technical Reports Server (NTRS)

Wheeler, Raymond M.; White, Rosemary G.; Salisbury, Frank B.

1986-01-01

Various hypotheses regarding the influence of ethylene on gravitropism in higher plant shoots were experimentally tested. It was found that ethylene at 1.0 and 10.0 cu cm/cu m decreased the rate of gravitropic bending in cocklebur stems, while 0.1 cm/cu m of ethylene had little effect. Treating cocklebur plants with 1.0 mmol aminoethoxyvinylglycine (AVG, an ethylene synthesis inhibitor) delayed stem bending compared with controls, but adding 0.1 cu cm/cu m ethylene in the surrounding atmosphere partially restored the rate of bending of AVG-treated plants. Virtually all newly synthesized ethylene appeared in bottom halves of horizontal stems, where ethylene concentrations were as much as 100 times those in upright stems or in top halves of horizontal stems. Auxin applied to one side of a vertical stem caused extreme bending away from that side; gibberellic acid, kinetin, and abscisic acid were without effect.

Purification and Kinetics of Higher Plant NADH:Nitrate Reductase.

PubMed

Campbell, W H; Smarrelli, J

1978-04-01

Squash cotyledon (Cucurbita pepo L.) NADH:nitrate reductase (NR) was purified 150-fold with 50% recovery by a single step procedure based on the affinity of the NR for blue-Sepharose. Blue-Sepharose, which is prepared by direct coupling of Cibacron blue to Sepharose, appears to bind squash NR at the NADH site. The NR can be purified in 2 to 3 hours to a specific activity of 2 mumol of NADH oxidized/minute * milligram of protein. Corn (Zea mays L.) leaf NR was also purified to a specific activity of 6.9 mumol of NADH oxidized/minute * milligram of protein using a blue-Sepharose affinity step. The blue-Sepharose method offers the advantages of a rapid purification of plant NR to a high specific activity with reasonable recovery of total activity.The kinetic mechanism of higher plant NR was investigated using these highly purified squash and corn NR preparations. Based on initial velocity and product inhibition studies utilizing both enzymes, a two-site ping-pong mechanism is proposed for NR. This kinetic mechanism incorporates the concept of the reduced NR transferring electrons from the NADH site to a physically separated nitrate site.

Plant Biology Personnel and Training at Doctorate-Granting Institutions. Higher Education Surveys Report. Survey Number 13.

ERIC Educational Resources Information Center

Chaney, Bradford; And Others

A survey instrument was sent to all doctorate-granting institutions and all institutions identified as offering doctorates in plant biology. Doctorate-granting institutions were identified using the U.S. Department of Education's Higher Education General Information Surveys (HEGIS) listings. Responses were received from plant biology program…

Risk assessment for selected xenobiotics by bioassay methods with higher plants

NASA Astrophysics Data System (ADS)

Günther, Petra; Pestemer, Wilfried

1990-05-01

Different bioassays with higher plants were approved for use in a bioassay procedure for testing of xenobiotics according to the German Chemicals Act. Selected environmental pollutants (atrazine, cadmium chloride, 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, thiourea), all from a list of reference chemicals, were tested with these methods. Dose-response curves for growth of oats and turnips were evaluated in soil and vermiculite (nonsorptive substrate), and availability to plants was calculated by comparing the EC50 values for one chemical in both substrates. The most active chemical was atrazine, followed by 2,6-dichlorobenzonitrile, pentachlorophenol, potassium dichromate, cadmium chloride, and thiourea. The least available compound to plants was pentachlorophenol, tested with turnips ( Brassica rapa var. rapa). The strongest inhibition of germination, demonstrated in an in vitro assay with garden cress ( Lepidium sativum), was found with 2,6-dichlorobenzonitrile, the lowest with atrazine. The effect of an extended exposure of the plants to the chemicals was evaluated in a long-term bioassay with oats ( Avena sativa) in hydroponic culture. Several dose-response curves during the growing period were derived. It was found that the EC50 values for atrazine and thiourea decreased markedly during the first four weeks; thereafter the changes were much smaller. As an overall conclusion, a bioassay procedure is proposed that can be included in the graduated plan recommended by the German Chemicals Act.

Metabolic engineering of higher plants and algae for isoprenoid production.

PubMed

Kempinski, Chase; Jiang, Zuodong; Bell, Stephen; Chappell, Joe

2015-01-01

Isoprenoids are a class of compounds derived from the five carbon precursors, dimethylallyl diphosphate, and isopentenyl diphosphate. These molecules present incredible natural chemical diversity, which can be valuable for humans in many aspects such as cosmetics, agriculture, and medicine. However, many terpenoids are only produced in small quantities by their natural hosts and can be difficult to generate synthetically. Therefore, much interest and effort has been directed toward capturing the genetic blueprint for their biochemistry and engineering it into alternative hosts such as plants and algae. These autotrophic organisms are attractive when compared to traditional microbial platforms because of their ability to utilize atmospheric CO2 as a carbon substrate instead of supplied carbon sources like glucose. This chapter will summarize important techniques and strategies for engineering the accumulation of isoprenoid metabolites into higher plants and algae by choosing the correct host, avoiding endogenous regulatory mechanisms, and optimizing potential flux into the target compound. Future endeavors will build on these efforts by fine-tuning product accumulation levels via the vast amount of available "-omic" data and devising metabolic engineering schemes that integrate this into a whole-organism approach. With the development of high-throughput transformation protocols and synthetic biology molecular tools, we have only begun to harness the power and utility of plant and algae metabolic engineering.

Oxidation of methionine residues: the missing link between stress and signalling responses in plants.

PubMed

Emes, Michael J

2009-08-13

In response to biotic and abiotic stresses, plants induce a complex array of pathways and protein phosphorylation cascades which generally lead to a response aimed at mitigating the particular insult. In many cases, H2O2 has been implicated as the signalling molecule, but, although progress has been made in assembling the downstream components of these signalling pathways, far less is known about the mechanism by which the signal is perceived. In this issue of the Biochemical Journal, Hardin et al. provide evidence for a plausible mechanism by which plants perceive H2O2. Evidence is presented for chemical oxidation of methionine residues by H2O2 at critical hydrophobic positions within the canonical motifs that define the phosphorylation sites of a number of enzymes, thus inhibiting binding of protein kinases. This process is reversible by MSR (methionine sulfoxide reductase) activity in vivo. Using synthetic peptides for a number of enzymes which are phosphorylated by families of protein kinases, including the CDPK (calcium-dependent protein kinase) and AMPK (AMP-activated protein kinase) families, coupled with in vivo studies of assimilatory plant nitrate reductase, the authors demonstrate that this mechanism regulates the ability of kinases to bind the target protein, directly linking oxidative signals to changes in protein phosphorylation. These results may have widespread implications for the perception of redox signalling in plants and animals.

Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria

PubMed Central

Balmer, Yves; Vensel, William H.; Tanaka, Charlene K.; Hurkman, William J.; Gelhaye, Eric; Rouhier, Nicolas; Jacquot, Jean-Pierre; Manieri, Wanda; Schürmann, Peter; Droux, Michel; Buchanan, Bob B.

2004-01-01

Mitochondria contain thioredoxin (Trx), a regulatory disulfide protein, and an associated flavoenzyme, NADP/Trx reductase, which provide a link to NADPH in the organelle. Unlike animal and yeast counterparts, the function of Trx in plant mitochondria is largely unknown. Accordingly, we have applied recently devised proteomic approaches to identify soluble Trx-linked proteins in mitochondria isolated from photosynthetic (pea and spinach leaves) and heterotrophic (potato tubers) sources. Application of the mitochondrial extracts to mutant Trx affinity columns in conjunction with proteomics led to the identification of 50 potential Trx-linked proteins functional in 12 processes: photorespiration, citric acid cycle and associated reactions, lipid metabolism, electron transport, ATP synthesis/transformation, membrane transport, translation, protein assembly/folding, nitrogen metabolism, sulfur metabolism, hormone synthesis, and stress-related reactions. Almost all of these targets were also identified by a fluorescent gel electrophoresis procedure in which reduction by Trx can be observed directly. In some cases, the processes targeted by Trx depended on the source of the mitochondria. The results support the view that Trx acts as a sensor and enables mitochondria to adjust key reactions in accord with prevailing redox state. These and earlier findings further suggest that, by sensing redox in chloroplasts and mitochondria, Trx enables the two organelles of photosynthetic tissues to communicate by means of a network of transportable metabolites such as dihydroxyacetone phosphate, malate, and glycolate. In this way, light absorbed and processed by means of chlorophyll can be perceived and function in regulating fundamental mitochondrial processes akin to its mode of action in chloroplasts. PMID:14983062

Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria.

PubMed

Balmer, Yves; Vensel, William H; Tanaka, Charlene K; Hurkman, William J; Gelhaye, Eric; Rouhier, Nicolas; Jacquot, Jean-Pierre; Manieri, Wanda; Schürmann, Peter; Droux, Michel; Buchanan, Bob B

2004-02-24

Mitochondria contain thioredoxin (Trx), a regulatory disulfide protein, and an associated flavoenzyme, NADP/Trx reductase, which provide a link to NADPH in the organelle. Unlike animal and yeast counterparts, the function of Trx in plant mitochondria is largely unknown. Accordingly, we have applied recently devised proteomic approaches to identify soluble Trx-linked proteins in mitochondria isolated from photosynthetic (pea and spinach leaves) and heterotrophic (potato tubers) sources. Application of the mitochondrial extracts to mutant Trx affinity columns in conjunction with proteomics led to the identification of 50 potential Trx-linked proteins functional in 12 processes: photorespiration, citric acid cycle and associated reactions, lipid metabolism, electron transport, ATP synthesis/transformation, membrane transport, translation, protein assembly/folding, nitrogen metabolism, sulfur metabolism, hormone synthesis, and stress-related reactions. Almost all of these targets were also identified by a fluorescent gel electrophoresis procedure in which reduction by Trx can be observed directly. In some cases, the processes targeted by Trx depended on the source of the mitochondria. The results support the view that Trx acts as a sensor and enables mitochondria to adjust key reactions in accord with prevailing redox state. These and earlier findings further suggest that, by sensing redox in chloroplasts and mitochondria, Trx enables the two organelles of photosynthetic tissues to communicate by means of a network of transportable metabolites such as dihydroxyacetone phosphate, malate, and glycolate. In this way, light absorbed and processed by means of chlorophyll can be perceived and function in regulating fundamental mitochondrial processes akin to its mode of action in chloroplasts.

Delayed expression of SAGs correlates with longevity in CMS wheat plants compared to its fertile plants.

PubMed

Semwal, Vimal Kumar; Singh, Bhupinder; Khanna-Chopra, Renu

2014-04-01

Reproductive sinks regulate monocarpic senescence in crop plants. Monocarpic senescence was studied in wheat fertile (cv. HW 2041) and its isonuclear cytoplasmic male sterile (CMS) line. CMS plants exhibited slower rate of senescence accompanied by longer green leaf area duration and slower deceleration in chlorophyll, protein content, PN and rubisco content coupled with lower protease activities than fertile (F) plants. CMS plants also exhibited lower ROS levels and less membrane damage than F plants. CMS plants maintained better antioxidant defense, less oxidative damage in chloroplast and higher transcript levels of both rbcL and rbcS genes during senescence than F plants. F plants exhibited early induction and higher expression of SAGs like serine and cysteine proteases, glutamine synthetases GS1 and GS2, WRKY53 transcription factor and decline in transcript levels of CAT1 and CAT2 genes than CMS plants. Hence, using genetically fertile and its CMS line of wheat it is confirmed that delayed senescence in the absence of reproductive sinks is linked with slower protein oxidation, rubisco degradation and delayed activation of SAGs. Better antioxidant defense in chloroplasts at later stages of senescence was able to mitigate the deleterious effects of ROS in CMS plants. We propose that delayed increase in ROS in cytoplasmic male sterile wheat plants resulted in delayed activation of WRKY53, SAGs and the associated biochemical changes than fertile plants.

Plant Sex Chromosomes.

PubMed

Charlesworth, Deborah

2016-04-29

Although individuals in most flowering plant species, and in many haploid plants, have both sex functions, dioecious species-in which individuals have either male or female functions only-are scattered across many taxonomic groups, and many species have genetic sex determination. Among these, some have visibly heteromorphic sex chromosomes, and molecular genetic studies are starting to uncover sex-linked markers in others, showing that they too have fully sex-linked regions that are either too small or are located in chromosomes that are too small to be cytologically detectable from lack of pairing, lack of visible crossovers, or accumulation of heterochromatin. Detailed study is revealing that, like animal sex chromosomes, plant sex-linked regions show evidence for accumulation of repetitive sequences and genetic degeneration. Estimating when recombination stopped confirms the view that many plants have young sex-linked regions, making plants of great interest for studying the timescale of these changes.

The cytoskeleton and gravitropism in higher plants

NASA Technical Reports Server (NTRS)

Blancaflor, Elison B.

2002-01-01

The cellular and molecular mechanisms underlying the gravitropic response of plants have continued to elude plant biologists despite more than a century of research. Lately there has been increased attention on the role of the cytoskeleton in plant gravitropism, but several controversies and major gaps in our understanding of cytoskeletal involvement in gravitropism remain. A major question in the study of plant gravitropism is how the cytoskeleton mediates early sensing and signal transduction events in plants. Much has been made of the actin cytoskeleton as the cellular structure that sedimenting amyloplasts impinge upon to trigger the downstream signaling events leading to the bending response. There is also strong molecular and biochemical evidence that the transport of auxin, an important player in gravitropism, is regulated by actin. Organizational changes in microtubules during the growth response phase of gravitropism have also been well documented, but the significance of such reorientations in controlling differential cellular growth is unclear. Studies employing pharmacological approaches to dissect cytoskeletal involvement in gravitropism have led to conflicting results and therefore need to be interpreted with caution. Despite the current controversies, the revolutionary advances in molecular, biochemical, and cell biological techniques have opened up several possibilities for further research into this difficult area. The myriad proteins associated with the plant cytoskeleton that are being rapidly characterized provide a rich assortment of candidate regulators that could be targets of the gravity signal transduction chain. Cytoskeletal and ion imaging in real time combined with mutant analysis promises to provide a fresh start into this controversial area of research.

Plant Diversity Impacts Decomposition and Herbivory via Changes in Aboveground Arthropods

PubMed Central

Ebeling, Anne; Meyer, Sebastian T.; Abbas, Maike; Eisenhauer, Nico; Hillebrand, Helmut; Lange, Markus; Scherber, Christoph; Vogel, Anja; Weigelt, Alexandra; Weisser, Wolfgang W.

2014-01-01

Loss of plant diversity influences essential ecosystem processes as aboveground productivity, and can have cascading effects on the arthropod communities in adjacent trophic levels. However, few studies have examined how those changes in arthropod communities can have additional impacts on ecosystem processes caused by them (e.g. pollination, bioturbation, predation, decomposition, herbivory). Therefore, including arthropod effects in predictions of the impact of plant diversity loss on such ecosystem processes is an important but little studied piece of information. In a grassland biodiversity experiment, we addressed this gap by assessing aboveground decomposer and herbivore communities and linking their abundance and diversity to rates of decomposition and herbivory. Path analyses showed that increasing plant diversity led to higher abundance and diversity of decomposing arthropods through higher plant biomass. Higher species richness of decomposers, in turn, enhanced decomposition. Similarly, species-rich plant communities hosted a higher abundance and diversity of herbivores through elevated plant biomass and C:N ratio, leading to higher herbivory rates. Integrating trophic interactions into the study of biodiversity effects is required to understand the multiple pathways by which biodiversity affects ecosystem functioning. PMID:25226237

Preliminary Modelling of Mass Flux at the Surface of Plant Leaves within the MELiSSA Higher Plant Compartments

NASA Astrophysics Data System (ADS)

Holmberg, Madeleine; Paille, Christel; Lasseur, Christophe

The ESA project Micro Ecological Life Support System Alternative (MELiSSA) is an ecosystem of micro-organisms and higher plants, constructed with the objective of being operated as a tool to understand artificial ecosystems to be used for a long-term or permanent manned planetary base (e.g. Moon or Mars). The purpose of such a system is to provide for generation of food, water recycling, atmospheric regeneration and waste management within defined standards of quality and reliability. As MELiSSA consists of individual compartments which are connected to each other, the robustness of the system is fully dependent on the control of each compartment, as well as the flow management between them. Quality of consumables and reliability of the ecosystem rely on the knowledge, understanding and control of each of the components. This includes the full understanding of all processes related to the higher plants. To progress in that direction, this paper focuses on the mechanical processes driving the gas and liquid exchanges between the plant leaf and its environment. The process responsible for the mass transfer on the surface of plant leaves is diffusion. The diffusion flux is dependent on the behaviour of the stoma of the leaf and also on the leaf boundary layer (BL). In this paper, the physiology of the leaf is briefly examined in order to relate parameters such as light quality, light quantity, CO2 concentration, temperature, leaf water potential, humidity, vapour pressure deficit (VPD) gradients and pollutants to the opening or closing of stomata. The diffusion process is described theoretically and the description is compared to empirical approaches. The variables of the BL are examined and the effect airflow in the compartment has on the BL is investigated. Also presented is the impact changes in different environmental parameters may have on the fluid exchanges. Finally, some tests, to evaluate the accuracy of the concluded model, are suggested.

Spatial epigenetics: linking nuclear structure and function in higher eukaryotes.

PubMed

Jackson, Dean A

2010-09-20

Eukaryotic cells are defined by the genetic information that is stored in their DNA. To function, this genetic information must be decoded. In doing this, the information encoded in DNA is copied first into RNA, during RNA transcription. Primary RNA transcripts are generated within transcription factories, where they are also processed into mature mRNAs, which then pass to the cytoplasm. In the cytoplasm these mRNAs can finally be translated into protein in order to express the genetic information as a functional product. With only rare exceptions, the cells of an individual multicellular eukaryote contain identical genetic information. However, as different genes must be expressed in different cell types to define the structure and function of individual tissues, it is clear that mechanisms must have evolved to regulate gene expression. In higher eukaryotes, mechanisms that regulate the interaction of DNA with the sites where nuclear functions are performed provide one such layer of regulation. In this chapter, I evaluate how a detailed understanding of nuclear structure and chromatin dynamics are beginning to reveal how spatial mechanisms link chromatin structure and function. As these mechanisms operate to modulate the genetic information in DNA, the regulation of chromatin function by nuclear architecture defines the concept of 'spatial epigenetics'.

Expression of 5 S rRNA genes linked to 35 S rDNA in plants, their epigenetic modification and regulatory element divergence

PubMed Central

2012-01-01

Background In plants, the 5 S rRNA genes usually occur as separate tandems (S-type arrangement) or, less commonly, linked to 35 S rDNA units (L-type). The activity of linked genes remains unknown so far. We studied the homogeneity and expression of 5 S genes in several species from family Asteraceae known to contain linked 35 S-5 S units. Additionally, their methylation status was determined using bisulfite sequencing. Fluorescence in situ hybridization was applied to reveal the sub-nuclear positions of rDNA arrays. Results We found that homogenization of L-type units went to completion in most (4/6) but not all species. Two species contained major L-type and minor S-type units (termed Ls-type). The linked genes dominate 5 S rDNA expression while the separate tandems do not seem to be expressed. Members of tribe Anthemideae evolved functional variants of the polymerase III promoter in which a residing C-box element differs from the canonical angiosperm motif by as much as 30%. On this basis, a more relaxed consensus sequence of a plant C-box: (5’-RGSWTGGGTG-3’) is proposed. The 5 S paralogs display heavy DNA methylation similarly as to their unlinked counterparts. FISH revealed the close association of 35 S-5 S arrays with nucleolar periphery indicating that transcription of 5 S genes may occur in this territory. Conclusions We show that the unusual linked arrangement of 5 S genes, occurring in several plant species, is fully compatible with their expression and functionality. This extraordinary 5 S gene dynamics is manifested at different levels, such as variation in intrachromosomal positions, unit structure, epigenetic modification and considerable divergence of regulatory motifs. PMID:22716941

Towards aging mechanisms of cross-linked polyethylene (XLPE) cable insulation materials in nuclear power plants

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

Liu, Shuaishuai; Fifield, Leonard S.; Bowler, Nicola

Cross-linked polyethylene (XLPE) cable insulation material undergoes simultaneous, accelerated thermal and gamma-radiation aging to simulate the long-term aging environment within nuclear power plants (NPPs). A variety of materials characterization tests, including scanning electron microscopy, thermo-gravimetric analysis, differential scanning calorimetry, oxidation induction time, gel-fraction and dielectric properties measurement, are conducted on pristine and differently aged XLPE samples. A preliminary model of one possible aging mechanism of XLPE cable insulation material under gamma radiation at elevated temperature of 115 °C is suggested.

Plant-plant competition outcomes are modulated by plant effects on the soil bacterial community.

PubMed

Hortal, S; Lozano, Y M; Bastida, F; Armas, C; Moreno, J L; Garcia, C; Pugnaire, F I

2017-12-19

Competition is a key process that determines plant community structure and dynamics, often mediated by nutrients and water availability. However, the role of soil microorganisms on plant competition, and the links between above- and belowground processes, are not well understood. Here we show that the effects of interspecific plant competition on plant performance are mediated by feedbacks between plants and soil bacterial communities. Each plant species selects a singular community of soil microorganisms in its rhizosphere with a specific species composition, abundance and activity. When two plant species interact, the resulting soil bacterial community matches that of the most competitive plant species, suggesting strong competitive interactions between soil bacterial communities as well. We propose a novel mechanism by which changes in belowground bacterial communities promoted by the most competitive plant species influence plant performance and competition outcome. These findings emphasise the strong links between plant and soil communities, paving the way to a better understanding of plant community dynamics and the effects of soil bacterial communities on ecosystem functioning and services.

Penicillinase-based enzyme-linked immunosorbent assay for the detection of plant viruses.

PubMed

Sudarshana, M R; Reddy, D V

1989-10-01

A penicillinase (PNC)-based, enzyme-linked immunosorbent assay (ELISA) was standardized to detect maize mosaic virus (MMV) in sorghum leaf extracts, peanut mottle virus (PMV) in pea leaf extracts, and tomato spotted wilt virus (TSWV) in peanut leaf extracts. Rabbit Fc-specific antibodies were conjugated with PNC by a single step glutaraldehyde bridge. Among several indicators tested, bromothymol blue (BTB) was found suitable for measuring PNC activity under simulated conditions. Two reagents, starch-iodine complex (SIC) and a mixed pH indicator, containing bromocresol purple and BTB (2:1) used earlier for the PNC-based ELISA, were compared with BTB for utilization in the PNC-based ELISA. SIC gave a slightly higher virus titre than BTB or the mixed pH indicator, but it often gave nonspecific reactions. Sodium or potassium salts of penicillin-G at 0.5-1.0 mg/ml and BTB at 0.2 mg/ml were found to be suitable as substrate-indicator mixture for PNC-based ELISA. The sensitivity of the PNC system was comparable to those of the alkaline phosphatase (ALP) and horseradish peroxidase (HRP) systems in detecting MMV, PMV, and TSWV. The PNC conjugate could be used at a greater dilution than those of the ALP and HRP conjugates and the BTB substrate mixture was stable for at least 3 weeks at 4 degrees C. Penicillin is readily available in developing countries, and at a substantially lower cost than p-nitrophenyl phosphate, the commonly used substrate for ALP in the plate ELISA. Thus the PNC-based ELISA provides a less expensive means for assaying plant viruses by ELISA.

Tolerance of chufa (Cyperus esculentus L.) plants, representing the higher plant compartment in bioregenerative life support systems, to super-optimal air temperatures

NASA Astrophysics Data System (ADS)

Shklavtsova, E. S.; Ushakova, S. A.; Shikhov, V. N.; Anishchenko, O. V.

2013-01-01

Plants intended to be included in the photosynthesizing compartment of the bioregenerative life support system (BLSS) need to be studied in terms of both their production parameters under optimal conditions and their tolerance to stress factors that might be caused by emergency situations. The purpose of this study was to investigate tolerance of chufa (Cyperus esculentus L.) plants to the super-optimal air temperature of 45 ± 1 °C as dependent upon PAR (photosynthetically active radiation) intensity and the duration of the exposure to the stress factor. Chufa plants were grown hydroponically, on expanded clay, under artificial light. The nutrient solution was Knop's mineral medium. Until the plants were 30 days old, they had been grown at 690 μmol m-2 s-1 PAR and air temperature 25 °C. Thirty-day-old plants were exposed to the temperature 45 °C for 6 h, 20 h, and 44 h at PAR intensities 690 μmol m-2 s-1 and 1150 μmol m-2 s-1. The exposure to the damaging air temperature for 44 h at 690 μmol m-2 s-1 PAR caused irreversible damage to PSA, resulting in leaf mortality. In chufa plants exposed to heat shock treatment at 690 μmol m-2 s-1 PAR for 6 h and 20 h, respiration exceeded photosynthesis, and CO2 release in the light was recorded. Functional activity of photosynthetic apparatus, estimated from parameters of pulse-modulated chlorophyll fluorescence in Photosystem 2 (PS 2), decreased 40% to 50%. After the exposure to the stress factor was finished, functional activity of PSA recovered its initial values, and apparent photosynthesis (Papparent) rate after a 20-h exposure to the stress factor was 2.6 times lower than before the elevation of the temperature. During the first hours of plant exposure to the temperature 45 °C at 1150 μmol m-2 s-1 PAR, respiration rate was higher than photosynthesis rate, but after 3-4 h of the exposure, photosynthetic processes exceeded oxidative ones and CO2 absorption in the light was recorded. At the end of the 6-h exposure

Linking seed germination and plant height: a case study of a wetland community on the eastern Tibet Plateau.

PubMed

Liu, Kun; Cao, Suzhen; Du, Guozhen; Baskin, Jerry M; Baskin, Carol C; Bu, Haiyan; Qi, Wei; Liang, Ting

2018-05-20

Seed germination is the earliest trait expressed in a plant's life history, and it can directly affect the expression of post germination traits. Plant height is central to plant ecological strategies, because it is a major determinant of the ability of a species to compete for light. Thus, linking seed germination and plant height at the community level is very important to understanding plant fitness and community structure. Here, we tested storage condition and temperature requirements for germination of 31 species from a wetland plant community on the eastern Tibet Plateau, and analyzed correlation of germination traits with plant height in relation to storage condition. Germination percentage was positively related to plant height, and this relationship disappeared when seeds were incubated at a low temperature (i.e. 5°C) or after they were stored under wet-cold conditions. The response of seeds to dry+wet-cold storage was negatively related to plant height. Based on the scores of each species on the first two principal components derived from PCA, species were classified into two categories by Hierarchical Clustering, and there was a significant difference between germination and plant height of species in these two categories. These results suggest that the requirements for seed germination together with seasonal change in environmental conditions determine the window for germination and in turn plant growth season and resource utilization and ultimately plant height. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Plant species richness sustains higher trophic levels of soil nematode communities after consecutive environmental perturbations.

PubMed

Cesarz, Simone; Ciobanu, Marcel; Wright, Alexandra J; Ebeling, Anne; Vogel, Anja; Weisser, Wolfgang W; Eisenhauer, Nico

2017-07-01

The magnitude and frequency of extreme weather events are predicted to increase in the future due to ongoing climate change. In particular, floods and droughts resulting from climate change are thought to alter the ecosystem functions and stability. However, knowledge of the effects of these weather events on soil fauna is scarce, although they are key towards functioning of terrestrial ecosystems. Plant species richness has been shown to affect the stability of ecosystem functions and food webs. Here, we used the occurrence of a natural flood in a biodiversity grassland experiment that was followed by a simulated summer drought experiment, to investigate the interactive effects of plant species richness, a natural flood, and a subsequent summer drought on nematode communities. Three and five months after the natural flooding, effects of flooding severity were still detectable in the belowground system. We found that flooding severity decreased soil nematode food-web structure (loss of K-strategists) and the abundance of plant feeding nematodes. However, high plant species richness maintained higher diversity and abundance of higher trophic levels compared to monocultures throughout the flood. The subsequent summer drought seemed to be of lower importance but reversed negative flooding effects in some cases. This probably occurred because the studied grassland system is well adapted to drought, or because drought conditions alleviated the negative impact of long-term soil waterlogging. Using soil nematodes as indicator taxa, this study suggests that high plant species richness can maintain soil food web complexity after consecutive environmental perturbations.

Interactions of metal-based engineered nanoparticles with aquatic higher plants: A review of the state of current knowledge.

PubMed

Thwala, Melusi; Klaine, Stephen J; Musee, Ndeke

2016-07-01

The rising potential for the release of engineered nanoparticles (ENPs) into aquatic environments requires evaluation of risks to protect ecological health. The present review examines knowledge pertaining to the interactions of metal-based ENPs with aquatic higher plants, identifies information gaps, and raises considerations for future research to advance knowledge on the subject. The discussion focuses on ENPs' bioaccessibility; uptake, adsorption, translocation, and bioaccumulation; and toxicity effects on aquatic higher plants. An information deficit surrounds the uptake of ENPs and associated dynamics, because the influence of ENP characteristics and water quality conditions has not been well documented. Dissolution appears to be a key mechanism driving bioaccumulation of ENPs, whereas nanoparticulates often adsorb to plant surfaces with minimal internalization. However, few reports document the internalization of ENPs by plants; thus, the role of nanoparticulates' internalization in bioaccumulation and toxicity remains unclear, requiring further investigation. The toxicities of metal-based ENPs mainly have been associated with dissolution as a predominant mechanism, although nano toxicity has also been reported. To advance knowledge in this domain, future investigations need to integrate the influence of ENP characteristics and water physicochemical parameters, as their interplay determines ENP bioaccessibility and influences their risk to health of aquatic higher plants. Furthermore, harmonization of test protocols is recommended for fast tracking the generation of comparable data. Environ Toxicol Chem 2016;35:1677-1694. © 2016 SETAC. © 2016 SETAC.

Nectar secretion dynamic links pollinator behavior to consequences for plant reproductive success in the ornithophilous mistletoe Psittacanthus robustus.

PubMed

Guerra, T J; Galetto, L; Silva, W R

2014-09-01

The mistletoe Psittacanthus robustus was studied as a model to link flower phenology and nectar secretion strategy to pollinator behaviour and the reproductive consequences for the plant. The bright-coloured flowers presented diurnal anthesis, opened asynchronously throughout the rainy season and produced copious dilute nectar as the main reward for pollinators. Most nectar was secreted just after flower opening, with little sugar replenishment after experimental removals. During the second day of anthesis in bagged flowers, the flowers quickly reabsorbed the offered nectar. Low values of nectar standing crop recorded in open flowers can be linked with high visitation rates by bird pollinators. Eight hummingbirds and two passerines were observed as potential pollinators. The most frequent flower visitors were the hummingbirds Eupetomena macroura and Colibri serrirostris, which actively defended flowering mistletoes. The spatial separation between anthers, stigma and nectar chamber promotes pollen deposition on flapping wings of hovering hummingbirds that usually probe many flowers per visit. Seed set did not differ between hand-, self- and cross-pollinated flowers, but these treatments set significantly more seeds than flowers naturally exposed to flower visitors. We suggest that the limitation observed in the reproductive success of this plant is not related to pollinator scarcity, but probably to the extreme frequency of visitation by territorial hummingbirds. We conclude that the costs and benefits of plant reproduction depend on the interaction strength between flowers and pollinators, and the assessment of nectar secretion dynamics, pollinator behaviour and plant breeding system allows clarification of the complexity of such associations. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Production characteristics of the "higher plants-soil-like substrate" system as an element of the bioregenerative life support system

NASA Astrophysics Data System (ADS)

Velichko, V. V.; Tikhomirov, A. A.; Ushakova, S. A.; Tikhomirova, N. A.; Shihov, V. N.; Tirranen, L. S.; Gribovskaya, I. A.

2013-01-01

The study addresses the possibility of long-duration operation of a higher plant conveyor, using a soil-like substrate (SLS) as the root zone. Chufa (Cyperus esculentus L.), radish (Raphanus sativus L.), and lettuce (Lactuca sativa L.) were used as study material. A chufa community consisting of 4 age groups and radish and lettuce communities consisting of 2 age groups were irrigated with a nutrient solution, which contained mineral elements extracted from the SLS. After each harvest, inedible biomass of the harvested plants and inedible biomasses of wheat and saltwort were added to the SLS. The amounts of the inedible biomasses of wheat and saltwort to be added to the SLS were determined based on the nitrogen content of the edible mass of harvested plants. CO2 concentration in the growth chamber was maintained within the range of 1100-1700 ppm. The results of the study show that higher plants can be grown quite successfully using the proposed process of plant waste utilization in the SLS. The addition of chufa inedible biomass to the SLS resulted in species-specific inhibition of growth of both cultivated crops and microorganisms in the "higher plants - SLS" system. There were certain differences between the amounts of some mineral elements removed from the SLS with the harvested edible biomass and those added to it with the inedible biomasses of wheat and saltwort.

Understanding water deficit stress-induced changes in the basic metabolism of higher plants - biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe.

PubMed

Shao, Hong-Bo; Chu, Li-Ye; Jaleel, C Abdul; Manivannan, P; Panneerselvam, R; Shao, Ming-An

2009-01-01

Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil-water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil-plant water relationships and soil-water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of

Need for higher fuel burnup at the Hatch Plant

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

Beckhman, J.T.

1996-03-01

Hatch is a BWR 4 and has been in operation for some time. The first unit became commercial about 1975. Obtaining higher burnups, or higher average discharge exposures, is nothing new at Hatch. Since we have started, the discharge exposure of the plant has increased. Now, of course, we are not approaching the numbers currently being discussed but, the average discharge exposure has increased from around 20,000 MWD/MTU in the early to mid-1980s to 34,000 MWD/MTU in 1994, I am talking about batch average values. There are also peak bundle and peak rod values. You will have to make themore » conversions if you think in one way or the other because I am talking in batch averages. During Hatch`s operating history we have had some problems with fuel failure. Higher burnup fuel raises a concern about how much fuel failure you are going to have. Fuel failure is, of course, an economic issue with us. Back in the early 1980s, we had a problem with crud-induced localized corrosion, known as CILC. We have gotten over that, but we had some times when it was up around 27 fuel failures a year. That is not a pleasant time to live through because it is not what you want from an economic viewpoint or any other. We have gotten that down. We have had some fuel failures recently, but they have not been related to fuel burnup or to corrosion. In fact, the number of failures has decreased from the early 1980s to the 90s even though burnup increased during that time. The fuel failures are more debris-related-type failures. In addition to increasing burnups, utilities are actively evaluating or have already incorporated power uprate and longer fuel cycles (e.g., 2-year cycles). The goal is to balance out the higher power density, longer cycles, higher burnup, and to have no leakers. Why do we as an industry want to have higher burnup fuel? That is what I want to tell you a little bit about.« less

Regulation of phosphate starvation responses in higher plants.

PubMed

Yang, Xiao Juan; Finnegan, Patrick M

2010-04-01

Phosphorus (P) is often a limiting mineral nutrient for plant growth. Many soils worldwide are deficient in soluble inorganic phosphate (P(i)), the form of P most readily absorbed and utilized by plants. A network of elaborate developmental and biochemical adaptations has evolved in plants to enhance P(i) acquisition and avoid starvation. Controlling the deployment of adaptations used by plants to avoid P(i) starvation requires a sophisticated sensing and regulatory system that can integrate external and internal information regarding P(i) availability. In this review, the current knowledge of the regulatory mechanisms that control P(i) starvation responses and the local and long-distance signals that may trigger P(i) starvation responses are discussed. Uncharacterized mutants that have P(i)-related phenotypes and their potential to give us additional insights into regulatory pathways and P(i) starvation-induced signalling are also highlighted and assessed. An impressive list of factors that regulate P(i) starvation responses is now available, as is a good deal of knowledge regarding the local and long-distance signals that allow a plant to sense and respond to P(i) availability. However, we are only beginning to understand how these factors and signals are integrated with one another in a regulatory web able to control the range of responses demonstrated by plants grown in low P(i) environments. Much more knowledge is needed in this agronomically important area before real gains can be made in improving P(i) acquisition in crop plants.

Linking plant hydraulics and beta diversity in tropical forests

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

Christoffersen, Bradley; Meir, Patrick; McDowell, Nate G.

In tropical forests, studies of xylem traits governing water transport through plants, or ‘hydraulic architecture’ (Tyree et al., 1991), and changes in species composition across environmental gradients, or ‘beta diversity’ (Gentry, 1988; Ackerly & Cornwell, 2007), have progressedmostly in parallel until recently (Hao et al., 2008; Bartlett et al., 2016). In this issue of New Phytologist, Cosme et al. (pp. 000–5 000) present a timely contribution to the intersection of plant hydraulic architecture (HA) with trait-based community ecology. Building on previous biogeographical work that demonstrated shifts in species composition (beta diversity) across a gradient from valleys to plateaus in centralmore » Amazonia (Schietti et al., 2014), Cosme et al. explore how variation in HA might underpin this sorting, sampling pairs of congeneric species restrictedmostly to either plateau or valley habitats. Valley species had significantly lower wood density and higher hydraulically-weighted vessel diameter and vessel area. By contrast, trees with some of the largest hydraulically-weighted vessel diameters existed in tall, deciduous plateau species, while the leaf: sapwood area ratio decreased with height in valley but not plateau species. These intriguing results suggest that species differentiation in water transport traits mediate edaphic filtering along the valley-toplateau gradient, in contrast to previous work where wood mechanical support mediated valley-to-plateau environmental filtering (Fortunel et al., 2014).« less

Global pattern of plant utilization across different organisms: Does plant apparency or plant phylogeny matter?

PubMed

Dai, Xiaohua; Zhang, Wei; Xu, Jiasheng; Duffy, Kevin J; Guo, Qingyun

2017-04-01

The present study is the first to consider human and nonhuman consumers together to reveal several general patterns of plant utilization. We provide evidence that at a global scale, plant apparency and phylogenetic isolation can be important predictors of plant utilization and consumer diversity. Using the number of species or genera or the distribution area of each plant family as the island "area" and the minimum phylogenetic distance to common plant families as the island "distance", we fitted presence-area relationships and presence-distance relationships with a binomial GLM (generalized linear model) with a logit link. The presence-absence of consumers among each plant family strongly depended on plant apparency (family size and distribution area); the diversity of consumers increased with plant apparency but decreased with phylogenetic isolation. When consumers extended their host breadth, unapparent plants became more likely to be used. Common uses occurred more often on common plants and their relatives, showing higher host phylogenetic clustering than uncommon uses. On the contrary, highly specialized uses might be related to the rarity of plant chemicals and were therefore very species-specific. In summary, our results provide a global illustration of plant-consumer combinations and reveal several general patterns of plant utilization across humans, insects and microbes. First, plant apparency and plant phylogenetic isolation generally govern plant utilization value, with uncommon and isolated plants suffering fewer parasites. Second, extension of the breadth of utilized hosts helps explain the presence of consumers on unapparent plants. Finally, the phylogenetic clustering structure of host plants is different between common uses and uncommon uses. The strength of such consistent plant utilization patterns across a diverse set of usage types suggests that the persistence and accumulation of consumer diversity and use value for plant species are

Conserved noncoding sequences (CNSs) in higher plants.

PubMed

Freeling, Michael; Subramaniam, Shabarinath

2009-04-01

Plant conserved noncoding sequences (CNSs)--a specific category of phylogenetic footprint--have been shown experimentally to function. No plant CNS is conserved to the extent that ultraconserved noncoding sequences are conserved in vertebrates. Plant CNSs are enriched in known transcription factor or other cis-acting binding sites, and are usually clustered around genes. Genes that encode transcription factors and/or those that respond to stimuli are particularly CNS-rich. Only rarely could this function involve small RNA binding. Some transcribed CNSs encode short translation products as a form of negative control. Approximately 4% of Arabidopsis gene content is estimated to be both CNS-rich and occupies a relatively long stretch of chromosome: Bigfoot genes (long phylogenetic footprints). We discuss a 'DNA-templated protein assembly' idea that might help explain Bigfoot gene CNSs.

A greater foraging scale, not a higher foraging precision, may facilitate invasion by exotic plants in nutrient-heterogeneous conditions.

PubMed

Chen, Bao-Ming; Su, Jin-Quan; Liao, Hui-Xuan; Peng, Shao-Lin

2018-03-05

Soil nutrient heterogeneity has been proposed to influence competitive outcomes among different plant species. Thus, it is crucial to understand the effects of environmental heterogeneity on competition between exotic invasive and native species. However, the effects of soil nutrient heterogeneity on the competition between invasive and native plants have rarely been linked to root foraging behaviour. In this study, a competition experiment was performed with two invasive-native species pairs (BP-VC, Bidens pilosa vs. Vernonia cinerea; MM-PS, Mikania micrantha vs. Paederia scandens) grown under homogeneous and heterogeneous conditions in a common greenhouse environment. Root activity was assessed by determining the amount of strontium (Sr) taken up by the shoot of each species. The invasive species exhibited a greater foraging scale, whereas the native species exhibited a higher foraging precision. A trade-off between foraging scale and precision was observed within each pair of invasive-native species. Compared with soil homogeneity, soil heterogeneity significantly increased the biomass of the two invasive species, B. pilosa and M. micrantha, under competitive conditions. Within each pair, the invasive species exhibited greater relative competitive ability with respect to shoot mass, and considerably more Sr taken up by the invasive species compared with the native species. The Sr acquisition results indicate that nutrient-poor conditions may facilitate the competitive ability of the native species V. cinerea, whereas M. micrantha may possess a stronger competitive ability regardless of soil nutrient conditions. Soil nutrient heterogeneity has the potential to promote the invasion of these two exotic species due to their larger foraging scale, stronger competitive ability and greater root activity relative to their counterpart native species. The present work highlights the importance of soil heterogeneity in plant invasion, particularly with regards to root

Linking the Weather Generator with Regional Climate Model: Effect of Higher Resolution

NASA Astrophysics Data System (ADS)

Dubrovsky, Martin; Huth, Radan; Farda, Ales; Skalak, Petr

2014-05-01

This contribution builds on our last year EGU contribution, which followed two aims: (i) validation of the simulations of the present climate made by the ALADIN-Climate Regional Climate Model (RCM) at 25 km resolution, and (ii) presenting a methodology for linking the parametric weather generator (WG) with RCM output (aiming to calibrate a gridded WG capable of producing realistic synthetic multivariate weather series for weather-ungauged locations). Now we have available new higher-resolution (6.25 km) simulations with the same RCM. The main topic of this contribution is an anser to a following question: What is an effect of using a higher spatial resolution on a quality of simulating the surface weather characteristics? In the first part, the high resolution RCM simulation of the present climate will be validated in terms of selected WG parameters, which are derived from the RCM-simulated surface weather series and compared to those derived from weather series observed in 125 Czech meteorological stations. The set of WG parameters will include statistics of the surface temperature and precipitation series. When comparing the WG parameters from the two sources (RCM vs observations), we interpolate the RCM-based parameters into the station locations while accounting for the effect of altitude. In the second part, we will discuss an effect of using the higher resolution: the results of the validation tests will be compared with those obtained with the lower-resolution RCM. Acknowledgements: The present experiment is made within the frame of projects ALARO-Climate (project P209/11/2405 sponsored by the Czech Science Foundation), WG4VALUE (project LD12029 sponsored by the Ministry of Education, Youth and Sports of CR) and VALUE (COST ES 1102 action).

Cross-linked collagen sponges loaded with plant polyphenols with inhibitory activity towards chronic wound enzymes.

PubMed

Antonio, Francesko; Guillem, Rocasalbas; Sonia, Touriño; Clara, Mattu; Piergiorgio, Gentile; Valeria, Chiono; Gianluca, Ciardelli; Tzanov, Tzanko

2011-10-01

Collagen sponges loaded with polyphenols from Hamamelis virginiana were investigated as active materials for chronic wound dressings, evaluating in vitro the inhibition of two major enzymes that impair the wound healing process - myeloperoxidase (MPO) and collagenase. Prior to polyphenols loading, collagen was cross-linked with genipin to improve its biostability. The effect of genipin cross-linking and polyphenol concentration in the development of mechanically and enzymatically stable sponges was studied. The tensile strength of the cross-linked collagen increased with the increase of the cross-linking degree, coupled to decrease in the elongation and the swelling capacity of the sponges. The stability of the sponges to collagenase digestion reached maximum when 1 mM genipin was used. However, the biostability decreased more than 10-fold after loading the sponges with polyphenols (0.5 mg/mL), nevertheless, this effect was partially overcome using higher concentration of polyphenols (1 and 2 mg/mL) to inhibit collagenase. Moreover, the polyphenols released from the sponges were sufficient for complete inhibition of MPO activity. No considerable cytotoxicity of the genipin cross-linked collagen loaded with polyphenols was observed evaluating the NIH 3T3 fibroblasts viability. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Higher plants as bioindicators of sulphur dioxide emissions in urban environments.

PubMed

Hijano, Concepción Fidalgo; Domínguez, Maria Dolores Petit; Gimínez, Rosario García; Sínchez, Pilar Hungría; García, Inís Sancho

2005-12-01

The evaluation of certain vascular plants that grow in the city of Madrid as biomonitors of SO(2) air pollution in urban environments has been carried out. Total concentration of sulphur in leaves of the chosen higher plants as well as other parameters in close relation to this contaminant (visible injury symptoms, chlorophyll a- and b-content and peroxidase activity) have been determined in order to study the spatial distribution and temporal changes in SO(2) deposition. Results obtained show that coniferous species such as Pinus pinea, were more sensitive to SO(2) atmospheric concentration than leafy species as Quercux ilex subspecies ballota and, in the same way, bush species, such as Pyracantha coccinea and Nerium oleander, were more sensitive than wooded species, such as Cedrus deodara and Pinus pinea, respectively. There is a higher accumulation of sulphur in vegetable species located near highways and dense traffic incidence roads and near areas with high density of population. The minimum values for accumulation of SO(2) were registered in winter and spring seasons (from January to April) due to the vegetative stop; while maximum values are obtained during the summer season (from June to September), due to the stoma opening. The highest increments in sulphur concentration, calculated as the difference between two consecutive months, are obtained in May and June for all considered species except for Cedrus deodara and Pyracantha coccinea, both species have few seasonal changes during the whole year. Some species are more sensitive to natural washing than others, showing a decrease in sulphur concentration after rainfall periods.

Composition of fungal soil communities varies with plant abundance and geographic origin

PubMed Central

Reininger, Vanessa; Martinez-Garcia, Laura B.; Sanderson, Laura; Antunes, Pedro M.

2015-01-01

Interactions of belowground fungal communities with exotic and native plant species may be important drivers of plant community structure in invaded grasslands. However, field surveys linking plant community structure with belowground fungal communities are missing. We investigated whether a selected number of abundant and relatively rare plants, either native or exotic, from an old-field site associate with different fungal communities. We also assessed whether these plants showed different symbiotic relationships with soil biota through their roots. We characterized the plant community and collected roots to investigate fungal communities using 454 pyrosequencing and assessed arbuscular mycorrhizal colonization and enemy-induced lesions. Differences in fungal communities were considered based on the assessment of α- and β diversity depending on plant ‘abundance’ and ‘origin’. Plant abundance and origin determined the fungal community. Fungal richness was higher for native abundant as opposed to relatively rare native plant species. However, this was not observed for exotics of contrasting abundance. Regardless of their origin, β diversity was higher for rare than for abundant species. Abundant exotics in the community, which happen to be grasses, were the least mycorrhizal whereas rare natives were most susceptible to enemy attack. Our results suggest that compared with exotics, the relative abundance of remnant native plant species in our old-field site is still linked to the structure of belowground fungal communities. In contrast, exotic species may act as a disturbing agent contributing towards the homogenization of soil fungal communities, potentially changing feedback interactions. PMID:26371291

Characterization of Zea mays endosperm C-24 sterol methyltransferase: one of two types of sterol methyltransferase in higher plants.

PubMed

Grebenok, R J; Galbraith, D W; Penna, D D

1997-08-01

We report the characterization of a higher-plant C-24 sterol methyltransferase by yeast complementation. A Zea mays endosperm expressed sequence tag (EST) was identified which, upon complete sequencing, showed 46% identity to the yeast C-24 methyltransferase gene (ERG6) and 75% and 37% amino acid identity to recently isolated higher-plant sterol methyltransferases from soybean and Arabidopsis, respectively. When placed under GALA regulation, the Z. mays cDNA functionally complemented the erg6 mutation, restoring ergosterol production and conferring resistance to cycloheximide. Complementation was both plasmid-dependent and galactose-inducible. The Z. mays cDNA clone contains an open reading frame encoding a 40 kDa protein containing motifs common to a large number of S-adenosyl-L-methionine methyltransferases (SMTs). Sequence comparisons and functional studies of the maize, soybean and Arabidopsis cDNAs indicates two types of C-24 SMTs exist in higher plants.

New insights into ferritin synthesis and function highlight a link between iron homeostasis and oxidative stress in plants.

PubMed

Briat, Jean-Francois; Ravet, Karl; Arnaud, Nicolas; Duc, Céline; Boucherez, Jossia; Touraine, Brigitte; Cellier, Francoise; Gaymard, Frederic

2010-05-01

Iron is an essential element for both plant productivity and nutritional quality. Improving plant iron content was attempted through genetic engineering of plants overexpressing ferritins. However, both the roles of these proteins in plant physiology, and the mechanisms involved in the regulation of their expression are largely unknown. Although the structure of ferritins is highly conserved between plants and animals, their cellular localization differs. Furthermore, regulation of ferritin gene expression in response to iron excess occurs at the transcriptional level in plants, in contrast to animals which regulate ferritin expression at the translational level. In this review, an overview of our knowledge of bacterial and mammalian ferritin synthesis and functions is presented. Then the following will be reviewed: (a) the specific features of plant ferritins; (b) the regulation of their synthesis during development and in response to various environmental cues; and (c) their function in plant physiology, with special emphasis on the role that both bacterial and plant ferritins play during plant-bacteria interactions. Arabidopsis ferritins are encoded by a small nuclear gene family of four members which are differentially expressed. Recent results obtained by using this model plant enabled progress to be made in our understanding of the regulation of the synthesis and the in planta function of these various ferritins. Studies on plant ferritin functions and regulation of their synthesis revealed strong links between these proteins and protection against oxidative stress. In contrast, their putative iron-storage function to furnish iron during various development processes is unlikely to be essential. Ferritins, by buffering iron, exert a fine tuning of the quantity of metal required for metabolic purposes, and help plants to cope with adverse situations, the deleterious effects of which would be amplified if no system had evolved to take care of free reactive iron.

The use of controlled microbial cenoses in producers' link to increase steady functioning of artificial ecosystems

NASA Astrophysics Data System (ADS)

Somova, Lydia; Mikheeva, Galina; Somova, Lydia

The life support systems (LSS) for long-term missions are to use cycling-recycling systems, including biological recycling. Simple ecosystems include 3 links: producers (plants), consumers (man, animals) and reducers (microorganisms). Microorganisms are substantial component of every link of LSS. Higher plants are the traditional regenerator of air and producer of food. They should be used in many successive generations of their reproduction in LSS. Controlled microbiocenoses can increase productivity of producer's link and protect plants from infections. The goal of this work was development of methodological bases of formation of stable, controlled microbiocenoses, intended for increase of productivity of plants and for obtaining ecologically pure production of plants. Main results of our investigations: 1. Experimental microbiocenoses, has been produced in view of the developed methodology on the basis of natural association of microorganisms by long cultivation on specially developed medium. Dominating groups are bacteria of genera: Lactobacillus, Streptococcus, Leuconostoc, Bifidobacterium, Rhodopseudomonas and yeast of genera: Kluyveromyces, Saccharomyces, Torulopsis. 2. Optimal parameters of microbiocenosis cultivation (t, pH, light exposure, biogenic elements concentrations) were experimentally established. Conditions of cultivation on which domination of different groups of microbiocenosis have been found. 3. It was shown, that processing of seeds of wheat, oats, bulbs and plants Allium cepa L. (an onions) with microbial association raised energy of germination of seeds and bulbs and promoted the increase (on 20-30 %) of growth green biomass and root system of plants in comparison with the control. This work is supported by grant, Yenissey , 07-04-96806

Gravitropism in Higher Plant Shoots 1

PubMed Central

Sliwinski, Julianne E.; Salisbury, Frank B.

1984-01-01

Cross and longitudinal sections were prepared for light microscopy from vertical control plants (Xanthium strumarium L. Chicago strain), free-bending horizontal stems, plants restrained 48 hours in a horizontal position, and plants restrained 48 hours and then released, bending immediately about 130°. Top cells of free-bending stems shrink or elongate little; bottom cells continue to elongate. In restrained stems, bottom cells elongate some and increase in diameter; top cells elongate about as much but decrease in diameter. Upon release, bottom cells elongate more and decrease in diameter, while top cells shorten and increase in diameter, accounting for the bend. During restraint, bottom cells take up water while tissue pressures increase; top cells fail to take up water although tissue pressures are decreasing. Settling of amyloplasts was observed in cells of the starch sheath. Removal of different amounts of stem (Xanthium; Lycopersicon esculentum Miller, cv Bonny Best; Ricinus communis L. cv Yolo Wonder) showed that perception of gravity occurs in the bending (elongation) zone, although bending of fourth and fifth internodes from the top was less than in uncut controls. Uniform application of 1% indoleacetic acid in lanolin to cut stem surfaces partially restored bending. Reversing the gradient in tension/compression in horizontal stems (top under compression, bottom under tension) did not affect gravitropic bending. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:16663939

[Neurological syndromes linked with the intake of plants and fungi containing a toxic component (I). Neurotoxic syndromes caused by the ingestion of plants, seeds and fruits].

PubMed

Carod-Artal, F J

A wide range of plants, seeds and fruits used for nutritional and medicinal purposes can give rise to neurotoxic symptoms. We review the neurological pathology associated with the acute or chronic consumption of plants, seeds and fruits in human beings and in animals. Of the plants that can trigger acute neurotoxic syndromes in humans, some of the most notable include Mandragora officinalis, Datura stramonium, Conium maculatum (hemlock), Coriaria myrtifolia (redoul), Ricinus communis, Gloriosa superba, Catharanthus roseus, Karwinskia humboldtiana and Podophyllum pelatum. We also survey different neurological syndromes linked with the ingestion of vegetable foodstuffs that are rich in cyanogenic glycosides, Jamaican vomiting sickness caused by Blighia sapida, Parkinson dementia ALS of Guam island and exposition to Cycas circinalis, Guadeloupean parkinsonism and exposition to Annonaceae, konzo caused by ingestion of wild manioc and neurolathyrism from ingestion of Lathyrus sativus, the last two being models of motor neurone disease. Locoism is a chronic disease that develops in livestock feeding on plants belonging to Astragalus and Oxytropis sp., Sida carpinifolia and Ipomea carnea, which are rich in swainsonine, a toxin that inhibits the enzyme alpha mannosidase and induces a cerebellar syndrome. The ingestion of neurotoxic seeds, fruits and plants included in the diet and acute poisoning by certain plants can give rise to different neurological syndromes, some of which are irreversible.

Comparative Genomic Analysis Indicates that Niche Adaptation of Terrestrial Flavobacteria Is Strongly Linked to Plant Glycan Metabolism

PubMed Central

Kolton, Max; Sela, Noa; Elad, Yigal; Cytryn, Eddie

2013-01-01

Flavobacteria are important members of aquatic and terrestrial bacterial communities, displaying extreme variations in lifestyle, geographical distribution and genome size. They are ubiquitous in soil, but are often strongly enriched in the rhizosphere and phyllosphere of plants. In this study, we compared the genome of a root-associated Flavobacterium that we recently isolated, physiologically characterized and sequenced, to 14 additional Flavobacterium genomes, in order to pinpoint characteristics associated with its high abundance in the rhizosphere. Interestingly, flavobacterial genomes vary in size by approximately two-fold, with terrestrial isolates having predominantly larger genomes than those from aquatic environments. Comparative functional gene analysis revealed that terrestrial and aquatic Flavobacteria generally segregated into two distinct clades. Members of the aquatic clade had a higher ratio of peptide and protein utilization genes, whereas members of the terrestrial clade were characterized by a significantly higher abundance and diversity of genes involved in metabolism of carbohydrates such as xylose, arabinose and pectin. Interestingly, genes encoding glycoside hydrolase (GH) families GH78 and GH106, responsible for rhamnogalacturonan utilization (exclusively associated with terrestrial plant hemicelluloses), were only present in terrestrial clade genomes, suggesting adaptation of the terrestrial strains to plant-related carbohydrate metabolism. The Peptidase/GH ratio of aquatic clade Flavobacteria was significantly higher than that of terrestrial strains (1.7±0.7 and 9.7±4.7, respectively), supporting the concept that this relation can be used to infer Flavobacterium lifestyles. Collectively, our research suggests that terrestrial Flavobacteria are highly adapted to plant carbohydrate metabolism, which appears to be a key to their profusion in plant environments. PMID:24086761

Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines

PubMed Central

Zhang, Yong-Jiang; Sack, Lawren; Cao, Kun-Fang; Wei, Xue-Mei; Li, Nan

2017-01-01

We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate. PMID:28186201

Higher accumulation of F1-V fusion recombinant protein in plants after induction of protein body formation.

PubMed

Alvarez, M Lucrecia; Topal, Emel; Martin, Federico; Cardineau, Guy A

2010-01-01

Improving foreign protein accumulation is crucial for enhancing the commercial success of plant-based production systems since product yields have a major influence on process economics. Cereal grain evolved to store large amounts of proteins in tightly organized aggregates. In maize, gamma-Zein is the major storage protein synthesized by the rough endoplasmic reticulum (ER) and stored in specialized organelles called protein bodies (PB). Zera (gamma-Zein ER-accumulating domain) is the N-terminal proline-rich domain of gamma-zein that is sufficient to induce the assembly of PB formation. Fusion of the Zera domain to proteins of interest results in assembly of dense PB-like, ER-derived organelles, containing high concentration of recombinant protein. Our main goal was to increase recombinant protein accumulation in plants in order to enhance the efficiency of orally-delivered plant-made vaccines. It is well known that oral vaccination requires substantially higher doses than parental formulations. As a part of a project to develop a plant-made plague vaccine, we expressed our model antigen, the Yersinia pestis F1-V antigen fusion protein, with and without a fused Zera domain. We demonstrated that Zera-F1-V protein accumulation was at least 3x higher than F1-V alone when expressed in three different host plant systems: Ncotiana benthamiana, Medicago sativa (alfalfa) and Nicotiana tabacum NT1 cells. We confirmed the feasibility of using Zera technology to induce protein body formation in non-seed tissues. Zera expression and accumulation did not affect plant development and growth. These results confirmed the potential exploitation of Zera technology to substantially increase the accumulation of value-added proteins in plants.

Function of Oxidative Cross-Linking of Cell Wall Structural Proteins in Plant Disease Resistance.

PubMed

Brisson, L. F.; Tenhaken, R.; Lamb, C.

1994-12-01

Elicitation of soybean cells causes a rapid insolubilization of two cell wall structural proteins, p33 and p100. Likewise, a short elicitation of 30 min rendered cell walls more refractory to enzyme digestion as assayed by the yield of protoplasts released. This effect could be ascribed to protein cross-linking because of its insensitivity to inhibitors of transcription (actinomycin D) and translation (cycloheximide) and its induction by exogenous H2O2. Moreover, the induced loss of protoplasts could be prevented by preincubation with DTT, which also blocks peroxidase-mediated oxidative cross-linking. The operation of protein insolubilization in plant defense was also demonstrated by its occurrence in the incompatible interaction but not in the compatible interaction between soybean and Pseudomonas syringae pv glycinea. Likewise, protein insolubilization was observed in bean during non-host hypersensitive resistance to the tobacco pathogen P. s. pv tabaci mediated by the hypersensitive resistance and pathogenicity (Hrp) gene cluster. Our data strongly suggest that rapid protein insolubilization leads to a strengthened cell wall, and this mechanism functions as a rapid defense in the initial stages of the hypersensitive response prior to deployment of transcription-dependent defenses.

Candidacy of a chitin-inducible gibberellin-responsive gene for a major locus affecting plant height in rice that is closely linked to Green Revolution gene sd1.

PubMed

Kovi, Mallikarjuna Rao; Zhang, Yushan; Yu, Sibin; Yang, Gaiyu; Yan, Wenhao; Xing, Yongzhong

2011-09-01

Appropriate plant height is crucial for lodging resistance to improve the rice crop yield. The application of semi-dwarf 1 led to the green revolution in the 1960s, by predominantly increasing the rice yield. However, the frequent use of single sd1 gene sources may cause genetic vulnerability to pests and diseases. Identifying useful novel semi-dwarf genes is important for the genetic manipulation of plant architecture in practical rice breeding. In this study, introgression lines derived from two parents contrasting in plant height, Zhenshan 97 and Pokkali were employed to locate a gene with a large effect on plant height by the bulk segregant analysis method. A major gene, ph1, was mapped to a region closely linked to sd1 on chromosome 1; the additive effects of ph1 were more than 50 cm on the plant height and 2 days on the heading date in a BC(4)F(2) population and its progeny. ph1 was then fine mapped to BAC AP003227. Gene annotation indicated that LOC_OS01g65990 encoding a chitin-inducible gibberellin-responsive protein (CIGR), which belongs to the GRAS family, might be the right candidate gene of ph1. Co-segregation analysis of the candidate gene-derived marker finally confirmed its identity as the candidate gene. A higher expression level of the CIGR was detected in all the tested tissues in tall plants compared to those of short plants, especially in the young leaf sheath containing elongating tissues, which indicated its importance role in regulating plant height. ph1 showed a tremendous genetic effect on plant height, which is distinct from sd1 and could be a new resource for breeding semi-dwarf varieties.

Sequence diversity patterns suggesting balancing selection in partially sex-linked genes of the plant Silene latifolia are not generated by demographic history or gene flow.

PubMed

Guirao-Rico, Sara; Sánchez-Gracia, Alejandro; Charlesworth, Deborah

2017-03-01

DNA sequence diversity in genes in the partially sex-linked pseudoautosomal region (PAR) of the sex chromosomes of the plant Silene latifolia is higher than expected from within-species diversity of other genes. This could be the footprint of sexually antagonistic (SA) alleles that are maintained by balancing selection in a PAR gene (or genes) and affect polymorphism in linked genome regions. SA selection is predicted to occur during sex chromosome evolution, but it is important to test whether the unexpectedly high sequence polymorphism could be explained without it, purely by the combined effects of partial linkage with the sex-determining region and the population's demographic history, including possible introgression from Silene dioica. To test this, we applied approximate Bayesian computation-based model choice to autosomal sequence diversity data, to find the most plausible scenario for the recent history of S. latifolia and then to estimate the posterior density of the most relevant parameters. We then used these densities to simulate variation to be expected at PAR genes. We conclude that an excess of variants at high frequencies at PAR genes should arise in S. latifolia populations only for genes with strong associations with fully sex-linked genes, which requires closer linkage with the fully sex-linked region than that estimated for the PAR genes where apparent deviations from neutrality were observed. These results support the need to invoke selection to explain the S. latifolia PAR gene diversity, and encourage further work to test the possibility of balancing selection due to sexual antagonism. © 2016 John Wiley & Sons Ltd.

Penetration and Toxicity of Nanomaterials in Higher Plants

PubMed Central

Chichiriccò, Giuseppe; Poma, Anna

2015-01-01

Nanomaterials (NMs) comprise either inorganic particles consisting of metals, oxides, and salts that exist in nature and may be also produced in the laboratory, or organic particles originating only from the laboratory, having at least one dimension between 1 and 100 nm in size. According to shape, size, surface area, and charge, NMs have different mechanical, chemical, electrical, and optical properties that make them suitable for technological and biomedical applications and thus they are being increasingly produced and modified. Despite their beneficial potential, their use may be hazardous to health owing to the capacity to enter the animal and plant body and interact with cells. Studies on NMs involve technologists, biologists, physicists, chemists, and ecologists, so there are numerous reports that are significantly raising the level of knowledge, especially in the field of nanotechnology; however, many aspects concerning nanobiology remain undiscovered, including the interactions with plant biomolecules. In this review we examine current knowledge on the ways in which NMs penetrate plant organs and interact with cells, with the aim of shedding light on the reactivity of NMs and toxicity to plants. These points are discussed critically to adjust the balance with regard to the risk to the health of the plants as well as providing some suggestions for new studies on this topic. PMID:28347040

The main goals of experiments with the higher plants in the project MARS - 500.

NASA Astrophysics Data System (ADS)

Sychev, Vladimir; Levinskikh, Margarita; Podolsky, Igor; Gushin, Vadim; Bingham, Gail; Bates, Scott

At the present step of development of manned flight to Mars there is a current opinion that including a greenhouse in the composition of Life Support Systems (LSS) of Martian expedition would essentially improve a spacecraft habitat conditions and also would have impact to preventing of a number of possible consequences of continuous presence of human in artificial environment. Development of design objectives of future space greenhouses applicable for conditions of Martian expedition should be based, in our opinion, not only on the results of real space experiments, conducted onboard of orbital stations, but also on the results of ground-based experiments. In connection with above considerations there is a number of technological, biological and psychological experiments is planned to be conducted in the frame of MARS-500 project to resolve questions related to incorporation of higher plants in LSS of inter-planetary flights. The questions include: testing of developed elements of the greenhouse construction and methods for cultivation of vegetables under conditions of imitation of the flight of Martian expedition; selection of breeds and species of vegetables, characterized by high speed of biomass accumulation, attractive taste and appearance; investigation of growth, development and metabolism of plants under long-term continuous cultivation in manned pressurized object; comparison of the productivity of the plants as a function of utilization of different light source; determination of maximum amount of planted biomass of the plants and number of possible vegetation under conditions of long-term utilization of vegetation chamber of the greenhouse without substrate replacement; investigation of crops dietetic preferences of crew members; estimation of quality of plant biomass using seeding of the plants by microorganisms and nitrates and vitamins content as markers; development and approbation of methodical approaches to estimation of psychological factors of

The Fatty Acid Composition of Phosphatidylglycerol and Sulfoquinovosyldiacylglycerol of Higher Plants in Relation to Chilling Sensitivity

PubMed Central

Kenrick, Janette R.; Bishop, David G.

1986-01-01

The fatty acid composition of phosphatidylglycerol and sulfoquinovosyldiacylglycerol has been measured in the leaves of 27 species of higher plants from six families whose members differed in their degrees of chilling sensitivity. The content of high melting point fatty acids (represented by the sum of hexadecanoic, trans-3-hexadecenoic and octadecanoic acids) in phosphatidylglycerols varied little between members of the same plant family and was not obviously related to the relative chilling sensitivity of members of that family. The saturated fatty acid content (hexadecanoic + octadecanoic acids) of sulfoquinovosyldiacylglycerols also appeared to be characteristic of a plant family, although some exceptions were found. In one case, (Carica papaya) the content of saturated fatty acids in sulfoquinovosyldiacylglycerol was sufficiently high to suggest that this lipid could undergo phase separations above 0°C. It is concluded that the content of high melting point fatty acids in leaf phosphatidylglycerol is not a direct indication of the chilling sensitivity of a plant, but rather may be a reflection of the genetic origin of that plant. PMID:16664962

[Impacts of human disturbance on the species composition of higher plants in the wetlands around Dianchi Lake, Yunnan Province of Southwest China].

PubMed

Xiang, Xi-Xi; Wu, Zhao-Lu; Luo, Kang; Ding, Hong-Bo; Zhang, Hai-Yan

2013-09-01

Introducing higher plants to build semi-natural wetland ecosystem is one of the key approaches to restore the wetlands and lakes that suffered from serious pollution and destruction. Based on the investigation data from 128 quadrats at 26 sampling sites in the wetlands around Dianchi Lake in December 2011-October 2012, and in combining with the references published in the 1960s, this paper discussed the impacts of human activities on the species composition of higher plants in the wetlands around the Lake. In 2012, there were 299 species of 88 families in the wetlands, of which, 181 species were native species, and 118 species were alien ones (including 32 invasive species). Of the 42 species of hydrophytes in the total species, 13 species were alien ones (including 2 invasive species). In comparing with the species data recorded in the 1960s, 232 plants were newly recorded and 43 species disappeared in 2012. Aquatic plants changed obviously. The decreased species were 2 submerged plants, 2 floating plants, and 5 floating leaved plants, and the increased species were 8 emergent plants. Fourteen community types were identified by cluster analysis, of which, the main communities were those dominated by alien species including Pistia stratiotes and Alternanthera philoxeroides. As compared with the data in the 1960s, the plant communities dominated by native species such as Ottelia acuminate and Vallisneria natans were not found presently. Therefore, in the practice of introducing higher plants to restore the degraded wetlands and lakes, it would be necessary to scientifically and appropriately select and blend plant species to avoid the wetland degradation by human activities.

Processes entangling interactions in communities: forbidden links are more important than abundance in a hummingbird-plant network.

PubMed

Vizentin-Bugoni, Jeferson; Maruyama, Pietro Kiyoshi; Sazima, Marlies

2014-04-07

Understanding the relative importance of multiple processes on structuring species interactions within communities is one of the major challenges in ecology. Here, we evaluated the relative importance of species abundance and forbidden links in structuring a hummingbird-plant interaction network from the Atlantic rainforest in Brazil. Our results show that models incorporating phenological overlapping and morphological matches were more accurate in predicting the observed interactions than models considering species abundance. This means that forbidden links, by imposing constraints on species interactions, play a greater role than species abundance in structuring the ecological network. We also show that using the frequency of interaction as a proxy for species abundance and network metrics to describe the detailed network structure might lead to biased conclusions regarding mechanisms generating network structure. Together, our findings suggest that species abundance can be a less important driver of species interactions in communities than previously thought.

Processes entangling interactions in communities: forbidden links are more important than abundance in a hummingbird–plant network

PubMed Central

Vizentin-Bugoni, Jeferson; Maruyama, Pietro Kiyoshi; Sazima, Marlies

2014-01-01

Understanding the relative importance of multiple processes on structuring species interactions within communities is one of the major challenges in ecology. Here, we evaluated the relative importance of species abundance and forbidden links in structuring a hummingbird–plant interaction network from the Atlantic rainforest in Brazil. Our results show that models incorporating phenological overlapping and morphological matches were more accurate in predicting the observed interactions than models considering species abundance. This means that forbidden links, by imposing constraints on species interactions, play a greater role than species abundance in structuring the ecological network. We also show that using the frequency of interaction as a proxy for species abundance and network metrics to describe the detailed network structure might lead to biased conclusions regarding mechanisms generating network structure. Together, our findings suggest that species abundance can be a less important driver of species interactions in communities than previously thought. PMID:24552835

NICS report links VOCs to respiratory problems

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

Kirschner, E.

1992-04-22

Children who live near the chemical plants of Kanawha Valley, WV, suffer more acute and chronic respiratory aliments than those farther away, says a Harvard University School of Public Health report. In the $1-million, five-year study commissioned by the National Institute for Chemical Studies (NICS:Charleston, WV) and funded by the Environmental Protection Agency, proximity to chemical plants that emit volatile organic compounds (VOCs) was linked to higher incidence of asthma, acute eye irritation, shortness of breath, and chronic cough. The researchers say they adjusted for most other factors, such as parental smoking and petroleum. {open_quotes}The research hypothesis was whether childrenmore » in the valley had more symptoms,{close_quotes} says NICS president Paul Hill. {open_quotes}Yes, there is a difference.{close_quotes} The study showed that some ailments were up to 28% more prevalent in children in the valley than in other Kanawha County children.« less

Comparative Studies of Enzymes Related to Serine Metabolism in Higher Plants 1

PubMed Central

Cheung, Geoffrey P.; Rosenblum, I. Y.; Sallach, H. J.

1968-01-01

The following enzymes related to serine metabolism in higher plants have been investigated: 1) d-3-phosphoglycerate dehydrogenase, 2) phosphohydroxypyruvate:l-glutamate transaminase, 3) d-glycerate dehydrogenase, and 4) hydroxypyruvate:l-alanine transaminase. Comparative studies on the distribution of the 2 dehydrogenases in seeds and leaves from various plants revealed that d-3-phosphoglycerate dehydrogenase is widely distributed in seeds in contrast to d-glycerate dehydrogenase, which is either absent or present at low levels, and that the reverse pattern is observed in green leaves. The levels of activity of the 4 enzymes listed above were followed in different tissues of the developing pea (Pisum sativum, var. Alaska). In the leaf, from the tenth to seventeenth day of germination, the specific activity of d-glycerate dehydrogenase increased markedly and was much higher than d-3-phosphoglycerate dehydrogenase which remained relatively constant during this time period. Etiolation resulted in a decrease in d-glycerate dehydrogenase and an increase in d-3-phosphoglycerate dehydrogenase activities. In apical meristem, on the other hand, the level of d-3-phosphoglycerate dehydrogenase exceeded that of d-glycerate dehydrogenase at all time periods studied. Low and decreasing levels of both dehydrogenases were found in epicotyl and cotyledon. The specific activities of the 2 transaminases remained relatively constant during development in both leaf and apical meristem. In general, however, the levels of phosphohydroxypyruvate:l-glutamate transaminase were comparable to those of d-3-phosphoglycerate dehydrogenase in a given tissue as were those for hydroxypyruvate: l-alanine transaminase and d-glycerate dehydrogenase. PMID:5699148

Predicting missing links and identifying spurious links via likelihood analysis

NASA Astrophysics Data System (ADS)

Pan, Liming; Zhou, Tao; Lü, Linyuan; Hu, Chin-Kun

2016-03-01

Real network data is often incomplete and noisy, where link prediction algorithms and spurious link identification algorithms can be applied. Thus far, it lacks a general method to transform network organizing mechanisms to link prediction algorithms. Here we use an algorithmic framework where a network’s probability is calculated according to a predefined structural Hamiltonian that takes into account the network organizing principles, and a non-observed link is scored by the conditional probability of adding the link to the observed network. Extensive numerical simulations show that the proposed algorithm has remarkably higher accuracy than the state-of-the-art methods in uncovering missing links and identifying spurious links in many complex biological and social networks. Such method also finds applications in exploring the underlying network evolutionary mechanisms.

Predicting missing links and identifying spurious links via likelihood analysis

PubMed Central

Pan, Liming; Zhou, Tao; Lü, Linyuan; Hu, Chin-Kun

2016-01-01

Real network data is often incomplete and noisy, where link prediction algorithms and spurious link identification algorithms can be applied. Thus far, it lacks a general method to transform network organizing mechanisms to link prediction algorithms. Here we use an algorithmic framework where a network’s probability is calculated according to a predefined structural Hamiltonian that takes into account the network organizing principles, and a non-observed link is scored by the conditional probability of adding the link to the observed network. Extensive numerical simulations show that the proposed algorithm has remarkably higher accuracy than the state-of-the-art methods in uncovering missing links and identifying spurious links in many complex biological and social networks. Such method also finds applications in exploring the underlying network evolutionary mechanisms. PMID:26961965

Concepts, strategies and potentials using hypo-g and other features of the space environment for commercialization using higher plants

NASA Technical Reports Server (NTRS)

Krikorian, A. D.

1985-01-01

Opportunities for releasing, capturing, constructing and/or fixing the differential expressions or response potentials of the higher plant genome in the hypo-g environment for commercialization are explored. General strategies include improved plant-growing, crop and forestry production systems which conserve soil, water, labor and energy resources, and nutritional partitioning and mobilization of nutrients and synthates. Tissue and cell culture techniques of commercial potential include the growing and manipulation of cultured plant cells in vitro in a bioreactor to produce biologicals and secondary plants of economic value. The facilitation of plant breeding, the cloning of specific pathogen-free materials, the elimination of growing point or apex viruses, and the increase of plant yield are other O-g applications. The space environment may be advantageous in somatic embryogenesis, the culture of alkaloids, and the development of completely new crop plant germ plasm.

Can plant phloem properties affect the link between ecosystem assimilation and respiration?

NASA Astrophysics Data System (ADS)

Mencuccini, M.; Hölttä, T.; Sevanto, S.; Nikinmaa, E.

2012-04-01

Phloem transport of carbohydrates in plants under field conditions is currently not well understood. This is largely the result of the lack of techniques suitable for measuring phloem physiological properties continuously under field conditions. This lack of knowledge is currently hampering our efforts to link ecosystem-level processes of carbon fixation, allocation and use, especially belowground. On theoretical grounds, the properties of the transport pathway from canopy to roots must be important in affecting the link between carbon assimilation and respiration, but it is unclear whether their effect is partially or entirely masked by processes occurring in other parts of the ecosystem. One can also predict the characteristic time scales over which these effects should occur and, as consequence, predict whether the transfer of turgor and osmotic signals from the site of carbon assimilation to the sites of carbon use are likely to control respiration. We will present two sources of evidence suggesting that the properties of the phloem transport system may affect processes that are dependent on the supply of carbon substrate, such as root or soil respiration. Firstly, we will summarize the results of a literature survey on soil and ecosystem respiration where the speed of transfer of photosynthetic sugars from the plant canopy to the soil surface was determined. Estimates of the transfer speed could be grouped according to whether the study employed isotopic or canopy soil flux-based techniques. These two groups provided very different estimates of transfer times likely because transport of sucrose molecules, and pressure-concentration waves, in phloem differed. Secondly, we will argue that simultaneous measurements of bark and xylem diameters provide a novel tool to determine the continuous variations of phloem turgor in vivo in the field. We will present a model that interprets these changes in xylem and live bark diameters and present data testing the model

Introducing an algal carbon-concentrating mechanism into higher plants: location and incorporation of key components.

PubMed

Atkinson, Nicky; Feike, Doreen; Mackinder, Luke C M; Meyer, Moritz T; Griffiths, Howard; Jonikas, Martin C; Smith, Alison M; McCormick, Alistair J

2016-05-01

Many eukaryotic green algae possess biophysical carbon-concentrating mechanisms (CCMs) that enhance photosynthetic efficiency and thus permit high growth rates at low CO2 concentrations. They are thus an attractive option for improving productivity in higher plants. In this study, the intracellular locations of ten CCM components in the unicellular green alga Chlamydomonas reinhardtii were confirmed. When expressed in tobacco, all of these components except chloroplastic carbonic anhydrases CAH3 and CAH6 had the same intracellular locations as in Chlamydomonas. CAH6 could be directed to the chloroplast by fusion to an Arabidopsis chloroplast transit peptide. Similarly, the putative inorganic carbon (Ci) transporter LCI1 was directed to the chloroplast from its native location on the plasma membrane. CCP1 and CCP2 proteins, putative Ci transporters previously reported to be in the chloroplast envelope, localized to mitochondria in both Chlamydomonas and tobacco, suggesting that the algal CCM model requires expansion to include a role for mitochondria. For the Ci transporters LCIA and HLA3, membrane location and Ci transport capacity were confirmed by heterologous expression and H(14) CO3 (-) uptake assays in Xenopus oocytes. Both were expressed in Arabidopsis resulting in growth comparable with that of wild-type plants. We conclude that CCM components from Chlamydomonas can be expressed both transiently (in tobacco) and stably (in Arabidopsis) and retargeted to appropriate locations in higher plant cells. As expression of individual Ci transporters did not enhance Arabidopsis growth, stacking of further CCM components will probably be required to achieve a significant increase in photosynthetic efficiency in this species. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

How the Plant Temperature Links to the Air Temperature in the Desert Plant Artemisia ordosica.

PubMed

Yu, Ming-Han; Ding, Guo-Dong; Gao, Guang-Lei; Sun, Bao-Ping; Zhao, Yuan-Yuan; Wan, Li; Wang, De-Ying; Gui, Zi-Yang

2015-01-01

Plant temperature (Tp) is an important indicator of plant health. To determine the dynamics of plant temperature and self-cooling ability of the plant, we measured Tp in Artemisia ordosica in July, in the Mu Us Desert of Northwest China. Related factors were also monitored to investigate their effects on Tp, including environmental factors, such as air temperature (Ta), relative humidity, wind speed; and physiological factors, such as leaf water potential, sap flow, and water content. The results indicate that: 1) Tp generally changes in conjunction with Ta mainly, and varies with height and among the plant organs. Tp in the young branches is most constant, while it is the most sensitive in the leaves. 2) Correlations between Tp and environmental factors show that Tp is affected mainly by Ta. 3) The self-cooling ability of the plant was effective by midday, with Tp being lower than Ta. 4) Increasing sap flow and leaf water potential showed that transpiration formed part of the mechanism that supported self-cooling. Increased in water conductance and specific heat at midday may be additional factors that contribute to plant cooling ability. Therefore, our results confirmed plant self-cooling ability. The response to high temperatures is regulated by both transpiration speed and an increase in stem water conductance. This study provides quantitative data for plant management in terms of temperature control. Moreover, our findings will assist species selection with taking plant temperature as an index.

Nutrient Intakes Linked to Better Health Outcomes Are Associated with Higher Diet Costs in the US

PubMed Central

Aggarwal, Anju; Monsivais, Pablo; Drewnowski, Adam

2012-01-01

Purpose Degrees of nutrient intake and food groups have been linked to differential chronic disease risk. However, intakes of specific nutrients may also be associated with differential diet costs and unobserved differences in socioeconomic status (SES). The present study examined degrees of nutrient intake, for every key nutrient in the diet, in relation to diet cost and SES. Methods Socio-demographic data for a stratified random sample of adult respondents in the Seattle Obesity Study were obtained through telephone survey. Dietary intakes were assessed using food frequency questionnaire (FFQ) (n = 1,266). Following standard procedures, nutrient intakes were energy-adjusted using the residual method and converted into quintiles. Diet cost for each respondent was estimated using Seattle supermarket retail prices for 384 FFQ component foods. Results Higher intakes of dietary fiber, vitamins A, C, D, E, and B12, beta carotene, folate, iron, calcium, potassium, and magnesium were associated with higher diet costs. The cost gradient was most pronounced for vitamin C, beta carotene, potassium, and magnesium. Higher intakes of saturated fats, trans fats and added sugars were associated with lower diet costs. Lower cost lower quality diets were more likely to be consumed by lower SES. Conclusion Nutrients commonly associated with a lower risk of chronic disease were associated with higher diet costs. By contrast, nutrients associated with higher disease risk were associated with lower diet costs. The cost variable may help somewhat explain why lower income groups fail to comply with dietary guidelines and have highest rates of diet related chronic disease. PMID:22662168

Research on the effects of altered gravity and other factors on the growth and development of higher plants

NASA Technical Reports Server (NTRS)

Brown, A. H.

1973-01-01

The establishment, maintenance and use of the NASA-UCSC Botanical Centrifuge is discussed. The broad goals of this project were: (1) to establish facilities for conducting experiments under conditions of sustained centrifugation; (2) to pursue research on the gravitational physiology of higher plants; (3) to develop experimental hardware suitable for studies of plant development in the weightless condition; and (4) to accommodate visiting investigators whose researches are of interest to the NASA Biomedical Program and who may require for some limited time, the use of a medium size centrifuge with associated facilities appropriate for plant physiological studies.

Experimental identification of Ca isotopic fractionations in higher plants

NASA Astrophysics Data System (ADS)

Cobert, Florian; Schmitt, Anne-Désirée; Bourgeade, Pascale; Labolle, François; Badot, Pierre-Marie; Chabaux, François; Stille, Peter

2011-10-01

Hydroponic experiments have been performed in order to identify the co-occurring geochemical and biological processes affecting the Ca isotopic compositions within plants. To test the influence of the Ca concentration and pH of the nutritive solution on the Ca isotopic composition of the different plant organs, four experimental conditions were chosen combining two different Ca concentrations (5 and 60 ppm) and two pHs (4 and 6). The study was performed on rapid growing bean plants in order to have a complete growth cycle. Several organs (root, stem, leaf, reproductive) were sampled at two different growth stages (10 days and 6 weeks of culture) and prepared for Ca isotopic measurements. The results allow to identify three Ca isotopic fractionation levels. The first one takes place when Ca enters the lateral roots, during Ca adsorption on cation-exchange binding sites in the apoplasm. The second one takes place when Ca is bound to the polygalacturonic acids (pectins) of the middle lamella of the xylem cell wall. Finally, the last fractionation occurs in the reproductive organs, also caused by cation-exchange processes with pectins. However, the cell wall structures of these organs and/or number of available exchange sites seem to be different to those of the xylem wall. These three physico-chemical fractionation mechanisms allow to enrich the organs in the light 40Ca isotope. The amplitude of the Ca isotopic fractionation within plant organs is highly dependent on the composition of the nutritive solution: low pH (4) and Ca concentrations (5 ppm) have no effect on the biomass increase of the plants but induce smaller fractionation amplitudes compared to those obtained from other experimental conditions. Thus, Ca isotopic signatures of bean plants are controlled by the external nutritive medium. This study highlights the potential of Ca isotopes to be applied in plant physiology (to identify Ca uptake, circulation and storage mechanisms within plants) and in

A lost link between a flightless parrot and a parasitic plant and the potential role of coprolites in conservation paleobiology.

PubMed

Wood, Jamie R; Wilmshurst, Janet M; Worthy, Trevor H; Holzapfel, Avi S; Cooper, Alan

2012-12-01

Late Quaternary extinctions and population fragmentations have severely disrupted animal-plant interactions globally. Detection of disrupted interactions often relies on anachronistic plant characteristics, such as spines in the absence of large herbivores or large fruit without dispersers. However, obvious anachronisms are relatively uncommon, and it can be difficult to prove a direct link between the anachronism and a particular faunal taxon. Analysis of coprolites (fossil feces) provides a novel way of exposing lost interactions between animals (depositors) and consumed organisms. We analyzed ancient DNA to show that a coprolite from the South Island of New Zealand was deposited by the rare and threatened kakapo (Strigops habroptilus), a large, nocturnal, flightless parrot. When we analyzed the pollen and spore content of the coprolite, we found pollen from the cryptic root-parasite Dactylanthus taylorii. The relatively high abundance (8.9% of total pollen and spores) of this zoophilous pollen type in the coprolite supports the hypothesis of a former direct feeding interaction between kakapo and D. taylorii. The ranges of both species have contracted substantially since human settlement, and their present distributions no longer overlap. Currently, the lesser short-tailed bat (Mystacina tuberculata) is the only known native pollinator of D. taylorii, but our finding raises the possibility that birds, and other small fauna, could have once fed on and pollinated the plant. If confirmed, through experimental work and observations, this finding may inform conservation of the plant. For example, it may be possible to translocate D. taylorii to predator-free offshore islands that lack bats but have thriving populations of endemic nectar-feeding birds. The study of coprolites of rare or extinct taxonomic groups provides a unique way forward to expand existing knowledge of lost plant and animal interactions and to identify pollination and dispersal syndromes. This

The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization

PubMed Central

Iwai, Hiroaki; Hokura, Akiko; Oishi, Masahiro; Chida, Hiroshi; Ishii, Tadashi; Sakai, Shingo; Satoh, Shinobu

2006-01-01

Deficiencies in boron, a microelement that is essential for the growth and development of higher plants, often cause problems in reproductive growth. Rhamnogalacturonan-II (RG-II) in cell wall pectin acts as the sole receptor for boron in plant cells, forming a borate cross-linked RG-II dimer (dRG-II-B), but the physiological functions of dRG-II-B remain unknown. We have previously shown that the pectin glucuronyltransferase 1 gene NpGUT1, which is involved in the biosynthesis of RG-II sugar chains, is essential for the formation of the RG-II-B complex, resulting in tight intercellular attachment in meristematic tissues. Because NpGUT1 expression was found to be abundant in reproductive organs in addition to meristematic tissues, we analyzed the expression and functions of NpGUT1 in more detail in tobacco reproductive tissues. Specific NpGUT1 expression was detected in the tapetum of flower buds and in the pollen, pollen tube tips, and transmitting tissue of the pistils of flowers. Dexamethasone-induced expression of the NpGUT1 antisense gene in flower buds resulted in the formation of sterile flowers with aberrant development of pollen and transmitting tissue. Pollen tubes could not pass through pistils with aborted transmitting tissue, and expression of an NpGUT1 antisense gene in germinating pollen inhibited pollen tube elongation, accompanied by the absence of pectin RG-II and boron in the pollen tube tip. These results indicate that expression of NpGUT1 is required for the development and functions of male and female tissues. PMID:17053077

Assessment of organochlorine pesticides residues in higher plants from oil exploration areas of Niger Delta, Nigeria.

PubMed

Sojinu, O Samuel; Sonibare, Oluwadayo O; Ekundayo, Olusegun O; Zeng, Eddy Y

2012-09-01

The concentrations and distributions of organochlorine pesticides (OCPs) in some higher plant samples collected from oil exploration areas of the Niger Delta, Nigeria were examined. The concentrations of Σ(25)OCP ranged from 82 to 424, 44 to 200 , 34 to 358, 33 to 106 and 16 to 75 ng/g in Olomoro, Oginni, Uzere, Irri and Calabar plants, respectively. The compositional profiles of the analysed OCPs in most of the plants showed no fresh inputs in the area. The OCPs detected in the samples could have resulted from pesticide usage for intense farming activities cum the use of pesticides to control household pests and insects in the area. Drilling fluids and corrosion inhibitors used in petroleum explorations also have chlorinated compounds as additives thereby serving as potential sources of OCPs. Among the studied plants, elephant grass showed high bioaccumulation and phytoremediation potentials of OCPs. The ΣHCH concentrations exceeded the allowable daily intake limit thereby serving as potential threat to humans. Copyright © 2012 Elsevier B.V. All rights reserved.

"Learning to Do" as a Pillar of Education and Its Links to Entrepreneurial Studies in Higher Education: European Contexts and Approaches

ERIC Educational Resources Information Center

Miclea, Mircea

2004-01-01

The author links the "learning to do" pillar, one of the four pillars of the Delors Report of 1996 , "Learning: The Treasure Within", to the principles and purposes of an entrepreneurial university and the aims of the European Commission and the Bologna Process to enhance the employability of graduates of higher education. An entrepreneurial…

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.

Accelerated increase in plant species richness on mountain summits is linked to warming.

PubMed

Steinbauer, Manuel J; Grytnes, John-Arvid; Jurasinski, Gerald; Kulonen, Aino; Lenoir, Jonathan; Pauli, Harald; Rixen, Christian; Winkler, Manuela; Bardy-Durchhalter, Manfred; Barni, Elena; Bjorkman, Anne D; Breiner, Frank T; Burg, Sarah; Czortek, Patryk; Dawes, Melissa A; Delimat, Anna; Dullinger, Stefan; Erschbamer, Brigitta; Felde, Vivian A; Fernández-Arberas, Olatz; Fossheim, Kjetil F; Gómez-García, Daniel; Georges, Damien; Grindrud, Erlend T; Haider, Sylvia; Haugum, Siri V; Henriksen, Hanne; Herreros, María J; Jaroszewicz, Bogdan; Jaroszynska, Francesca; Kanka, Robert; Kapfer, Jutta; Klanderud, Kari; Kühn, Ingolf; Lamprecht, Andrea; Matteodo, Magali; di Cella, Umberto Morra; Normand, Signe; Odland, Arvid; Olsen, Siri L; Palacio, Sara; Petey, Martina; Piscová, Veronika; Sedlakova, Blazena; Steinbauer, Klaus; Stöckli, Veronika; Svenning, Jens-Christian; Teppa, Guido; Theurillat, Jean-Paul; Vittoz, Pascal; Woodin, Sarah J; Zimmermann, Niklaus E; Wipf, Sonja

2018-04-01

Globally accelerating trends in societal development and human environmental impacts since the mid-twentieth century 1-7 are known as the Great Acceleration and have been discussed as a key indicator of the onset of the Anthropocene epoch 6 . While reports on ecological responses (for example, changes in species range or local extinctions) to the Great Acceleration are multiplying 8, 9 , it is unknown whether such biotic responses are undergoing a similar acceleration over time. This knowledge gap stems from the limited availability of time series data on biodiversity changes across large temporal and geographical extents. Here we use a dataset of repeated plant surveys from 302 mountain summits across Europe, spanning 145 years of observation, to assess the temporal trajectory of mountain biodiversity changes as a globally coherent imprint of the Anthropocene. We find a continent-wide acceleration in the rate of increase in plant species richness, with five times as much species enrichment between 2007 and 2016 as fifty years ago, between 1957 and 1966. This acceleration is strikingly synchronized with accelerated global warming and is not linked to alternative global change drivers. The accelerating increases in species richness on mountain summits across this broad spatial extent demonstrate that acceleration in climate-induced biotic change is occurring even in remote places on Earth, with potentially far-ranging consequences not only for biodiversity, but also for ecosystem functioning and services.

[Effect of salt stress on respiration metabolism in higher plants].

PubMed

Mittova, V O; Igamberdiev, A U

2000-01-01

We studied the activity of NADP-dependent isocitrate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, catalase, and peroxidase as well as the rate of 14CO2 release after introduction of labeled substrates for glycolysis and citrate acid cycle within 24 h after salt stress (1% NaCl) in 10-14 days old germinants of wheat (Triticum aestivum L.) and maize (Zea mays L.) as well as thallus of small duckweed (Wolffia arrhiza (L.) Hork ex Wimmer). Oscillations in the enzymes activity with 4-6 h period have been revealed under stress conditions. Activity of glycolysis decreased in wheat and maize and increased in duckweed under the influence of stress stimulus. Six hours after NaCl action decarboxylation of exogenous citrate and succinate was enhanced in all three plants while the rate of exogenous malate decarboxylation was decreased. We conclude that adaptation of higher plans to salinization is accompanied by rearrangements in oxidative metabolism reflected by oscillations in activity of the enzymes involved in oxidative metabolism.

Wound signaling: The missing link in plant regeneration.

PubMed

Chen, Lyuqin; Sun, Beibei; Xu, Lin; Liu, Wu

2016-10-02

Wounding is the first event that occurs in plant regeneration. However, wound signaling in plant regeneration is barely understood. Using a simple system of de novo root organogenesis from Arabidopsis thaliana leaf explants, we analyzed the genes downstream of wound signaling. Leaf explants may produce at least two kinds of wound signals to trigger short-term and long-term wound signaling. Short-term wound signaling is primarily involved in controlling auxin behavior and the fate transition of regeneration-competent cells, while long-term wound signaling mainly modulates the cellular environment at the wound site and maintains the auxin level in regeneration-competent cells. YUCCA (YUC) genes, which are involved in auxin biogenesis, are targets of short-term wound signaling in mesophyll cells and of long-term wound signaling in regeneration-competent cells. The expression patterns of YUCs provide important information about the molecular basis of wound signaling in plant regeneration.

Linking Genetic Variation in Adaptive Plant Traits to Climate in Tetraploid and Octoploid Basin Wildrye [Leymus cinereus (Scribn. & Merr.) A. Love] in the Western U.S.

PubMed

Johnson, R C; Vance-Borland, Ken

2016-01-01

Few studies have assessed how ploidy type within a species affects genetic variation among populations in relation to source climates. Basin wildrye (Leymus cinereus (Scribn. & Merr.) A. Love) is a large bunchgrass common in the intermountain Western U.S. found in both octoploid and tetraploid types. In common gardens at two sites over two years differences in both ploidy type and genetic variation within ploidy were observed in phenology, morphology, and production traits on 57 octoploid and 52 tetraploid basin wildrye from the intermountain Western U.S. (P<0.01). Octoploids had larger leaves, longer culms, and greater crown circumference than tetraploids but the numerical ranges of plant traits and their source climates overlapped between ploidy types. Still, among populations octoploids often had greater genetic variation for traits and occupied more diverse climates than tetraploids. Genetic variation for both ploidy types was linked to source climates in canonical correlation analysis, with the first two variates explaining 70% of the variation. Regression of those canonical variates with seed source climate variables produced models that explained 64% and 38% of the variation, respectively, and were used to map 15 seed zones covering 673,258 km2. Utilization of these seed zones will help ensure restoration with adaptive seed sources for both ploidy types. The link between genetic traits and seed source climates suggests climate driven natural selection and adaptive evolution in basin wildrye. The more diverse climates occupied by octoploids and higher trait variation suggests a higher capacity for ecological differentiation than tetraploids in the intermountain Western U.S.

Reorganization of microtubules in endosperm cells and cell fragments of the higher plant Haemanthus in vivo

PubMed Central

1986-01-01

The reorganization of the microtubular meshwork was studied in intact Haemanthus endosperm cells and cell fragments (cytoplasts). This higher plant tissue is devoid of a known microtubule organizating organelle. Observations on living cells were correlated with microtubule arrangements visualized with the immunogold method. In small fragments, reorganization did not proceed. In medium and large sized fragments, microtubular converging centers formed first. Then these converging centers reorganized into either closed bushy microtubular spiral or chromosome-free cytoplasmic spindles/phragmoplasts. Therefore, the final shape of organized microtubular structures, including spindle shaped, was determined by the initial size of the cell fragments and could be achieved without chromosomes or centrioles. Converging centers elongate due to the formation of additional structures resembling microtubular fir trees. These structures were observed at the pole of the microtubular converging center in anucleate fragments, accessory phragmoplasts in nucleated cells, and in the polar region of the mitotic spindle during anaphase. Therefore, during anaphase pronounced assembly of new microtubules occurs at the polar region of acentriolar spindles. Moreover, statistical analysis demonstrated that during the first two-thirds of anaphase, when chromosomes move with an approximately constant speed, kinetochore fibers shorten, while the length of the kinetochore fiber complex remains constant due to the simultaneous elongation of their integral parts (microtubular fir trees). The half-spindle shortens only during the last one-third of anaphase. These data contradict the presently prevailing view that chromosome-to-pole movements in acentriolar spindles of higher plants are concurrent with the shortening of the half-spindle, the self- reorganizing property of higher plant microtubules (tubulin) in vivo. It may be specific for cells without centrosomes and may be superimposed also on other

A complete mitochondrial genome of wheat (Triticum aestivum cv. Chinese Yumai), and fast evolving mitochondrial genes in higher plants.

PubMed

Cui, Peng; Liu, Huitao; Lin, Qiang; Ding, Feng; Zhuo, Guoyin; Hu, Songnian; Liu, Dongcheng; Yang, Wenlong; Zhan, Kehui; Zhang, Aimin; Yu, Jun

2009-12-01

Plant mitochondrial genomes, encoding necessary proteins involved in the system of energy production, play an important role in the development and reproduction of the plant. They occupy a specific evolutionary pattern relative to their nuclear counterparts. Here, we determined the winter wheat (Triticum aestivum cv. Chinese Yumai) mitochondrial genome in a length of 452 and 526 bp by shotgun sequencing its BAC library. It contains 202 genes, including 35 known protein-coding genes, three rRNA and 17 tRNA genes, as well as 149 open reading frames (ORFs; greater than 300 bp in length). The sequence is almost identical to the previously reported sequence of the spring wheat (T. aestivum cv. Chinese Spring); we only identified seven SNPs (three transitions and four transversions) and 10 indels (insertions and deletions) between the two independently acquired sequences, and all variations were found in non-coding regions. This result confirmed the accuracy of the previously reported mitochondrial sequence of the Chinese Spring wheat. The nucleotide frequency and codon usage of wheat are common among the lineage of higher plant with a high AT-content of 58%. Molecular evolutionary analysis demonstrated that plant mitochondrial genomes evolved at different rates, which may correlate with substantial variations in metabolic rate and generation time among plant lineages. In addition, through the estimation of the ratio of non-synonymous to synonymous substitution rates between orthologous mitochondrion-encoded genes of higher plants, we found an accelerated evolutionary rate that seems to be the result of relaxed selection.

Cross-linked polyvinyl alcohol films as alkaline battery separators

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Manzo, M. A.; Gonzalez-Sanabria, O. D.

1983-01-01

Cross-linking methods have been investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality (one-step method). Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. Then pilot-plant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide-zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

Cross-linked polyvinyl alcohol films as alkaline battery separators

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Manzo, M. A.; Gonzalez-Sanabria, O. D.

1982-01-01

Cross-linking methods were investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality (one-step method). Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. The pilot-plant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide - zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

Synthesising topological links

DOE PAGES

Baas, Nils A.; Seeman, Nadrian C.; Stacey, Andrew

2014-10-14

In this paper, we discuss the chemical synthesis of topological links, in particular higher order links which have the Brunnian property (namely that removal of any one component unlinks the entire system). Finally, we suggest how to obtain both two dimensional and three dimensional objects (surfaces and solids, respectively) which also have this Brunnian property.

Higher concentration of interleukin 6 - A possible link between major depressive disorder and childhood abuse.

PubMed

Munjiza, Ana; Kostic, Milutin; Pesic, Danilo; Gajic, Milan; Markovic, Ivanka; Tosevski, Dusica Lecic

2018-06-01

Little is known about the correlation between IL-6 and childhood abuse and neglect which may be risk factors for the development of affective disorders in adulthood. The aim of this study was to analyze differences in serum concentrations of IL-6 between patients with major depressive disorder and healthy controls, and to investigate possible correlations with adverse childhood experiences. Peripheral venous blood samples were obtained from 64 patients who fulfilled DSM-IV-R criteria for a current major depressive episode without psychotic symptoms (MDD) and 53 healthy controls, matched for age and gender. Participants were assessed by the Beck Depression Inventory (BDI), Childhood Trauma Questionnaire (CTQ), Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating Scale (HARS). The concentration of IL-6 was significantly higher in patients with major depressive disorder compared to healthy controls. The total score of childhood trauma questionnaire highly statistically significantly correlated with IL-6 levels in patient group. Persons who were physically abused, physically neglected and emotionally abused had higher levels of IL-6. Interleukin 6 as a pro-inflammatory immune marker could be an important developmental mediator linking physical and emotional abuse in early life with the development of depressive disorder in adulthood. Copyright © 2018. Published by Elsevier B.V.

Lower resistance and higher tolerance of invasive host plants: biocontrol agents reach high densities but exert weak control.

PubMed

Wang, Yi; Huang, Wei; Siemann, Evan; Zou, Jianwen; Wheeler, Gregory S; Carrillo, Juli; Ding, Jianqing

2011-04-01

Invasive plants often have novel biotic interactions in their introduced ranges. Their defense to herbivory may differ from their native counterparts, potentially influencing the effectiveness of biological control. If invasive plants have decreased resistance but increased tolerance to enemies, insect herbivores may rapidly build up their populations but exert weak control. Moreover, resource availability to plants may affect the efficacy of biological control agents. We tested these predictions using Chinese tallow tree (Triadica sebifera) and two specialist herbivores (Heterapoderopsis bicallosicollis and Gadirtha inexacta) that are candidates for biological control. We performed a pair of field common garden experiments in China in which Triadica seedlings from the native or introduced range were grown in low or high light conditions and subjected to different levels of herbivory by each herbivore in a factorial design. We found that Heterapoderopsis achieved greater densities on tallow trees from the introduced range or when trees were grown in high light conditions. When Gadirtha was raised in the lab on tallow tree foliage we found that it performed better (larger pupal size) when fed foliage from introduced populations. However, introduced populations generally had greater herbivore tolerance such that the impact of each agent on plant performance was lower than on native populations despite higher herbivore loads. Tallow trees grew more slowly and achieved smaller sizes in lower light levels, but the impact of biological control agents was comparable to that found for higher light levels. Plants from introduced populations grew larger than those from native populations in all conditions. Our results suggest that reduced resistance and increased tolerance to herbivory in introduced populations may impede success of biological control programs. Biological control practitioners should include plants from the introduced range in the prerelease evaluation

Linking altitudinal gradients and temperature responses of plant phenology in the Bavarian Alps.

PubMed

Cornelius, C; Estrella, N; Franz, H; Menzel, A

2013-01-01

Global climate change influences ecosystems across the world. Alpine plant communities have already experienced serious impacts, and will continue to do so as climate change continues. The aim of our study was to determine the sensitivity of woody and herbaceous species to shifts in temperature along an altitudinal gradient. Since 1994, park rangers have been making phenological observations at 24 sites from 680 to 1425 m a.s.l. Each year 21 plant species were observed once or twice weekly from March to July; with a main focus on flowering and leaf unfolding. Our study showed a very high degree of dependence of phenophases and species on inter-annual temperature variation and altitude. Averaged over all species and phenophases, there was a delay of 3.8 days with every 100 m increase in altitude and, across all elevations, an advance of phenophases of 6 days per 1 °C increase in temperature. Temperature lapse rates assessed indirectly by phenology, as the quotient of altitudinal to temperature response coefficients, were higher than directly calculated from March to July mean temperatures, most likely due to snow effects. Furthermore, a significant difference in sensitivity to temperature change was found between growth forms (herbs versus trees). Sensitivity was less pronounced in events occurring later in the season. Our results show that species reactions will differ in magnitude during global warming. Consequently, impacts of shifts in the timing of phenological events on plant migration and plant-pollinator interactions due to rising temperatures should be considered at the species level. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Seed sprout production: Consumables and a foundation for higher plant growth in space

NASA Technical Reports Server (NTRS)

Day, Michelle; Thomas, Terri; Johnson, Steve; Luttges, Marvin

1990-01-01

Seed sprouts can be produced as a source of fresh vegetable materials and as higher plant seedlings in space. Sprout production was undertaken to evaluate the mass accumulations possible, the technologies needed, and the reliability of the overall process. Baseline experiments corroborated the utility of sprout production protocols for a variety of seed types. The automated delivery of saturated humidity effectively supplants labor intensive manual soaking techniques. Automated humidification also lend itself to modest centrifugal sprout growth environments. A small amount of ultraviolet radiation effectively suppressed bacterial and fungal contamination, and the sprouts were suitable for consumption.

Biochemical Hydrogen Isotope Fractionation during Lipid Biosynthesis in Higher Plants

NASA Astrophysics Data System (ADS)

Kahmen, A.; Gamarra, B.; Cormier, M. A.

2014-12-01

Although hydrogen isotopes (δ2H) of leaf wax lipids are increasingly being applied as (paleo-) hydrological proxies, we still do not understand some of the basic processes that shape the δ2H values of these compounds. In general, it is believed that three variables shape the δ2H values of leaf wax lipids: source water δ2H values, evaporative deuterium (2H) enrichment of leaf water and the biosynthetic fractionation (ɛbio) during the synthesis of organic compounds. While the influences of source water δ2H values and leaf water evaporative 2H enrichment have been well documented, very little is known how ɛbio shapes the δ2H values of plant-derived lipids. I will present the results from recent experiments, where we show that the magnitude of ɛbio, and thus the δ2H value of plant-derived lipids, strongly depends on the carbon (C) metabolism of a plant. Specifically, I will show that plants that rely for their tissue formation on recently assimilated C have δ2H values in their n-alkanes that are up to 60‰ more negative than plants that depend for their tissue formation on stored carbohydrates. Our findings can be explained by the fact that NADPH is the primary source of hydrogen in plant lipids and that the δ2H value of NADPH differs whether NADPH was generated directly in the light reaction of photosynthesis or whether it was generated by processing stored carbohydrates. As such, the δ2H values of plant-derived lipids will directly depend on whether the tissue containing these lipids was synthesized using recent assimilates, e.g. in a C autonomous state or, if it was synthesized from stored or otherwise aquired C sources, e.g. in a not C autonomous state. Given the magnidude of this effect, our results have important implications for interpretation of plant-derived lipid δ2H values when used as (paleo-) hydrological proxies. In addition, our results suggest, that δ2H values of plant-derived lipids could be employed as a new tools to assess the C

Gravitropism in Higher Plant Shoots 1

PubMed Central

Mueller, Wesley J.; Salisbury, Frank B.; Blotter, P. Thomas

1984-01-01

Dimensional changes during gravitropic bending of cocklebur (Xanthium strumarium L.) dicot stems were measured using techniques of stereo photogrammetry. The differential growth is from an increased growth rate on the bottom of the stem and a stopping or contraction of the top. Contraction of the top was especially evident upon release and immediate bending of horizontal stems that had been restrained between stiff wires for 36 hours. The energy for this could have been stored in both the top and bottom, since the bottom elongated, and the top contracted. Forces developed during bending were measured by fastening a stem tip to the end of a bar with attached strain gauges and recording electrical output from the strain gauges. Restrained mature cocklebur stems continued to accumulate potential energy for bending for about 120 hours, after which the recorded force reached a maximum. Pressures within castor bean (Ricinus communis L.) stems were also measured with 3.5-millimeter diameter pressure transducers. As expected, the pressure on the bottom of the restrained plants increased with time; pressures decreased in vertical controls, tops of restrained stems, and bottoms of free-bending stems. Pressures increased in tops of free-bending stems. When restrained plants were released, pressure on the bottom decreased and pressure on the top increased. Results suggest a possible role for cell contraction in the top of stems bending upward in response to gravity. Images Fig. 5 Fig. 11 PMID:16663987

Do plant population and planting date make a difference in corn production?

USDA-ARS?s Scientific Manuscript database

One management practice that can positively or negatively impact corn yield is plant population. Yield potential can also be influenced by the date of planting, which is strongly linked to the at-planting and in-season weather and climatic conditions. Even when considering management changes, we nee...

Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology.

PubMed

Jepsen, Jane U; Hagen, Snorre B; Karlsen, Stein-Rune; Ims, Rolf A

2009-12-07

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000-2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.

Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology

PubMed Central

Jepsen, Jane U.; Hagen, Snorre B.; Karlsen, Stein-Rune; Ims, Rolf A.

2009-01-01

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000–2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks. PMID:19740876

Use resources of human exometabolites of different oxidation levels for higher plants cultivation on the soil-like substrate as applied to closed ecosystems

NASA Astrophysics Data System (ADS)

Tikhomirov, Alexander A.; Kudenko, Yurii; Ushakova, Sofya; Tirranen, Lyalya; Gribovskaya, Illiada; Gros, Jean-Bernard; Lasseur, Christophe

The technology of ‘wet incineration' of human exometabolites and inedible plants biomass by means of H2 O2 in alternating electromagnetic field to increase a closure of mass exchange processes in bioregenerative life support systems (BLSS) was developed at the Institute of Biophysics of the Siberian Branch of Russian Academy of Sciences (Krasnoyarsk, Russia). Human exometabolites mineralized can be used in a nutrient solution for plants cultivation in the BLSS phototrophic link. The objective of the given work appears to be the study of use resources of human exometabolites of different oxidation levels processed by the abovementioned method for higher plants cultivation on the soil-like substrate (SLS). The mineralized human wastes were tested for the purpose of their sterility. Then the effect of human exometabolites of different oxidation levels both on wheat productivity and on the SLS microflora composition was examined. The SLS extract with a definite amount of human mineralized wastes was used as an irrigation solution. The conducted experiments demonstrated that the H2 O2 decreasing to 1 ml on 1 g of feces and to 0.25 ml on 1 ml of urine had not affected the sterility of mineralized human wastes. Wheat cultivation on the SLS with the addition in an irrigation solution of mineralized human wastes in the amount simulating 1/6 of a daily human diet showed the absence of basic dependence of plants productivity on oxidation level of human exometabolites. Yet the analysis of the microflora composition of the irrigation solutions demonstrated its dependence on the oxidation level of the exometabolites introduced. The amount of yeast-like fungi increased in 20 times in the solutions containing less oxidized exometabolites in comparison with the variant in which the human wastes were subjected to a full-scale oxidation. Besides, the solutions with less oxidized exometabolites displayed a bigger content of plant pathogenic bacteria and denitrifies. Consequently the

[Plant hormones, plant growth regulators].

PubMed

Végvári, György; Vidéki, Edina

2014-06-29

Plants seem to be rather defenceless, they are unable to do motion, have no nervous system or immune system unlike animals. Besides this, plants do have hormones, though these substances are produced not in glands. In view of their complexity they lagged behind animals, however, plant organisms show large scale integration in their structure and function. In higher plants, such as in animals, the intercellular communication is fulfilled through chemical messengers. These specific compounds in plants are called phytohormones, or in a wide sense, bioregulators. Even a small quantity of these endogenous organic compounds are able to regulate the operation, growth and development of higher plants, and keep the connection between cells, tissues and synergy between organs. Since they do not have nervous and immume systems, phytohormones play essential role in plants' life.

Traditional uses of plants in a rural community of Mozambique and possible links with Miombo degradation and harvesting sustainability.

PubMed

Bruschi, Piero; Mancini, Matteo; Mattioli, Elisabetta; Morganti, Michela; Signorini, Maria Adele

2014-07-23

Miombo woodlands play an important role in the livelihood of people living in sub-equatorial African countries, contributing to satisfy basic human needs such as food, medicine, fuelwood and building materials. However, over-exploitation of plant resources and unsustainable harvest practices can potentially degrade forests. The aim of this study was to document the use of Miombo plant products, other than medicinal plants, in local communities, within a wider framework in which we discussed possible links between traditional uses and conservation status of the used species and of the whole Miombo environment. Fieldwork took place in four communities of Muda-Serração, central Mozambique. We conducted semi-structured interviews with 52 informants about their knowledge, use and harvesting practices of useful plants. A survey on local Miombo vegetation was also carried out in order to assess abundance and distribution of useful woody plants cited in the interviews in areas exposed to different exploitation rates. A Conservation Priority index was also applied to rank conservation values of each used woody species. Ninety-eight plants cited by the informants were botanically identified. The most relevant general category was represented by food plants (45 species), followed by handicraft plants (38 species) and domestic plants (37 species). Among the 54 woody species observed in vegetation plots, 52% were cited as useful in the interviews. Twenty-six woody species found in 'natural' Miombo areas were not found in 'degraded' ones: of these, 46% were cited in the interviews (58% in the food category, 50% in the handicraft category, 25% in the domestic category and 8% in the fishing category). Results of conservation ranking showed that 7 woody species deserve conservation priority in the investigated area. This study shows that the communities investigated rely heavily on local forest products for their daily subsistence requirements in food, firewood/charcoal and

Enzyme-linked immunosorbent assay for the quantitative/qualitative analysis of plant secondary metabolites.

PubMed

Sakamoto, Seiichi; Putalun, Waraporn; Vimolmangkang, Sornkanok; Phoolcharoen, Waranyoo; Shoyama, Yukihiro; Tanaka, Hiroyuki; Morimoto, Satoshi

2018-01-01

Immunoassays are antibody-based analytical methods for quantitative/qualitative analysis. Since the principle of immunoassays is based on specific antigen-antibody reaction, the assays have been utilized worldwide for diagnosis, pharmacokinetic studies by drug monitoring, and the quality control of commercially available products. Berson and Yalow were the first to develop an immunoassay, known as radioimmunoassay (RIA), for detecting endogenous plasma insulin [1], a development for which Yalow was awarded the Nobel Prize in Physiology or Medicine in 1977. Even today, after half a century, immunoassays are widely utilized with some modifications from the originally proposed system, e.g., radioisotopes have been replaced with enzymes because of safety concerns regarding the use of radioactivity, which is referred to as enzyme immunoassay/enzyme-linked immunosorbent assay (ELISA). In addition, progress has been made in ELISA with the recent advances in recombinant DNA technology, leading to increase in the range of antibodies, probes, and even systems. This review article describes ELISA and its applications for the detection of plant secondary metabolites.

Integrative modelling reveals mechanisms linking productivity and plant species richness.

PubMed

Grace, James B; Anderson, T Michael; Seabloom, Eric W; Borer, Elizabeth T; Adler, Peter B; Harpole, W Stanley; Hautier, Yann; Hillebrand, Helmut; Lind, Eric M; Pärtel, Meelis; Bakker, Jonathan D; Buckley, Yvonne M; Crawley, Michael J; Damschen, Ellen I; Davies, Kendi F; Fay, Philip A; Firn, Jennifer; Gruner, Daniel S; Hector, Andy; Knops, Johannes M H; MacDougall, Andrew S; Melbourne, Brett A; Morgan, John W; Orrock, John L; Prober, Suzanne M; Smith, Melinda D

2016-01-21

How ecosystem productivity and species richness are interrelated is one of the most debated subjects in the history of ecology. Decades of intensive study have yet to discern the actual mechanisms behind observed global patterns. Here, by integrating the predictions from multiple theories into a single model and using data from 1,126 grassland plots spanning five continents, we detect the clear signals of numerous underlying mechanisms linking productivity and richness. We find that an integrative model has substantially higher explanatory power than traditional bivariate analyses. In addition, the specific results unveil several surprising findings that conflict with classical models. These include the isolation of a strong and consistent enhancement of productivity by richness, an effect in striking contrast with superficial data patterns. Also revealed is a consistent importance of competition across the full range of productivity values, in direct conflict with some (but not all) proposed models. The promotion of local richness by macroecological gradients in climatic favourability, generally seen as a competing hypothesis, is also found to be important in our analysis. The results demonstrate that an integrative modelling approach leads to a major advance in our ability to discern the underlying processes operating in ecological systems.

The CW domain, a structural module shared amongst vertebrates, vertebrate-infecting parasites and higher plants.

PubMed

Perry, Jason; Zhao, Yunde

2003-11-01

A previously undetected domain, named CW for its conserved cysteine and tryptophan residues, appears to be a four-cysteine zinc-finger motif found exclusively in vertebrates, vertebrate-infecting parasites and higher plants. Of the twelve distinct nuclear protein families that comprise the CW domain-containing superfamily, only the microrchida (MORC) family has begun to be characterized. However, several families contain other domains suggesting a relationship between the CW domain and either chromatin methylation status or early embryonic development.

Modeling evapotranspiration based on plant hydraulic theory can predict spatial variability across an elevation gradient and link to biogeochemical fluxes

NASA Astrophysics Data System (ADS)

Mackay, D. S.; Frank, J.; Reed, D.; Whitehouse, F.; Ewers, B. E.; Pendall, E.; Massman, W. J.; Sperry, J. S.

2012-04-01

In woody plant systems transpiration is often the dominant component of total evapotranspiration, and so it is key to understanding water and energy cycles. Moreover, transpiration is tightly coupled to carbon and nutrient fluxes, and so it is also vital to understanding spatial variability of biogeochemical fluxes. However, the spatial variability of transpiration and its links to biogeochemical fluxes, within- and among-ecosystems, has been a challenge to constrain because of complex feedbacks between physical and biological controls. Plant hydraulics provides an emerging theory with the rigor needed to develop testable hypotheses and build useful models for scaling these coupled fluxes from individual plants to regional scales. This theory predicts that vegetative controls over water, energy, carbon, and nutrient fluxes can be determined from the limitation of plant water transport through the soil-xylem-stomata pathway. Limits to plant water transport can be predicted from measurable plant structure and function (e.g., vulnerability to cavitation). We present a next-generation coupled transpiration-biogeochemistry model based on this emerging theory. The model, TREEScav, is capable of predicting transpiration, along with carbon and nutrient flows, constrained by plant structure and function. The model incorporates tightly coupled mechanisms of the demand and supply of water through the soil-xylem-stomata system, with the feedbacks to photosynthesis and utilizable carbohydrates. The model is evaluated by testing it against transpiration and carbon flux data along an elevation gradient of woody plants comprising sagebrush steppe, mid-elevation lodgepole pine forests, and subalpine spruce/fir forests in the Rocky Mountains. The model accurately predicts transpiration and carbon fluxes as measured from gas exchange, sap flux, and eddy covariance towers. The results of this work demonstrate that credible spatial predictions of transpiration and related

Modeling stomatal conductance in the Earth system: linking leaf water-use efficiency and water transport along the soil-plant-atmosphere continuum

NASA Astrophysics Data System (ADS)

Bonan, G. B.; Williams, M.; Fisher, R. A.; Oleson, K. W.

2014-05-01

The empirical Ball-Berry stomatal conductance model is commonly used in Earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must both be empirically parameterized. We evaluated the Ball-Berry model used in the Community Land Model version 4.5 (CLM4.5) and an alternative stomatal conductance model that links leaf gas exchange, plant hydraulic constraints, and the soil-plant-atmosphere continuum (SPA) to numerically optimize photosynthetic carbon gain per unit water loss while preventing leaf water potential dropping below a critical minimum level. We evaluated two alternative optimization algorithms: intrinsic water-use efficiency (Δ An/Δ gs, the marginal carbon gain of stomatal opening) and water-use efficiency (Δ An/Δ El, the marginal carbon gain of water loss). We implemented the stomatal models in a multi-layer plant canopy model, to resolve profiles of gas exchange, leaf water potential, and plant hydraulics within the canopy, and evaluated the simulations using: (1) leaf analyses; (2) canopy net radiation, sensible heat flux, latent heat flux, and gross primary production at six AmeriFlux sites spanning 51 site-years; and (3) parameter sensitivity analyses. Without soil moisture stress, the performance of the SPA stomatal conductance model was generally comparable to or somewhat better than the Ball-Berry model in flux tower simulations, but was significantly better than the Ball-Berry model when there was soil moisture stress. Functional dependence of gs on soil moisture emerged from the physiological theory linking leaf water-use efficiency and water flow to and from the leaf along the soil-to-leaf pathway rather than being imposed a priori, as in the Ball-Berry model. Similar functional dependence of gs on Ds emerged from the water-use efficiency optimization. Sensitivity analyses showed that two parameters (stomatal efficiency and

Gravitropism in Higher Plant Shoots 1

PubMed Central

Wheeler, Raymond M.; White, Rosemary G.; Salisbury, Frank B.

1986-01-01

Ethylene at 1.0 and 10.0 cubic centimeters per cubic meter decreased the rate of gravitropic bending in stems of cocklebur (Xanthium strumarium L.) and tomato (Lycopersicon esculentum Mill), but 0.1 cubic centimeter per cubic meter ethylene had little effect. Treating cocklebur plants with 1.0 millimolar aminoethoxyvinylglycine (AVG) (ethylene synthesis inhibitor) delayed stem bending compared with controls, but adding 0.1 cubic centimeter per cubic meter ethylene in the surrounding atmosphere (or applying 0.1% ethephon solution) partially restored the rate of bending of AVG-treated plants. Ethylene increases in bending stems, and AVG inhibits this. Virtually all newly synthesized ethylene appeared in bottom halves of horizontal stems, where ethylene concentrations were as much as 100 times those in upright stems or in top halves of horizontal stems. This was especially true when horizontal stems were physically restrained from bending. Ethylene might promote cell elongation in bottom tissues of a horizontal stem or indicate other factors there (e.g. a large amount of `functioning' auxin). Or top and bottom tissues may become differentially sensitive to ethylene. Auxin applied to one side of a vertical stem caused extreme bending away from that side; gibberellic acid, kinetin, and abscisic acid were without effect. Acidic ethephon solutions applied to one side of young seedlings of cocklebur, tomato, sunflower (Helianthus annuus L.), and soybean (Glycine max [L.] Merr.) caused bending away from that side, but neutral ethephon solutions did not cause bending. Buffered or unbuffered acid (HCl) caused similar bending. Neutral ethephon solutions produced typical ethylene symptoms (i.e. epinasty, inhibition of stem elongation). HCl or acidic ethephon applied to the top of horizontal stems caused downward bending, but these substances applied to the bottom of such stems inhibited growth and upward bending—an unexpected result. PMID:11539089

Linking agricultural practices, mycorrhizal fungi, and traits mediating plant-insect interactions.

PubMed

Barber, Nicholas A; Kiers, E Toby; Theis, Nina; Hazzard, Ruth V; Adler, Lynn S

2013-10-01

Agricultural management has profound effects on soil communities. Activities such as fertilizer inputs can modify the composition of arbuscular mycorrhizal fungi (AMF) communities, which form important symbioses with the roots of most crop plants. Intensive conventional agricultural management may select for less mutualistic AMF with reduced benefits to host plants compared to organic management, but these differences are poorly understood. AMF are generally evaluated based on their direct growth effects on plants. However, mycorrhizal colonization also may alter plant traits such as tissue nutrients, defensive chemistry, or floral traits, which mediate important plant-insect interactions like herbivory and pollination. To determine the effect of AMF from different farming practices on plant performance and traits that putatively mediate species interactions, we performed a greenhouse study by inoculating Cucumis sativus (cucumber, Cucurbitaceae) with AMF from conventional farms, organic farms, and a commercial AMF inoculum. We measured growth and a suite of plant traits hypothesized to be important predictors of herbivore resistance and pollinator attraction. Several leaf and root traits and flower production were significantly affected by AMF inoculum. Both conventional and organic AMF reduced leaf P content but increased Na content compared to control and commercial AMF. Leaf defenses were unaffected by AMF treatments, but conventional AMF increased root cucurbitacin C, the primary defensive chemical of C. sativus, compared to organic AMF. These effects may have important consequences for herbivore preference and population dynamics. AMF from both organic and conventional farms decreased flower production relative to commercial and control treatments, which may reduce pollinator attraction and plant reproduction. AMF from both farm types also reduced seed germination, but effects on plant growth were limited. Our results suggest that studies only considering AMF

Hormonal interactions and gene regulation can link monoecy and environmental plasticity to the evolution of dioecy in plants.

PubMed

Golenberg, Edward M; West, Nicholas W

2013-06-01

Most models for dioecy in flowering plants assume that dioecy arises directly from hermaphroditism through a series of independent feminizing and masculinizing mutations that become chromosomally linked. However, dioecy appears to evolve most frequently through monoecious grades. The major genetic models do not explain the evolution of unisexual flowers in monoecious and submonoecious populations, nor do they account for environmentally induced sexual plasticity. In this review, we explore the roles of environmental stress and hormones on sex determination, and propose a model that can explain the evolution of dioecy through monoecy, and the mechanisms of environmental sex determination. Environmental stresses elicit hormones that allow plants to mediate the negative effects of the stresses. Many of these same hormones are involved in the regulation of floral developmental genes. Recent studies have elucidated the mechanisms whereby these hormones interact and can act as switchpoints in regulatory pathways. Consequently, differential concentrations of plant hormones can regulate whole developmental pathways, providing a mechanism for differential development within isogenic individuals such as seen in monoecious plants. Sex-determining genes in such systems will evolve to generate clusters of coexpressed suites. Coexpression rather than coinheritance of gender-specific genes will define the sexual developmental fate. Therefore, selection for gender type will drive evolution of the regulatory sequences of such genes rather than their synteny. Subsequent mutations to hyper- or hyposensitive alleles within the hormone response pathway can result in segregating dioecious populations. Simultaneously, such developmental systems will remain sensitive to external stimuli that modify hormone responses.

Potential link between plant and fungal distributions in a dipterocarp rainforest: community and phylogenetic structure of tropical ectomycorrhizal fungi across a plant and soil ecotone.

PubMed

Peay, Kabir G; Kennedy, Peter G; Davies, Stuart J; Tan, Sylvester; Bruns, Thomas D

2010-01-01

*Relatively little is known about diversity or structure of tropical ectomycorrhizal communities or their roles in tropical ecosystem dynamics. In this study, we present one of the largest molecular studies to date of an ectomycorrhizal community in lowland dipterocarp rainforest. *We sampled roots from two 0.4 ha sites located across an ecotone within a 52 ha forest dynamics plot. Our plots contained > 500 tree species and > 40 species of ectomycorrhizal host plants. Fungi were identified by sequencing ribosomal RNA genes. *The community was dominated by the Russulales (30 species), Boletales (17), Agaricales (18), Thelephorales (13) and Cantharellales (12). Total species richness appeared comparable to molecular studies of temperate forests. Community structure changed across the ecotone, although it was not possible to separate the role of environmental factors vs host plant preferences. Phylogenetic analyses were consistent with a model of community assembly where habitat associations are influenced by evolutionary conservatism of functional traits within ectomycorrhizal lineages. *Because changes in the ectomycorrhizal fungal community parallel those of the tree community at this site, this study demonstrates the potential link between the distribution of tropical tree diversity and the distribution of tropical ectomycorrhizal diversity in relation to local-scale edaphic variation.

Photosynthetic and respiratory activity in germfree higher plant species

NASA Technical Reports Server (NTRS)

1976-01-01

Equipment developed for the study of gas exchange in germfree plants is described. The equipment includes a gas exchange chamber to house the plant under study, a gas feed assembly to introduce and remove gas from the chamber, and a clinostat to rotate the apparatus. Fluorescent and incandescent lights are used to illuminate the chamber and a sealed plastic barrier is used to isolate the potting soil from the chamber atmosphere. The gas outflow from the chamber can be diverted to an infrared CO2 analyzer. The performance of the system was evaluated.

Plant probiotic bacteria Bacillus and Paraburkholderia improve growth, yield and content of antioxidants in strawberry fruit.

PubMed

Rahman, Mosaddiqur; Sabir, Abdullah As; Mukta, Julakha Akter; Khan, Md Mohibul Alam; Mohi-Ud-Din, Mohammed; Miah, Md Giashuddin; Rahman, Mahfuzur; Islam, M Tofazzal

2018-02-06

Strawberry is an excellent source of natural antioxidants with high capacity of scavenging free radicals. This study evaluated the effects of two plant probiotic bacteria, Bacillus amylolequefaciens BChi1 and Paraburkholderia fungorum BRRh-4 on growth, fruit yield and antioxidant contents in strawberry fruits. Root dipping of seedlings (plug plants) followed by spray applications of both probiotic bacteria in the field on foliage significantly increased fruit yield (up to 48%) over non-treated control. Enhanced fruit yield likely to be linked with higher root and shoot growth, individual and total fruit weight/plant and production of phytohormone by the probiotic bacteria applied on plants. Interestingly, the fruits from plants inoculated with the isolates BChi1 and BRRh-4 had significantly higher contents of phenolics, carotenoids, flavonoids and anthocyanins over non-treated control. Total antioxidant activities were also significantly higher (p < 0.05) in fruits of strawberry plants treated with both probiotic bacteria. To the best of our knowledge, this is the first report of significant improvement of both yield and quality of strawberry fruits by the application of plant probiotic bacteria BChi1 and BRRh-4 in a field condition. Further study is needed to elucidate underlying mechanism of growth and quality improvement of strawberry fruits by probiotic bacteria.

Linking root hydraulic properties to carbon allocation patterns in annual plant

NASA Astrophysics Data System (ADS)

Hosseini, A.; Ewers, B. E.; Adjesiwor, A. T.; Kniss, A. R.

2017-12-01

Incorporation of root structure and function into biophysical models is an important tool to predict plant water and nutrient uptake from the soil, plant carbon (C) assimilation, partitioning and release to the soils. Most of the models describing root water uptake (RWU) are based on semi-empirical (i.e. built on physiological hypotheses, but still combined with empirical functions) approaches and hydraulic parameters involved are hardly available. Root conductance is essential to define the interaction between soil-to-root and canopy-to-atmosphere. Also root hydraulic limitations to water flow can impact gas exchange rates and plant biomass partitioning. In this study, sugar beet (B. vulgaris) seeds under two treatments, grass (Kentucky bluegrass) and no grass (control), were planted in 19 L plastic buckets in June 2016. Photosynthetic characteristics (e.g. gas exchange and chlorophyll fluorescence), leaf morphology and anatomy, root morphology and above and below ground biomass of the plants was monitored at 15, 30, 50, 70 and 90 days after planting (DAP). Further emphasis was placed on the limits to water flow by coupling of hydraulic conductance (k) whole root-system with water relation parameters and gas exchange rates in fully established plants.

Traditional uses of plants in a rural community of Mozambique and possible links with Miombo degradation and harvesting sustainability

PubMed Central

2014-01-01

Background Miombo woodlands play an important role in the livelihood of people living in sub-equatorial African countries, contributing to satisfy basic human needs such as food, medicine, fuelwood and building materials. However, over-exploitation of plant resources and unsustainable harvest practices can potentially degrade forests. The aim of this study was to document the use of Miombo plant products, other than medicinal plants, in local communities, within a wider framework in which we discussed possible links between traditional uses and conservation status of the used species and of the whole Miombo environment. Methods Fieldwork took place in four communities of Muda-Serração, central Mozambique. We conducted semi-structured interviews with 52 informants about their knowledge, use and harvesting practices of useful plants. A survey on local Miombo vegetation was also carried out in order to assess abundance and distribution of useful woody plants cited in the interviews in areas exposed to different exploitation rates. A Conservation Priority index was also applied to rank conservation values of each used woody species. Results Ninety-eight plants cited by the informants were botanically identified. The most relevant general category was represented by food plants (45 species), followed by handicraft plants (38 species) and domestic plants (37 species). Among the 54 woody species observed in vegetation plots, 52% were cited as useful in the interviews. Twenty-six woody species found in ‘natural’ Miombo areas were not found in ‘degraded’ ones: of these, 46% were cited in the interviews (58% in the food category, 50% in the handicraft category, 25% in the domestic category and 8% in the fishing category). Results of conservation ranking showed that 7 woody species deserve conservation priority in the investigated area. Conclusions This study shows that the communities investigated rely heavily on local forest products for their daily subsistence

Biological effects of weightlessness and clinostatic conditions registered in cells of root meristem and cap of higher plants

NASA Astrophysics Data System (ADS)

Sytnik, K. M.; Kordyum, E. L.; Belyavskaya, N. A.; Nedukha, E. M.; Tarasenko, V. A.

Research in cellular reproduction, differentiation and vital activity, i.e. processes underlying the development and functioning of organisms, plants included, is essential for solving fundamental and applied problems of space biology. Detailed anatomical analysis of roots of higher plants grown on board the Salyut 6 orbital research station show that under conditions of weightlessness for defined duration mitosis, cytokinesis and tissue differentiation in plant vegetative organs occur essentially normally. At the same time, certain rearrangements in the structural organization of cellular organelles - mainly the plastid apparatus, mitochondria, Golgi apparatus and nucleus - are established in the root meristem and cap of the experimental plants. This is evidence for considerable changes in cellular metabolism. The structural changes in the subcellular level arising under spaceflight conditions are partially absent in clinostat experiments designed to simulate weightlessness. Various clinostatic conditions have different influences on the cell structural and functional organization than does space flight. It is suggested that alterations of cellular metabolism under weightlessness and clinostatic conditions occur within existing genetic programs.

Aluminum, a Friend or Foe of Higher Plants in Acid Soils

PubMed Central

Bojórquez-Quintal, Emanuel; Escalante-Magaña, Camilo; Echevarría-Machado, Ileana; Martínez-Estévez, Manuel

2017-01-01

Aluminum (Al) is the most abundant metal in the earth’s crust, but its availability depends on soil pH. Despite this abundance, Al is not considered an essential element and so far no experimental evidence has been put forward for a biological role. In plants and other organisms, Al can have a beneficial or toxic effect, depending on factors such as, metal concentration, the chemical form of Al, growth conditions and plant species. Here we review recent advances in the study of Al in plants at physiological, biochemical and molecular levels, focusing mainly on the beneficial effect of Al in plants (stimulation of root growth, increased nutrient uptake, the increase in enzyme activity, and others). In addition, we discuss the possible mechanisms involved in improving the growth of plants cultivated in soils with acid pH, as well as mechanisms of tolerance to the toxic effect of Al. PMID:29075280

Cell biology of aluminum toxicity and tolerance in higher plants.

PubMed

Matsumoto, H

2000-01-01

Aluminum is the major element in the soil and exists as a stable complex with oxygen and silicate in neutral and weakly acidic soil. When the soil pH is lower than 4.5-5.0, Al is solubilized in the soil water and absorbed by plant roots. Absorbed Al inhibits root elongation severely, and the elongation of roots exposed to Al3+ as low as mumol level is inhibited within an hour(s). Thus much research has been conducted to understand the mechanism of Al toxicity and tolerance. Al is located specifically at the root apex. Al-sensitive plants absorb more Al than do Al-tolerant plants, and thus the exclusion mechanism of Al is the major idea for Al tolerance. The understanding of Al stress in plants is important for stable food production in future. Al is a complicated ion in its chemical form and biological function. In this chapter, mechanisms of Al toxicity and tolerance proposed during the past few decades as well as future topics are described from physiological and molecular points of view.

Traversing the Links between Heavy Metal Stress and Plant Signaling

PubMed Central

Jalmi, Siddhi K.; Bhagat, Prakash K.; Verma, Deepanjali; Noryang, Stanzin; Tayyeba, Sumaira; Singh, Kirti; Sharma, Deepika; Sinha, Alok K.

2018-01-01

Plants confront multifarious environmental stresses widely divided into abiotic and biotic stresses, of which heavy metal stress represents one of the most damaging abiotic stresses. Heavy metals cause toxicity by targeting crucial molecules and vital processes in the plant cell. One of the approaches by which heavy metals act in plants is by over production of reactive oxygen species (ROS) either directly or indirectly. Plants act against such overdose of metal in the environment by boosting the defense responses like metal chelation, sequestration into vacuole, regulation of metal intake by transporters, and intensification of antioxidative mechanisms. This response shown by plants is the result of intricate signaling networks functioning in the cell in order to transmit the extracellular stimuli into an intracellular response. The crucial signaling components involved are calcium signaling, hormone signaling, and mitogen activated protein kinase (MAPK) signaling that are discussed in this review. Apart from signaling components other regulators like microRNAs and transcription factors also have a major contribution in regulating heavy metal stress. This review demonstrates the key role of MAPKs in synchronously controlling the other signaling components and regulators in metal stress. Further, attempts have been made to focus on metal transporters and chelators that are regulated by MAPK signaling. PMID:29459874

Plant Water Relations.

ERIC Educational Resources Information Center

Tomley, David

1982-01-01

Some simple field investigations on plant water relations are described which demonstrate links between physiological and external environmental factors. In this way, a more complex picture of a plant and how it functions within its habitat and the effects the environment has on it can be built up. (Author/JN)

The Role of Higher Education in Linking Arts, Culture, and Economic Development

ERIC Educational Resources Information Center

Steinkamp, Judith S.

2004-01-01

In the knowledge economy, colleges and universities are realigning academic initiatives to link more closely with regional needs. They are unique catalysts for forming community alliances to focus on issues of economic development, neighborhood revitalization, and cultural tourism. In partnership with business, municipalities, and cultural…

Production characteristics of lettuce Lactuca sativa L. in the frame of the first crop tests in the Higher Plant Chamber integrated into the MELiSSA Pilot Plant

NASA Astrophysics Data System (ADS)

Tikhomirova, Natalia; Lawson, Jamie; Stasiak, Michael; Dixon, Mike; Paille, Christel; Peiro, Enrique; Fossen, Arnaud; Godia, Francesc

Micro-Ecological Life Support System Alternative (MELiSSA) is an artificial closed ecosystem that is considered a tool for the development of a bioregenerative life support system for manned space missions. One of the five compartments of MELiSSA loop -Higher Plant Chamber was recently integrated into the MELiSSA Pilot Plant facility at Universitat Aut`noma deo Barcelona. The main contributions expected by integration of this photosynthetic compartment are oxygen, water, vegetable food production and CO2 consumption. Production characteristics of Lactuca sativa L., as a MELiSSA candidate crop, were investigated in this work in the first crop experiments in the MELiSSA Pilot Plant facility. The plants were grown in batch culture and totaled 100 plants with a growing area 5 m long and 1 m wide in a sealed controlled environment. Several replicates of the experiments were carried out with varying duration. It was shown that after 46 days of lettuce cultivation dry edible biomass averaged 27, 2 g per plant. However accumulation of oxygen in the chamber, which required purging of the chamber, and decrease in the food value of the plants was observed. Reducing the duration of the tests allowed uninterrupted test without opening the system and also allowed estimation of the crop's carbon balance. Results of productivity, tissue composition, nutrient uptake and canopy photosynthesis of lettuce regardless of test duration are discussed in the paper.

Plant stress signalling: understanding and exploiting plant-plant interactions.

PubMed

Pickett, J A; Rasmussen, H B; Woodcock, C M; Matthes, M; Napier, J A

2003-02-01

When plants are attacked by insects, volatile chemical signals can be released, not only from the damaged parts, but also systemically from other parts of the plant and this continues after cessation of feeding by the insect. These signals are perceived by olfactory sensory mechanisms in both the herbivorous insects and their parasites. Molecular structures involved can be characterized by means of electrophysiological assays, using the insect sensory system linked to chemical analysis. Evidence is mounting that such signals can also affect neighbouring intact plants, which initiate defence by the induction of further signalling systems, such as those that increase parasitoid foraging. Furthermore, insect electrophysiology can be used in the identification of plant compounds having effects on the plants themselves. It has been found recently that certain plants can release stress signals even when undamaged, and that these can cause defence responses in intact plants. These discoveries provide the basis for new crop protection strategies, that are either delivered by genetic modification of plants or by conventionally produced plants to which the signal is externally applied. Delivery can also be made by means of mixed seed strategies in which the provoking and recipient plants are grown together. Related signalling discoveries within the rhizosphere seem set to extend these approaches into new ways of controlling weeds, by exploiting the elusive potential of allelopathy, but through signalling rather than by direct physiological effects.

Effect of woody and herbaceous plants on chemical weathering of basalt material

NASA Astrophysics Data System (ADS)

Mark, N.; Dontsova, K.; Barron-Gafford, G. A.

2011-12-01

acids exuded by plants and respired CO2 have been linked to mineral weathering. Increased weathering in grass treatments also resulted in higher concentrations of plant nutrients. No effect of temperature on plant exudation or basalt weathering was observed in the course of the experiment. This work links physiological plant responses to temperature and water stress by two vegetation types with below-ground processes that result in soil evolution.

Direct isolation of a functional violaxanthin cycle domain from thylakoid membranes of higher plants.

PubMed

Goss, Reimund; Greifenhagen, Anne; Bergner, Juliane; Volke, Daniela; Hoffmann, Ralf; Wilhelm, Christian; Schaller-Laudel, Susann

2017-04-01

A special domain of the thylakoid membrane of higher plants has been isolated which carries out the de-epoxidation of the xanthophyll cycle pigment violaxanthin to zeaxanthin. Recent models indicate that in the chloroplast of higher plants, the violaxanthin (V) cycle takes place within specialized domains in the thylakoid membrane. Here, we describe a new procedure to directly isolate such a domain in functional state. The procedure consists of a thylakoid membrane isolation at a pH value of 5.2 which realizes the binding of the enzyme V de-epoxidase (VDE) to the membrane throughout the preparation process. Isolated thylakoid membranes are then solubilized with the very mild detergent n-dodecyl α-D-maltoside and the pigment-protein complexes are separated by sucrose gradient ultracentrifugation. The upper main fraction of the sucrose gradient represents a V cycle domain which consists of the major light-harvesting complex of photosystem II (LHCII), a special lipid composition with an enrichment of the galactolipid monogalactosyldiacylglycerol (MGDG) and the VDE. The domain is isolated in functional state as evidenced by the ability to convert the LHCII-associated V to zeaxanthin. The direct isolation of a V cycle domain proves the most important hypotheses concerning the de-epoxidation reaction in intact thylakoid membranes. It shows that the VDE binds to the thylakoid membrane at low pH values of the thylakoid lumen, that it binds to membrane regions enriched in LHCII, and that the domain contains high amounts of MGDG. The last point is in line with the importance of the galactolipid for V solubilisation and, by providing inverted hexagonal lipid structures, for VDE activity.

Experiential Learning in Higher Education: Linking Classroom and Community. ASHE-ERIC Higher Education Report No. 7.

ERIC Educational Resources Information Center

Cantor, Jeffrey A.

This report reviews the literature and research on the use of experiential learning in higher education, focusing on classroom-community linkages. It defines experiential learning and reviews the current employment of experiential learning in higher education. An introductory section explains the politics and policy issues of experiential learning…

Structures and Strategies for Linking the Higher Education and Employment Communities. Higher Education/CETA Project Monograph.

ERIC Educational Resources Information Center

Clark, Donald M.; Rinehart, Richard L.

A model is presented for establishing or improving cooperative relationships between higher education and the employment community, as part of the American Council on Education's Higher Education/Comprehensive Employment and Training Act (CETA) Project, which was supported by the Fund for the Improvement of Postsecondary Education. Attention is…

The insects as an assessment tool of ecotoxicology associated with metal toxic plants.

PubMed

Azmat, Rafia; Moin, Sumeira; Saleem, Ailyan

2018-04-01

In this article, the assessment of lethal effects of Copper (Cu) on Luffa acutangula and Spinacia oleracea plants investigated in relation to the presence of insect species Oxycarenus hyalinipennis. The analysis of Cu-treated plants displays the information of rapid growth of Oxycarenus hyalinipennis species in triplicate. However, results showed that the impact of metal toxicity appeared as the reduced growth rate of plants, and dense growth of the insect species Oxycarenus halinipennis followed by the chewing/degradation of the toxic plant. The insect's inductees into polluted plants were justified by morphological and primary molecular level using plant stress hypothesis through analysis of the primary chemistry of leaves and roots. That includes various sugar contents which substantiated that these compounds act as the best feeding stimulant from oviposition to adult stage of the insects and accountable for the enactment of insects in the toxic plants. The relationship of these insects to the toxic plants linked with the higher contents of glucose, carbohydrates, and cellulose. The higher carbohydrate and cellulose content in both plants species under Cu accumulation exhibited more signs of insect mutilation over control plants and the lack of chemical resistances allowed the adult insects to spread, survive, reproduce and live long. The presence of insects developed relationships that assimilate all developmental, biological, and the interactive toxicity of Cu in both plant species which indicate the risk associated with these plants. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of prolonged drought on stem non-structural carbohydrates content and post-drought hydraulic recovery in Laurus nobilis L.: The possible link between carbon starvation and hydraulic failure.

PubMed

Trifilò, Patrizia; Casolo, Valentino; Raimondo, Fabio; Petrussa, Elisa; Boscutti, Francesco; Lo Gullo, Maria Assunta; Nardini, Andrea

2017-11-01

Drought-induced tree decline is a complex event, and recent hypotheses suggest that hydraulic failure and carbon starvation are co-responsible for this process. We tested the possible role of non-structural carbohydrates (NSC) content on post-drought hydraulic recovery, to verify the hypothesis that embolism reversal represents a mechanistic link between carbon starvation and stem hydraulics. Measurements were performed in laurel plants subjected to similar water stress levels either over short or long term, to induce comparable embolism levels. Plants subjected to mild and prolonged water shortage (S) showed reduced growth, adjustment of turgor loss point driven by changes in both osmotic potential at full turgor and bulk modulus of elasticity, a lower content of soluble NSC and a higher content of starch with respect to control (C) plants. Moreover, S plants showed a lower ability to recover from xylem embolism than C plants, even after irrigation. Our data suggest that plant carbon status might indirectly influence plant performance during and after drought via effects on xylem hydraulic functioning, supporting the view of a possible mechanistic link between the two processes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The specific features of methionine biosynthesis and metabolism in plants

PubMed Central

Ravanel, Stéphane; Gakière, Bertrand; Job, Dominique; Douce, Roland

1998-01-01

Plants, unlike other higher eukaryotes, possess all the necessary enzymatic equipment for de novo synthesis of methionine, an amino acid that supports additional roles than simply serving as a building block for protein synthesis. This is because methionine is the immediate precursor of S-adenosylmethionine (AdoMet), which plays numerous roles of being the major methyl-group donor in transmethylation reactions and an intermediate in the biosynthesis of polyamines and of the phytohormone ethylene. In addition, AdoMet has regulatory function in plants behaving as an allosteric activator of threonine synthase. Among the AdoMet-dependent reactions occurring in plants, methylation of cytosine residues in DNA has raised recent interest because impediment of this function alters plant morphology and induces homeotic alterations in flower organs. Also, AdoMet metabolism seems somehow implicated in plant growth via an as yet fully understood link with plant-growth hormones such as cytokinins and auxin and in plant pathogen interactions. Because of this central role in cellular metabolism, a precise knowledge of the biosynthetic pathways that are responsible for homeostatic regulation of methionine and AdoMet in plants has practical implications, particularly in herbicide design. PMID:9636232

Structure of the higher plant light harvesting complex I: in vivo characterization and structural interdependence of the Lhca proteins.

PubMed

Klimmek, Frank; Ganeteg, Ulrika; Ihalainen, Janne A; van Roon, Henny; Jensen, Poul E; Scheller, Henrik V; Dekker, Jan P; Jansson, Stefan

2005-03-01

We have investigated the structure of the higher plant light harvesting complex of photosystem I (LHCI) by analyzing PSI-LHCI particles isolated from a set of Arabidopsis plant lines, each lacking a specific Lhca (Lhca1-4) polypeptide. Functional antenna size measurements support the recent finding that there are four Lhca proteins per PSI in the crystal structure [Ben-Shem, A., Frolow, F., and Nelson, N. (2003) Nature 426, 630-635]. According to HPLC analyses the number of pigment molecules bound within the LHCI is higher than expected from reconstitution studies or analyses of isolated native LHCI. Comparison of the spectra of the particles from the different lines reveals chlorophyll absorption bands peaking at 696, 688, 665, and 655 nm that are not present in isolated PSI or LHCI. These bands presumably originate from "gap" or "linker" pigments that are cooperatively coordinated by the Lhca and/or PSI proteins, which we have tentatively localized in the PSI-LHCI complex.

[Survivability and morphologic anomalies in higher plants wolffia arrhiza following exposure to heavy ions of the galactic space radiation].

PubMed

Nevzgodina, L V; Kaminskaia, E V; Maksimova, E N; Fatsius, R; Sherrer, K; Shtraukh, V

2000-01-01

Experimental data on the effects of spaceflight factors, space radiation in particular, on higher plant Wolffia arrhiza firstly exposed in the "Bioblock" assembly and measurements made by physical track detectors of heavy ions (HI) are presented. Death of individual Wolffia plants and morphologic anomalies were the basic evaluation criteria. The peculiar feature of this biological object consists in the possibility to reveal delayed effects after 1-2 months since space flight as Wolffia has a high rate of vegetative reproduction. German investigators through microscopic examination of track detectors performed identification of individual plants affected by HI. With specially developed software and a coordinate system of supposition of biolayers and track detectors with the accuracy of 1 micron, tracks and even separate sections of individual HI tracks were determined in biological objects. Thereafter each Wolffia plant hit by HI was examined and data were compared with other variants. As a result, correlation between Wolffia death rate and morphologic anomalies were determined at different times post flight and topography of HI tracks was found. It is hypothesized that morphological anomalies in Walffia were caused by direct hits of plant germs by heavy ions or close passage of particles.

Attenuation of the jasmonate burst, plant defensive traits, and resistance to specialist monarch caterpillars on shaded common milkweed (Asclepias syriaca).

PubMed

Agrawal, Anurag A; Kearney, Emily E; Hastings, Amy P; Ramsey, Trey E

2012-07-01

Plant responses to herbivory and light competition are often in opposing directions, posing a potential conflict for plants experiencing both stresses. For sun-adapted species, growing in shade typically makes plants more constitutively susceptible to herbivores via reduced structural and chemical resistance traits. Nonetheless, the impact of light environment on induced resistance has been less well-studied, especially in field experiments that link physiological mechanisms to ecological outcomes. Accordingly, we studied induced resistance of common milkweed (Asclepias syriaca, a sun-adapted plant), and linked hormonal responses, resistance traits, and performance of specialist monarch caterpillars (Danaus plexippus) in varying light environments. In natural populations, plants growing under forest-edge shade showed reduced levels of resistance traits (lower leaf toughness, cardenolides, and trichomes) and enhanced light-capture traits (higher specific leaf area, larger leaves, and lower carbon-to-nitrogen ratio) compared to paired plants in full sun. In a field experiment repeated over two years, only milkweeds growing in full sun exhibited induced resistance to monarchs, whereas plants growing in shade were constitutively more susceptible and did not induce resistance. In a more controlled field experiment, plant hormones were higher in the sun (jasmonic acid, salicylic acid, abscisic acid, indole acidic acid) and were induced by herbivory (jasmonic acid and abscisic acid). In particular, the jasmonate burst following herbivory was halved in plants raised in shaded habitats, and this correspondingly reduced latex induction (but not cardenolide induction). Thus, we provide a mechanistic basis for the attenuation of induced plant resistance in low resource environments. Additionally, there appears to be specificity in these interactions, with light-mediated impacts on jasmonate-induction being stronger for latex exudation than cardenolides.

Links between plant and fungal diversity in habitat fragments of coastal shrubland

DOE PAGES

Maltz, Mia R.; Treseder, Kathleen K.; McGuire, Krista L.

2017-09-19

Habitat fragmentation is widespread across ecosystems, detrimentally affecting biodiversity. Although most habitat fragmentation studies have been conducted on macroscopic organisms, microbial communities and fungal processes may also be threatened by fragmentation. This study investigated whether fragmentation, and the effects of fragmentation on plants, altered fungal diversity and function within a fragmented shrubland in southern California. Using fluorimetric techniques, we assayed enzymes from plant litter collected from fragments of varying sizes to investigate enzymatic responses to fragmentation. To isolate the effects of plant richness from those of fragment size on fungi, we deployed litter bags containing different levels of plant littermore » diversity into the largest fragment and incubated in the field for one year. Following field incubation, we determined litter mass loss and conducted molecular analyses of fungal communities. We found that leaf-litter enzyme activity declined in smaller habitat fragments with less diverse vegetation. Moreover, we detected greater litter mass loss in litter bags containing more diverse plant litter. Additionally, bags with greater plant litter diversity harbored greater numbers of fungal taxa. These findings suggest that both plant litter resources and fungal function may be affected by habitat fragmentation's constraints on plants, possibly because plant species differ chemically, and may thus decompose at different rates. Diverse plant assemblages may produce a greater variety of litter resources and provide more ecological niche space, which may support greater numbers of fungal taxa. Thus, reduced plant diversity may constrain both fungal taxa richness and decomposition in fragmented coastal shrublands. Altogether, our findings provide evidence that even fungi may be affected by human-driven habitat fragmentation via direct effects of fragmentation on plants. Our findings underscore the importance of

Links between plant and fungal diversity in habitat fragments of coastal shrubland

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

Maltz, Mia R.; Treseder, Kathleen K.; McGuire, Krista L.

Habitat fragmentation is widespread across ecosystems, detrimentally affecting biodiversity. Although most habitat fragmentation studies have been conducted on macroscopic organisms, microbial communities and fungal processes may also be threatened by fragmentation. This study investigated whether fragmentation, and the effects of fragmentation on plants, altered fungal diversity and function within a fragmented shrubland in southern California. Using fluorimetric techniques, we assayed enzymes from plant litter collected from fragments of varying sizes to investigate enzymatic responses to fragmentation. To isolate the effects of plant richness from those of fragment size on fungi, we deployed litter bags containing different levels of plant littermore » diversity into the largest fragment and incubated in the field for one year. Following field incubation, we determined litter mass loss and conducted molecular analyses of fungal communities. We found that leaf-litter enzyme activity declined in smaller habitat fragments with less diverse vegetation. Moreover, we detected greater litter mass loss in litter bags containing more diverse plant litter. Additionally, bags with greater plant litter diversity harbored greater numbers of fungal taxa. These findings suggest that both plant litter resources and fungal function may be affected by habitat fragmentation's constraints on plants, possibly because plant species differ chemically, and may thus decompose at different rates. Diverse plant assemblages may produce a greater variety of litter resources and provide more ecological niche space, which may support greater numbers of fungal taxa. Thus, reduced plant diversity may constrain both fungal taxa richness and decomposition in fragmented coastal shrublands. Altogether, our findings provide evidence that even fungi may be affected by human-driven habitat fragmentation via direct effects of fragmentation on plants. Our findings underscore the importance of

Recent advances in plant-herbivore interactions

PubMed Central

Burkepile, Deron E.; Parker, John D.

2017-01-01

Plant-herbivore interactions shape community dynamics across marine, freshwater, and terrestrial habitats. From amphipods to elephants and from algae to trees, plant-herbivore relationships are the crucial link generating animal biomass (and human societies) from mere sunlight. These interactions are, thus, pivotal to understanding the ecology and evolution of virtually any ecosystem. Here, we briefly highlight recent advances in four areas of plant-herbivore interactions: (1) plant defense theory, (2) herbivore diversity and ecosystem function, (3) predation risk aversion and herbivory, and (4) how a changing climate impacts plant-herbivore interactions. Recent advances in plant defense theory, for example, highlight how plant life history and defense traits affect and are affected by multiple drivers, including enemy pressure, resource availability, and the local plant neighborhood, resulting in trait-mediated feedback loops linking trophic interactions with ecosystem nutrient dynamics. Similarly, although the positive effect of consumer diversity on ecosystem function has long been recognized, recent advances using DNA barcoding to elucidate diet, and Global Positioning System/remote sensing to determine habitat selection and impact, have shown that herbivore communities are probably even more functionally diverse than currently realized. Moreover, although most diversity-function studies continue to emphasize plant diversity, herbivore diversity may have even stronger impacts on ecosystem multifunctionality. Recent studies also highlight the role of risk in plant-herbivore interactions, and risk-driven trophic cascades have emerged as landscape-scale patterns in a variety of ecosystems. Perhaps not surprisingly, many plant-herbivore interactions are currently being altered by climate change, which affects plant growth rates and resource allocation, expression of chemical defenses, plant phenology, and herbivore metabolism and behavior. Finally, we conclude by

Results of the first stage (2002-2009) of investigation of higher plants onboard RS ISS, as an element of future closed Life Support Systems

NASA Astrophysics Data System (ADS)

Sychev, Vladimir; Levinskikh, Margarita; Podolsky, Igor; Bingham, Gail; Novikova, Nataliya; Sugimoto, Manabu

A key task for biomedical human support in long-term manned space expeditions is the develop-ment of the Life Support System (LSS). It is expected that in the first continuous interplanetary expeditions LSS of only a few biological elements of the LSS, such as higher plants will be in-cluded. Therefore, investigations of growth and development of higher plants for consideration in the LSS are of high importance. In a period from October, 2002 to December 2009, 15 ex-periments on cultivation of different plants, including two genetically marked species of dwarf peas, a leaf vegetable strain of Mizuna, radish, barley and wheat were conducted in space greenhouse "LADA" onboard Russian Segment (RS) of International Space Station (ISS). The experiments resulted in the conclusion that the properties of growth and development of plants grown in space greenhouse "LADA" were unaffected by spaceflight conditions. In experiments conducted in a period from 2003 to 2005, it was shown for the first time that pea plants pre-serve reproductive functions, forming viable seeds during at least four continuous full cycles of ontogenesis ("seed to seed") under spaceflight conditions. No changes were found in the genetic apparatus of the pea plants in the four "space" generations. Since 2005, there have been routine collections of microbiological samples from the surfaces of the plants grown on-board in "LADA" greenhouse. Analysis has shown that the properties of contamination of the plants grown aboard by microorganism contain no abnormal patterns. Since 2008, the plants cultivated in "LADA" greenhouse have been frozen onboard RS ISS in the MELFI refrigerator and transferred to the Earth for further investigations. Investigations of Mizuna plants grown and frozen onboard of ISS, showed no differences between "ground control" and "space" plants in chemical and biochemical properties. There also no stress-response was found in kashinriki strain barley planted and frozen onboard ISS.

Glycerophosphocholine metabolism in higher plant cells. Evidence of a new glyceryl-phosphodiester phosphodiesterase.

PubMed

van der Rest, Benoît; Boisson, Anne-Marie; Gout, Elisabeth; Bligny, Richard; Douce, Roland

2002-09-01

Glycerophosphocholine (GroPCho) is a diester that accumulates in different physiological processes leading to phospholipid remodeling. However, very little is known about its metabolism in higher plant cells. (31)P-Nuclear magnetic resonance spectroscopy and biochemical analyses performed on carrot (Daucus carota) cells fed with GroPCho revealed the existence of an extracellular GroPCho phosphodiesterase. This enzymatic activity splits GroPCho into sn-glycerol-3-phosphate and free choline. In vivo, sn-glycerol-3-phosphate is further hydrolyzed into glycerol and inorganic phosphate by acid phosphatase. We visualized the incorporation and the compartmentation of choline and observed that the major choline pool was phosphorylated and accumulated in the cytosol, whereas a minor fraction was incorporated in the vacuole as free choline. Isolation of plasma membranes, culture medium, and cell wall proteins enabled us to localize this phosphodiesterase activity on the cell wall. We also report the existence of an intracellular glycerophosphodiesterase. This second activity is localized in the vacuole and hydrolyzes GroPCho in a similar fashion to the cell wall phosphodiesterase. Both extra- and intracellular phosphodiesterases are widespread among different plant species and are often enhanced during phosphate deprivation. Finally, competition experiments on the extracellular phosphodiesterase suggested a specificity for glycerophosphodiesters (apparent K(m) of 50 microM), which distinguishes it from other phosphodiesterases previously described in the literature.

Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

PubMed Central

Algeo, T. J.

1998-01-01

The Devonian Period was characterized by major changes in both the terrestrial biosphere, e.g. the evolution of trees and seed plants and the appearance of multi-storied forests, and in the marine biosphere, e.g. an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface between the lithosphere and atmosphere/hydrosphere, and the role of land plants in mediating weathering processes at this interface. The effectiveness of terrestrial floras in weathering was significantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Devonian. In this regard, the most important palaeobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in a transient intensification of pedogenesis (soil formation) and to large increases in the thickness and areal extent of soils. Enhanced chemical weathering may have led to increased riverine nutrient fluxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon fluxes. Long-term effects included drawdown of atmospheric pCO2 and global cooling, leading to a brief Late Devonian glaciation, which set the stage for icehouse conditions during the Permo-Carboniferous. This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial-marine teleconnections is needed.

Regulation of sucrose metabolism in higher plants: localization and regulation of activity of key enzymes

NASA Technical Reports Server (NTRS)

Winter, H.; Huber, S. C.; Brown, C. S. (Principal Investigator)

2000-01-01

Sucrose (Suc) plays a central role in plant growth and development. It is a major end product of photosynthesis and functions as a primary transport sugar and in some cases as a direct or indirect regulator of gene expression. Research during the last 2 decades has identified the pathways involved and which enzymes contribute to the control of flux. Availability of metabolites for Suc synthesis and 'demand' for products of sucrose degradation are important factors, but this review specifically focuses on the biosynthetic enzyme sucrose-phosphate synthase (SPS), and the degradative enzymes, sucrose synthase (SuSy), and the invertases. Recent progress has included the cloning of genes encoding these enzymes and the elucidation of posttranslational regulatory mechanisms. Protein phosphorylation is emerging as an important mechanism controlling SPS activity in response to various environmental and endogenous signals. In terms of Suc degradation, invertase-catalyzed hydrolysis generally has been associated with cell expansion, whereas SuSy-catalyzed metabolism has been linked with biosynthetic processes (e.g., cell wall or storage products). Recent results indicate that SuSy may be localized in multiple cellular compartments: (1) as a soluble enzyme in the cytosol (as traditionally assumed); (2) associated with the plasma membrane; and (3) associated with the actin cytoskeleton. Phosphorylation of SuSy has been shown to occur and may be one of the factors controlling localization of the enzyme. The purpose of this review is to summarize some of the recent developments relating to regulation of activity and localization of key enzymes involved in sucrose metabolism in plants.

Diets higher in animal and plant protein are associated with lower adiposity and do not impair kidney function in US adults.

PubMed

Berryman, Claire E; Agarwal, Sanjiv; Lieberman, Harris R; Fulgoni, Victor L; Pasiakos, Stefan M

2016-09-01

Higher-protein diets are associated with decreased adiposity and greater HDL cholesterol than lower protein diets. Whether these benefits can be attributed to a specific protein source (i.e., nondairy animal, dairy, or plant) is unknown, and concerns remain regarding the impact of higher-protein diets on kidney function. The objective of this study was to evaluate trends of protein source on markers of cardiometabolic disease risk and kidney function in US adults. Total, nondairy animal, dairy, and plant protein intake were estimated with the use of 24-h recall data from NHANES 2007-2010 (n = 11,111; ≥19 y). Associations between source-specific protein intake and health outcomes were determined with the use of models that adjusted for sex, race and ethnicity, age, physical activity, poverty-to-income ratio, individual intake (grams per kilogram) for each of the other 2 protein sources, body mass index (BMI) (except for weight-related variables), and macronutrient (carbohydrate, fiber, and total and saturated fat) intake. Mean ± SE total protein intake was 82.3 ± 0.8 g/d (animal: 37.4 ± 0.5 g/d; plant: 24.7 ± 0.3 g/d; and dairy: 13.4 ± 0.3 g/d). Both BMI and waist circumference were inversely associated [regression coefficient (95% CI)] with animal [-0.199 (-0.265, -0.134), P < 0.0001; -0.505 (-0.641, -0.370), P < 0.0001] and plant [-0.346 (-0.455, -0.237), P < 0.0001; -0.826 (-1.114, -0.538), P < 0.0001] protein intake. Blood urea nitrogen concentrations increased across deciles for animal [0.313 (0.248, 0.379), P < 0.0001; decile 1-10: 11.6 ± 0.2 to 14.9 ± 0.3 mg/dL] and dairy [0.195 (0.139, 0.251), P < 0.0001; decile 1-10: 12.7 ± 0.2 to 13.9 ± 0.2 mg/dL] but not plant protein intake. Glomerular filtration rate and blood creatinine were not associated with intake of any protein source. Diets higher in plant and animal protein, independent of other dietary factors, are associated with cardiometabolic benefits, particularly improved central adiposity

Herbivore-Triggered Electrophysiological Reactions: Candidates for Systemic Signals in Higher Plants and the Challenge of Their Identification1

PubMed Central

Zimmermann, Matthias R.; Will, Torsten; Felle, Hubert H.; Furch, Alexandra C.U.

2016-01-01

In stressed plants, electrophysiological reactions (elRs) are presumed to contribute to long-distance intercellular communication between distant plant parts. Because of the focus on abiotic stress-induced elRs in recent decades, biotic stress-triggered elRs have been widely ignored. It is likely that the challenge to identify the particular elR types (action potential [AP], variation potential, and system potential [SP]) was responsible for this course of action. Thus, this survey focused on insect larva feeding (Spodoptera littoralis and Manduca sexta) that triggers distant APs, variation potentials, and SPs in monocotyledonous and dicotyledonous plant species (Hordeum vulgare, Vicia faba, and Nicotiana tabacum). APs were detected only after feeding on the stem/culm, whereas SPs were observed systemically following damage to both stem/culm and leaves. This was attributed to the unequal vascular innervation of the plant and a selective electrophysiological connectivity of the plant tissue. However, striking variations in voltage patterns were detected for each elR type. Further analyses (also in Brassica napus and Cucurbita maxima) employing complementary electrophysiological approaches in response to different stimuli revealed various reasons for these voltage pattern variations: an intrinsic plasticity of elRs, a plant-specific signature of elRs, a specific influence of the applied (a)biotic trigger, the impact of the technical approach, and/or the experimental setup. As a consequence, voltage pattern variations, which are not irregular but rather common, need to be included in electrophysiological signaling analysis. Due to their widespread occurrence, systemic propagation, and respective triggers, elRs should be considered as candidates for long-distance communication in higher plants. PMID:26872949

Temperature stress and plant sexual reproduction: uncovering the weakest links.

PubMed

Zinn, Kelly E; Tunc-Ozdemir, Meral; Harper, Jeffrey F

2010-04-01

The reproductive (gametophytic) phase in flowering plants is often highly sensitive to hot or cold temperature stresses, with even a single hot day or cold night sometimes being fatal to reproductive success. This review describes studies of temperature stress on several crop plants, which suggest that pollen development and fertilization may often be the most sensitive reproductive stage. Transcriptome and proteomic studies on several plant species are beginning to identify stress response pathways that function during pollen development. An example is provided here of genotypic differences in the reproductive stress tolerance between two ecotypes of Arabidopsis thaliana Columbia (Col) and Hilversum (Hi-0), when reproducing under conditions of hot days and cold nights. Hi-0 exhibited a more severe reduction in seed set, correlated with a reduction in pollen tube growth potential and tropism defects. Hi-0 thus provides an Arabidopsis model to investigate strategies for improved stress tolerance in pollen. Understanding how different plants cope with stress during reproductive development offers the potential to identify genetic traits that could be manipulated to improve temperature tolerance in selected crop species being cultivated in marginal climates.

THE BIOSYNTHESIS OF HYDROXYBENZOIC ACIDS IN HIGHER PLANTS

DTIC Science & Technology

some species. Ortho hydroxybenzoic acids were shown to arise from phenylalanine and cinnamic acid ....Radioactive para-hydroxybenzoic, vanillic and syringic acids were shown to be synthesized in a variety of plants from the corresponding...hydroxycinnamic acids labelled in the beta-position. Decarboxylation of the hydroxybenzoic acids indicated that nearly all the activity was contained in the

Has the plant genetic variability any role in models of water transfer in the soil-plant-atmosphere continuum ?

NASA Astrophysics Data System (ADS)

Tardieu, F.

2012-04-01

Water transfer in the SPAC is essentially linked to environmental conditions such as evaporative demand or soil water potential, and physical parameters such as soil hydraulic capacity or hydraulic conductivity. Models used in soil science most often represent the plant via a small number of variables such as the water flux that crosses the base of the stem or the root length (or area) in each soil layer. Because there is an increasing demand for computer simulations of plants that would perform better under water deficit, models of SPA water transfer are needed that could better take into account the genetic variability of traits involved in plant hydraulics. (i) The water flux through the plant is essentially limited by stomata, which present a much higher resistance to water flow than those in the soil - root continuum. This can lead to unexpected relations between flux, leaf water potential and root hydraulic conductance. (ii) A large genetic variability exists within and between species for stomatal control, with important consequences for the minimum soil water potential that is accessible to the plant. In particular, isohydric plants that maintain leaf water potential in a narrow range via stomatal control have a higher (nearer to 0) 'wilting point' than anisohydric plants that allow leaf water potential to reach very low values. (iii) The conductivity for water transfer in roots and shoots is controlled by plants via aquaporins. It largely varies with time of the day, water and nutrient status, in particular via plant hormones and circadian rhythms. Models of SPA water transfer with a time definition of minutes to hour should probably not ignore this, while those with longer time steps are probably less sensitive to changes in plant hydraulic conductivity. (iv) The "dogma" that dense root systems provide tolerance to water deficit is profoundly affected when the balance "H2O gain vs C investment" is taken into account. At least three programmes of recurrent

An expanding universe of circadian networks in higher plants.

PubMed

Pruneda-Paz, Jose L; Kay, Steve A

2010-05-01

Extensive circadian clock networks regulate almost every biological process in plants. Clock-controlled physiological responses are coupled with daily oscillations in environmental conditions resulting in enhanced fitness and growth vigor. Identification of core clock components and their associated molecular interactions has established the basic network architecture of plant clocks, which consists of multiple interlocked feedback loops. A hierarchical structure of transcriptional feedback overlaid with regulated protein turnover sets the pace of the clock and ultimately drives all clock-controlled processes. Although originally described as linear entities, increasing evidence suggests that many signaling pathways can act as both inputs and outputs within the overall network. Future studies will determine the molecular mechanisms involved in these complex regulatory loops. 2010 Elsevier Ltd. All rights reserved.

TCP three-way handshake: linking developmental processes with plant immunity.

PubMed

Lopez, Jessica A; Sun, Yali; Blair, Peter B; Mukhtar, M Shahid

2015-04-01

The TCP gene family encodes plant-specific transcription factors involved in growth and development. Equally important are the interactions between TCP factors and other pathways extending far beyond development, as they have been found to regulate a variety of hormonal pathways and signaling cascades. Recent advances reveal that TCP factors are targets of pathogenic effectors and are likely to play a vital role in plant immunity. Our focus is on reviewing the involvement of TCP in known pathways and shedding light on other linkages in the nexus of plant immunity centered around TCP factors with an emphasis on the convergence of effectors, interconnected hormonal networks, utility of the circadian clock, and the potential mechanisms by which pathogen defense may occur. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methods of expressing and detecting activity of expansin in plant cells

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

Hood, Elizabeth E.; Yoon, Sangwoong

A method of expressing heterologous expansin in a plant cell is provided where a nucleic acid molecule encoding expansin is introduced into the plant cell and in an embodiment is operably linked to a promoter preferentially expressing in the seed tissue of the plant, and in another embodiment is linked to a promoter preferentially expressing in the embryo tissue of the seed. An embodiment provides the nucleic acid molecule is operably linked to a second nucleic acid molecule that directs expression to the endoplasmic reticulum, vacuole or cell wall. Plants and plant parts expressing expansin are provided. An assay formore » detection of expansin activity is also provided.« less

Organization of transport from endoplasmic reticulum to Golgi in higher plants.

PubMed

Andreeva, A V; Zheng, H; Saint-Jore, C M; Kutuzov, M A; Evans, D E; Hawes, C R

2000-01-01

In plant cells, the organization of the Golgi apparatus and its interrelationships with the endoplasmic reticulum differ from those in mammalian and yeast cells. Endoplasmic reticulum and Golgi apparatus can now be visualized in plant cells in vivo with green fluorescent protein (GFP) specifically directed to these compartments. This makes it possible to study the dynamics of the membrane transport between these two organelles in the living cells. The GFP approach, in conjunction with a considerable volume of data about proteins participating in the transport between endoplasmic reticulum and Golgi in yeast and mammalian cells and the identification of their putative plant homologues, should allow the establishment of an experimental model in which to test the involvement of the candidate proteins in plants. As a first step towards the development of such a system, we are using Sar1, a small G-protein necessary for vesicle budding from the endoplasmic reticulum. This work has demonstrated that the introduction of Sar1 mutants blocks the transport from endoplasmic reticulum to Golgi in vivo in tobacco leaf epidermal cells and has therefore confirmed the feasibility of this approach to test the function of other proteins that are presumably involved in this step of endomembrane trafficking in plant cells.

PlantDB – a versatile database for managing plant research

PubMed Central

Exner, Vivien; Hirsch-Hoffmann, Matthias; Gruissem, Wilhelm; Hennig, Lars

2008-01-01

Background Research in plant science laboratories often involves usage of many different species, cultivars, ecotypes, mutants, alleles or transgenic lines. This creates a great challenge to keep track of the identity of experimental plants and stored samples or seeds. Results Here, we describe PlantDB – a Microsoft® Office Access database – with a user-friendly front-end for managing information relevant for experimental plants. PlantDB can hold information about plants of different species, cultivars or genetic composition. Introduction of a concise identifier system allows easy generation of pedigree trees. In addition, all information about any experimental plant – from growth conditions and dates over extracted samples such as RNA to files containing images of the plants – can be linked unequivocally. Conclusion We have been using PlantDB for several years in our laboratory and found that it greatly facilitates access to relevant information. PMID:18182106

Nano and micro mechanical properties of uncross-linked and cross-linked chitosan films

PubMed Central

Aryaei, Ashkan; Jayatissa, Ahalapitiya H.; Jayasuriya, A. Champa

2016-01-01

The aim of this study is to determine the nano and micro mechanical properties for uncross-linked and cross-linked chitosan films. Specifically, we looked at nanoindentation hardness, microhardness, and elastic modulus. It is important to study the nano and microscale mechanical properties of chitosan since chitosan has been widely used for biomedical applications. Using the solvent-cast method, the chitosan films were prepared at room temperature on the cleaned glass plates. The chitosan solution was prepared by dissolving chitosan in acetic acid 1% (v/v). Tripolyphosphate (TPP) was used to create the cross-links between amine groups in chitosan and phosphate groups in TPP. In this study, atomic force microscopy was used to measure the nanoindentation hardness and surface topography of the uncross-linked and cross-linked chitosan films. Elastic modulus was then calculated from the nanoindentation results. The effective elastic modulus was determined by microhardness with some modifications to previous theories. The microhardness of the chitosan films were measured using Vicker’s hardness meter under three different loads. Our results show that the microhardness and elastic modulus for cross-linked chitosan films are higher than the uncross-linked films. However, the cross-linked chitosan films show increased brittleness when compared to uncross-linked films. By increasing the load magnitude, the microhardness increases for both uncross-linked and cross-linked chitosan films. PMID:22100082

Biochar-stimulated plant performance is strongly linked to microbial diversity and metabolic potential in the rhizosphere.

PubMed

Kolton, Max; Graber, Ellen R; Tsehansky, Ludmila; Elad, Yigal; Cytryn, Eddie

2017-02-01

The 'biochar effect' depicts a phenomenon in which biochar soil amendment enhances plant performance by promoting growth and suppressing disease. Although this phenomenon has been observed in numerous studies, the mode of action that explains it is currently unknown. In order to elucidate mechanisms responsible for the 'biochar effect', we comprehensively monitored tomato plant development and resistance to the foliar fungal pathogen Botrytis cinerea, in biochar-amended and nonamended soils using native biochar and washed biochar, striped of labile chemical constituents. We concomitantly assessed bacterial community succession in the rhizosphere by high-throughput 16S rRNA gene amplicon sequencing and carbon-source utilization profiling. Biochar had little impact on plant physiological parameters. However, both native and washed biochar treatments were characterized by higher rhizosphere bacterial diversity and enhanced carbohydrate and phenolic compound utilization rates coupled to stimulation of bacteria known to degrade phenolic compounds. This study indicates that the 'biochar effect' is at least partially dictated by increased diversity and changes in metabolic potential in the rhizosphere microbiome, which is primarily triggered by the recalcitrant carbon backbone of the biochar and tightly bound compounds. It corresponds to the growing consensus that soil amendments which enhance microbial diversity have important benefits to ecosystem functioning. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Ab initio calculations of the Fe(II) and Fe(III) isotopic effects in citrates, nicotianamine, and phytosiderophore, and new Fe isotopic measurements in higher plants

NASA Astrophysics Data System (ADS)

Moynier, Frédéric; Fujii, Toshiyuki; Wang, Kun; Foriel, Julien

2013-05-01

Iron is one of the most abundant transition metal in higher plants and variations in its isotopic compositions can be used to trace its utilization. In order to better understand the effect of plant-induced isotopic fractionation on the global Fe cycling, we have estimated by quantum chemical calculations the magnitude of the isotopic fractionation between different Fe species relevant to the transport and storage of Fe in higher plants: Fe(II)-citrate, Fe(III)-citrate, Fe(II)-nicotianamine, and Fe(III)-phytosiderophore. The ab initio calculations show firstly, that Fe(II)-nicotianamine is ˜3‰ (56Fe/54Fe) isotopically lighter than Fe(III)-phytosiderophore; secondly, even in the absence of redox changes of Fe, change in the speciation alone can create up to ˜1.5‰ isotopic fractionation. For example, Fe(III)-phytosiderophore is up to 1.5‰ heavier than Fe(III)-citrate2 and Fe(II)-nicotianamine is up to 1‰ heavier than Fe(II)-citrate. In addition, in order to better understand the Fe isotopic fractionation between different plant components, we have analyzed the iron isotopic composition of different organs (roots, seeds, germinated seeds, leaves and stems) from six species of higher plants: the dicot lentil (Lens culinaris), and the graminaceous monocots Virginia wild rye (Elymus virginicus), Johnsongrass (Sorghum halepense), Kentucky bluegrass (Poa pratensis), river oat (Uniola latifolia), and Indian goosegrass (Eleusine indica). The calculations may explain that the roots of strategy-II plants (Fe(III)-phytosiderophore) are isotopically heavier (by about 1‰ for the δ56Fe) than the upper parts of the plants (Fe transported as Fe(III)-citrate in the xylem or Fe(II)-nicotianamine in the phloem). In addition, we suggest that the isotopic variations observed between younger and older leaves could be explained by mixing of Fe received from the xylem and the phloem.

Bridging Multiple Lines Of Evidence To Quantify Plant Phenology And Assess Links To Dryland Ecosystem Function

NASA Astrophysics Data System (ADS)

Browning, D. M.; Tweedie, C. E.; Vivoni, E. R.; Maynard, J. J.; Karl, J.

2015-12-01

The clear and pressing need to reliably identify and predict shifts in plant phenology at landscape scales requires a critical link between mechanistic understanding of climate drivers and broad scale forecasts of plant responses to climate change. A multi-scale phenology study co-located with two eddy covariance towers was initiated on the Jornada Basin LTER in New Mexico in 2010 to bridge phenology patterns at the plant level with those representing aggregated signals at the landscape level. The study integrates phenology observations collected in the field along with those collected via remotely using imagery from phenocams, unmanned aerial vehicles (UAVs), and satellite sensors along with estimates of carbon flux. We applied the Breaks for Additive Seasonal and Trend (BFAST) time series algorithm to MODIS 250-m NDVI greenness index values to partition the NDVI signal into components representing the long-term trend, seasonal periodicity, and residuals and identified significant shifts in the NDVI signal (i.e., "breaks"). Previous work verified breaks representing significant deviations from the BFAST seasonal and trend models using field-estimated plant biomass collected between 2000 and 2014. We subsequently examine estimates of fractional cover by functional group derived from UAV images acquired 2010 through 2015. At a mixed grassland site, the BFAST algorithm detected four breaks in the trend model denoting significant increases in NDVI in May 2004, July 2006, and March 2010 and a significant decrease in May 2012. The 2004 and 2006 breaks corresponded to herbaceous vegetation responses to rainfall following prolonged periods of drought. The 2012 decrease in NDVI corresponded to the marked reduction of herbaceous biomass following an exceptionally dry period in late 2010-2011. Seasonal breaks representing changes in the timing and magnitude of NDVI identified in July 2006 and September 2008 coincide with rapid increases in production of annual species in

A cysteine-rich plant protein potentiates Potyvirus movement through an interaction with the virus genome-linked protein VPg.

PubMed

Dunoyer, P; Thomas, C; Harrison, S; Revers, F; Maule, A

2004-03-01

We have identified a cellular factor that interacts with the virus genome-linked proteins (VPgs) of a diverse range of potyviruses. The factor, called Potyvirus VPg-interacting protein (PVIP), is a plant-specific protein with homologues in all the species examined, i.e., pea, Arabidopsis thaliana, and Nicotiana benthamiana. The sequence of PVIP does not identify a specific function, although the existence of a "PHD finger" domain may implicate the protein in transcriptional control through chromatin remodeling. Deletion analysis using the yeast two-hybrid system showed that the determinants of the interaction lay close to the N terminus of VPg; indeed, the N-terminal 16 amino acids were shown to be both necessary and sufficient for the interaction with at least one PVIP protein. From a sequence comparison of different potyvirus VPg proteins, a specific amino acid at position 12 was directly implicated in the interaction. This part of VPg is distinct from regions associated with other functional roles of VPg. Through mutation of Turnip mosaic virus (TuMV) at VPg position 12, we showed that the interaction with PVIP affected systemic symptoms in infected plants. This resulted from reduced cell-to-cell and systemic movement more than reduced virus replication, as visualized by comparing green fluorescent protein-tagged wild-type and mutant viruses. Furthermore, by using RNA interference of PVIP in Arabidopsis, we showed that reduced expression of PVIP genes reduced susceptibility to TuMV infection. We conclude that PVIP functions as an ancillary factor to support potyvirus movement in plants.

Early Successional Microhabitats Allow the Persistence of Endangered Plants in Coastal Sand Dunes

PubMed Central

2015-01-01

Many species are adapted to disturbance and occur within dynamic, mosaic landscapes that contain early and late successional microhabitats. Human modification of disturbance regimes alters the availability of microhabitats and may affect the viability of species in these ecosystems. Because restoring historical disturbance regimes is typically expensive and requires action at large spatial scales, such restoration projects must be justified by linking the persistence of species with successional microhabitats. Coastal sand dune ecosystems worldwide are characterized by their endemic biodiversity and frequent disturbance. Dune-stabilizing invasive plants alter successional dynamics and may threaten species in these ecosystems. We examined the distribution and population dynamics of two federally endangered plant species, the annual Layia carnosa and the perennial Lupinus tidestromii, within a dune ecosystem in northern California, USA. We parameterized a matrix population model for L. tidestromii and examined the magnitude by which the successional stage of the habitat (early or late) influenced population dynamics. Both species had higher frequencies and L. tidestromii had higher frequency of seedlings in early successional habitats. Lupinus tidestromii plants in early successional microhabitats had higher projected rates of population growth than those associated with stabilized, late successional habitats, due primarily to higher rates of recruitment in early successional microhabitats. These results support the idea that restoration of disturbance is critical in historically dynamic landscapes. Our results suggest that large-scale restorations are necessary to allow persistence of the endemic plant species that characterize these ecosystems. PMID:25835390

Linking plant ecology and long-term hydrology to improve wetland restoration success

Treesearch

P.V. Caldwell; M.J. Vepraskas; J.D. Gregory; R.W. Skaggs; R.L. Huffman

2011-01-01

Although millions of dollars are spent restoring wetlands, failures are common, in part because the planted vegetation cannot survive in the restored hydrology. Wetland restoration would be more successful if the hydrologic requirements of wetland plant communities were known so that the most appropriate plants could be selected for the range of projected hydrology at...

Retrofitting the Williams Energy Services Ignacio Plant for higher throughput and recovery

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

Lynch, J.T.; Pitman, R.N.

1999-07-01

The Ignacio Plant located near Durango, Colorado was originally designed to process 346 MMscfd of feed gas and to recover approximately 82% of the contained ethane. Based on increasing volumes of available feed gas, Williams Energy Services (WES) undertook a study to investigate alternatives for increasing plant capacity and ethane recovery. This study led to the selection of Ortloff's Recycle Split-Vapor (RSV) process for retrofitting the existing facility because it offered several very important advantages: maximum utilization of existing equipment, a 30% increase in plant feed handling capacity and an increase in average ethane recovery to 94% without adding residuemore » compressors. This paper presents the comparative case analysis that led to the selection of the RSV design. It also describes the modifications required for the retrofit, all of which can be accomplished with minimum plant down time. The modified Ignacio Plant is scheduled for startup in March 1999.« less

The cell biology of lignification in higher plants

PubMed Central

Barros, Jaime; Serk, Henrik; Granlund, Irene; Pesquet, Edouard

2015-01-01

Background Lignin is a polyphenolic polymer that strengthens and waterproofs the cell wall of specialized plant cell types. Lignification is part of the normal differentiation programme and functioning of specific cell types, but can also be triggered as a response to various biotic and abiotic stresses in cells that would not otherwise be lignifying. Scope Cell wall lignification exhibits specific characteristics depending on the cell type being considered. These characteristics include the timing of lignification during cell differentiation, the palette of associated enzymes and substrates, the sub-cellular deposition sites, the monomeric composition and the cellular autonomy for lignin monomer production. This review provides an overview of the current understanding of lignin biosynthesis and polymerization at the cell biology level. Conclusions The lignification process ranges from full autonomy to complete co-operation depending on the cell type. The different roles of lignin for the function of each specific plant cell type are clearly illustrated by the multiple phenotypic defects exhibited by knock-out mutants in lignin synthesis, which may explain why no general mechanism for lignification has yet been defined. The range of phenotypic effects observed include altered xylem sap transport, loss of mechanical support, reduced seed protection and dispersion, and/or increased pest and disease susceptibility. PMID:25878140

Sodium chloride accumulation in glycophyte plants with cyanobacterial symbionts

PubMed Central

Sancho, Leopoldo G; Pintado, Ana; Saco, Dolores; Martín, Soledad; Arróniz-Crespo, María; Angel Casermeiro, Miguel; de la Cruz Caravaca, Maria Teresa; Cameron, Steven; Rozzi, Ricardo

2017-01-01

Abstract The majority of plant species are glycophytes and are not salt-tolerant and maintain low sodium levels within their tissues; if. high tissue sodium concentrations do occur, it is in response to elevated environmental salt levels. Here we report an apparently novel and taxonomically diverse grouping of plants that continuously maintain high tissue sodium contents and share the rare feature of possessing symbiotic cyanobacteria. Leaves of Gunnera magellanica in Tierra del Fuego always had sodium contents (dry weight basis) of around 4.26 g kg−1, about 20 times greater than measured in other higher plants in the community (0.29 g kg−1). Potassium and chloride levels were also elevated. This was not a response to soil sodium and chloride levels as these were low at all sites. High sodium contents were also confirmed in G. magellanica from several other sites in Tierra del Fuego, in plants taken to, and cultivated in Madrid for 2 years at low soil salt conditions, and also in other free living or cultivated species of Gunnera from the UK and New Zealand. Gunnera species are the only angiosperms that possess cyanobacterial symbionts so we analysed other plants that have this rather rare symbiosis, all being glycophytes. Samples of Azolla, a floating aquatic fern, from Europe and New Zealand all had even higher sodium levels than Gunnera. Roots of the gymnosperm Cycas revoluta had lower sodium contents (2.52 ± 0.34 g kg−1) but still higher than the non-symbiotic glycophytes. The overaccumulation of salt even when it is at low levels in the environment appears to be linked to the possession of a cyanobacterial symbiosis although the actual functional basis is unclear. PMID:29225764

INTERNAL FILTERS: PROSPECTS FOR UV-ACCLIMATION IN HIGHER PLANTS

EPA Science Inventory

Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation (400-700nm) to the chloroplasts, while removing much of the damaging ultraviolet-B (UV-B, 280-320 nm) radiation. Flavonoids are important in this wavelength-selective ab...

Inclusion of human mineralized exometabolites and fish wastes as a source of higher plant mineral nutrition in BTLSS mass exchange

NASA Astrophysics Data System (ADS)

Tikhomirova, Natalia; Tikhomirov, Alexander A.; Ushakova, Sofya; Anischenko, Olesya; Trifonov, Sergey V.

Human exometabolites inclusion into an intrasystem mass exchange will allow increasing of a closure level of a biological-technical life support system (BTLSS). Previously at the IBP SB RAS it was shown that human mineralized exometabolites could be incorporated in the BTLSS mass exchange as a mineral nutrition source for higher plants. However, it is not known how that combined use of human mineralized exometabolites and fish wastes in the capacity of nutrient medium, being a part of the BTLSS consumer wastes, will affect the plant productivity. Several wheat vegetations were grown in an uneven-aged conveyor on a neutral substrate. A mixture of human mineralized exometabolites and fish wastes was used as a nutrient solution in the experiment treatment and human mineralized exometabolites were used in the control. Consequently, a high wheat yield in the experiment treatment practically equal to the control yield was obtained. Thus, mineralized fish wastes can be an additional source of macro-and micronutrients for plants, and use of such wastes for the plant mineral nutrition allows increasing of BTLSS closure level.

Phosphoinositide kinases and the synthesis of polyphosphoinositides in higher plant cells

NASA Technical Reports Server (NTRS)

Drobak, B. K.; Dewey, R. E.; Boss, W. F.; Davies, E. (Principal Investigator)

1999-01-01

Phosphoinositides are a family of inositol-containing phospholipids which are present in all eukaryotic cells. Although in most cells these lipids, with the exception of phosphatidylinositol, constitute only a very minor proportion of total cellular lipids, they have received immense attention by researchers in the past 15-20 years. This is due to the discovery that these lipids, rather than just having structural functions, play key roles in a wide range of important cellular processes. Much less is known about the plant phosphoinositides than about their mammalian counterparts. However, it has been established that a functional phosphoinositide system exists in plant cells and it is becoming increasingly clear that inositol-containing lipids are likely to play many important roles throughout the life of a plant. It is not our intention to give an exhaustive overview of all aspects of the field, but rather we focus on the phosphoinositide kinases responsible for the synthesis of all phosphorylated forms of phosphatidylinositol. Also, we mention some of the aspects of current phosphoinositide research which, in our opinion, are most likely to provide a suitable starting point for further research into the role of phosphoinositides in plants.

Plant and soil nutrient stoichiometry along primary ecological successions: Is there any link?

PubMed Central

Di Palo, Francesca

2017-01-01

Ecological stoichiometry suggests that plant Nitrogen (N)-to-Phosphorus (P) ratios respond to changes in both soil N:P stoichiometry and soil N and P availability. Thus we would expect that soil and plant N:P ratios be significantly related along natural gradients of soil development such as those associated with primary ecological successions. Here we explicitly search for linkages between plant and soil N:P stoichiometry along four primary successions distributed across Europe. We measured N and P content in soils and plant compartments (leaf, stem and root) of 72 wild plant species distributed along two sand dune and two glacier successions where soil age ranges from few to thousand years old. Overall we found that soil N:P ratios strongly increased along successional stages, however, plant N:P ratios were neither related to soil N:P stoichiometry nor to changes in soil N and P availability. Instead changes in plant nutrient stoichiometry were “driven” by plant-functional-group identity. Not only N:P ratios differed between legumes, grasses and forbs but each of these plant functional groups maintained N:P ratios relatively constant across pioneer, middle and advanced successional stages. Our evidence is that soil nutrient stoichiometry may not be a good predictor of changes in plant N:P stoichiometry along natural primary ecological successions, which have not reached yet a retrogressive stage. This could be because wild-plants rely on mechanisms of internal nutrient regulation, which make them less dependent to changes in soil nutrient availability under unpredictable environmental conditions. Further studies need to clarify what underlying evolutionary and eco-physiological mechanisms determine changes in nutrient stoichiometry in plant species distributed across natural environmental gradients. PMID:28787437

The Plant Ontology as a Tool for Comparative Plant Anatomy and Genomic Analyses

PubMed Central

Cooper, Laurel; Walls, Ramona L.; Elser, Justin; Gandolfo, Maria A.; Stevenson, Dennis W.; Smith, Barry; Preece, Justin; Athreya, Balaji; Mungall, Christopher J.; Rensing, Stefan; Hiss, Manuel; Lang, Daniel; Reski, Ralf; Berardini, Tanya Z.; Li, Donghui; Huala, Eva; Schaeffer, Mary; Menda, Naama; Arnaud, Elizabeth; Shrestha, Rosemary; Yamazaki, Yukiko; Jaiswal, Pankaj

2013-01-01

The Plant Ontology (PO; http://www.plantontology.org/) is a publicly available, collaborative effort to develop and maintain a controlled, structured vocabulary (‘ontology’) of terms to describe plant anatomy, morphology and the stages of plant development. The goals of the PO are to link (annotate) gene expression and phenotype data to plant structures and stages of plant development, using the data model adopted by the Gene Ontology. From its original design covering only rice, maize and Arabidopsis, the scope of the PO has been expanded to include all green plants. The PO was the first multispecies anatomy ontology developed for the annotation of genes and phenotypes. Also, to our knowledge, it was one of the first biological ontologies that provides translations (via synonyms) in non-English languages such as Japanese and Spanish. As of Release #18 (July 2012), there are about 2.2 million annotations linking PO terms to >110,000 unique data objects representing genes or gene models, proteins, RNAs, germplasm and quantitative trait loci (QTLs) from 22 plant species. In this paper, we focus on the plant anatomical entity branch of the PO, describing the organizing principles, resources available to users and examples of how the PO is integrated into other plant genomics databases and web portals. We also provide two examples of comparative analyses, demonstrating how the ontology structure and PO-annotated data can be used to discover the patterns of expression of the LEAFY (LFY) and terpene synthase (TPS) gene homologs. PMID:23220694

Final Report for Regulation of Embryonic Development in Higher Plants

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

Harada, John J.

2013-10-22

The overall goal of the project was to define the cellular processes that underlie embryo development in plants at a mechanistic level. Our studies focused on a critical transcriptional regulator, Arabidopsis LEAFY COTYLEDON (LEC1), that is necessary and sufficient to induce processes required for embryo development. Because LEC1 regulates lipid accumulation during the maturation phase of embryo development, information about LEC1 may be useful in designing approaches to enhance biofuel production in plants. During the tenure of this project, we determined the molecular mechanisms by which LEC1 acts as a transcription factor in embryos. We also identified genes directly regulatedmore » by LEC1 and showed that many of these genes are involved in maturation processes. This information has been useful in dissecting the gene regulatory networks controlling embryo development. Finally, LEC1 is a novel isoform of a transcription factor that is conserved among eukaryotes, and LEC1 is active primarily in seeds. Therefore, we determined that the LEC1-type transcription factors first appeared in lycophytes during land plant evolution. Together, this study provides basic information that has implications for biofuel production.« less

CBL-CIPK network for calcium signaling in higher plants

NASA Astrophysics Data System (ADS)

Luan, Sheng

Plants sense their environment by signaling mechanisms involving calcium. Calcium signals are encoded by a complex set of parameters and decoded by a large number of proteins including the more recently discovered CBL-CIPK network. The calcium-binding CBL proteins specifi-cally interact with a family of protein kinases CIPKs and regulate the activity and subcellular localization of these kinases, leading to the modification of kinase substrates. This represents a paradigm shift as compared to a calcium signaling mechanism from yeast and animals. One example of CBL-CIPK signaling pathways is the low-potassium response of Arabidopsis roots. When grown in low-K medium, plants develop stronger K-uptake capacity adapting to the low-K condition. Recent studies show that the increased K-uptake is caused by activation of a specific K-channel by the CBL-CIPK network. A working model for this regulatory pathway will be discussed in the context of calcium coding and decoding processes.

Growth and development in higher plants under simulated microgravity conditions on a 3-dimensional clinostat.

PubMed

Shimazu, T; Yuda, T; Miyamoto, K; Yamashita, M; Ueda, J

2001-01-01

Growth and development of etiolated pea (Pisum sativum L. cv. Alaska) and maize (Zea mays L. cv. Golden Cross Bantam) seedlings grown under simulated microgravity conditions were intensively studied using a 3-dimensional clinostat as a simulator of weightlessness. Epicotyls of etiolated pea seedlings grown on the clinostat were the most oriented toward the direction far from cotyledons. Mesocotyls of etiolated maize seedlings grew at random and coleoptiles curved slightly during clinostat rotation. Clinostat rotation promoted the emergence of the 3rd internodes in etiolated pea seedlings, while it significantly inhibited the growth of the 1st internodes. In maize seedlings, the growth of coleoptiles was little affected by clinostat rotation, but that of mesocotyls was suppressed, and therefore, the emergence of the leaf out of coleoptile was promoted. Clinostat rotation reduced the osmotic concentration in the 1st internodes of pea seedlings, although it has little effect on the 2nd and the 3rd internodes. Clinostat rotation also reduced the osmotic concentrations in both coleoptiles and mesocotyls of maize seedlings. Cell-wall extensibilities of the 1st and the 3rd internodes of pea seedlings grown on the clinostat were significantly lower and higher as compared with those on 1 g conditions, respectively. Cell-wall extensibility of mesocotyls in seedlings grown on the clinostat also decreased. Changes in cell wall properties seem to be well correlated to the growth of each organ in pea and maize seedlings. These results suggest that the growth and development of plants is controlled under gravity on earth, and that the growth responses of higher plants to microgravity conditions are regulated by both cell-wall mechanical properties and osmotic properties of stem cells. c 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Toxicity of combined chromium(VI) and phenanthrene pollution on the seed germination, stem lengths, and fresh weights of higher plants.

PubMed

Hu, Shuangqing; Gu, Hairong; Cui, Chunyan; Ji, Rong

2016-08-01

Studies of the interaction and toxicity of pollutant combinations such as heavy metals and PAHs are of practical importance in the remediation and monitoring of the industrial soil environment. This study investigated the single and combined toxicity of chromium(VI) and phenanthrene on three important higher plants: mung beans (Phaseolus aureus), pakchoi cabbage (Brassica chinensis), and rice (Oryza sativa). In experiments using artificial soil matrix, the EC10 and EC20 of the two pollutants, alone and in combination, were analyzed with respect to seed germination, stem length, and above-ground fresh weight of these higher plants. The additive index method was used to evaluate the combined biological toxicity of chromium(VI) and phenanthrene. The results showed that the EC20 of chromium(VI) on the stem lengths of mung beans, pakchoi cabbage, and rice was 289, 248, and 550 mg kg(-1), respectively. The corresponding EC20 values for the fresh weights of the three plants were 334, 307, and 551 mg kg(-1). The EC20 of phenanthrene on the stem lengths of mung beans, pakchoi cabbage, and rice was 528, 426, and 628 mg kg(-1), respectively. The corresponding EC20 values for the fresh weights of the three plants were 696, 585, and 768 mg kg(-1). The EC20 of a combination of chromium(VI) and phenanthrene on the stem lengths of mung beans, pakchoi cabbage, and rice was 192, 173, and 279 mg kg(-1), respectively, and 200, 205, and 271 mg kg(-1) for the fresh weights of the three plants. The single and combined exposure of soil to chromium(VI) and phenanthrene had deleterious effects on plants in the early stage of growth. Overall, pakchoi cabbage was more sensitive than mung beans and rice. The two pollutants exerted synergistic effects on the stem lengths and above-ground fresh weights of both mung beans and rice but antagonistic effects on pakchoi cabbage. The results of this study also suggested pakchoi cabbage as a sensitive indicator of soil pollution.

Design and implementation of components for a bioregenerative system for growing higher order plants in space

NASA Technical Reports Server (NTRS)

Brakman, B.; Dioso, L.; Parker, D.; Segal, L.; Merriman, C.; Howard, I.; Vu, H.; Anderson, K.; Riley, S.; Amery, D.

1989-01-01

This report summarizes the efforts of the NASA/USRA Advanced Design Program during the 1988-89 scholastic year. The primary goal was to address specific needs in the design of an integrated system to grow higher order plants in space. The initial phase of the design effort concentrated on studying such a system and identifying its needs. Once these needs were defined, emphasis was placed on the design and fabrication of devices to meet them. Specific attention was placed on a hand-held harvester, a nutrient concentration sensor, an air-water separator, and a closed-loop biological system simulation.

Plant mycorrhizal traits in Europe in relation to climatic and edaphic gradients

NASA Astrophysics Data System (ADS)

Guillermo Bueno, C.; Gerz, Maret; Zobel, Martin; Moora, Mari

2017-04-01

Around 90% of plant species associate with mycorrhizal fungi. The symbiosis is known to provide plants with soil N, P and water, and fungi with plant photosynthesized carbohydrates. However, not all mycorrhizal symbioses are identical. The identity of associated plant and fungal species differs, as does the effect of the symbiosis on nutrient cycling and ecosystems more generally. In this study, we analysed the European distribution of two plant mycorrhizal traits in relation to climatic and edaphic drivers. We used the European distribution of the frequency of mycorrhizal colonization (plant mycorrhizal status); whether mycorrhizal fungi either always (obligately mycorrhizal, OM), or sometimes (facultatively mycorrhizal, FM) colonize plant roots, and the four main plant mycorrhizal types; arbuscular (AM), ecto-(ECM), ericoid (ERM), and non-mycorrhizal (NM) plants. We expected AM species to predominate in ecosystems where most soil nutrients occur in inorganic forms (lower latitudes) and those with higher soil pH. By contrast, due to the saprophytic abilities of ECM and ERM fungi, we expected ECM and ERM plants to predominate in ecosystems where nutrients are bound to organic compounds (higher latitudes) and those with lower soil pH. NM plant species are known to be common in disturbed habitats or in extremely phosphorus poor ecosystems, such as the Arctic tundra. Our results showed that the distribution of mycorrhizal types was driven by temperature and soil pH, with increases of NM, ECM and ERM, and decreases of AM, with latitude. FM predominated over OM species and this difference increased with latitude and was dependent on temperature drivers only. These results represent the first evidence at a European scale of plant mycorrhizal distribution patterns linked with climatic and edaphic gradients, supporting the idea of a tight relationship between the mycorrhizal symbiosis and nutrient cycling.

Comparison of the suitability of two lichen species and one higher plant for monitoring airborne heavy metals.

PubMed

Aprile, Giuseppa Grazia; Di Salvatore, Mina; Carratù, Giovanna; Mingo, Antonio; Carafa, Anna Maria

2010-03-01

We compared the capacity to accumulate airborne heavy metals of two lichens (Flavoparmelia caperata and Parmotrema chinense) and one higher plant (Nerium oleander) at a very densely populated urban site near Naples. After 15, 45, 75, and 120 days of exposure at four sites with different levels of air pollution, equal portions of thalli and 20 leaves were collected, and four environmentally significant elements, Fe, Cu, Zn, and Pb, were measured by inductively coupled plasma analysis. To compare the accumulation rates of lichens and the vascular plant, we determined an index of relative accumulation rate of pollutants during time and the ratio between the concentrations of each element in exposed samples to that of control samples (exposed-to-control ratio). Our data indicate F. caperata as being the most suitable bioaccumulator, followed by P. chinense. N. oleander was also found to be a useful heavy metal biomonitor though not suitable as a bioaccumulator.

Linking Plant Specialization to Dependence in Interactions for Seed Set in Pollination Networks

PubMed Central

Tur, Cristina; Castro-Urgal, Rocío; Traveset, Anna

2013-01-01

Studies on pollination networks have provided valuable information on the number, frequency, distribution and identity of interactions between plants and pollinators. However, little is still known on the functional effect of these interactions on plant reproductive success. Information on the extent to which plants depend on such interactions will help to make more realistic predictions of the potential impacts of disturbances on plant-pollinator networks. Plant functional dependence on pollinators (all interactions pooled) can be estimated by comparing seed set with and without pollinators (i.e. bagging flowers to exclude them). Our main goal in this study was thus to determine whether plant dependence on current insect interactions is related to plant specialization in a pollination network. We studied two networks from different communities, one in a coastal dune and one in a mountain. For ca. 30% of plant species in each community, we obtained the following specialization measures: (i) linkage level (number of interactions), (ii) diversity of interactions, and (iii) closeness centrality (a measure of how much a species is connected to other plants via shared pollinators). Phylogenetically controlled regression analyses revealed that, for the largest and most diverse coastal community, plants highly dependent on pollinators were the most generalists showing the highest number and diversity of interactions as well as occupying central positions in the network. The mountain community, by contrast, did not show such functional relationship, what might be attributable to their lower flower-resource heterogeneity and diversity of interactions. We conclude that plants with a wide array of pollinator interactions tend to be those that are more strongly dependent upon them for seed production and thus might be those more functionally vulnerable to the loss of network interaction, although these outcomes might be context-dependent. PMID:24205187

Linking plant specialization to dependence in interactions for seed set in pollination networks.

PubMed

Tur, Cristina; Castro-Urgal, Rocío; Traveset, Anna

2013-01-01

Studies on pollination networks have provided valuable information on the number, frequency, distribution and identity of interactions between plants and pollinators. However, little is still known on the functional effect of these interactions on plant reproductive success. Information on the extent to which plants depend on such interactions will help to make more realistic predictions of the potential impacts of disturbances on plant-pollinator networks. Plant functional dependence on pollinators (all interactions pooled) can be estimated by comparing seed set with and without pollinators (i.e. bagging flowers to exclude them). Our main goal in this study was thus to determine whether plant dependence on current insect interactions is related to plant specialization in a pollination network. We studied two networks from different communities, one in a coastal dune and one in a mountain. For ca. 30% of plant species in each community, we obtained the following specialization measures: (i) linkage level (number of interactions), (ii) diversity of interactions, and (iii) closeness centrality (a measure of how much a species is connected to other plants via shared pollinators). Phylogenetically controlled regression analyses revealed that, for the largest and most diverse coastal community, plants highly dependent on pollinators were the most generalists showing the highest number and diversity of interactions as well as occupying central positions in the network. The mountain community, by contrast, did not show such functional relationship, what might be attributable to their lower flower-resource heterogeneity and diversity of interactions. We conclude that plants with a wide array of pollinator interactions tend to be those that are more strongly dependent upon them for seed production and thus might be those more functionally vulnerable to the loss of network interaction, although these outcomes might be context-dependent.

Links between Higher Education and Employers in Malawi: The Need for a Dialogue?

ERIC Educational Resources Information Center

Hall, David; Thomas, Harold

2005-01-01

The development of skills for employment is an important international policy area, but one that has been relatively ignored in sub-Saharan Africa. This paper reports on findings from a research project in Malawi, supported by the Department for International Development (DFID), that explored the links that exist between employers and the higher…

Visible light-induced oxidation of unsaturated components of cutins: a significant process during the senescence of higher plants.

PubMed

Rontani, Jean-François; Rabourdin, Adélaïde; Pinot, Franck; Kandel, Sylvie; Aubert, Claude

2005-02-01

9-Hydroperoxy-18-hydroxyoctadec-10(trans)-enoic and 10-hydroperoxy-18-hydroxyoctadec-8(trans)-enoic acids deriving from type II (i.e. involving 1O2) photooxidation of 18-hydroxyoleic acid were detected after visible light-induced senescence experiments carried out with Petroselinum sativum and subsequent cutin depolymerisation. These results showed that in senescent plants, where the 1O2 formation rate exceeds the quenching capacity of the photoprotective system, 1O2 can migrate outside the chloroplasts and affect the unsaturated components of cutins. Significant amounts of 9,18-dihydroxyoctadec-10(trans)-enoic and 10,18-dihydroxyoctadec-8(trans)-enoic acids resulting from the reduction of these photoproducts of 18-hydroxyoleic acid were also detected in different natural samples. These results well support the significance of the photooxidation of the unsaturated components of higher plant cutins in the natural environment.

Cytisus scoparius (L.) Link: Scotch broom

Treesearch

Susan E. Meyer

2008-01-01

The genus Cytisus comprises about 80 species native to Eurasia and North Africa. Many are cultivated as ornamentals, and several of these have become more or less naturalized in the United States, especially in California (Munz and Keck 1959). Scotch broom - C. scoparius (L.) Link - was planted extensively for erosion control during the first half of the century (Gill...

Engineering sciences design. Design and implementation of components for a bioregenerative system for growing higher order plants in space

NASA Technical Reports Server (NTRS)

Nevill, Gale E., Jr.

1989-01-01

The primary goal was to address specific needs in the design of an integrated system to grow higher plants in space. With the needs defined, the emphasis was placed on the design and fabrication of devices to meet these needs. Specific attention was placed on a hand-held harvester, a nutrient concentration sensor, an air-water separator, and a closed-loop biological system simulation.

Can plant biotechnology help break the HIV-malaria link?

PubMed

Vamvaka, E; Twyman, R M; Christou, P; Capell, T

2014-01-01

The population of sub-Saharan Africa is at risk from multiple, poverty-related endemic diseases. HIV and malaria are the most prevalent, but they disproportionately affect different groups of people, i.e. HIV predominantly affects sexually-active adults whereas malaria has a greater impact on children and pregnant women. Nevertheless, there is a significant geographical and epidemiological overlap which results in bidirectional and synergistic interactions with important consequences for public health. The immunosuppressive effects of HIV increase the risk of infection when individuals are exposed to malaria parasites and also the severity of malaria symptoms. Similarly, acute malaria can induce a temporary increase in the HIV viral load. HIV is associated with a wide range of opportunistic infections that can be misdiagnosed as malaria, resulting in the wasteful misuse of antimalarial drugs and a failure to address the genuine cause of the disease. There is also a cumulative risk of toxicity when antiretroviral and antimalarial drugs are given to the same patients. Synergistic approaches involving the control of malaria as a strategy to fight HIV/AIDS and vice versa are therefore needed in co-endemic areas. Plant biotechnology has emerged as a promising approach to tackle poverty-related diseases because plant-derived drugs and vaccines can be produced inexpensively in developing countries and may be distributed using agricultural infrastructure without the need for a cold chain. Here we explore some of the potential contributions of plant biotechnology and its integration into broader multidisciplinary public health programs to combat the two diseases in developing countries. Copyright © 2014 Elsevier Inc. All rights reserved.

OsSUV3 transgenic rice maintains higher endogenous levels of plant hormones that mitigates adverse effects of salinity and sustains crop productivity.

PubMed

Sahoo, Ranjan Kumar; Ansari, Mohammad Wahid; Tuteja, Renu; Tuteja, Narendra

2014-01-01

The SUV3 (suppressor of Var 3) gene encodes a DNA and RNA helicase, which is localized in the mitochondria. Plant SUV3 has not yet been characterized in detail. However, the Arabidopsis ortholog of SUV3 (AT4G14790) has been shown to be involved in embryo sac development. Previously, we have reported that rice SUV3 functions as DNA and RNA helicase and provides salinity stress tolerance by maintaining photosynthesis and antioxidant machinery. Here, we report further analysis of the transgenic OsSUV3 rice plants under salt stress. The transgenic OsSUV3 overexpressing rice T1 lines showed significantly higher endogenous content of plant hormones viz., gibberellic acid (GA3), zeatin (Z) and indole-3-acetic acid (IAA) in leaf, stem and root as compared to wild-type (WT), vector control (VC) and antisense (AS) plants under salt (200 mM NaCl) stress condition. A similar trend of endogenous plant hormones profile was also reflected in the T2 generation of OsSUV3 transgenic rice under defined parameters and stress condition. In response to stress, OsSUV3 rice plants maintained plant hormone levels that regulate the expression of several stress-induced genes and reduce adverse effects of salt on plant growth and development and therefore sustains crop productivity.

Phylogeny, plant species, and plant diversity influence carbon use phenotypes among Fusarium populations in the rhizosphere microbiome

USDA-ARS?s Scientific Manuscript database

Carbon use by microorganisms in the rhizosphere microbiome has been linked to plant pathogen suppression and increased mineralization of soil nutrients for plant uptake, however factors that influence carbon use traits are poorly understood for most microbial groups. This work characterized the rela...

Tobacco Mosaic Virus Infection Results in an Increase in Recombination Frequency and Resistance to Viral, Bacterial, and Fungal Pathogens in the Progeny of Infected Tobacco Plants1[C][W][OA

PubMed Central

Kathiria, Palak; Sidler, Corinne; Golubov, Andrey; Kalischuk, Melanie; Kawchuk, Lawrence M.; Kovalchuk, Igor

2010-01-01

Our previous experiments showed that infection of tobacco (Nicotiana tabacum) plants with Tobacco mosaic virus (TMV) leads to an increase in homologous recombination frequency (HRF). The progeny of infected plants also had an increased rate of rearrangements in resistance gene-like loci. Here, we report that tobacco plants infected with TMV exhibited an increase in HRF in two consecutive generations. Analysis of global genome methylation showed the hypermethylated genome in both generations of plants, whereas analysis of methylation via 5-methyl cytosine antibodies demonstrated both hypomethylation and hypermethylation. Analysis of the response of the progeny of infected plants to TMV, Pseudomonas syringae, or Phytophthora nicotianae revealed a significant delay in symptom development. Infection of these plants with TMV or P. syringae showed higher levels of induction of PATHOGENESIS-RELATED GENE1 gene expression and higher levels of callose deposition. Our experiments suggest that viral infection triggers specific changes in progeny that promote higher levels of HRF at the transgene and higher resistance to stress as compared with the progeny of unstressed plants. However, data reported in these studies do not establish evidence of a link between recombination frequency and stress resistance. PMID:20498336

Abiotic stress and the plant circadian clock

PubMed Central

Sanchez, Alfredo; Shin, Jieun

2011-01-01

In this review, we focus on the interaction between the circadian clock of higher plants to that of metabolic and physiological processes that coordinate growth and performance under a predictable, albeit changing environment. In this, the phytochrome and cryptochrome photoreceptors have shown to be important, but not essential for oscillator control under diurnal cycles of light and dark. From this foundation, we will examine how emerging findings have firmly linked the circadian clock, as a central mediator in the coordination of metabolism, to maintain homeostasis. This occurs by oscillator synchronization of global transcription, which leads to a dynamic control of a host of physiological processes. These include the determination of the levels of primary and secondary metabolites, and the anticipation of future environmental stresses, such as mid-day drought and midnight coldness. Interestingly, metabolic and stress cues themselves appear to feedback on oscillator function. In such a way, the circadian clock of plants and abiotic-stress tolerance appear to be firmly interconnected processes. PMID:21325898

Protein intrinsic disorder in plants.

PubMed

Pazos, Florencio; Pietrosemoli, Natalia; García-Martín, Juan A; Solano, Roberto

2013-09-12

To some extent contradicting the classical paradigm of the relationship between protein 3D structure and function, now it is clear that large portions of the proteomes, especially in higher organisms, lack a fixed structure and still perform very important functions. Proteins completely or partially unstructured in their native (functional) form are involved in key cellular processes underlain by complex networks of protein interactions. The intrinsic conformational flexibility of these disordered proteins allows them to bind multiple partners in transient interactions of high specificity and low affinity. In concordance, in plants this type of proteins has been found in processes requiring these complex and versatile interaction networks. These include transcription factor networks, where disordered proteins act as integrators of different signals or link different transcription factor subnetworks due to their ability to interact (in many cases simultaneously) with different partners. Similarly, they also serve as signal integrators in signaling cascades, such as those related to response to external stimuli. Disordered proteins have also been found in plants in many stress-response processes, acting as protein chaperones or protecting other cellular components and structures. In plants, it is especially important to have complex and versatile networks able to quickly and efficiently respond to changing environmental conditions since these organisms cannot escape and have no other choice than adapting to them. Consequently, protein disorder can play an especially important role in plants, providing them with a fast mechanism to obtain complex, interconnected and versatile molecular networks.

Protein intrinsic disorder in plants

PubMed Central

Pazos, Florencio; Pietrosemoli, Natalia; García-Martín, Juan A.; Solano, Roberto

2013-01-01

To some extent contradicting the classical paradigm of the relationship between protein 3D structure and function, now it is clear that large portions of the proteomes, especially in higher organisms, lack a fixed structure and still perform very important functions. Proteins completely or partially unstructured in their native (functional) form are involved in key cellular processes underlain by complex networks of protein interactions. The intrinsic conformational flexibility of these disordered proteins allows them to bind multiple partners in transient interactions of high specificity and low affinity. In concordance, in plants this type of proteins has been found in processes requiring these complex and versatile interaction networks. These include transcription factor networks, where disordered proteins act as integrators of different signals or link different transcription factor subnetworks due to their ability to interact (in many cases simultaneously) with different partners. Similarly, they also serve as signal integrators in signaling cascades, such as those related to response to external stimuli. Disordered proteins have also been found in plants in many stress-response processes, acting as protein chaperones or protecting other cellular components and structures. In plants, it is especially important to have complex and versatile networks able to quickly and efficiently respond to changing environmental conditions since these organisms cannot escape and have no other choice than adapting to them. Consequently, protein disorder can play an especially important role in plants, providing them with a fast mechanism to obtain complex, interconnected and versatile molecular networks. PMID:24062761

Plant Genome Resources at the National Center for Biotechnology Information

PubMed Central

Wheeler, David L.; Smith-White, Brian; Chetvernin, Vyacheslav; Resenchuk, Sergei; Dombrowski, Susan M.; Pechous, Steven W.; Tatusova, Tatiana; Ostell, James

2005-01-01

The National Center for Biotechnology Information (NCBI) integrates data from more than 20 biological databases through a flexible search and retrieval system called Entrez. A core Entrez database, Entrez Nucleotide, includes GenBank and is tightly linked to the NCBI Taxonomy database, the Entrez Protein database, and the scientific literature in PubMed. A suite of more specialized databases for genomes, genes, gene families, gene expression, gene variation, and protein domains dovetails with the core databases to make Entrez a powerful system for genomic research. Linked to the full range of Entrez databases is the NCBI Map Viewer, which displays aligned genetic, physical, and sequence maps for eukaryotic genomes including those of many plants. A specialized plant query page allow maps from all plant genomes covered by the Map Viewer to be searched in tandem to produce a display of aligned maps from several species. PlantBLAST searches against the sequences shown in the Map Viewer allow BLAST alignments to be viewed within a genomic context. In addition, precomputed sequence similarities, such as those for proteins offered by BLAST Link, enable fluid navigation from unannotated to annotated sequences, quickening the pace of discovery. NCBI Web pages for plants, such as Plant Genome Central, complete the system by providing centralized access to NCBI's genomic resources as well as links to organism-specific Web pages beyond NCBI. PMID:16010002

LAILAPS: the plant science search engine.

PubMed

Esch, Maria; Chen, Jinbo; Colmsee, Christian; Klapperstück, Matthias; Grafahrend-Belau, Eva; Scholz, Uwe; Lange, Matthias

2015-01-01

With the number of sequenced plant genomes growing, the number of predicted genes and functional annotations is also increasing. The association between genes and phenotypic traits is currently of great interest. Unfortunately, the information available today is widely scattered over a number of different databases. Information retrieval (IR) has become an all-encompassing bioinformatics methodology for extracting knowledge from complex, heterogeneous and distributed databases, and therefore can be a useful tool for obtaining a comprehensive view of plant genomics, from genes to traits. Here we describe LAILAPS (http://lailaps.ipk-gatersleben.de), an IR system designed to link plant genomic data in the context of phenotypic attributes for a detailed forward genetic research. LAILAPS comprises around 65 million indexed documents, encompassing >13 major life science databases with around 80 million links to plant genomic resources. The LAILAPS search engine allows fuzzy querying for candidate genes linked to specific traits over a loosely integrated system of indexed and interlinked genome databases. Query assistance and an evidence-based annotation system enable time-efficient and comprehensive information retrieval. An artificial neural network incorporating user feedback and behavior tracking allows relevance sorting of results. We fully describe LAILAPS's functionality and capabilities by comparing this system's performance with other widely used systems and by reporting both a validation in maize and a knowledge discovery use-case focusing on candidate genes in barley. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

Role of plant-rock interactions in the N cycle of oligotrophic environments

NASA Astrophysics Data System (ADS)

Gaddis, E. E.; Zaharescu, D. G.; Dontsova, K.; Chorover, J.; Galey, M.; Huxman, T. E.

2013-12-01

The vital role of nitrogen--an abundant, but inaccessible building block for growth--in plants is well known. At the same time, plants and microorganisms are driving forces for accumulation of available N in the soils as they form. A deep understanding of N cycle initiation, progression, and link to ecological systems and their development is therefore necessary. A mesocosm experiment was set up with the goal of exploring the role of interactions between four rock types and biota on N fate in oligotrophic environments. Basalt, rhyolite, granite, and schist were used with 6 treatments: abiotic control; microbes only; grass and microbes; pine and microbes; grass, microbes, and mycorrhizal fungi; and pine, microbes, and mycorrhizal fungi. Pinus ponderosa and Buchloe dactyloides were seeded on the different rock media and maintained with purified air and water but no nutrient additions for 8 month. Throughout the experiment leachate solution was collected and its chemical composition characterized, including organic and inorganic C and N. In addition, plant roots were scanned and their images analyzed to quantify their morphological features. Root parameters included measurements of length, surface area, diameter, volume, the number of tips, forks and links, altitude, and overall plant biomass. Over the 8 month period, there was sustained vegetation growth on all rocks without N addition. A high C:N ratio was seen across all substrates, indicating N deficiency. A strong relationship was observed between total N removal in soil leachate and a number of plant parameters, including plant biomass, total surface area of the roots, sum of the root tips, and total root volume. These relationships were the strongest in basalt, where the pines had higher root surface area than grasses and this was accompanied by higher total N in leachate. There was also a positive correlation between total N removal and the total biomass, total N and the sum of the root tips, and total N and

Requirements of blue, UV-A, and UV-B light for normal growth of higher plants, as assessed by action spectra for growth and related phenomena

NASA Technical Reports Server (NTRS)

Hashimoto, T.

1994-01-01

Artificial lighting is very important for experimental purposes, as well as for the practical use of plants when not enough sunlight is available. To grow green higher plants in their normal forms under artificial lighting constructing efficient and economically reasonable lighting systems is not an easy task. One possible approach would be to simulate sunlight in intensity and the radiation spectrum, but its high construction and running costs are not likely to allow its use in practice. Sunlight may be excessive in irradiance in some or all portions of the spectrum. Reducing irradiance and removing unnecessary wavebands might lead to an economically feasible light source. However, removing or reducing a particular waveband from sunlight for testing is not easy. Another approach might be to find the wavebands required for respective aspects of plant growth and to combine them in a proper ratio and intensity. The latter approach seems more practical and economical, and the aim of this Workshop lies in advancing this approach. I summarize our present knowledge on the waveband requirements of higher plants for the regions of blue, UV-A and UV-B.

Requirements of blue, UV-A, and UV-B light for normal growth of higher plants, as assessed by actions spectra for growth and related phenomena

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

Hashimoto, T.

1994-12-31

It is very important for experimental purposes, as well as for the practical use of plants when not enough sunlight is available. To grow green higher plants in their normal forms under artificial lighting constructing efficient and economically reasonable lighting systems is not an easy task. One possible approach would be to simulate sunlight in intensity and the radiation spectrum, but its high construction and running costs are not likely to allow its use in practice. Sunlight may be excessive in irradiance in some or all portions of the spectrum. Reducing irradiance and removing unnecessary wavebands might lead to anmore » economically feasible light source. However, removing or reducing a particular waveband from sunlight for testing is not easy. Another approach might be to find the wavebands required for respective aspects of plant growth and to combine them in a proper ratio and intensity. The latter approach seems more practical and economical, and the aim of this Workshop lies in advancing this approach. I summarize our present knowledge on the waveband requirements of higher plants for the regions of blue, UV-A and UV-B.« less

Plant Invasions in China – Challenges and Chances

PubMed Central

Axmacher, Jan C.; Sang, Weiguo

2013-01-01

Invasive species cause serious environmental and economic harm and threaten global biodiversity. We set out to investigate how quickly invasive plant species are currently spreading in China and how their resulting distribution patterns are linked to socio-economic and environmental conditions. A comparison of the invasive plant species density (log species/log area) reported in 2008 with current data shows that invasive species were originally highly concentrated in the wealthy, southeastern coastal provinces of China, but they are currently rapidly spreading inland. Linear regression models based on the species density and turnover of invasive plants as dependent parameters and principal components representing key socio-economic and environmental parameters as predictors indicate strong positive links between invasive plant density and the overall phytodiversity and associated climatic parameters. Principal components representing socio-economic factors and endemic plant density also show significant positive links with invasive plant density. Urgent control and eradication measures are needed in China's coastal provinces to counteract the rapid inland spread of invasive plants. Strict controls of imports through seaports need to be accompanied by similarly strict controls of the developing horticultural trade and underpinned by awareness campaigns for China's increasingly affluent population to limit the arrival of new invaders. Furthermore, China needs to fully utilize its substantial native phytodiversity, rather than relying on exotics, in current large-scale afforestation projects and in the creation of urban green spaces. PMID:23691164

The Heavy Links between Geological Events and Vascular Plants Evolution: A Brief Outline

PubMed Central

Piombino, Aldo

2016-01-01

Since the rise of photosynthesis, life has influenced terrestrial atmosphere, particularly the O2 and the CO2 content (the latter being originally more than 95%), changing the chemistry of waters, atmosphere, and soils. Billions of years after, a far offspring of these first unicellular forms conquered emerging lands, not only completely changing landscape, but also modifying geological cycles of deposition and erosion, many chemical and physical characteristics of soils and fresh waters, and, more, the cycle of various elements. So, there are no doubts that vascular plants modified geology; but it is true that also geology has affected (and, more, has driven) plant evolution. New software, PyRate, has determined vascular plant origin and diversification through a Bayesian analysis of fossil record from Silurian to today, particularly observing their origination and extinction rate. A comparison between PyRate data and geological history suggests that geological events massively influenced plant evolution and that also the rise of nonflowering seed plants and the fast diffusion of flowering plants can be explained, almost partly, with the environmental condition changes induced by geological phenomena. PMID:26966609

The Heavy Links between Geological Events and Vascular Plants Evolution: A Brief Outline.

PubMed

Piombino, Aldo

2016-01-01

Since the rise of photosynthesis, life has influenced terrestrial atmosphere, particularly the O2 and the CO2 content (the latter being originally more than 95%), changing the chemistry of waters, atmosphere, and soils. Billions of years after, a far offspring of these first unicellular forms conquered emerging lands, not only completely changing landscape, but also modifying geological cycles of deposition and erosion, many chemical and physical characteristics of soils and fresh waters, and, more, the cycle of various elements. So, there are no doubts that vascular plants modified geology; but it is true that also geology has affected (and, more, has driven) plant evolution. New software, PyRate, has determined vascular plant origin and diversification through a Bayesian analysis of fossil record from Silurian to today, particularly observing their origination and extinction rate. A comparison between PyRate data and geological history suggests that geological events massively influenced plant evolution and that also the rise of nonflowering seed plants and the fast diffusion of flowering plants can be explained, almost partly, with the environmental condition changes induced by geological phenomena.

Identifying and naming plant-pathogenic fungi: past, present, and future.

PubMed

Crous, Pedro W; Hawksworth, David L; Wingfield, Michael J

2015-01-01

Scientific names are crucial in communicating knowledge about fungi. In plant pathology, they link information regarding the biology, host range, distribution, and potential risk. Our understanding of fungal biodiversity and fungal systematics has undergone an exponential leap, incorporating genomics, web-based systems, and DNA data for rapid identification to link species to metadata. The impact of our ability to recognize hitherto unknown organisms on plant pathology and trade is enormous and continues to grow. Major challenges for phytomycology are intertwined with the Genera of Fungi project, which adds DNA barcodes to known biodiversity and corrects the application of old, established names via epi- or neotypification. Implementing the one fungus-one name system and linking names to validated type specimens, cultures, and reference sequences will provide the foundation on which the future of plant pathology and the communication of names of plant pathogens will rest.

Congruence and diversity of butterfly-host plant associations at higher taxonomic levels.

PubMed

Ferrer-Paris, José R; Sánchez-Mercado, Ada; Viloria, Ángel L; Donaldson, John

2013-01-01

We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1) is there a general correlation between host diversity and butterfly species richness?, (2) has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3) what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea) and 1,193 genera (66.3%). The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp.) from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae), and Satyrinae (42.6% of all Nymphalidae). We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test) was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids), but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages.

Congruence and Diversity of Butterfly-Host Plant Associations at Higher Taxonomic Levels

PubMed Central

Ferrer-Paris, José R.; Sánchez-Mercado, Ada; Viloria, Ángel L.; Donaldson, John

2013-01-01

We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1) is there a general correlation between host diversity and butterfly species richness?, (2) has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3) what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea) and 1,193 genera (66.3%). The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp.) from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae), and Satyrinae (42.6% of all Nymphalidae). We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test) was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids), but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages. PMID:23717448

Processes for producing polyhydroxybutyrate and related polyhydroxyalkanoates in the plastids of higher plants

DOEpatents

Somerville, C.R.; Nawrath, C.; Poirier, Y.

1997-03-11

The present invention relates to a process for producing poly-D-(-)-3-hydroxybutyric acid (PHB) and related polyhydroxyalkanoates (PHA) in the plastids of plants. The production of PHB is accomplished by genetically transforming plants with modified genes from microorganisms. The genes encode the enzymes required to synthesize PHB from acetyl-CoA or related metabolites and are fused with additional plant sequences for targeting the enzymes to the plastid. 37 figs.

Processes for producing polyhydroxybutyrate and related polyhydroxyalkanoates in the plastids of higher plants

DOEpatents

Somerville, Christopher R.; Nawrath, Christiane; Poirier, Yves

1997-03-11

The present invention relates to a process for producing poly-D-(-)-3-hydroxybutyric acid (PHB) and related polyhydroxyalkanoates (PHA) in the plastids of plants. The production of PHB is accomplished by genetically transforming plants with modified genes from microorganisms. The genes encode the enzymes required to synthesize PHB from acetyl-CoA or related metabolites and are fused with additional plant sequences for targeting the enzymes to the plastid.

Radiation cross-linked collagen/dextran dermal scaffolds: effects of dextran on cross-linking and degradation.

PubMed

Zhang, Yaqing; Zhang, Xiangmei; Xu, Ling; Wei, Shicheng; Zhai, Maolin

2015-01-01

Ionizing radiation effectively cross-links collagen into network with enhanced anti-degradability and biocompatibility, while radiation-cross-linked collagen scaffold lacks flexibility, satisfactory surface appearance, and performs poor in cell penetration and ingrowth. To make the radiation-cross-linked collagen scaffold to serve as an ideal artificial dermis, dextran was incorporated into collagen. Scaffolds with the collagen/dextran (Col/Dex) ratios of 10/0, 7/3, and 5/5 were fabricated via (60)Co γ-irradiation cross-linking, followed by lyophilization. The morphology, microstructure, physicochemical, and biological properties were investigated. Compared with pure collagen, scaffolds with dextran demonstrated more porous appearance, enhanced hydrophilicity while the cross-linking density was lower with the consequence of larger pore size, higher water uptake, as well as reduced stiffness. Accelerated degradation was observed when dextran was incorporated in both the in vitro and in vivo assays, which led to earlier integration with cell and host tissue. The effect of dextran on degradation was ascribed to the decreased cross-linking density, looser microstructure, more porous and hydrophilic surface. Considering the better appearance, softness, moderate degradation rate due to controllable cross-linking degree and good biocompatibility as well, radiation-cross-linked collagen/dextran scaffolds are expected to serve as promising artificial dermal substitutes.

Genotoxicity Assessment of Volatile Organic Compounds in Landfill Gas Emission Using Comet Assay in Higher Terrestrial Plant.

PubMed

Na Roi-Et, Veerapas; Chiemchaisri, Wilai; Chiemchaisri, Chart

2017-02-01

Genotoxicity model is developed to assess the individual subacute toxicity of benzene, toluene, ethylbenzene, and xylene (BTEX) at very low levels as in a landfill gas. Golden Pothos (Epipremnum aureum), a higher plant, was tested under variation of benzene 54-5656 ng/L, toluene 10-4362 ng/L, ethylbenzene 28-4997 ng/L, xylene 53-4845 ng/L, for 96 h. DNA fragmentation in plant leaves were investigated via comet assay. The results show that DNA migration ratio increased with the BTEX concentrations, but at different rates. The 50% effective concentration (EC 50 ) of DNA fragmentation from the dose-response relationships indicated toluene has the highest EC 50 value and followed by benzene, xylene and ethylbenzene. Alternatively, ethylbenzene has the highest toxicity unit and followed by xylene, benzene and toluene as described by toxicity unit (TU). In conclusion, comet assay of Pothos can be used in differentiating DNA fragmentation against very low levels of BTEX in the atmosphere. Pothos is recommended for genotoxicity assessment of a low BTEX contaminated atmosphere.

Plants are less negatively affected by flooding when growing in species-rich plant communities.

PubMed

Wright, Alexandra J; de Kroon, Hans; Visser, Eric J W; Buchmann, Tina; Ebeling, Anne; Eisenhauer, Nico; Fischer, Christine; Hildebrandt, Anke; Ravenek, Janneke; Roscher, Christiane; Weigelt, Alexandra; Weisser, Wolfgang; Voesenek, Laurentius A C J; Mommer, Liesje

2017-01-01

Flooding is expected to increase in frequency and severity in the future. The ecological consequences of flooding are the combined result of species-specific plant traits and ecological context. However, the majority of past flooding research has focused on individual model species under highly controlled conditions. An early summer flooding event in a grassland biodiversity experiment in Jena, Germany, provided the opportunity to assess flooding responses of 60 grassland species in monocultures and 16-species mixtures. We examined plant biomass, species-specific traits (plant height, specific leaf area (SLA), root aerenchyma, starch content) and soil porosity. We found that, on average, plant species were less negatively affected by the flood when grown in higher-diversity plots in July 2013. By September 2013, grasses were unaffected by the flood regardless of plant diversity, and legumes were severely negatively affected regardless of plant diversity. Plants with greater SLA and more root aerenchyma performed better in September. Soil porosity was higher in higher-diversity plots and had a positive effect on plant performance. As floods become more frequent and severe in the future, growing flood-sensitive plants in higher-diversity communities and in soil with greater soil aeration may attenuate the most negative effects of flooding. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Rubisco oligomers composed of linked small and large subunits assemble in tobacco plastids and have higher affinities for CO2 and O2.

PubMed

Whitney, Spencer Michael; Kane, Heather Jean; Houtz, Robert L; Sharwood, Robert Edward

2009-04-01

Manipulation of Rubisco within higher plants is complicated by the different genomic locations of the large (L; rbcL) and small (S; RbcS) subunit genes. Although rbcL can be accurately modified by plastome transformation, directed genetic manipulation of the multiple nuclear-encoded RbcS genes is more challenging. Here we demonstrate the viability of linking the S and L subunits of tobacco (Nicotiana tabacum) Rubisco using a flexible 40-amino acid tether. By replacing the rbcL in tobacco plastids with an artificial gene coding for a S40L fusion peptide, we found that the fusions readily assemble into catalytic (S40L)8 and (S40L)16 oligomers that are devoid of unlinked S subunits. While there was little or no change in CO2/O2 specificity or carboxylation rate of the Rubisco oligomers, their Kms for CO2 and O2 were reduced 10% to 20% and 45%, respectively. In young maturing leaves of the plastome transformants (called ANtS40L), the S40L-Rubisco levels were approximately 20% that of wild-type controls despite turnover of the S40L-Rubisco oligomers being only slightly enhanced relative to wild type. The reduced Rubisco content in ANtS40L leaves is partly attributed to problems with folding and assembly of the S40L peptides in tobacco plastids that relegate approximately 30% to 50% of the S40L pool to the insoluble protein fraction. Leaf CO2-assimilation rates in ANtS40L at varying pCO2 corresponded with the kinetics and reduced content of the Rubisco oligomers. This fusion strategy provides a novel platform to begin simultaneously engineering Rubisco L and S subunits in tobacco plastids.

Access to Higher Education. Intergovernmental Conference on Policies for Higher Education in the 80s (Paris, France, October 12-14, 1981).

ERIC Educational Resources Information Center

Squires, Geoffrey; And Others

Access to higher education in countries that are members of the Organisation for Economic Co-operation and Development (OECD) is addressed. The following topics are considered: principles for quantitative planning of higher education, admission policies and the institutional framework, changing links between secondary and higher education, access…

A controlled aquatic ecological life support system (CAELSS) for combined production of fish and higher plant biomass suitable for integration into a lunar or planetary base.

PubMed

Blum, V; Andriske, M; Eichhorn, H; Kreuzberg, K; Schreibman, M P

1995-10-01

Based on the construction principle of the already operative Closed Equilibrated Biological Aquatic System (C.E.B.A.S.) the concept of an aquaculture system for combined production of animal and plant biomass was developed. It consists of a tank for intensive fish culture which is equipped with a feeding lock representing also a trap for biomass removal followed by a water recycling system. This is an optimized version of the original C.E.B.A.S. filters adapted to higher water pollutions. It operates in a fully biological mode and is able to convert the high ammonia ion concentrations excreted by the fish gills into nitrite ions. The second biomass production site is a higher plant cultivator with an internal fiber optics light distributor which may utilize of solar energy. The selected water plant is a tropical rootless duckweed of the genus Wolffia which possesses a high capacity in nitrate elimination and is terrestrially cultured as a vegetable for human nutrition in Southeast Asia. It is produced in an improved suspension culture which allows the removal of excess biomass by tangential centrifugation. The plant cultivator is able to supply the whole system with oxygen for respiration and eliminates vice versa the carbon dioxide exhaled by the fish via photosynthesis. A gas exchanger may be used for emergency purposes or to deliver excess oxygen into the environment and may be implemented into the air regeneration system of a closed environment of higher order. The plant biomass is fed into a biomass processor which delivers condensed fresh and dried biomass as pellets. The recovered water is fed back into the aquaculture loop. The fresh plants can be used for human nutrition immediately or can be stored after sterilization in an adequate packing. The dried Wolffia pellets are collected and brought into the fish tank by an automated feeder. In parallel the water from the plant cultivator is driven back to the animal tank by a pump. The special feature of the

Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants

PubMed Central

Kulasek, Milena; Bernacki, Maciej Jerzy; Ciszak, Kamil; Witoń, Damian; Karpiński, Stanisław

2016-01-01

Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes. PMID:27273581

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.

Plants and men in space - A new field in plant physiology

NASA Technical Reports Server (NTRS)

Andre, M.; Macelroy, R. D.

1990-01-01

Results are presented on a comparison of nutritional values of and human psychological responses to algae and of higher plants considered for growth as food on long-term missions in space, together with the technological complexities of growing these plants. The comparison shows the advantages of higher plants, with results suggesting that a high level of material recycling can be obtained. It is noted that the issue of space gravity may be not a major problem for plants because of the possibility that phototropism can provide an alternative sense of direction. Problems of waste recycling can be solved in association with plant cultivation, and a high degree of autonomy of food production can be obtained.

Native Plant and Microbial Contributions to a Negative Plant-Plant Interaction1[OA

PubMed Central

Bains, Gurdeep; Sampath Kumar, Amutha; Rudrappa, Thimmaraju; Alff, Emily; Hanson, Thomas E.; Bais, Harsh P.

2009-01-01

A number of hypotheses have been suggested to explain why invasive exotic plants dramatically increase their abundance upon transport to a new range. The novel weapons hypothesis argues that phytotoxins secreted by roots of an exotic plant are more effective against naïve resident competitors in the range being invaded. The common reed Phragmites australis has a diverse population structure including invasive populations that are noxious weeds in North America. P. australis exudes the common phenolic gallic acid, which restricts the growth of native plants. However, the pathway for free gallic acid production in soils colonized by P. australis requires further elucidation. Here, we show that exotic, invasive P. australis contain elevated levels of polymeric gallotannin relative to native, noninvasive P. australis. We hypothesized that polymeric gallotannin can be attacked by tannase, an enzymatic activity produced by native plant and microbial community members, to release gallic acid in the rhizosphere and exacerbate the noxiousness of P. australis. Native plants and microbes were found to produce high levels of tannase while invasive P. australis produced very little tannase. These results suggest that both invasive and native species participate in signaling events that initiate the execution of allelopathy potentially linking native plant and microbial biochemistry to the invasive traits of an exotic species. PMID:19776161

Foliar pH as a new plant trait: can it explain variation in foliar chemistry and carbon cycling processes among subarctic plant species and types?

PubMed

Cornelissen, J H C; Quested, H M; van Logtestijn, R S P; Pérez-Harguindeguy, N; Gwynn-Jones, D; Díaz, S; Callaghan, T V; Press, M C; Aerts, R

2006-03-01

Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However, foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or ecosystem traits and processes.

PHYSIOLOGY OF ION TRANSPORT ACROSS THE TONOPLAST OF HIGHER PLANTS.

PubMed

Barkla, Bronwyn J.; Pantoja, Omar

1996-06-01

The vacuole of plant cells plays an important role in the homeostasis of the cell. It is involved in the regulation of cytoplasmic pH, sequestration of toxic ions and xenobiotics, regulation of cell turgor, storage of amino acids, sugars and CO2 in the form of malate, and possibly as a source for elevating cytoplasmic calcium. All these activities are driven by two primary active transport mechanisms present in the vacuolar membrane (tonoplast). These two mechanisms employ high-energy metabolites to pump protons into the vacuole, establishing a proton electrochemical potential that mediates the transport of a diverse range of solutes. Within the past few years, great advances at the molecular and functional levels have been made on the characterization and identification of these mechanisms. The aim of this review is to summarize these studies in the context of the physiology of the plant cell.

Trait plasticity, not values, best corresponds with woodland plant success in novel and manipulated habitats

Treesearch

Robert J. Warren; Jeffrey K. Lake

2012-01-01

Aims: The clustering of plants with similar leaf traits along environmental gradients may arise from adaptation as well as acclimation to heterogeneous habitat conditions. Determining the forces that shape plant leaf traits requires both linking variation in trait morphology with abiotic gradients and linking that trait variation with plant performance under varying...

Medicinal Plants from Northeastern Brazil against Alzheimer's Disease

PubMed Central

Ribeiro, Alan Bezerra; Alves, Daniela Ribeiro; Rodrigues, Ana Livya Moreira; dos Santos, Leonardo Hunaldo; de Menezes, Jane Eire Silva Alencar

2017-01-01

Alzheimer's disease (AD) has been linked with oxidative stress, acetylcholine deficiency in the brain, and inflammatory processes. In the northeast region of Brazil, various plants are used to treat several diseases associated with these processes; then an antioxidant test was performed with those plants in a previous work and twelve species with higher antioxidant activity were selected for AChE inhibition evaluation. The phenolic compounds content was determined by Folin–Ciocalteu test and flavonoid content with AlCl3 reagent using UV-visible spectrophotometry. The antioxidant activity was assessed analyzing the inhibitory activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate (ABTS) and by the β-carotene/linoleic acid system and acetylcholinesterase inhibition using qualitative and quantitative tests. The combination of better acetylcholinesterase inhibitory and antioxidant activities pointed out six species, in descending order, as the best potential sources of therapeutic agents against AD: Hancornia speciosa > Myracrodruon urundeuva > Copaifera langsdorffii > Stryphnodendron coriaceum > Psidium guajava > Mangifera indica. Besides, the phenolic compounds in the species probably contribute to these activities. However, further pharmacological studies to assess the specific applications of these plants against AD are required to confirm these results. PMID:28316633

Developing Emotionally Intelligent Leadership in Higher Education

ERIC Educational Resources Information Center

Parrish, Dominique

2011-01-01

It is widely accepted that the success of higher education institutions is dependent on effective competent leaders and leadership. There is also growing evidence to support the proposition that emotional intelligence is strongly linked to effective leadership in the higher education setting. Additionally, the premise that emotional intelligence…

Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

1996-01-01

The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

Common sex-linked deleterious alleles in a plant parasitic fungus alter infection success but show no pleiotropic advantage.

PubMed

Giraud, T; Jonot, O; Shykoff, J A

2006-05-01

Microbotryum violaceum is a fungus that causes the sterilizing anther smut disease in Caryophyllaceae. Its diploid teliospores normally produce equal proportions of haploid sporidia of its two mating types. However natural populations contain high frequencies of individuals producing sporidia of only one mating type ('biased strains'). This mating type-ratio bias is caused by deleterious alleles at haploid phase ('haplo-lethals') linked to the mating type locus that can be transmitted only by intra-tetrad selfing. We used experimental inoculations to test some of the hypotheses proposed to explain the maintenance of haplo-lethals. We found a disadvantage of biased strains in infection ability and high intra-tetrad mating rates. Biased strains had no higher competitive ability nor shorter latency and their higher spore production per flower appeared insufficient to compensate their disadvantages. These findings were only consistent with the hypothesis that haplo-lethals are maintained under a metapopulation structure because of high intra-tetrad selfing rates, founder effects and selection at the population level.

The sheltered genetic load linked to the s locus in plants: new insights from theoretical and empirical approaches in sporophytic self-incompatibility.

PubMed

Llaurens, Violaine; Gonthier, Lucy; Billiard, Sylvain

2009-11-01

Inbreeding depression and mating systems evolution are closely linked, because the purging of deleterious mutations and the fitness of individuals may depend on outcrossing vs. selfing rates. Further, the accumulation of deleterious mutations may vary among genomic regions, especially for genes closely linked to loci under balancing selection. Sporophytic self-incompatibility (SSI) is a common genetic mechanism in angiosperm that enables hermaphrodite plants to avoid selfing and promote outcrossing. The SSI phenotype is determined by the S locus and may depend on dominance relationships among alleles. Since most individuals are heterozygous at the S locus and recombination is suppressed in the S-locus region, it has been suggested that deleterious mutations could accumulate at genes linked to the S locus, generating a "sheltered load." In this article, we first theoretically investigate the conditions generating sheltered load in SSI. We show that deleterious mutations can accumulate in linkage with specific S alleles, and particularly if those S alleles are dominant. Second, we looked for the presence of sheltered load in Arabidopsis halleri using CO(2) gas treatment to overcome self-incompatibility. By examining the segregation of S alleles and measuring the relative fitness of progeny, we found significant sheltered load associated with the most dominant S allele (S15) of three S alleles tested. This sheltered load seems to be expressed at several stages of the life cycle and to have a larger effect than genomic inbreeding depression.

Compositions and methods relating to transgenic plants and cellulosic ethanol production

DOEpatents

Tien, Ming [State College, PA; Carlson, John [Port Matilda, PA; Liang, Haiying [Clemson, SC

2012-04-24

Transgenic lignocellulosic plants are provided according to embodiments of the present invention, the transgenic plants transformed with an expression cassette encoding a protein operably linked to a signal peptide which targets the protein to a cell wall of the transgenic plant, where at least 5% of the total amino acid residues of the protein are tyrosine, lysine, serine, threonine or cysteine. Methods of increasing lignin-protein bonds in a lignocellulosic plant are provided according to embodiments of the present invention which include expressing a recombinant nucleic acid in a lignocellulosic plant, the recombinant nucleic acid encoding a protein operably linked to a signal peptide which targets the protein to the cell wall of a plant, where at least 5% of the total amino acid residues of the protein are tyrosine, lysine, serine, threonine or cysteine.

Identification of the alternative terminal oxidase of higher plant mitochondria

PubMed Central

Elthon, Thomas E.; McIntosh, Lee

1987-01-01

In addition to cytochrome oxidase, plant mitochondria have a second terminal oxidase called the alternative oxidase. The alternative oxidase is of great interest in that energy is not conserved when electrons flow through it. The potential energy of the system is thus lost as heat, and, in plants with high levels of the alternative oxidase, this results in thermogenesis. We have purified the alternative oxidase from mitochondria of the thermogenic spadix of Sauromatum guttatum and have identified its polypeptide constituents by using polyclonal antibodies. A 166-fold purification was achieved through a combination of cation-exchange (carboxymethyl-Sepharose) and hydrophobic-interaction (phenyl-Sepharose) chromatography. Polyclonal antibodies raised to the CM-Sepharose fractions readily immunoprecipitated alternative oxidase activity and immunoprecipitated four of the proteins that copurify with the activity. These proteins have apparent molecular masses of 37, 36, 35.5, and 35 kDa. Polyclonal antibodies raised individually to the 37-, 36-, and 35.5- plus 35-kDa proteins cross-reacted with all of these proteins, indicating the presence of common antigenic sites. The 37-kDa protein appears to be constitutive in Sauromatum, whereas expression of the 36- and 35-kDa proteins was correlated with presence of alternative pathway activity. The 35.5-kDa protein appears with loss of alternative pathway activity during senescence, indicating that this protein may be a degradation product of the 36-kDa protein. Binding of anti-36-kDa protein antibodies to total mitochondrial protein blots of five plant species indicated that similar proteins were always present when alternative pathway activity was observed. Images PMID:16593898

UV-A radiation effects on higher plants: Exploring the known unknown.

PubMed

Verdaguer, Dolors; Jansen, Marcel A K; Llorens, Laura; Morales, Luis O; Neugart, Susanne

2017-02-01

Ultraviolet-A radiation (UV-A: 315-400nm) is a component of solar radiation that exerts a wide range of physiological responses in plants. Currently, field attenuation experiments are the most reliable source of information on the effects of UV-A. Common plant responses to UV-A include both inhibitory and stimulatory effects on biomass accumulation and morphology. UV-A effects on biomass accumulation can differ from those on root: shoot ratio, and distinct responses are described for different leaf tissues. Inhibitory and enhancing effects of UV-A on photosynthesis are also analysed, as well as activation of photoprotective responses, including UV-absorbing pigments. UV-A-induced leaf flavonoids are highly compound-specific and species-dependent. Many of the effects on growth and development exerted by UV-A are distinct to those triggered by UV-B and vary considerably in terms of the direction the response takes. Such differences may reflect diverse UV-perception mechanisms with multiple photoreceptors operating in the UV-A range and/or variations in the experimental approaches used. This review highlights a role that various photoreceptors (UVR8, phototropins, phytochromes and cryptochromes) may play in plant responses to UV-A when dose, wavelength and other conditions are taken into account. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Plant polyadenylation factors: conservation and variety in the polyadenylation complex in plants.

PubMed

Hunt, Arthur G; Xing, Denghui; Li, Qingshun Q

2012-11-20

Polyadenylation, an essential step in eukaryotic gene expression, requires both cis-elements and a plethora of trans-acting polyadenylation factors. The polyadenylation factors are largely conserved across mammals and fungi. The conservation seems also extended to plants based on the analyses of Arabidopsis polyadenylation factors. To extend this observation, we systemically identified the orthologs of yeast and human polyadenylation factors from 10 plant species chosen based on both the availability of their genome sequences and their positions in the evolutionary tree, which render them representatives of different plant lineages. The evolutionary trajectories revealed several interesting features of plant polyadenylation factors. First, the number of genes encoding plant polyadenylation factors was clearly increased from "lower" to "higher" plants. Second, the gene expansion in higher plants was biased to some polyadenylation factors, particularly those involved in RNA binding. Finally, while there are clear commonalities, the differences in the polyadenylation apparatus were obvious across different species, suggesting an ongoing process of evolutionary change. These features lead to a model in which the plant polyadenylation complex consists of a conserved core, which is rather rigid in terms of evolutionary conservation, and a panoply of peripheral subunits, which are less conserved and associated with the core in various combinations, forming a collection of somewhat distinct complex assemblies. The multiple forms of plant polyadenylation complex, together with the diversified polyA signals may explain the intensive alternative polyadenylation (APA) and its regulatory role in biological functions of higher plants.

Expression of multiple proteins in transgenic plants

DOEpatents

Vierstra, Richard D.; Walker, Joseph M.

2002-01-01

A method is disclosed for the production of multiple proteins in transgenic plants. A DNA construct for introduction into plants includes a provision to express a fusion protein of two proteins of interest joined by a linking domain including plant ubiquitin. When the fusion protein is produced in the cells of a transgenic plant transformed with the DNA construction, native enzymes present in plant cells cleave the fusion protein to release both proteins of interest into the cells of the transgenic plant. Since the proteins are produced from the same fusion protein, the initial quantities of the proteins in the cells of the plant are approximately equal.

Plants: Novel Developmental Processes.

ERIC Educational Resources Information Center

Goldberg, Robert B.

1988-01-01

Describes the diversity of plants. Outlines novel developmental and complex genetic processes that are specific to plants. Identifies approaches that can be used to solve problems in plant biology. Cites the advantages of using higher plants for experimental systems. (RT)

Can Stress-Induced Biochemical Differences drive Variation in the Hydrogen Isotope Composition of Leaf Wax n-Alkanes from Terrestrial Higher Plants?

NASA Astrophysics Data System (ADS)

Eley, Y.; Pedentchouk, N.; Dawson, L.

2014-12-01

Recent research has identified that interspecies variation in leaf wax n-alkane 2H/1H from plants growing at the same geographical location can exceed 100‰. These differences cannot easily be explained by mechanisms that influence the isotopic composition of leaf water. Biochemical processes are therefore likely to drive some of this variability. Currently, however, little is known about the relative importance of different biochemical processes in shaping n-alkane hydrogen isotope composition. To explore this issue, we combined n-alkane δ2H analysis with measurements of: (i) the percentage content of leaf C and N; and (ii) foliar δ15N, from seven plants growing at Stiffkey salt marsh, Norfolk, UK. These species differ biochemically in respect of the protective compounds they produce under salt or water stressed conditions, with monocots generally producing more carbohydrates, and dicots producing more nitrogenous compounds. We found that monocots had higher %C, while dicots had higher %N and 15N-enriched leaf tissue. We identified a systematic relationship between the nature of the dominant protective compound produced (carbohydrate vs. nitrogenous) and n-alkane 2H/1H: species with a greater proportion of carbohydrates have more negative δ2H values. These findings might imply that shifts in the relative contribution of H to pyruvate from NADPH (2H-depleted) and recycled carbohydrates (2H-enriched) can influence n-alkane δ2H. The 2H-depletion of monocot n-alkanes relative to dicots may therefore be due to a greater proportion of NADPH-derived H incorporated into pyruvate because of their enhanced demand for carbohydrates. The production of protective compounds in plant species is a common response to a range of abiotic stresses (e.g. high UV irradiation, drought, salinity, high/low temperature). Species-specific biochemical responses to stress could therefore influence n-alkane 2H/1H across a range of habitats. This study highlights the importance of detailed

Teachers' Care in Higher Education: Contesting Gendered Constructions

ERIC Educational Resources Information Center

Mariskind, Clare

2014-01-01

There is little research on care in higher education, and yet for many of those who teach in higher education institutions, care is an important part of their work. Care in the compulsory education sector has traditionally been linked to the feminine, and this paper considers whether this is also the case in higher education. It investigates how…

Do University Students, Alumni, Educators and Employers Link Assessment and Graduate Employability?

ERIC Educational Resources Information Center

Kinash, Shelley; McGillivray, Laura; Crane, Linda

2018-01-01

Within higher education literature, "assessment" and "graduate employability" are linked and co-presented, in that quality student assessment is purported to enhance employability. This research was designed to query the extent to which these same conceptual links are perceived by those actively involved in higher education.…

AMT1;1 transgenic rice plants with enhanced NH4 + permeability show superior growth and higher yield under optimal and suboptimal NH4 + conditions

PubMed Central

Rothstein, Steven J.

2014-01-01

The major source of nitrogen for rice (Oryza sativa L.) is ammonium (NH4 +). The NH4 + uptake of roots is mainly governed by membrane transporters, with OsAMT1;1 being a prominent member of the OsAMT1 gene family that is known to be involved in NH4 + transport in rice plants. However, little is known about its involvement in NH4 + uptake in rice roots and subsequent effects on NH4 + assimilation. This study shows that OsAMT1;1 is a constitutively expressed, nitrogen-responsive gene, and its protein product is localized in the plasma membrane. Its expression level is under the control of circadian rhythm. Transgenic rice lines (L-2 and L-3) overexpressing the OsAMT1;1 gene had the same root structure as the wild type (WT). However, they had 2-fold greater NH4 + permeability than the WT, whereas OsAMT1;1 gene expression was 20-fold higher than in the WT. Analogous to the expression, transgenic lines had a higher NH4 + content in the shoots and roots than the WT. Direct NH4 + fluxes in the xylem showed that the transgenic lines had significantly greater uptake rates than the WT. Higher NH4 + contents also promoted higher expression levels of genes in the nitrogen assimilation pathway, resulting in greater nitrogen assimilates, chlorophyll, starch, sugars, and grain yield in transgenic lines than in the WT under suboptimal and optimal nitrogen conditions. OsAMT1;1 also enhanced overall plant growth, especially under suboptimal NH4 + levels. These results suggest that OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions. PMID:24420570

AMT1;1 transgenic rice plants with enhanced NH4(+) permeability show superior growth and higher yield under optimal and suboptimal NH4(+) conditions.

PubMed

Ranathunge, Kosala; El-Kereamy, Ashraf; Gidda, Satinder; Bi, Yong-Mei; Rothstein, Steven J

2014-03-01

The major source of nitrogen for rice (Oryza sativa L.) is ammonium (NH4(+)). The NH4(+) uptake of roots is mainly governed by membrane transporters, with OsAMT1;1 being a prominent member of the OsAMT1 gene family that is known to be involved in NH4(+) transport in rice plants. However, little is known about its involvement in NH4(+) uptake in rice roots and subsequent effects on NH4(+) assimilation. This study shows that OsAMT1;1 is a constitutively expressed, nitrogen-responsive gene, and its protein product is localized in the plasma membrane. Its expression level is under the control of circadian rhythm. Transgenic rice lines (L-2 and L-3) overexpressing the OsAMT1;1 gene had the same root structure as the wild type (WT). However, they had 2-fold greater NH4(+) permeability than the WT, whereas OsAMT1;1 gene expression was 20-fold higher than in the WT. Analogous to the expression, transgenic lines had a higher NH4(+) content in the shoots and roots than the WT. Direct NH4(+) fluxes in the xylem showed that the transgenic lines had significantly greater uptake rates than the WT. Higher NH4(+) contents also promoted higher expression levels of genes in the nitrogen assimilation pathway, resulting in greater nitrogen assimilates, chlorophyll, starch, sugars, and grain yield in transgenic lines than in the WT under suboptimal and optimal nitrogen conditions. OsAMT1;1 also enhanced overall plant growth, especially under suboptimal NH4(+) levels. These results suggest that OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions.

Tracing the link between plant volatile organic compound emissions and CO2 fluxes and by stable isotopes

NASA Astrophysics Data System (ADS)

Werner, Christiane; Wegener, Frederik; Jardine, Kolby

2015-04-01

The vegetation exerts a large influence on the atmosphere through the emission of volatile organic compounds (VOCs) and the emission and uptake of the greenhouse gas CO2. Despite the enormous importance, processes controlling plant carbon allocation into primary and secondary metabolism, such as photosynthetic carbon uptake, respiratory CO2 emission and VOC synthesis, remains unclear. Moreover, vegetation-atmosphere CO2 exchange is associated with a large isotopic imprint due to photosynthetic carbon isotope discrimination and 13C-fractionation during respiratory CO2 release1. The latter has been proposed to be related to carbon partitioning in the metabolic branching points of the respiratory pathways and secondary metabolism, which are linked via a number of interfaces including the central metabolite pyruvate. Notably, it is a known substrate in a large array of secondary pathways leading to the biosynthesis of many volatile organic compounds (VOCs), such as volatile isoprenoids, oxygenated VOCs, aromatics, fatty acid oxidation products, which can be emitted by plants. Here we investigate the linkage between VOC emissions, CO2 fluxes and associated isotope effects based on simultaneous real-time measurements of stable carbon isotope composition of branch respired CO2 (CRDS) and VOC fluxes (PTR-MS). We utilized positionally specific 13C-labeled pyruvate branch feeding experiments in the mediterranean shrub (Halimium halimifolium) to trace the partitioning of C1, C2, and C3 carbon atoms of pyruvate into VOCs versus CO2 emissions in the light and in the dark. In the light, we found high emission rates of a large array of VOC including volatile isoprenoids, oxygenated VOCs, green leaf volatiles, aromatics, sulfides, and nitrogen containing VOCs. These observations suggest that in the light, H. halimifolium dedicates a high carbon flux through secondary biosynthetic pathways including the pyruvate dehydrogenase bypass, mevalonic acid, MEP/DOXP, shikimic acid, and

Compositions and methods relating to transgenic plants and cellulosic ethanol production

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

Tien, Ming; Carlson, John; Liang, Haiying

Transgenic lignocellulosic plants are provided according to embodiments of the present invention, the transgenic plants transformed with an expression cassette encoding a protein operably linked to a signal peptide which targets the protein to a cell wall of the transgenic plant, where at least 5% of the total amino acid residues of the protein are tyrosine, lysine, serine, threonine or cysteine. Methods of increasing lignin-protein bonds in a lignocellulosic plant are provided according to embodiments of the present invention which include expressing a recombinant nucleic acid in a lignocellulosic plant, the recombinant nucleic acid encoding a protein operably linked tomore » a signal peptide which targets the protein to the cell wall of a plant, where at least 5% of the total amino acid residues of the protein are tyrosine, lysine, serine, threonine or cysteine.« less

Lessons from Red Data Books: Plant Vulnerability Increases with Floral Complexity.

PubMed

Stefanaki, Anastasia; Kantsa, Aphrodite; Tscheulin, Thomas; Charitonidou, Martha; Petanidou, Theodora

2015-01-01

The architectural complexity of flower structures (hereafter referred to as floral complexity) may be linked to pollination by specialized pollinators that can increase the probability of successful seed set. As plant-pollinator systems become fragile, a loss of such specialized pollinators could presumably result in an increased likelihood of pollination failure. This is an issue likely to be particularly evident in plants that are currently rare. Using a novel index describing floral complexity we explored whether this aspect of the structure of flowers could be used to predict vulnerability of plant species to extinction. To do this we defined plant vulnerability using the Red Data Book of Rare and Threatened Plants of Greece, a Mediterranean biodiversity hotspot. We also tested whether other intrinsic (e.g. life form, asexual reproduction) or extrinsic (e.g. habitat, altitude, range-restrictedness) factors could affect plant vulnerability. We found that plants with high floral complexity scores were significantly more likely to be vulnerable to extinction. Among all the floral complexity components only floral symmetry was found to have a significant effect, with radial-flower plants appearing to be less vulnerable. Life form was also a predictor of vulnerability, with woody perennial plants having significantly lower risk of extinction. Among the extrinsic factors, both habitat and maximum range were significantly associated with plant vulnerability (coastal plants and narrow-ranged plants are more likely to face higher risk). Although extrinsic and in particular anthropogenic factors determine plant extinction risk, intrinsic traits can indicate a plant's proneness to vulnerability. This raises the potential threat of declining global pollinator diversity interacting with floral complexity to increase the vulnerability of individual plant species. There is potential scope for using plant-pollinator specializations to identify plant species particularly at

Plant sterols and plant stanols in the management of dyslipidaemia and prevention of cardiovascular disease.

PubMed

Gylling, Helena; Plat, Jogchum; Turley, Stephen; Ginsberg, Henry N; Ellegård, Lars; Jessup, Wendy; Jones, Peter J; Lütjohann, Dieter; Maerz, Winfried; Masana, Luis; Silbernagel, Günther; Staels, Bart; Borén, Jan; Catapano, Alberico L; De Backer, Guy; Deanfield, John; Descamps, Olivier S; Kovanen, Petri T; Riccardi, Gabriele; Tokgözoglu, Lale; Chapman, M John

2014-02-01

This EAS Consensus Panel critically appraised evidence relevant to the benefit to risk relationship of functional foods with added plant sterols and/or plant stanols, as components of a healthy lifestyle, to reduce plasma low-density lipoprotein-cholesterol (LDL-C) levels, and thereby lower cardiovascular risk. Plant sterols/stanols (when taken at 2 g/day) cause significant inhibition of cholesterol absorption and lower LDL-C levels by between 8 and 10%. The relative proportions of cholesterol versus sterol/stanol levels are similar in both plasma and tissue, with levels of sterols/stanols being 500-/10,000-fold lower than those of cholesterol, suggesting they are handled similarly to cholesterol in most cells. Despite possible atherogenicity of marked elevations in circulating levels of plant sterols/stanols, protective effects have been observed in some animal models of atherosclerosis. Higher plasma levels of plant sterols/stanols associated with intakes of 2 g/day in man have not been linked to adverse effects on health in long-term human studies. Importantly, at this dose, plant sterol/stanol-mediated LDL-C lowering is additive to that of statins in dyslipidaemic subjects, equivalent to doubling the dose of statin. The reported 6-9% lowering of plasma triglyceride by 2 g/day in hypertriglyceridaemic patients warrants further evaluation. Based on LDL-C lowering and the absence of adverse signals, this EAS Consensus Panel concludes that functional foods with plant sterols/stanols may be considered 1) in individuals with high cholesterol levels at intermediate or low global cardiovascular risk who do not qualify for pharmacotherapy, 2) as an adjunct to pharmacologic therapy in high and very high risk patients who fail to achieve LDL-C targets on statins or are statin- intolerant, 3) and in adults and children (>6 years) with familial hypercholesterolaemia, in line with current guidance. However, it must be acknowledged that there are no randomised, controlled

Developing a model of plant hormone interactions

PubMed Central

Wang, Yu Hua

2011-01-01

Plant growth and development is influenced by mutual interactions among plant hormones. The five classical plant hormones are auxins, cytokinins, gibberellins, abscisic acid and ethylene. They are small diffusible molecules that easily penetrate between cells. In addition, newer classes of plant hormones have been identified such as brassinosteroids, jasmonic acid, salicylic acid and various small proteins or peptides. These hormones also play important roles in the regulation of plant growth and development. This review begins with a brief summary of the current findings on plant hormones. Based on this knowledge, a conceptual model about interactions among plant hormones is built so as to link and develop an understanding of the diverse functions of different plant hormones as a whole in plants. PMID:21406974

Salmonella interactions with plants and their associated microbiota

USDA-ARS?s Scientific Manuscript database

The increase in the incidence of gastroenteritis outbreaks linked to the consumption of foods of plant origin has ignited public concern and scientific interest in understanding interactions of human enteric pathogens with plants. Enteric disease caused by non-typhoidal Salmonella is a major public ...

N(4)C-ethyl-N(4)C cross-linked DNA: synthesis and characterization of duplexes with interstrand cross-links of different orientations.

PubMed

Noronha, Anne M; Noll, David M; Wilds, Christopher J; Miller, Paul S

2002-01-22

The preparation and physical properties of short DNA duplexes that contain a N(4)C-ethyl-N(4)C interstrand cross-link are described. Duplexes that contain an interstrand cross-link between mismatched C-C residues and duplexes in which the C residues of a -CG- or -GC- step are linked to give "staggered" interstrand cross-links were prepared using a novel N(4)C-ethyl-N(4)C phosphoramidite reagent. Duplexes with the C-C mismatch cross-link have UV thermal transition temperatures that are 25 degrees C higher than the melting temperatures of control duplexes in which the cross-link is replaced with a G-C base pair. It appears that this cross-link stabilizes adjacent base pairs and does not perturb the structure of the helix, a conclusion that is supported by the CD spectrum of this duplex and by molecular models. An even higher level of stabilization, 49 degrees C, is seen with the duplex that contains a -CG- staggered cross-link. Molecular models suggest that this cross-link may induce propeller twisting in the cross-linked base pairs, and the CD spectrum of this duplex exhibits an unusual negative band at 298 nm, although the remainder of the spectrum is similar to that of B-form DNA. Mismatched C-C or -CG- staggered cross-linked duplexes that have complementary overhanging ends can undergo self-ligation catalyzed by T4 DNA ligase. Analysis of the ligated oligomers by nondenaturing polyacrylamide gel electrophoresis shows that the resulting oligomers migrate in a manner similar to that of a mixture of non-cross-linked control oligomers and suggests that these cross-links do not result in significant bending of the helix. However, the orientation of the staggered cross-link can have a significant effect on the structure and stability of the cross-linked duplex. Thus, the thermal stability of the duplex that contains a -GC- staggered cross-link is 10 degrees C lower than the melting temperature of the control, non-cross-linked duplex. Unlike the -CG- staggered cross-link

Expression of hepatitis B surface antigen in transgenic plants.

PubMed Central

Mason, H S; Lam, D M; Arntzen, C J

1992-01-01

Tobacco plants were genetically transformed with the gene encoding hepatitis B surface antigen (HBsAg) linked to a nominally constitutive promoter. Enzyme-linked immunoassays using a monoclonal antibody directed against human serum-derived HBsAg revealed the presence of HBsAg in extracts of transformed leaves at levels that correlated with mRNA abundance. This suggests that there were no major inherent limitations of transcription or translation of this foreign gene in plants. Recombinant HBsAg was purified from transgenic plants by immunoaffinity chromatography and examined by electron microscopy. Spherical particles with an average diameter of 22 nm were observed in negatively stained preparations. Sedimentation of transgenic plant extracts in sucrose and cesium chloride density gradients showed that the recombinant HBsAg and human serum-derived HBsAg had similar physical properties. Because the HBsAg produced in transgenic plants is antigenically and physically similar to the HBsAg particles derived from human serum and recombinant yeast, which are used as vaccines, we conclude that transgenic plants hold promise as low-cost vaccine production systems. Images PMID:1465391

The Aboriginal Australian cosmic landscape. Part 2: Plant connections with the skyworld

NASA Astrophysics Data System (ADS)

Clarke, Philip A.

2015-03-01

In the recorded mythology of Aboriginal Australia there is frequent mention of the Skyworld as the upper part of a total landscape that possessed topography linked with that of Earth and the Underworld. The heavens were perceived as a country with the same species of plants and animals that existed below. In Aboriginal tradition, large trees were seen as connecting terrestrial space with the sky above, while the movements of celestial bodies were linked to seasonal changes observed with plants on Earth. This paper describes the links between the floras of Earth and the Skyworld.

Changing Concepts of Equity in Transforming UK Higher Education: Implications for Future Pedagogies and Practices in Global Higher Education

ERIC Educational Resources Information Center

David, Miriam E.

2011-01-01

This paper is about changing concepts of equity in UK higher education. In particular, it charts the moves from concepts about gender equality as about women's education as a key issue in twentieth century higher education to questions of men's education in the twenty-first century. These changing concepts of equity are linked to wider social and…

Application of plant cell and tissue culture for the production of phytochemicals in medicinal plants.

PubMed

Pant, Bijaya

2014-01-01

Approximately 80% of the world inhabitants depend on the medicinal plants in the form of traditional formulations for their primary health care system well as in the treatment of a number of diseases since the ancient time. Many commercially used drugs have come from the information of indigenous knowledge of plants and their folk uses. Linking of the indigenous knowledge of medicinal plants to modern research activities provides a new reliable approach, for the discovery of novel drugs much more effectively than with random collection. Increase in population and increasing demand of plant products along with illegal trade are causing depletion of medicinal plants and many are threatened in natural habitat. Plant tissue culture technique has proved potential alternative for the production of desirable bioactive components from plants, to produce the enough amounts of plant material that is needed and for the conservation of threatened species. Different plant tissue culture systems have been extensively studied to improve and enhance the production of plant chemicals in various medicinal plants.

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts.

PubMed

Albert, Markus; Kaiser, Bettina; van der Krol, Sander; Kaldenhoff, Ralf

2010-09-01

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance. Calcium (Ca(2+)) release is the major second messenger during signal transduction. Therefore, we have studied Ca(2+) spiking in tomato and tobacco during infection with C. reflexa. In our recently published study Ca(2+) signals were monitored as bioluminescence in aequorin-expressing tomato plants after the onset of C. reflexa infestation. Signals at the attachment sites were observed from 30 to 48 h after infection. In an assay with leaf disks of aequorin-expressing tomato which were treated with different C. reflexa plant extracts it turned out that the substance that induced Ca(2+) release in the host plant was closely linked to the parasite's haustoria.

Advanced genetic tools for plant biotechnology.

PubMed

Liu, Wusheng; Yuan, Joshua S; Stewart, C Neal

2013-11-01

Basic research has provided a much better understanding of the genetic networks and regulatory hierarchies in plants. To meet the challenges of agriculture, we must be able to rapidly translate this knowledge into generating improved plants. Therefore, in this Review, we discuss advanced tools that are currently available for use in plant biotechnology to produce new products in plants and to generate plants with new functions. These tools include synthetic promoters, 'tunable' transcription factors, genome-editing tools and site-specific recombinases. We also review some tools with the potential to enable crop improvement, such as methods for the assembly and synthesis of large DNA molecules, plant transformation with linked multigenes and plant artificial chromosomes. These genetic technologies should be integrated to realize their potential for applications to pressing agricultural and environmental problems.

Leaf bacterial diversity mediates plant diversity and ecosystem function relationships.

PubMed

Laforest-Lapointe, Isabelle; Paquette, Alain; Messier, Christian; Kembel, Steven W

2017-06-01

Research on biodiversity and ecosystem functioning has demonstrated links between plant diversity and ecosystem functions such as productivity. At other trophic levels, the plant microbiome has been shown to influence host plant fitness and function, and host-associated microbes have been proposed to influence ecosystem function through their role in defining the extended phenotype of host organisms However, the importance of the plant microbiome for ecosystem function has not been quantified in the context of the known importance of plant diversity and traits. Here, using a tree biodiversity-ecosystem functioning experiment, we provide strong support for the hypothesis that leaf bacterial diversity is positively linked to ecosystem productivity, even after accounting for the role of plant diversity. Our results also show that host species identity, functional identity and functional diversity are the main determinants of leaf bacterial community structure and diversity. Our study provides evidence of a positive correlation between plant-associated microbial diversity and terrestrial ecosystem productivity, and a new mechanism by which models of biodiversity-ecosystem functioning relationships can be improved.

Suppressive composts: microbial ecology links between abiotic environments and healthy plants.

PubMed

Hadar, Yitzhak; Papadopoulou, Kalliope K

2012-01-01

Suppressive compost provides an environment in which plant disease development is reduced, even in the presence of a pathogen and a susceptible host. Despite the numerous positive reports, its practical application is still limited. The main reason for this is the lack of reliable prediction and quality control tools for evaluation of the level and specificity of the suppression effect. Plant disease suppression is the direct result of the activity of consortia of antagonistic microorganisms that naturally recolonize the compost during the cooling phase of the process. Thus, it is imperative to increase the level of understanding of compost microbial ecology and population dynamics. This may lead to the development of an ecological theory for complex ecosystems as well as favor the establishment of hypothesis-driven studies.

[The chiral mutagens: cytogenetic effects on higher plants].

PubMed

Morgun, V V; Larchenko, E A; Kostianovskiĭ, R G; Keterinchuk, A M

2011-01-01

The paper covers investigation of cytogenetic activity of chiral mutagens and their specific effects on the plant cells chromosomes of soft winter wheat (Triticum aestivum L.). Comparative analysis of cytogenetic activity of chiral NEU: S(+)1-N-nitroso- 1-N-methyl-3-N-sec-buthylureas (S(+)NMsBU) and R(-)1-N-nitroso- 1N-methyl-3-Nsec-buthylureas (R(-)NMsBU) on winter wheat was performed. As it was shown by the frequency of chromosomal aberrations the S(+) stereoisomer was twice more active than R(-). In addition to typical anaphase aberrations (fragments, bridges, lagging chromosomes) the numerous mitosis pathologies were revealed - K-mitoses, hyperspiralization and despiralization of chromosomes, unequal allocation of chromosomes between the daughter nuclei, mass fragmentation, nondisjunction and chromosome adhesion, three-pole mitoses, etc. Neither of the mentioned pathologies was observed under the action of NEU and gamma-rays.

Parametric study of potential early commercial MHD power plants. Task 3: Parameter variation of plant size

NASA Technical Reports Server (NTRS)

Hals, F. A.

1981-01-01

Plants with a nominal output of 200 and 500 MWe and conforming to the same design configuration as the Task II plant were investigated. This information is intended to permit an assessment of the competitiveness of first generation MHD/steam plants with conventional steam plants over the range of 200 to 1000 MWe. The results show that net plant efficiency of the MHD plant is significantly higher than a conventional steam plant of corresponding size. The cost of electricity is also less for the MHD plant over the entire plant size range. As expected, the cost differential is higher for the larger plant and decreases with plant size. Even at the 200 MWe capacity, however, the differential in COE between the MHD plant and the conventional plant is sufficient attractive to warrant serious consideration. Escalating fuel costs will enhance the competitive position of MHD plants because they can utilize the fuel more efficiently than conventional steam plants.

Student Perceptions of Themselves as "Consumers" of Higher Education

ERIC Educational Resources Information Center

Tomlinson, Michael

2017-01-01

This article first offers a survey of what has become an area of increasing interest in higher education: the rise of the so-called "student-consumer". This has been linked in part to the marketisation of higher education and the increased personal financial contributions individual students make towards their higher education. Drawing…

Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil-plant-atmosphere continuum

NASA Astrophysics Data System (ADS)

Bonan, G. B.; Williams, M.; Fisher, R. A.; Oleson, K. W.

2014-09-01

The Ball-Berry stomatal conductance model is commonly used in earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must be empirically parameterized. We evaluated the Ball-Berry model used in the Community Land Model version 4.5 (CLM4.5) and an alternative stomatal conductance model that links leaf gas exchange, plant hydraulic constraints, and the soil-plant-atmosphere continuum (SPA). The SPA model simulates stomatal conductance numerically by (1) optimizing photosynthetic carbon gain per unit water loss while (2) constraining stomatal opening to prevent leaf water potential from dropping below a critical minimum. We evaluated two optimization algorithms: intrinsic water-use efficiency (ΔAn /Δgs, the marginal carbon gain of stomatal opening) and water-use efficiency (ΔAn /ΔEl, the marginal carbon gain of transpiration water loss). We implemented the stomatal models in a multi-layer plant canopy model to resolve profiles of gas exchange, leaf water potential, and plant hydraulics within the canopy, and evaluated the simulations using leaf analyses, eddy covariance fluxes at six forest sites, and parameter sensitivity analyses. The primary differences among stomatal models relate to soil moisture stress and vapor pressure deficit responses. Without soil moisture stress, the performance of the SPA stomatal model was comparable to or slightly better than the CLM Ball-Berry model in flux tower simulations, but was significantly better than the CLM Ball-Berry model when there was soil moisture stress. Functional dependence of gs on soil moisture emerged from water flow along the soil-to-leaf pathway rather than being imposed a priori, as in the CLM Ball-Berry model. Similar functional dependence of gs on Ds emerged from the ΔAn/ΔEl optimization, but not the ΔAn /gs optimization. Two parameters (stomatal efficiency and root hydraulic

Computer, Video, and Rapid-Cycling Plant Projects in an Undergraduate Plant Breeding Course.

ERIC Educational Resources Information Center

Michaels, T. E.

1993-01-01

Studies the perceived effectiveness of four student projects involving videotape production, computer conferencing, microcomputer simulation, and rapid-cycling Brassica breeding for undergraduate plant breeding students in two course offerings in consecutive years. Linking of the computer conferencing and video projects improved the rating of the…

Plant response to biotic stress: Is there a common epigenetic response during plant-pathogenic and symbiotic interactions?

PubMed

Zogli, Prince; Libault, Marc

2017-10-01

Plants constantly interact with pathogenic and symbiotic microorganisms. Recent studies have revealed several regulatory mechanisms controlling these interactions. Among them, the plant defense system is activated not only in response to pathogenic, but also in response to symbiotic microbes. Interestingly, shortly after symbiotic microbial recognition, the plant defense system is suppressed to promote plant infection by symbionts. Research studies have demonstrated the influence of the plant epigenome in modulating both pathogenic and symbiotic plant-microbe interactions, thereby influencing plant survival, adaptation and evolution of the plant response to microbial infections. It is however unclear if plant pathogenic and symbiotic responses share similar epigenomic profiles or if epigenomic changes differentially regulate plant-microbe symbiosis and pathogenesis. In this mini-review, we provide an update of the current knowledge of epigenomic control on plant immune responses and symbiosis, with a special attention being paid to knowledge gap and potential strategies to fill-in the missing links. Copyright © 2017 Elsevier B.V. All rights reserved.

Pervasive and strong effects of plants on soil chemistry: a meta-analysis of individual plant 'Zinke' effects.

PubMed

Waring, Bonnie G; Álvarez-Cansino, Leonor; Barry, Kathryn E; Becklund, Kristen K; Dale, Sarah; Gei, Maria G; Keller, Adrienne B; Lopez, Omar R; Markesteijn, Lars; Mangan, Scott; Riggs, Charlotte E; Rodríguez-Ronderos, María Elizabeth; Segnitz, R Max; Schnitzer, Stefan A; Powers, Jennifer S

2015-08-07

Plant species leave a chemical signature in the soils below them, generating fine-scale spatial variation that drives ecological processes. Since the publication of a seminal paper on plant-mediated soil heterogeneity by Paul Zinke in 1962, a robust literature has developed examining effects of individual plants on their local environments (individual plant effects). Here, we synthesize this work using meta-analysis to show that plant effects are strong and pervasive across ecosystems on six continents. Overall, soil properties beneath individual plants differ from those of neighbours by an average of 41%. Although the magnitudes of individual plant effects exhibit weak relationships with climate and latitude, they are significantly stronger in deserts and tundra than forests, and weaker in intensively managed ecosystems. The ubiquitous effects of plant individuals and species on local soil properties imply that individual plant effects have a role in plant-soil feedbacks, linking individual plants with biogeochemical processes at the ecosystem scale. © 2015 The Author(s).

Lessons from Red Data Books: Plant Vulnerability Increases with Floral Complexity

PubMed Central

Stefanaki, Anastasia; Kantsa, Aphrodite; Tscheulin, Thomas; Charitonidou, Martha; Petanidou, Theodora

2015-01-01

The architectural complexity of flower structures (hereafter referred to as floral complexity) may be linked to pollination by specialized pollinators that can increase the probability of successful seed set. As plant—pollinator systems become fragile, a loss of such specialized pollinators could presumably result in an increased likelihood of pollination failure. This is an issue likely to be particularly evident in plants that are currently rare. Using a novel index describing floral complexity we explored whether this aspect of the structure of flowers could be used to predict vulnerability of plant species to extinction. To do this we defined plant vulnerability using the Red Data Book of Rare and Threatened Plants of Greece, a Mediterranean biodiversity hotspot. We also tested whether other intrinsic (e.g. life form, asexual reproduction) or extrinsic (e.g. habitat, altitude, range-restrictedness) factors could affect plant vulnerability. We found that plants with high floral complexity scores were significantly more likely to be vulnerable to extinction. Among all the floral complexity components only floral symmetry was found to have a significant effect, with radial-flower plants appearing to be less vulnerable. Life form was also a predictor of vulnerability, with woody perennial plants having significantly lower risk of extinction. Among the extrinsic factors, both habitat and maximum range were significantly associated with plant vulnerability (coastal plants and narrow-ranged plants are more likely to face higher risk). Although extrinsic and in particular anthropogenic factors determine plant extinction risk, intrinsic traits can indicate a plant’s proneness to vulnerability. This raises the potential threat of declining global pollinator diversity interacting with floral complexity to increase the vulnerability of individual plant species. There is potential scope for using plant—pollinator specializations to identify plant species particularly

The photosynthetic response of tobacco plants overexpressing ice plant aquaporin McMIPB to a soil water deficit and high vapor pressure deficit.

PubMed

Kawase, Miki; Hanba, Yuko T; Katsuhara, Maki

2013-07-01

We investigated the photosynthetic capacity and plant growth of tobacco plants overexpressing ice plant (Mesembryanthemum crystallinum L.) aquaporin McMIPB under (1) a well-watered growth condition, (2) a well-watered and temporal higher vapor pressure deficit (VPD) condition, and (3) a soil water deficit growth condition to investigate the effect of McMIPB on photosynthetic responses under moderate soil and atmospheric humidity and water deficit conditions. Transgenic plants showed a significantly higher photosynthesis rate (by 48 %), higher mesophyll conductance (by 52 %), and enhanced growth under the well-watered growth condition than those of control plants. Decreases in the photosynthesis rate and stomatal conductance from ambient to higher VPD were slightly higher in transgenic plants than those in control plants. When plants were grown under the soil water deficit condition, decreases in the photosynthesis rate and stomatal conductance were less significant in transgenic plants than those in control plants. McMIPB is likely to work as a CO2 transporter, as well as control the regulation of stomata to water deficits.

Reactive Oxygen Species Generation-Scavenging and Signaling during Plant-Arbuscular Mycorrhizal and Piriformospora indica Interaction under Stress Condition.

PubMed

Nath, Manoj; Bhatt, Deepesh; Prasad, Ram; Gill, Sarvajeet S; Anjum, Naser A; Tuteja, Narendra

2016-01-01

A defined balance between the generation and scavenging of reactive oxygen species (ROS) is essential to utilize ROS as an adaptive defense response of plants under biotic and abiotic stress conditions. Moreover, ROS are not only a major determinant of stress response but also act as signaling molecule that regulates various cellular processes including plant-microbe interaction. In particular, rhizosphere constitutes the biologically dynamic zone for plant-microbe interactions which forms a mutual link leading to reciprocal signaling in both the partners. Among plant-microbe interactions, symbiotic associations of arbuscular mycorrhizal fungi (AMF) and arbuscular mycorrhizal-like fungus especially Piriformospora indica with plants are well known to improve plant growth by alleviating the stress-impacts and consequently enhance the plant fitness. AMF and P. indica colonization mainly enhances ROS-metabolism, maintains ROS-homeostasis, and thereby averts higher ROS-level accrued inhibition in plant cellular processes and plant growth and survival under stressful environments. This article summarizes the major outcomes of the recent reports on the ROS-generation, scavenging and signaling in biotic-abiotic stressed plants with AMF and P. indica colonization. Overall, a detailed exploration of ROS-signature kinetics during plant-AMF/ P. indica interaction can help in designing innovative strategies for improving plant health and productivity under stress conditions.

Cellulose microfibrils in plants: biosynthesis, deposition, and integration into the cell wall.

PubMed

Brett, C T

2000-01-01

Cellulose occurs in all higher plants and some algae, fungi, bacteria, and animals. It forms microfibrils containing the crystalline allomorphs, cellulose I alpha and I beta. Cellulose molecules are 500-15,000 glucose units long. What controls molecular size is unknown. Microfibrils are elongated by particle rosettes in the plasma membrane (cellulose synthase complexes). The precursor, UDP-glucose, may be generated from sucrose at the site of synthesis. The biosynthetic mechanism may involve lipid-linked intermediates. Cellulose synthase has been purified from bacteria, but not from plants. In plants, disrupted cellulose synthase may form callose. Cellulose synthase genes have been isolated from bacteria and plants. Cellulose-deficient mutants have been characterised. The deduced amino acid sequence suggests possible catalytic mechanisms. It is not known whether synthesis occurs at the reducing or nonreducing end. Endoglucanase may play a role in synthesis. Nascent cellulose molecules associate by Van der Waals and hydrogen bonds to form microfibrils. Cortical microtubules control microfibril orientation, thus determining the direction of cell growth. Self-assembly mechanisms may operate. Microfibril integration into the wall occurs by interactions with matrix polymers during microfibril formation.

Recent advances in corneal collagen cross-linking

PubMed Central

Sachdev, Gitansha Shreyas; Sachdev, Mahipal

2017-01-01

Corneal collagen cross-linking has become the preferred modality of treatment for corneal ectasia since its inception in late 1990s. Numerous studies have demonstrated the safety and efficacy of the conventional protocol. Our understanding of the cross-linking process is ever evolving, with its wide implications in the form of accelerated and pulsed protocols. Newer advancements in technology include various riboflavin formulations and the ability to deliver higher fluence protocols with customised irradiation patterns. A greater degree of customisation is likely the path forward, which will aim at achieving refractive improvements along with disease stability. The use of cross-linking for myopic correction is another avenue under exploration. Combination of half fluence cross-linking with refractive correction for high errors to prevent post LASIK regression is gaining interest. This review aims to highlight the various advancements in the cross-linking technology and its clinical applications. PMID:28905820

Effect of Designated Pollutants on Plants

DTIC Science & Technology

1977-11-01

fungi are root symbionts on higher plants. There was no effect on the fungus when mycorrhizal plants were exposed to HCl although ozone-exposed plants...MYCORRHIZAE In the last decade much attention has been focused on the ability of root-inhabiting vesicular - arbuscular (VA) mycorrhizae to improve...University of California, Riverside, California. Tinker, P. B., 1975, Effects of vesicular - arbuscular mycorrhiza on higher plants, 29th Symposium of the

The Airspace Concepts Evaluation System Architecture and System Plant

NASA Technical Reports Server (NTRS)

Windhorst, Robert; Meyn, Larry; Manikonda, Vikram; Carlos, Patrick; Capozzi, Brian

2006-01-01

The Airspace Concepts Evaluation System is a simulation of the National Airspace System. It includes models of flights, airports, airspaces, air traffic controls, traffic flow managements, and airline operation centers operating throughout the United States. It is used to predict system delays in response to future capacity and demand scenarios and perform benefits assessments of current and future airspace technologies and operational concepts. Facilitation of these studies requires that the simulation architecture supports plug and play of different air traffic control, traffic flow management, and airline operation center models and multi-fidelity modeling of flights, airports, and airspaces. The simulation is divided into two parts that are named, borrowing from classical control theory terminology, control and plant. The control consists of air traffic control, traffic flow management, and airline operation center models, and the plant consists of flight, airport, and airspace models. The plant can run open loop, in the absence of the control. However, undesired affects, such as conflicts and over congestions in the airspaces and airports, can occur. Different controls are applied, "plug and played", to the plant. A particular control is evaluated by analyzing how well it managed conflicts and congestions. Furthermore, the terminal area plants consist of models of airports and terminal airspaces. Each model consists of a set of nodes and links which are connected by the user to form a network. Nodes model runways, fixes, taxi intersections, gates, and/or other points of interest, and links model taxiways, departure paths, and arrival paths. Metering, flow distribution, and sequencing functions can be applied at nodes. Different fidelity model of how a flight transits are can be used by links. The fidelity of the model can be adjusted by the user by either changing the complexity of the node/link network-or the way that the link models how the flights transit

Exoproteome analysis reveals higher abundance of proteins linked to alkaline stress in persistent Listeria monocytogenes strains.

PubMed

Rychli, Kathrin; Grunert, Tom; Ciolacu, Luminita; Zaiser, Andreas; Razzazi-Fazeli, Ebrahim; Schmitz-Esser, Stephan; Ehling-Schulz, Monika; Wagner, Martin

2016-02-02

The foodborne pathogen Listeria monocytogenes, responsible for listeriosis a rare but severe infection disease, can survive in the food processing environment for month or even years. So-called persistent L. monocytogenes strains greatly increase the risk of (re)contamination of food products, and are therefore a great challenge for food safety. However, our understanding of the mechanism underlying persistence is still fragmented. In this study we compared the exoproteome of three persistent strains with the reference strain EGDe under mild stress conditions using 2D differential gel electrophoresis. Principal component analysis including all differentially abundant protein spots showed that the exoproteome of strain EGDe (sequence type (ST) 35) is distinct from that of the persistent strain R479a (ST8) and the two closely related ST121 strains 4423 and 6179. Phylogenetic analyses based on multilocus ST genes showed similar grouping of the strains. Comparing the exoproteome of strain EGDe and the three persistent strains resulted in identification of 22 differentially expressed protein spots corresponding to 16 proteins. Six proteins were significantly increased in the persistent L. monocytogenes exoproteomes, among them proteins involved in alkaline stress response (e.g. the membrane anchored lipoprotein Lmo2637 and the NADPH dehydrogenase NamA). In parallel the persistent strains showed increased survival under alkaline stress, which is often provided during cleaning and disinfection in the food processing environments. In addition, gene expression of the proteins linked to stress response (Lmo2637, NamA, Fhs and QoxA) was higher in the persistent strain not only at 37 °C but also at 10 °C. Invasion efficiency of EGDe was higher in intestinal epithelial Caco2 and macrophage-like THP1 cells compared to the persistent strains. Concurrently we found higher expression of proteins involved in virulence in EGDe e.g. the actin-assembly-inducing protein ActA and the

The Future of Tennessee: Higher Education 1987-1993.

ERIC Educational Resources Information Center

Tennessee Higher Education Commission, Nashville.

This master plan for higher education in Tennessee sketches a framework for the continued improvement of postsecondary institutions and emphasizes the critical links between higher education and other components of the state. A set of principles and achievement targets undergirding the master plan are outlined. Specific action is called for in…

The Role of Margin in Link Design and Optimization

NASA Technical Reports Server (NTRS)

Cheung, K.

2015-01-01

Link analysis is a system engineering process in the design, development, and operation of communication systems and networks. Link models that are mathematical abstractions representing the useful signal power and the undesirable noise and attenuation effects (including weather effects if the signal path transverses through the atmosphere) that are integrated into the link budget calculation that provides the estimates of signal power and noise power at the receiver. Then the link margin is applied which attempts to counteract the fluctuations of the signal and noise power to ensure reliable data delivery from transmitter to receiver. (Link margin is dictated by the link margin policy or requirements.) A simple link budgeting approach assumes link parameters to be deterministic values typically adopted a rule-of-thumb policy of 3 dB link margin. This policy works for most S- and X-band links due to their insensitivity to weather effects. But for higher frequency links like Ka-band, Ku-band, and optical communication links, it is unclear if a 3 dB link margin would guarantee link closure. Statistical link analysis that adopted the 2-sigma or 3-sigma link margin incorporates link uncertainties in the sigma calculation. (The Deep Space Network (DSN) link margin policies are 2-sigma for downlink and 3-sigma for uplink.) The link reliability can therefore be quantified statistically even for higher frequency links. However in the current statistical link analysis approach, link reliability is only expressed as the likelihood of exceeding the signal-to-noise ratio (SNR) threshold that corresponds to a given bit-error-rate (BER) or frame-error-rate (FER) requirement. The method does not provide the true BER or FER estimate of the link with margin, or the required signalto-noise ratio (SNR) that would meet the BER or FER requirement in the statistical sense. In this paper, we perform in-depth analysis on the relationship between BER/FER requirement, operating SNR, and

Rhizospheric fungi and their link with the nitrogen-fixing Frankia harbored in host plant Hippophae rhamnoides L.

PubMed

Zhou, Xue; Tian, Lei; Zhang, Jianfeng; Ma, Lina; Li, Xiujun; Tian, Chunjie

2017-12-01

Sea buckthorn (Hippophae rhamnoides L.) is a pioneer plant used for land reclamation and an appropriate material for studying the interactions of symbiotic microorganisms because of its nitrogen-fixing root nodules and mycorrhiza. We used high-throughput sequencing to reveal the diversities and community structures of rhizospheric fungi and their link with nitrogen-fixing Frankia harbored in sea buckthorn collected along an altitude gradient from the Qinghai Tibet Plateau to interior areas. We found that the fungal diversities and compositions varied between different sites. Ascomycota, Basidiomycota, and Zygomycota were the dominant phyla. The distribution of sea buckthorn rhizospheric fungi was driven by both environmental factors and the geographic distance. Among all examined soil characteristics, altitude, AP, and pH were found to have significant (p < 0.05) effect on the rhizospheric fungal community. The rhizospheric fungal communities became more distinct as the distance increased. Moreover, co-inertia analysis identified significant co-structures between Frankia and AMF communities in the rhizosphere of sea buckthorn. We conclude that at the large scale, there are certain linkages between nitrogen-fixing bacteria and the AMF expressed in the distributional pattern. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel arabinan and galactan oligosaccharides from dicotyledonous plants

NASA Astrophysics Data System (ADS)

Wefers, Daniel; Tyl, Catrin; Bunzel, Mirko

2014-11-01

Arabinans and galactans are neutral pectic side chains and an important part of the cell walls of dicotyledonous plants. To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment. LC-MS2 and one- and two-dimensional NMR spectroscopy were used for unambiguous structural characterization. It was demonstrated that arabinans contain β-(1→3)-linked arabinobiose as a side chain in quinoa seeds, while potato galactan was comprised of β-(1→4)-linked galactopyranoses which are interspersed with α-(1→4)-linked arabinopyranoses. Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized. The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

Internal Audit in Higher Education.

ERIC Educational Resources Information Center

Holmes, Alison, Ed.; Brown, Sally, Ed.

This book describes a range of examples of internal audit in higher education as part of a process of the exchange of good practice. The book recognizes well-established links with audit theory from other contexts and makes use of theoretical perspectives explored in the financial sector. The chapters are: (1) "Quality Audit Issues"…

Methods of affecting nitrogen assimilation in plants

DOEpatents

Coruzzi, Gloria; Gutierrez, Rodrigo A.; Nero, Damion C.

2016-10-11

Provided herein are compositions and methods for producing transgenic plants. In specific embodiments, transgenic plants comprise a construct comprising a polynucleotide encoding CCA1, GLK1 or bZIP1, operably linked to a plant-specific promote, wherein the CCA1, GLK1 or bZIP1 is ectopically overexpressed in the transgenic plants, and wherein the promoter is optionally a constitutive or inducible promoter. In other embodiments, transgenic plants in which express a lower level of CCA1, GLK1 or bZIP1 are provided. Also provided herein are commercial products (e.g., pulp, paper, paper products, or lumber) derived from the transgenic plants (e.g., transgenic trees) produced using the methods provided herein.

Rapid Y degeneration and dosage compensation in plant sex chromosomes

PubMed Central

Papadopulos, Alexander S. T.; Chester, Michael; Ridout, Kate; Filatov, Dmitry A.

2015-01-01

The nonrecombining regions of animal Y chromosomes are known to undergo genetic degeneration, but previous work has failed to reveal large-scale gene degeneration on plant Y chromosomes. Here, we uncover rapid and extensive degeneration of Y-linked genes in a plant species, Silene latifolia, that evolved sex chromosomes de novo in the last 10 million years. Previous transcriptome-based studies of this species missed unexpressed, degenerate Y-linked genes. To identify sex-linked genes, regardless of their expression, we sequenced male and female genomes of S. latifolia and integrated the genomic contigs with a high-density genetic map. This revealed that 45% of Y-linked genes are not expressed, and 23% are interrupted by premature stop codons. This contrasts with X-linked genes, in which only 1.3% of genes contained stop codons and 4.3% of genes were not expressed in males. Loss of functional Y-linked genes is partly compensated for by gene-specific up-regulation of X-linked genes. Our results demonstrate that the rate of genetic degeneration of Y-linked genes in S. latifolia is as fast as in animals, and that the evolutionary trajectories of sex chromosomes are similar in the two kingdoms. PMID:26438872

Inherent and environmental patterns in biomass allocation and allometry among higher plants

NASA Astrophysics Data System (ADS)

Poorter, Hendrik

2017-04-01

It is well-known that plants may adjust the distribution of biomass over leaves, stems and roots depending on environmental conditions. It is also clear that size is an important factor as well. However, good quantitative insights are lacking. In this talk I analyse biomass allocation patterns to leaves, stems and roots of herbs and woody species. A database was compiled with 11.000 records of leaf, stem and root biomass for 1200 species. First, I'll derive general dose-response curves that describe the relationship between biomass allocation and the 12 most important a-biotic environmental factors and compare them with the changes in leaf, stem and root morphology. Second, I'll focus on allometric relationships between the various organs and test to what extent they comply with models like that for Metabolic Scaling Theory, where the slope of the log-log relationship between leaf and root biomass is expected to have a value of ¾. Third, I analyse how leaf, stem and root mass fractions change as a function of total plant size. This offers a great opportunity to test to what extent there are systematic differences in allocation patterns related to phylogeny (e.g. Gymnosperms vs. Angiosperms, grasses vs. herbaceous dicots) and functional group (e.g. deciduous vs. evergreens). Poorter et al. (2012) Biomass allocation to leaves, stems and roots: meta-analyses of interspecific variation and environmental control. New Phytol. 193: 30-50. Poorter & Sack (2012) Pitfalls and possibilities in the analysis of biomass allocation patterns in plants. Front. Plant Sci. 3: 259. Poorter et al. (2015) How does biomass distribution change with size and differ among species? New Phytol. 208: 736-749

Auxin crosstalk to plant immune networks: a plant-pathogen interaction perspective.

PubMed

Naseem, Muhammad; Srivastava, Mugdha; Tehseen, Muhammad; Ahmed, Nazeer

2015-01-01

The plant hormone auxin regulates a whole repertoire of plant growth and development. Many plant-associated microorganisms, by virtue of their auxin production capability, mediate phytostimulation effects on plants. Recent studies, however, demonstrate diverse mechanisms whereby plant pathogens manipulate auxin biosynthesis, signaling and transport pathways to promote host susceptibility. Auxin responses have been coupled to their antagonistic and synergistic interactions with salicylic acid and jasmonate mediated defenses, respectively. Here, we discuss that a better understanding of auxin crosstalk to plant immune networks would enable us to engineer crop plants with higher protection and low unintended yield losses.

Advanced genetic tools for plant biotechnology

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

Liu, WS; Yuan, JS; Stewart, CN

2013-10-09

Basic research has provided a much better understanding of the genetic networks and regulatory hierarchies in plants. To meet the challenges of agriculture, we must be able to rapidly translate this knowledge into generating improved plants. Therefore, in this Review, we discuss advanced tools that are currently available for use in plant biotechnology to produce new products in plants and to generate plants with new functions. These tools include synthetic promoters, 'tunable' transcription factors, genome-editing tools and site-specific recombinases. We also review some tools with the potential to enable crop improvement, such as methods for the assembly and synthesis ofmore » large DNA molecules, plant transformation with linked multigenes and plant artificial chromosomes. These genetic technologies should be integrated to realize their potential for applications to pressing agricultural and environmental problems.« less

Steroid plant hormones: effects outside plant kingdom.

PubMed

Zhabinskii, Vladimir N; Khripach, Natalia B; Khripach, Vladimir A

2015-05-01

Brassinosteroids (BS) are the first group of steroid-hormonal compounds isolated from and acting in plants. Among numerous physiological effects of BS growth stimulation and adaptogenic activities are especially remarkable. In this review, we provide evidence that BS possess similar types of activity also beyond plant kingdom at concentrations comparable with those for plants. This finding allows looking at steroids from a new point of view: how common are the mechanisms of steroid bioregulation in different types of organisms from protozoa to higher animals. Copyright © 2014 Elsevier Inc. All rights reserved.

Suppression of the invasive plant mile-a-minute (Mikania micrantha) by local crop sweet potato (Ipomoea batatas) by means of higher growth rate and competition for soil nutrients.

PubMed

Shen, Shicai; Xu, Gaofeng; Clements, David Roy; Jin, Guimei; Chen, Aidong; Zhang, Fudou; Kato-Noguchi, Hisashi

2015-01-28

There are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. Competitive crops may provide potent management tools against invasive plants. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-a-minute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. The trial incorporated seven ratios of sweet potato and mile-a-minute plants in 25 m(2) plots. In monoculture, the total biomass, biomass of adventitious root, leafstalk length, and leaf area of sweet potato were all higher than those of mile-a-minute, and in mixed culture the plant height, branch, leaf, stem node, adventitious root, flowering and biomass of mile-a-minute were suppressed significantly (P < 0.05). The relative yield (RY) of mile-a-minute and sweet potato was less than 1.0 in mixed culture, indicating that intraspecific competition was less than interspecific competition. The competitive balance index of sweet potato demonstrated a higher competitive ability than mile-a-minute. Except pH, other soil nutrient contents of initial soil (CK) were significantly higher than those of seven treatments. The concentrations of soil organic matter, total N, total K, available N, available P, available K, exchange Ca, exchange Mg, available Mn, and available B were significantly greater (P < 0.05) in mile-a-minute monoculture soil than in sweet potato monoculture soil, and were reduced by the competition of sweet potato in the mixture. Evidently sweet potato has a competitive advantage in terms of plant growth characteristics and greater absorption of soil nutrients. Thus, planting sweet potato is a promising technique for reducing infestations of mile-a-minute, providing weed management benefits and economic returns from harvest of sweet

Linking plant functional trait plasticity and the large increase in forest water use efficiency

NASA Astrophysics Data System (ADS)

Mastrotheodoros, Theodoros; Pappas, Christoforos; Molnar, Peter; Burlando, Paolo; Keenan, Trevor F.; Gentine, Pierre; Gough, Christopher M.; Fatichi, Simone

2017-09-01

Elevated atmospheric CO2 concentrations are expected to enhance photosynthesis and reduce stomatal conductance, thus increasing plant water use efficiency. A recent study based on eddy covariance flux observations from Northern Hemisphere forests showed a large increase in inherent water use efficiency (IWUE). Here we used an updated version of the same data set and robust uncertainty quantification to revisit these contemporary IWUE trends. We tested the hypothesis that the observed IWUE increase could be attributed to interannual trends in plant functional traits, potentially triggered by environmental change. We found that IWUE increased by 1.3% yr-1, which is less than previously reported but still larger than theoretical expectations. Numerical simulations with the Tethys-Chloris ecosystem model using temporally static plant functional traits cannot explain this increase. Simulations with plant functional trait plasticity, i.e., temporal changes in model parameters such as specific leaf area and maximum Rubisco capacity, match the observed trends in IWUE. Our results show that trends in plant functional traits, equal to 1.0% yr-1, can explain the observed IWUE trends. Thus, at decadal or longer time scales, trait plasticity could potentially influence forest water, carbon, and energy fluxes with profound implications for both the monitoring of temporal changes in plant functional traits and their representation in Earth system models.

Why Linking Budgets to Plans Has Proven Difficult in Higher Education.

ERIC Educational Resources Information Center

Schmidtlein, Frank A.

1990-01-01

Conclusions from two studies (including a three-year nationwide study of higher education institutional planning) concern types of planning (strategic, program, facility, operational, budget, and issue-specific), and limitations (the limited powers of prediction and the political character of planning and budgeting). Types of budgeting processes…

Impairment of soil health due to fly ash-fugitive dust deposition from coal-fired thermal power plants.

PubMed

Raja, R; Nayak, A K; Shukla, A K; Rao, K S; Gautam, Priyanka; Lal, B; Tripathi, R; Shahid, M; Panda, B B; Kumar, A; Bhattacharyya, P; Bardhan, G; Gupta, S; Patra, D K

2015-11-01

Thermal power stations apart from being source of energy supply are causing soil pollution leading to its degradation in fertility and contamination. Fine particle and trace element emissions from energy production in coal-fired thermal power plants are associated with significant adverse effects on human, animal, and soil health. Contamination of soil with cadmium, nickel, copper, lead, arsenic, chromium, and zinc can be a primary route of human exposure to these potentially toxic elements. The environmental evaluation of surrounding soil of thermal power plants in Odisha may serve a model study to get the insight into hazards they are causing. The study investigates the impact of fly ash-fugitive dust (FAFD) deposition from coal-fired thermal power plant emissions on soil properties including trace element concentration, pH, and soil enzymatic activities. Higher FAFD deposition was found in the close proximity of power plants, which led to high pH and greater accumulation of heavy metals. Among the three power plants, in the vicinity of NALCO, higher concentrations of soil organic carbon and nitrogen was observed whereas, higher phosphorus content was recorded in the proximity of NTPC. Multivariate statistical analysis of different variables and their association indicated that FAFD deposition and soil properties were influenced by the source of emissions and distance from source of emission. Pollution in soil profiles and high risk areas were detected and visualized using surface maps based on Kriging interpolation. The concentrations of chromium and arsenic were higher in the soil where FAFD deposition was more. Observance of relatively high concentration of heavy metals like cadmium, lead, nickel, and arsenic and a low concentration of enzymatic activity in proximity to the emission source indicated a possible link with anthropogenic emissions.

Plant-frugivore interactions in an intact tropical forest in north-east Thailand.

PubMed

Sankamethawee, Wangworn; Pierce, Andrew J; Gale, George A; Hardesty, Britta Denise

2011-09-01

Fleshy-fruited plants in tropical forests largely rely on vertebrate frugivores to disperse their seeds. Although this plant-animal interaction is typically considered a diffuse mutualism, it is fundamental as it provides the template on which tropical forest communities are structured. We applied a mutualistic network approach to investigate the relationship between small-fruited fleshy plant species and the fruit-eating bird community in an intact evergreen forest in northeast Thailand. A minimum of 53 bird species consumed fruits of 136 plant species. Plant-avian frugivore networks were highly asymmetrical, with observed networks filling 30% of all potential links. Whereas some of the missing links in the present study might be due to undersampling, forbidden links can be attributed to size constraints, accessibility and phenological uncoupling, and although the majority of missing links were unknown (58.2%), many were probably due to a given bird species being either rare or only a very occasional fruit eater. The most common frugivores were bulbuls, barbets and fairy-bluebirds, which were responsible for the majority of fruit removal from small fleshy fruited species in our system. Migratory birds seemed to be a minor component of the plant-frugivore networks, accounting for only 3% of feeding visits to fruiting trees; they filled 2% of the overall potential networks. The majority of interactions were generalized unspecific; however, Saurauia roxburghii Wall. appeared to be dependent on flowerpeckers for dispersal, while Thick-billed Pigeons were only seen to eat figs. © 2011 ISZS, Blackwell Publishing and IOZ/CAS.

PGSB PlantsDB: updates to the database framework for comparative plant genome research.

PubMed

Spannagl, Manuel; Nussbaumer, Thomas; Bader, Kai C; Martis, Mihaela M; Seidel, Michael; Kugler, Karl G; Gundlach, Heidrun; Mayer, Klaus F X

2016-01-04

PGSB (Plant Genome and Systems Biology: formerly MIPS) PlantsDB (http://pgsb.helmholtz-muenchen.de/plant/index.jsp) is a database framework for the comparative analysis and visualization of plant genome data. The resource has been updated with new data sets and types as well as specialized tools and interfaces to address user demands for intuitive access to complex plant genome data. In its latest incarnation, we have re-worked both the layout and navigation structure and implemented new keyword search options and a new BLAST sequence search functionality. Actively involved in corresponding sequencing consortia, PlantsDB has dedicated special efforts to the integration and visualization of complex triticeae genome data, especially for barley, wheat and rye. We enhanced CrowsNest, a tool to visualize syntenic relationships between genomes, with data from the wheat sub-genome progenitor Aegilops tauschii and added functionality to the PGSB RNASeqExpressionBrowser. GenomeZipper results were integrated for the genomes of barley, rye, wheat and perennial ryegrass and interactive access is granted through PlantsDB interfaces. Data exchange and cross-linking between PlantsDB and other plant genome databases is stimulated by the transPLANT project (http://transplantdb.eu/). © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Generation of poly-β-hydroxybutyrate from acetate in higher plants: Detection of acetoacetyl CoA reductase- and PHB synthase- activities in rice.

PubMed

Tsuda, Hirohisa; Shiraki, Mari; Inoue, Eri; Saito, Terumi

2016-08-20

It has been reported that Poly-β-hydroxybutyrate (PHB) is generated from acetate in the rice root. However, no information is available about the biosynthetic pathway of PHB from acetate in plant cells. In the bacterium Ralstonia eutropha H16 (R. eutropha), PHB is synthesized from acetyl CoA by the consecutive reaction of three enzymes: β-ketothiolase (EC: 2.3.1.9), acetoacetyl CoA reductase (EC: 1.1.1.36) and PHB synthase (EC: 2.3.1.-). Thus, in this study, we examined whether the above three enzymatic activities were also detected in rice seedlings. The results clearly showed that the activities of the above three enzymes were all detected in rice. In particular, the PHB synthase activity was detected specifically in the sonicated particulate fractions (2000g 10min precipitate (ppt) and the 8000g 30min ppt) of rice roots and leaves. In addition to these enzyme activities, several new experimental results were obtained on PHB synthesis in higher plants: (a) (14)C-PHB generated from 2-(14)C-acetate was mainly localized in the 2000g 10min ppt and the 8000g 30min ppt of rice root. (b) Addition of acetate (0.1-10mM) to culture medium of rice seedlings did not increase the content of PHB in the rice root or leaf. (c) In addition to C3 plants, PHB was generated from acetate in a C4 plant (corn) and in a CAM plant (Bryophyllum pinnatum). d) Washing with ethylenediaminetetraacetic acid (EDTA) strongly suggested that the PHB synthesized from acetate was of plant origin and was not bacterial contamination. Copyright © 2016 Elsevier GmbH. All rights reserved.

The Missing Link in Australian Tertiary Education: Short-Cycle Higher Education

ERIC Educational Resources Information Center

Moodie, Gavin

2003-01-01

The blurring of the boundary between Australian vocational education and training and higher education is leading to a reconsideration of the current structure of Australian tertiary education. This paper starts with the main overlap of the Australian tertiary education sectors, diplomas and advanced diplomas. The ambiguous treatment of these…

Microbial Hub Taxa Link Host and Abiotic Factors to Plant Microbiome Variation

PubMed Central

Agler, Matthew T.; Ruhe, Jonas; Kroll, Samuel; Morhenn, Constanze; Kim, Sang-Tae; Weigel, Detlef; Kemen, Eric M.

2016-01-01

Plant-associated microorganisms have been shown to critically affect host physiology and performance, suggesting that evolution and ecology of plants and animals can only be understood in a holobiont (host and its associated organisms) context. Host-associated microbial community structures are affected by abiotic and host factors, and increased attention is given to the role of the microbiome in interactions such as pathogen inhibition. However, little is known about how these factors act on the microbial community, and especially what role microbe–microbe interaction dynamics play. We have begun to address this knowledge gap for phyllosphere microbiomes of plants by simultaneously studying three major groups of Arabidopsis thaliana symbionts (bacteria, fungi and oomycetes) using a systems biology approach. We evaluated multiple potential factors of microbial community control: we sampled various wild A. thaliana populations at different times, performed field plantings with different host genotypes, and implemented successive host colonization experiments under lab conditions where abiotic factors, host genotype, and pathogen colonization was manipulated. Our results indicate that both abiotic factors and host genotype interact to affect plant colonization by all three groups of microbes. Considering microbe–microbe interactions, however, uncovered a network of interkingdom interactions with significant contributions to community structure. As in other scale-free networks, a small number of taxa, which we call microbial “hubs,” are strongly interconnected and have a severe effect on communities. By documenting these microbe–microbe interactions, we uncover an important mechanism explaining how abiotic factors and host genotypic signatures control microbial communities. In short, they act directly on “hub” microbes, which, via microbe–microbe interactions, transmit the effects to the microbial community. We analyzed two “hub” microbes (the

Spectral Reflectance Properties of Wetlands Plants

DTIC Science & Technology

1994-08-01

metabolism (Figure 1). Flood-intolerant plants also produce malate ; however, malate is converted to pyruvate, which is further reduced to ethanol...adapted to flooded conditions. For example, flood tolerance has been linked to the production and accumulation of non-toxic malate as a by- product of...oxidation (REDOX) potential. REDOX potential Figure l. Metabolic pathways for o tolernt and flood tolernt describes the reducing plants dted from MiLc

PV integration into a CSP plant

NASA Astrophysics Data System (ADS)

Carvajal, Javier López; Barea, Jose M.; Barragan, Jose; Ortega, Carlos

2017-06-01

This paper describes a preliminary techno-economic analysis of the integration of a PV plant into an optimized Parabolic Trough Plant in order to reduce the online consumptions and thus, increase the net electricity injected into the grid. The idea is to assess the feasibility of such project and see what configuration would be the optimal. An extra effort has been made in terms of modelling as the analysis has to be done to the integrated CSP + PV plant instead of analyzing them independently. Two different technologies have been considered for the PV plant, fix and one-axis tracking. Additionally three different scenarios have been considered for the CSP plant auxiliary consumptions as they are essential for determining the optimal PV plant (the higher the auxiliary consumption the higher the optimal PV plant). As could be expected, the results for all cases with PV show an improvement in terms of electricity generation and also in terms of LCOE with respect to the CSP plant. Such improvement is slightly higher with tracking technology for this specific study. Although this exercise has been done to an already designed CSP plant (so only the PV plant had to be optimized), the methodology could be applied for the optimization of an integrated CSP + PV plant during the design phase.

Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion.

PubMed

Smith, Jennifer N; Emlen, Douglas J; Pearson, Dean E

2016-01-01

Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe's architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations.

Linking Emotional Intelligence to Achieve Technology Enhanced Learning in Higher Education

ERIC Educational Resources Information Center

Kruger, Janette; Blignaut, A. Seugnet

2013-01-01

Higher education institutions (HEIs) increasingly use technology-enhanced learning (TEL) environments (e.g. blended learning and e-learning) to improve student throughput and retention rates. As the demand for TEL courses increases, expectations rise for faculty to meet the challenge of using TEL effectively. The promises that TEL holds have not…

MIPS PlantsDB: a database framework for comparative plant genome research.

PubMed

Nussbaumer, Thomas; Martis, Mihaela M; Roessner, Stephan K; Pfeifer, Matthias; Bader, Kai C; Sharma, Sapna; Gundlach, Heidrun; Spannagl, Manuel

2013-01-01

The rapidly increasing amount of plant genome (sequence) data enables powerful comparative analyses and integrative approaches and also requires structured and comprehensive information resources. Databases are needed for both model and crop plant organisms and both intuitive search/browse views and comparative genomics tools should communicate the data to researchers and help them interpret it. MIPS PlantsDB (http://mips.helmholtz-muenchen.de/plant/genomes.jsp) was initially described in NAR in 2007 [Spannagl,M., Noubibou,O., Haase,D., Yang,L., Gundlach,H., Hindemitt, T., Klee,K., Haberer,G., Schoof,H. and Mayer,K.F. (2007) MIPSPlantsDB-plant database resource for integrative and comparative plant genome research. Nucleic Acids Res., 35, D834-D840] and was set up from the start to provide data and information resources for individual plant species as well as a framework for integrative and comparative plant genome research. PlantsDB comprises database instances for tomato, Medicago, Arabidopsis, Brachypodium, Sorghum, maize, rice, barley and wheat. Building up on that, state-of-the-art comparative genomics tools such as CrowsNest are integrated to visualize and investigate syntenic relationships between monocot genomes. Results from novel genome analysis strategies targeting the complex and repetitive genomes of triticeae species (wheat and barley) are provided and cross-linked with model species. The MIPS Repeat Element Database (mips-REdat) and Catalog (mips-REcat) as well as tight connections to other databases, e.g. via web services, are further important components of PlantsDB.

MIPS PlantsDB: a database framework for comparative plant genome research

PubMed Central

Nussbaumer, Thomas; Martis, Mihaela M.; Roessner, Stephan K.; Pfeifer, Matthias; Bader, Kai C.; Sharma, Sapna; Gundlach, Heidrun; Spannagl, Manuel

2013-01-01

The rapidly increasing amount of plant genome (sequence) data enables powerful comparative analyses and integrative approaches and also requires structured and comprehensive information resources. Databases are needed for both model and crop plant organisms and both intuitive search/browse views and comparative genomics tools should communicate the data to researchers and help them interpret it. MIPS PlantsDB (http://mips.helmholtz-muenchen.de/plant/genomes.jsp) was initially described in NAR in 2007 [Spannagl,M., Noubibou,O., Haase,D., Yang,L., Gundlach,H., Hindemitt, T., Klee,K., Haberer,G., Schoof,H. and Mayer,K.F. (2007) MIPSPlantsDB–plant database resource for integrative and comparative plant genome research. Nucleic Acids Res., 35, D834–D840] and was set up from the start to provide data and information resources for individual plant species as well as a framework for integrative and comparative plant genome research. PlantsDB comprises database instances for tomato, Medicago, Arabidopsis, Brachypodium, Sorghum, maize, rice, barley and wheat. Building up on that, state-of-the-art comparative genomics tools such as CrowsNest are integrated to visualize and investigate syntenic relationships between monocot genomes. Results from novel genome analysis strategies targeting the complex and repetitive genomes of triticeae species (wheat and barley) are provided and cross-linked with model species. The MIPS Repeat Element Database (mips-REdat) and Catalog (mips-REcat) as well as tight connections to other databases, e.g. via web services, are further important components of PlantsDB. PMID:23203886

LinkedIn as a Learning Tool in Business Education

ERIC Educational Resources Information Center

Cooper, Brett; Naatus, Mary Kate

2014-01-01

This article summarizes the existing research on social media as a learning tool in higher education and adds to the literature on incorporating social media tools into collegiate business education by suggesting specific course content areas of business where LinkedIn exercises and training can be incorporated. LinkedIn as a classroom tool cannot…

Most of ADP·glucose linked to starch biosynthesis occurs outside the chloroplast in source leaves

PubMed Central

Baroja-Fernández, Edurne; Muñoz, Francisco José; Zandueta-Criado, Aitor; Morán-Zorzano, María Teresa; Viale, Alejandro Miguel; Alonso-Casajús, Nora; Pozueta-Romero, Javier

2004-01-01

Sucrose and starch are end products of two segregated gluconeogenic pathways, and their production takes place in the cytosol and chloroplast of green leaves, respectively. According to this view, the plastidial ADP·glucose (ADPG) pyrophosphorylase (AGP) is the sole enzyme catalyzing the synthesis of the starch precursor molecule ADPG. However, a growing body of evidences indicates that starch formation involves the import of cytosolic ADPG to the chloroplast. This evidence is consistent with the idea that synthesis of the ADPG linked to starch biosynthesis takes place in the cytosol by means of sucrose synthase, whereas AGP channels the glucose units derived from the starch breakdown. To test this hypothesis, we first investigated the subcellular localization of ADPG. Toward this end, we constructed transgenic potato plants that expressed the ADPG-cleaving adenosine diphosphate sugar pyrophosphatase (ASPP) from Escherichia coli either in the chloroplast or in the cytosol. Source leaves from plants expressing ASPP in the chloroplast exhibited reduced starch and normal ADPG content as compared with control plants. Most importantly however, leaves from plants expressing ASPP in the cytosol showed a large reduction of the levels of both ADPG and starch, whereas hexose phosphates increased as compared with control plants. No pleiotropic changes in photosynthetic parameters and maximum catalytic activities of enzymes closely linked to starch and sucrose metabolism could be detected in the leaves expressing ASPP in the cytosol. The overall results show that, essentially similar to cereal endosperms, most of the ADPG linked to starch biosynthesis in source leaves occurs in the cytosol. PMID:15326306

DNA cross-linking by dehydromonocrotaline lacks apparent base sequence preference.

PubMed

Rieben, W Kurt; Coulombe, Roger A

2004-12-01

Pyrrolizidine alkaloids (PAs) are ubiquitous plant toxins, many of which, upon oxidation by hepatic mixed-function oxidases, become reactive bifunctional pyrrolic electrophiles that form DNA-DNA and DNA-protein cross-links. The anti-mitotic, toxic, and carcinogenic action of PAs is thought to be caused, at least in part, by these cross-links. We wished to determine whether the activated PA pyrrole dehydromonocrotaline (DHMO) exhibits base sequence preferences when cross-linked to a set of model duplex poly A-T 14-mer oligonucleotides with varying internal and/or end 5'-d(CG), 5'-d(GC), 5'-d(TA), 5'-d(CGCG), or 5'-d(GCGC) sequences. DHMO-DNA cross-links were assessed by electrophoretic mobility shift assay (EMSA) of 32P endlabeled oligonucleotides and by HPLC analysis of cross-linked DNAs enzymatically digested to their constituent deoxynucleosides. The degree of DNA cross-links depended upon the concentration of the pyrrole, but not on the base sequence of the oligonucleotide target. Likewise, HPLC chromatograms of cross-linked and digested DNAs showed no discernible sequence preference for any nucleotide. Added glutathione, tyrosine, cysteine, and aspartic acid, but not phenylalanine, threonine, serine, lysine, or methionine competed with DNA as alternate nucleophiles for cross-linking by DHMO. From these data it appears that DHMO exhibits no strong base preference when forming cross-links with DNA, and that some cellular nucleophiles can inhibit DNA cross-link formation.

Involvement of plant endogenous ABA in Bacillus megaterium PGPR activity in tomato plants.

PubMed

Porcel, Rosa; Zamarreño, Ángel María; García-Mina, José María; Aroca, Ricardo

2014-01-25

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil bacteria which benefit plants by improving plant productivity and immunity. The mechanisms involved in these processes include the regulation of plant hormone levels such as ethylene and abscisic acid (ABA). The aim of the present study was to determine whether the activity of Bacillus megaterium PGPR is affected by the endogenous ABA content of the host plant. The ABA-deficient tomato mutants flacca and sitiens and their near-isogenic wild-type parental lines were used. Growth, stomatal conductance, shoot hormone concentration, competition assay for colonization of tomato root tips, and root expression of plant genes expected to be modulated by ABA and PGPR were examined. Contrary to the wild-type plants in which PGPR stimulated growth rates, PGPR caused growth inhibition in ABA-deficient mutant plants. PGPR also triggered an over accumulation of ethylene in ABA-deficient plants which correlated with a higher expression of the pathogenesis-related gene Sl-PR1b. Positive correlation between over-accumulation of ethylene and a higher expression of Sl-PR1b in ABA-deficient mutant plants could indicate that maintenance of normal plant endogenous ABA content may be essential for the growth promoting action of B. megaterium by keeping low levels of ethylene production.

Higher organization and histone modification of the plant nucleus and chromosome.

PubMed

Wako, T; Fukui, K

2010-07-01

Plants have a wide range of genome sizes. The length of each DNA molecule is usually much longer than the diameter of the cell and the length of each metaphase chromosome is effectively shortened to progress through mitosis. Thus some questions arise, such as: How is genomic DNA folded and shortened into chromosomes? What kind of proteins and/or their modifications contribute to chromosome structure? Are there any upper limits for the ratio of DNA volume to nuclear volume? This review attempts to answer these questions based on recent advances in chromosome research. Genomic DNA is first folded into nucleosomal fibers and then superfolded into metaphase chromosomes to sufficiently shorten its length to less than the upper limit for normal progression of cell division. Nucleosomes play structural roles, not only for DNA folding, but also for determination of euchromatin, heterochromatin, and centromeres, together with post-translational modifications and replacement of core histones with histone variants, and for the regulation of their structure and transcriptional status. More than 200 proteins of human metaphase chromosomes have been identified, including 5 types of nucleosome histones. They are categorized into 4 groups, and a 4-layer model of the human metaphase chromosome has been developed. There are upper limits for DNA volume. In all plants examined to date the DNA volume does not exceed 3% of the nuclear volume. Histone modification also has an impact on the spatial distribution of chromosomes within a nucleus, which seems to be related to the plant genome size. These points are discussed as well, as they are essential to maintain proper nuclear functions. Copyright 2010 S. Karger AG, Basel.

Biological consilience of hydrogen sulfide and nitric oxide in plants: Gases of primordial earth linking plant, microbial and animal physiologies.

PubMed

Yamasaki, Hideo; Cohen, Michael F

2016-05-01

Hydrogen sulfide (H2S) is produced in the mammalian body through the enzymatic activities of cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3MST). A growing number of studies have revealed that biogenic H2S produced in tissues is involved in a variety of physiological responses in mammals including vasorelaxation and neurotransmission. It is now evident that mammals utilize H2S to regulate multiple signaling systems, echoing the research history of the gaseous signaling molecules nitric oxide (NO) and carbon monoxide (CO) that had previously only been recognized for their cytotoxicity. In the human diet, meats (mammals, birds and fishes) and vegetables (plants) containing cysteine and other sulfur compounds are the major dietary sources for endogenous production of H2S. Plants are primary producers in ecosystems on the earth and they synthesize organic sulfur compounds through the activity of sulfur assimilation. Although plant H2S-producing activities have been known for a long time, our knowledge of H2S biology in plant systems has not been updated to the extent of mammalian studies. Here we review recent progress on H2S studies, highlighting plants and bacteria. Scoping the future integration of H2S, NO and O2 biology, we discuss a possible linkage between physiology, ecology and evolutional biology of gas metabolisms that may reflect the historical changes of the Earth's atmospheric composition. Copyright © 2016 Elsevier Inc. All rights reserved.

Bioaugmentation in growing plants for lunar bases

NASA Astrophysics Data System (ADS)

Zaets, I.; Burlak, O.; Rogutskyy, I.; Vasilenko, A.; Mytrokhyn, O.; Lukashov, D.; Foing, B.; Kozyrovska, N.

2011-03-01

Microorganisms may be a key element in a precursory scenario of growing pioneer plants for extraterrestrial exploration. They can be used for plant inoculation to leach nutritional elements from regolith, to alleviate lunar stressors, as well as to decompose both lunar rocks and the plant straw in order to form a protosoil. Bioleaching capacities of both French marigold (Tagetes patula L.) and the associated bacteria in contact with a lunar rock simulant (terrestrial anorthosite) were examined using the model plant-bacteria microcosms under controlled conditions. Marigold accumulated K, Na, Fe, Zn, Ni, and Cr at higher concentrations in anorthosite compared to the podzol soil. Plants inoculated with the consortium of well-defined species of bacteria accumulated higher levels of K, Mg, and Mn, but lower levels of Ni, Cr, Zn, Na, Ca, Fe, which exist at higher levels in anorthosite. Bacteria also affected the Са/Mg and Fe/Mn ratios in the biomass of marigold grown on anorthosite. Despite their growth retardation, the inoculated plants had 15% higher weight on anorthosite than noninoculated plants. The data suggest that the bacteria supplied basic macro-and microelements to the model plant.

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts

PubMed Central

Kaiser, Bettina; van der Krol, Sander; Kaldenhoff, Ralf

2010-01-01

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance. Calcium (Ca2+) release is the major second messenger during signal transduction. Therefore, we have studied Ca2+ spiking in tomato and tobacco during infection with C. reflexa. In our recently published study1 Ca2+ signals were monitored as bioluminescence in aequorin-expressing tomato plants after the onset of C. reflexa infestation. Signals at the attachment sites were observed from 30 to 48 h after infection. In an assay with leaf disks of aequorin-expressing tomato which were treated with different C. reflexa plant extracts it turned out that the substance that induced Ca2+ release in the host plant was closely linked to the parasite's haustoria. PMID:20818172

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition.

PubMed

Podgórska, Anna; Burian, Maria; Gieczewska, Katarzyna; Ostaszewska-Bugajska, Monika; Zebrowski, Jacek; Solecka, Danuta; Szal, Bożena

2017-01-01

Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO 3 - ) and ammonium (NH 4 + ). However, the composition of the N source is important, because excess of NH 4 + promotes morphological disorders. Plants cultured on NH 4 + as the sole N source exhibit serious growth inhibition, commonly referred to as "ammonium toxicity syndrome." NH 4 + -mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH 4 + nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH 4 + as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH 4 + toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH 4 + -mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia , a receptor-like kinase involved in the control of cell wall extension.

Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower

PubMed Central

Velázquez, Luciano; Alberdi, Ignacio; Paz, Cosme; Aguirrezábal, Luis

2017-01-01

Increased transpiration efficiency (the ratio of biomass to water transpired, TE) could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level) TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs. PMID:29204153

Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower.

PubMed

Velázquez, Luciano; Alberdi, Ignacio; Paz, Cosme; Aguirrezábal, Luis; Pereyra Irujo, Gustavo

2017-01-01

Increased transpiration efficiency (the ratio of biomass to water transpired, TE) could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level) TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs.

Two O-linked N-acetylglucosamine transferase genes of Arabidopsis thaliana L. Heynh. have overlapping functions necessary for gamete and seed development.

PubMed Central

Hartweck, Lynn M; Scott, Cheryl L; Olszewski, Neil E

2002-01-01

The Arabidopsis SECRET AGENT (SEC) and SPINDLY (SPY) proteins are similar to animal O-linked N-acetylglucosamine transferases (OGTs). OGTs catalyze the transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to Ser/Thr residues of proteins. In animals, O-GlcNAcylation has been shown to affect protein activity, stability, and/or localization. SEC protein expressed in Escherichia coli had autocatalytic OGT activity. To determine the function of SEC in plants, two tDNA insertional mutants were identified and analyzed. Although sec mutant plants did not exhibit obvious phenotypes, sec and spy mutations had a synthetic lethal interaction. This lethality was incompletely penetrant in gametes and completely penetrant postfertilization. The rate of both female and male sec spy gamete transmission was higher in plants heterozygous for both mutations than in plants heterozygous for sec and homozygous for spy. Double-mutant embryos aborted at various stages of development and no double-mutant seedlings were obtained. These results indicate that OGT activity is required during gametogenesis and embryogenesis with lethality occurring when parentally derived SEC, SPY, and/or O-GlcNAcylated proteins become limiting. PMID:12136030

Higher Education in Scotland: Differentiation and Diversion? The Impact of College-University Progression Links

ERIC Educational Resources Information Center

Gallacher, Jim

2014-01-01

This paper addresses the issue of the impact of expansion and differentiation on widening access to higher education. In particular, it considers the impact of the growing importance of full-time short-cycle higher education in Scotland's colleges of further and higher education, the progression pathways which have now been established from these…

Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion

PubMed Central

Emlen, Douglas J.; Pearson, Dean E.

2016-01-01

Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders’ web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe’s architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations. PMID:27082240

Internationalization and Culture in Higher Education

ERIC Educational Resources Information Center

Lumby, Jacky; Foskett, Nick

2016-01-01

Internationalization has attained great significance in Higher Education, driven by both educational philosophy and commercial imperatives. Cultural change is implied as both a related process and as a goal. The article considers the multifaceted ways in which culture might be conceived and linked to different orientations to internationalization.…

Plant traits related to nitrogen uptake influence plant-microbe competition.

PubMed

Moreau, Delphine; Pivato, Barbara; Bru, David; Busset, Hugues; Deau, Florence; Faivre, Céline; Matejicek, Annick; Strbik, Florence; Philippot, Laurent; Mougel, Christophe

2015-08-01

Plant species are important drivers of soil microbial communities. However, how plant functional traits are shaping these communities has received less attention though linking plant and microbial traits is crucial for better understanding plant-microbe interactions. Our objective was to determine how plant-microbe interactions were affected by plant traits. Specifically we analyzed how interactions between plant species and microbes involved in nitrogen cycling were affected by plant traits related to 'nitrogen nutrition in interaction with soil nitrogen availability. Eleven plant species, selected along an oligotrophic-nitrophilic gradient, were grown individually in a nitrogen-poor soil with two levels of nitrate availability. Plant traits for both carbon and nitrogen nutrition were measured and the genetic structure and abundance of rhizosphere. microbial communities, in particular the ammonia oxidizer and nitrate reducer guilds, were analyzed. The structure of the bacterial community in the rhizosphere differed significantly between plant species and these differences depended on nitrogen availability. The results suggest that the rate of nitrogen uptake per unit of root biomass and per day is a key plant trait, explaining why the effect of nitrogen availability on the structure of the bacterial community depends on the plant species. We also showed that the abundance of nitrate reducing bacteria always decreased with increasing nitrogen uptake per unit of root biomass per day, indicating that there was competition for nitrate between plants and nitrate reducing bacteria. This study demonstrates that nitrate-reducing microorganisms may be adversely affected by plants with a high nitrogen uptake rate. Our work puts forward the role of traits related to nitrogen in plant-microbe interactions, whereas carbon is commonly considered as the main driver. It also suggests that plant traits related to ecophysiological processes, such as nitrogen uptake rates, are more

Genetics of host plant use and life history in the comma butterfly across Europe: varying modes of inheritance as a potential reproductive barrier.

PubMed

Nygren, G H; Nylin, S; Stefanescu, C

2006-11-01

Comma butterflies (Nymphalidae: Polygonia c-album L.) from one Belgian site and three Spanish sites were crossed with butterflies from a Swedish population in order to investigate inheritance of female host plant choice, egg mass and larval growth rate. We found three different modes of inheritance for the three investigated traits. In line with earlier results from crosses between Swedish and English populations, the results regarding female oviposition preference (choice between Urtica dioica and Salix caprea) showed X-linked inheritance to be of importance for the variation between Sweden and the other sites. Egg mass and growth rate did not show any sex-linked inheritance. Egg mass differences between populations seem to be controlled mainly by additive autosomal genes, as hybrids showed intermediate values. The growth rates of both hybrid types following reciprocal crossings were similar to each other but consistently higher than for the two source populations, suggesting a nonadditive mode of inheritance which is not sex-linked. The different modes of inheritance for host plant preference vs. important life history traits are likely to result in hybrids with unfit combinations of traits. This type of potential reproductive barrier based on multiple ecologically important traits deserves more attention, as it should be a common situation for instance in the early stages of population divergence in host plant usage, facilitating ecological speciation.

The microbiome of medicinal plants: diversity and importance for plant growth, quality and health.

PubMed

Köberl, Martina; Schmidt, Ruth; Ramadan, Elshahat M; Bauer, Rudolf; Berg, Gabriele

2013-12-20

Past medicinal plant research primarily focused on bioactive phytochemicals, however, the focus is currently shifting due to the recognition that a significant number of phytotherapeutic compounds are actually produced by associated microbes or through interaction with their host. Medicinal plants provide an enormous bioresource of potential use in modern medicine and agriculture, yet their microbiome is largely unknown. The objective of this review is (i) to introduce novel insights into the plant microbiome with a focus on medicinal plants, (ii) to provide details about plant- and microbe-derived ingredients of medicinal plants, and (iii) to discuss possibilities for plant growth promotion and plant protection for commercial cultivation of medicinal plants. In addition, we also present a case study performed both to analyse the microbiome of three medicinal plants (Matricaria chamomilla L., Calendula officinalis L., and Solanum distichum Schumach. and Thonn.) cultivated on organically managed Egyptian desert farm and to develop biological control strategies. The soil microbiome of the desert ecosystem was comprised of a high abundance of Gram-positive bacteria of prime importance for pathogen suppression under arid soil conditions. For all three plants, we observed a clearly plant-specific selection of the microbes as well as highly specific diazotrophic communities that overall identify plant species as important drivers in structural and functional diversity. Lastly, native Bacillus spec. div. strains were able to promote plant growth and elevate the plants' flavonoid production. These results underline the numerous links between the plant-associated microbiome and the plant metabolome.

Inhibition of processing of plant N-linked oligosaccharides by castanospermine.

PubMed

Hori, H; Pan, Y T; Molyneux, R J; Elbein, A D

1984-02-01

Castanospermine (1,6,7,8-tetrahydroxyoctahydroindolizine) is a plant alkaloid that inhibits lysosomal alpha- and beta-glucosidase. It also inhibits processing of influenza viral glycoproteins by inhibiting glucosidase I and leads to altered glycoproteins with Glc3Man7GlcNAc2 structures. Castanospermine was tested as an inhibitor of glycoprotein processing in suspension-cultured soybean cells. Soybean cells were pulse-labeled with [2-3H]mannose and chased for varying periods in unlabeled medium. In normal cells, the initial glycopeptides contained oligosaccharides having Glc3Man9GlcNAc2 to Glc1Man9GlcNAc2 structures and these were trimmed during the chase to Man9GlcNac2 to Man7GlcNAc2 structures. In the presence of castanospermine, no trimming of glucose residues occurred although some mannose residues were apparently still removed. Thus, the major oligosaccharide in the glycopeptides of castanospermine-incubated cells after a 90-min chase was a Glc3Man7GlcNAc2 structure. Smaller amounts of Glc3Man6GlcNAc2 and Glc3Man5GlcNAc2 were also identified. Thus, in plant cells, castanospermine also prevents the removal of the outermost glucose residue.

The Plant Phenology Ontology: A New Informatics Resource for Large-Scale Integration of Plant Phenology Data.

PubMed

Stucky, Brian J; Guralnick, Rob; Deck, John; Denny, Ellen G; Bolmgren, Kjell; Walls, Ramona

2018-01-01

Plant phenology - the timing of plant life-cycle events, such as flowering or leafing out - plays a fundamental role in the functioning of terrestrial ecosystems, including human agricultural systems. Because plant phenology is often linked with climatic variables, there is widespread interest in developing a deeper understanding of global plant phenology patterns and trends. Although phenology data from around the world are currently available, truly global analyses of plant phenology have so far been difficult because the organizations producing large-scale phenology data are using non-standardized terminologies and metrics during data collection and data processing. To address this problem, we have developed the Plant Phenology Ontology (PPO). The PPO provides the standardized vocabulary and semantic framework that is needed for large-scale integration of heterogeneous plant phenology data. Here, we describe the PPO, and we also report preliminary results of using the PPO and a new data processing pipeline to build a large dataset of phenology information from North America and Europe.

The Importance of State and Plant Characteristics in Determining the Environmental Compliance Costs of Chemical Manufacturing Plants: Evidence from the PACE Survey, 1979-1990 Summary (1994)

EPA Pesticide Factsheets

Summary of the author's dissertation: links the U.S. Census Bureau's Pollution Abatement Costs and Expenditures data on a plant-by-plant basis with the data in their Longitudinal Research Database (LRD) to examine chemical industry compliance costs.

A Link-Level Simulator of the cdma2000 Reverse-Link Physical Layer

PubMed Central

Gharavi, H.; Chin, F.; Ban, K.; Wyatt-Millington, R.

2003-01-01

The cdma2000 system is an evolutionary enhancement of the IS-95 standards which support 3G services defined by the International Telecommunications Union (ITU). cdma2000 comes in two phases: 1XRTT and 3XRTT (1X and 3X indicates the number of 1.25 MHz wide radio carrier channels used and RTT stands for Radio Transmission Technology). The cdma2000 1XRTT, which operates within a 1.25 MHz bandwidth, can be utilized in existing IS-95 CDMA channels as it uses the same bandwidth, while 3XRTT requires the commitment of 5 MHz bandwidth to support higher data rates. This paper describes a software model implementation of the cdma2000 reverse link and its application for evaluating the effect of rake receiver design parameters on the system performance under various multipath fading conditions. The cdma2000 models were developed at the National Institute of Standards and Technology (NIST), using SPW (Signal Processing Worksystem) commercial software tools. The model has been developed in a generic manner that includes all the reverse link six radio configurations and their corresponding data rates, according to cdma2000 specifications. After briefly reviewing the traffic channel characteristics of the cdma2000 reverse link (subscriber to base station), the paper discusses the rake receiver implementation including an ideal rake receiver. It then evaluates the performance of each receiver for a Spreading Rate 3 (3XRTT) operation, which is considered as a true “3G” cdma2000 technology. These evaluations are based on the vehicular IMT-2000 (International Mobile Telecommunication 2000) channel model using the link budget defined in cdma2000 specifications for the reverse link. PMID:27413613

Eco-geophysical imaging of watershed-scale soil patterns links with plant community spatial patterns

USDA-ARS?s Scientific Manuscript database

The extent to which soil resource availability, nutrients or 1 moisture, control the structure, function and diversity of plant communities has aroused considerable interest in the past decade, and remains topical in light of global change. Numerous plant communities are controlled either by water o...

[Distribution of HCB discharged from a chemical plant in plants].

PubMed

Chen, Jing; Wang, Lin-Ling; Lu, Xiao-Hua; Yuan, Song-Hu; Liu, Xi-Xiang; Wang, Yue; Zhao, Qian; Mei, Ling-Fang

2009-04-15

The distribution characteristics of hexachlorobenzene (HCB) in plant and rhizosphere soil in contamination conduit, a nearby river and a cropland were studied and the impact factors were also discussed. The results are summarized as follows: the range of the HCB concentration in plant and rhizosphere soil in investigation area were respectively from 4.45 microg x kg(-1) to 1,189.89 microg x kg(-1) (dw) and from 27.93 microg x kg(-1) to 3,480.71 microg x kg(-1) (dw). Higher enrichment of HCB in woodplant than herbs due to higher fat concentration in woodplant in the contamination conduit and the rich concentrtion factor of woodplant and herbs were 0.41-2.55 and 0.01-1.34. The range of HCB concentrations in plants in nearby croplands was significantly wide (4.45-333.1 microg x kg(-1)) while HCB concentrations in different parts of plant were various, e.g. HCB concentrations in fruit, root and shoot of taro were 318.77 microg x kg(-1), 281.02 microg x kg(-1) and 10.94 microg x kg(-1). There was a remarkable positive relation between the concentrations of HCB in plant and fat concentration of plant while no relativity between the concentrations of HCB in plant and those in ground soils in the contamination conduit and cropland. The concentration levels of HCB in plant and rhizosphere soil in river were dramatically decreased with increasing distance from contaminated conduit. There was a remarkable positive relation between the concentrations of HCB in plant and those in ground soils but no relation between concentrations of HCB in plant and fat concentration of plant in river. The distribution characteristics of HCB in plants were influenced by contaminated levels, fat concentration and Partition-transfer model.

Over-expression of AtPAP2 in Camelina sativa leads to faster plant growth and higher seed yield

PubMed Central

2012-01-01

Background Lipids extracted from seeds of Camelina sativa have been successfully used as a reliable source of aviation biofuels. This biofuel is environmentally friendly because the drought resistance, frost tolerance and low fertilizer requirement of Camelina sativa allow it to grow on marginal lands. Improving the species growth and seed yield by genetic engineering is therefore a target for the biofuels industry. In Arabidopsis, overexpression of purple acid phosphatase 2 encoded by Arabidopsis (AtPAP2) promotes plant growth by modulating carbon metabolism. Overexpression lines bolt earlier and produce 50% more seeds per plant than wild type. In this study, we explored the effects of overexpressing AtPAP2 in Camelina sativa. Results Under controlled environmental conditions, overexpression of AtPAP2 in Camelina sativa resulted in longer hypocotyls, earlier flowering, faster growth rate, higher photosynthetic rate and stomatal conductance, increased seed yield and seed size in comparison with the wild-type line and null-lines. Similar to transgenic Arabidopsis, activity of sucrose phosphate synthase in leaves of transgenic Camelina was also significantly up-regulated. Sucrose produced in photosynthetic tissues supplies the building blocks for cellulose, starch and lipids for growth and fuel for anabolic metabolism. Changes in carbon flow and sink/source activities in transgenic lines may affect floral, architectural, and reproductive traits of plants. Conclusions Lipids extracted from the seeds of Camelina sativa have been used as a major constituent of aviation biofuels. The improved growth rate and seed yield of transgenic Camelina under controlled environmental conditions have the potential to boost oil yield on an area basis in field conditions and thus make Camelina-based biofuels more environmentally friendly and economically attractive. PMID:22472516

Temporal interactions of plant - insect - predator after infection of bacterial pathogen on rice plants.

PubMed

Sun, Ze; Liu, Zhuang; Zhou, Wen; Jin, Huanan; Liu, Hao; Zhou, Aiming; Zhang, Aijun; Wang, Man-Qun

2016-05-17

Pathogenic infection on plants may affect interactions of host-plants with their herbivores, as well as the herbivores with their predators. In this study, the effects of infection by pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo), which causes a vascular disease in rice, on rice plants and consequent interactions with a rice herbivore, brown rice planthopper (BPH) Nilaparvata lugens, and its major predator, Cyrtorhinus lividipennis, were investigated. The results showed that the rice plants exhibited increased resistance to BPH only at 3 d post-inoculation of Xoo, while the Xoo infection did not affect the development and fecundity of BPH. BPH exhibited a higher preference to Xoo infected rice plants, whereas C. lividipennis preferred the Xoo infected rice plants after BPH fed, but preferred healthy rice plants without BPH fed. Volatile organic compounds emitted from Xoo rice were significantly higher than those from healthy rice plants, Xoo infection on BPH fed plants caused rice plants to emit more the herbivore-induced plant volatiles, while all of these changes correlated to the temporal dimension. These results demonstrated that Xoo infection significantly influenced the interactions of rice plants with two non-vectors, BPH and its predator, although these effects exhibited in a temporal pattern after infection.

Effects of Higher and Lower Level Writing-To-Learn Assignments on Higher and Lower Level Examination Questions

ERIC Educational Resources Information Center

Nevid, Jeffrey S.; Ambrose, Michael A.; Pyun, Yea Seul

2017-01-01

Our study examined whether brief writing-to-learn assignments linked to lower and higher levels in Bloom's taxonomy affected performance differentially on examination performance in assessing these skill levels. Using a quasi-random design, 91 undergraduate students in an introductory psychology class completed eight lower level and eight higher…

Citizen Science: linking the recent rapid advances of plant flowering in Canada with climate variability.

PubMed

Gonsamo, Alemu; Chen, Jing M; Wu, Chaoyang

2013-01-01

The timing of crucial events in plant life cycles is shifting in response to climate change. We use phenology records from PlantWatch Canada 'Citizen Science' networks to study recent rapid shifts of flowering phenology and its relationship with climate. The average first flower bloom day of 19 Canadian plant species has advanced by about 9 days during 2001-2012. 73% of the rapid and unprecedented first bloom day advances are explained by changes in mean annual national temperature, allowing the reconstruction of historic flower phenology records starting from 1948. The overall trends show that plant flowering in Canada is advancing by about 9 days per °C. This analysis reveals the strongest biological signal yet of climate warming in Canada. This finding has broad implications for niche differentiation among coexisting species, competitive interactions between species, and the asynchrony between plants and the organisms they interact with.

Are plants sentient?

PubMed

Calvo, Paco; Sahi, Vaidurya Pratap; Trewavas, Anthony

2017-11-01

Feelings in humans are mental states representing groups of physiological functions that usually have defined behavioural purposes. Feelings, being evolutionarily ancient, are thought to be coordinated in the brain stem of animals. One function of the brain is to prioritise between competing mental states and, thus, groups of physiological functions and in turn behaviour. Plants use groups of coordinated physiological activities to deal with defined environmental situations but currently have no known mental state to prioritise any order of response. Plants do have a nervous system based on action potentials transmitted along phloem conduits but which in addition, through anastomoses and other cross-links, forms a complex network. The emergent potential for this excitable network to form a mental state is unknown, but it might be used to distinguish between different and even contradictory signals to the individual plant and thus determine a priority of response. This plant nervous system stretches throughout the whole plant providing the potential for assessment in all parts and commensurate with its self-organising, phenotypically plastic behaviour. Plasticity may, in turn, depend heavily on the instructive capabilities of local bioelectric fields enabling both a degree of behavioural independence but influenced by the condition of the whole plant. © 2017 John Wiley & Sons Ltd.