Arsenic-phosphorus interactions in the soil-plant-microbe system: Dynamics of uptake, suppression and toxicity to plants.

PubMed

Anawar, Hossain M; Rengel, Zed; Damon, Paul; Tibbett, Mark

2018-02-01

High arsenic (As) concentrations in the soil, water and plant systems can pose a direct health risk to humans and ecosystems. Phosphate (Pi) ions strongly influence As availability in soil, its uptake and toxicity to plants. Better understanding of As(V)-Pi interactions in soils and plants will facilitate a potential remediation strategy for As contaminated soils, reducing As uptake by crop plants and toxicity to human populations via manipulation of soil Pi content. However, the As(V)-Pi interactions in soil-plant systems are complex, leading to contradictory findings among different studies. Therefore, this review investigates the role of soil type, soil properties, minerals, Pi levels in soil and plant, Pi transporters, mycorrhizal association and microbial activities on As-Pi interactions in soils and hydroponics, and uptake by plants, elucidate the key mechanisms, identify key knowledge gaps and recommend new research directions. Although Pi suppresses As uptake by plants in hydroponic systems, in soils it could either increase or decrease As availability and toxicity to plants depending on the soil types, properties and charge characteristics. In soil, As(V) availability is typically increased by the addition of Pi. At the root surface, the Pi transport system has high affinity for Pi over As(V). However, Pi concentration in plant influences the As transport from roots to shoots. Mycorrhizal association may reduce As uptake via a physiological shift to the mycorrhizal uptake pathway, which has a greater affinity for Pi over As(V) than the root epidermal uptake pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fate and Uptake of Pharmaceuticals in Soil–Plant Systems

PubMed Central

2014-01-01

Pharmaceuticals have been detected in the soil environment where there is the potential for uptake into crops. This study explored the fate and uptake of pharmaceuticals (carbamazepine, diclofenac, fluoxetine, propranolol, sulfamethazine) and a personal care product (triclosan) in soil–plant systems using radish (Raphanus sativus) and ryegrass (Lolium perenne). Five of the six chemicals were detected in plant tissue. Carbamazepine was taken up to the greatest extent in both the radish (52 μg/g) and ryegrass (33 μg/g), whereas sulfamethazine uptake was below the limit of quantitation (LOQ) (<0.01 μg/g). In the soil, concentrations of diclofenac and sulfamethazine dropped below the LOQ after 7 days. However, all pharmaceuticals were still detectable in the pore water at the end of the experiment. The results demonstrate the ability of plant species to accumulate pharmaceuticals from soils with uptake apparently specific to both plant species and chemical. Results can be partly explained by the hydrophobicity and extent of ionization of each chemical in the soil. PMID:24405013

Mechanisms for the increase in phosphorus uptake of waterlogged plants: soil phosphorus availability, root morphology and uptake kinetics.

PubMed

Rubio, Gerardo; Oesterheld, Martín; Alvarez, Carina R; Lavado, Raúl S

1997-10-01

Waterlogging frequently reduces plant biomass allocation to roots. This response may result in a variety of alterations in mineral nutrition, which range from a proportional lowering of whole-plant nutrient concentration as a result of unchanged uptake per unit of root biomass, to a maintenance of nutrient concentration by means of an increase in uptake per unit of root biomass. The first objective of this paper was to test these two alternative hypothetical responses. In a pot experiment, we evaluated how plant P concentration of Paspalum dilatatum, (a waterlogging-tolerant grass from the Flooding Pampa, Argentina) was affected by waterlogging and P supply and how this related to changes in root-shoot ratio. Under both soil P levels waterlogging reduced root-shoot ratios, but did not reduce P concentration. Thus, uptake of P per unit of root biomass increased under waterlogging. Our second objective was to test three non-exclusive hypotheses about potential mechanisms for this increase in P uptake. We hypothesized that the greater P uptake per unit of root biomass was a consequence of: (1) an increase in soil P availability induced by waterlogging; (2) a change in root morphology, and/or (3) an increase in the intrinsic uptake capacity of each unit of root biomass. To test these hypotheses we evaluated (1) changes in P availability induced by waterlogging; (2) specific root length of waterlogged and control plants, and (3) P uptake kinetics in excised roots from waterlogged and control plants. The results supported the three hypotheses. Soil P avail-ability was higher during waterlogging periods, roots of waterlogged plants showed a morphology more favorable to nutrient uptake (finer roots) and these roots showed a higher physiological capacity to absorb P. The results suggest that both soil and plant mechanisms contributed to compensate, in terms of P nutrition, for the reduction in allocation to root growth. The rapid transformation of the P uptake system is

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

NASA Astrophysics Data System (ADS)

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

2008-12-01

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

Dioxin uptake by Indian plant species.

PubMed

Pandey, J S; Kumar, R; Wate, S R

2008-08-01

Dioxins like various gaseous pollutants and aerosols can be scavenged by appropriate vegetative greenbelts. Based on their stomatal properties and the models for contaminant uptake, uptake of dioxin (2,3,7,8-TCDD) by three important Indian plant species, viz. Eugenia jambolana (Jamun), Azadirachta indica (Neem) and Ficus religiosa (Peepal), has been estimated. 2,3,7,8-TCDD is a contaminant with severe harmful ecological ramifications. Computations show that Ficus religiosa has highest uptake capacity. The present exercise has its utility in designing appropriate green-belts for mitigating adverse environmental and human health impacts due to dioxins. This can be an effective management option for mitigating the damages caused by dioxins.

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were <0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were < 0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

Plant Growth and Phosphorus Uptake of Three Riparian Grass Species

USDA-ARS?s Scientific Manuscript database

Riparian buffers can significantly reduce sediment-bound phosphorus (P) entering surface water, but control of dissolved P inputs is more challenging. Because plant roots remove P from soil solution, it follows that plant uptake will reduce dissolved P losses. We evaluated P uptake of smooth bromegr...

Trace element uptake and distribution in plants.

PubMed

Graham, Robin D; Stangoulis, James C R

2003-05-01

There are similarities between mammals and plants in the absorption and transport of trace elements. The chemistry of trace element uptake from food sources in both cases is based on the thermodynamics of adsorption on charged solid surfaces embedded in a solution phase of charged ions and metal-binding ligands together with redox systems in the case of iron and some other elements. Constitutive absorption systems function in nutrient uptake during normal conditions, and inducible "turbo" systems increase the supply of a particular nutrient during deficiency. Iron uptake is the most studied of the micronutrients, and divides the plant kingdom into two groups: dicotyledonous plants have a turbo system that is an upregulated version of the constitutive system, which consists of a membrane-bound reductase and an ATP-driven hydrogen ion extrusion pump; and monocotyledonous plants have a constitutive system similar to that of the dicots, but with an inducible system remarkably different that uses the mugeneic acid class of phytosiderophores (PS). The PS system may in fact be an important port of entry for iron from an iron-rich but exceedingly iron-insoluble lithosphere into the iron-starved biosphere. Absorption of trace metals in these graminaceous plants is normally via divalent ion channels after reduction in the plasma membrane. Once absorbed, iron can be stored in plants as phytoferritin or transported to active sites by transport-specific ligands. The transport of iron and zinc into seeds is dominated by the phloem sap system, which has a high pH that requires chelation of heavy metals. Loading into grains involves three or four genes each that control chelation, membrane transport and deposition as phytate.

Comparative uptake of plutonium from soils by Brassica juncea and Helianthus annuus.

PubMed

Lee, J H; Hossner, L R; Attrep, M; Kung, K S

2002-01-01

Plutonium uptake by Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) from soils with varying chemical composition and contaminated with Pu complexes (Pu-nitrate [239Pu(NO3)4], Pu-citrate [239Pu(C6H5O7)], and Pu-diethylenetriaminepentaacetic acid (Pu-DTPA [239Pu-C14H23O10N3]) was investigated. Sequential extraction of soils incubated with applied Pu was used to determine the distribution of Pu in the various soil fractions. The initial Pu activity levels in soils were 44.40-231.25 Bq g(-1) as Pu-nitrate Pu-citrate, or Pu-DTPA. A difference in Pu uptake between treatments of Pu-nitrate and Pu-citrate without chelating agent was observed only with Indian mustard in acidic Crowley soil. The uptake of Pu by plants was increased with increasing DTPA rates, however, the Pu concentration of plants was not proportionally increased with increasing application rate of Pu to soil. Plutonium uptake from Pu-DTPA was significantly higher from the acid Crowley soil than from the calcareous Weswood soil. The uptake of Pu from the soils was higher in Indian mustard than in sunflower. Sequential extraction of Pu showed that the ion-exchangeable Pu fraction in soils was dramatically increased with DTPA treatment and decreased with time of incubation. Extractability of Pu in all fractions was not different when Pu-nitrate and Pu-citrate were applied to the same soil. More Pu was associated with the residual Pu fraction without DTPA application. Consistent trends with time of incubation for other fractions were not apparent. The ion-exchangeable fraction, assumed as plant-available Pu, was significantly higher in acid soil compared with calcareous soil with or without DTPA treatment. When the calcareous soil was treated with DTPA, the ion-exchangeable Pu was comparatively less influenced. This fraction in the soil was more affected with time of incubation. The lowest extractable Pu was from a pH 6.55 Crockett soil that contained the highest clay compared to the other

Plant Nitrogen Uptake in Terrestrial Biogeochemical Models

NASA Astrophysics Data System (ADS)

Marti, Alejandro; Cox, Peter; Sitch, Stephen; Jones, Chris; Liddicoat, spencer

2013-04-01

Most terrestrial biogeochemical models featured in the last Intergovernmental Panel on Climate Change (IPPC) Assessment Report highlight the importance of the terrestrial Carbon sequestration and feedbacks between the terrestrial Carbon cycle and the climate system. However, these models have been criticized for overestimating predicted Carbon sequestration and its potential climate feedback when calculating the rate of future climate change because they do not account for the Carbon sequestration constraints caused by nutrient limitation, particularly Nitrogen (N). This is particularly relevant considering the existence of a substantial deficit of Nitrogen for plants in most areas of the world. To date, most climate models assume that plants have access to as much Nitrogen as needed, but ignore the nutrient requirements for new vegetation growth. Determining the natural demand and acquisition for Nitrogen and its associated resource optimization is key when accounting for the Carbon sequestration constrains caused by nutrient limitation. The few climate models that include C-N dynamics have illustrated that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. This reduction in growth is partially offset by an increase in the availability of nutrients resulting from an accelerated rate of decomposition of dead plants and other organic matter that occurring with a rise in temperature. However, this offset does not counterbalance the reduced level of plant growth calculated by natural nutrient limitations. Additionally, Nitrogen limitation is also expected to become more pronounced in some ecosystems as atmospheric CO2 concentration increases; resulting in less new growth and higher atmospheric CO2 concentrations than originally expected. This study compares alternative models of plant N uptake as found in different terrestrial biogeochemical models against field measurements, and introduces a new N-uptake

Uptake of Cadmium by Flue-Cured Tobacco Plants: Exploring Bioavailability

NASA Astrophysics Data System (ADS)

Holzer, I.; Robarge, W. P.; Vann, M. C.

2015-12-01

Scientific understanding of cadmium (Cd) cycling in North Carolina tobacco plants and soils has lagged, even as production of flue-cured tobacco remains an important part of the NC economy ($903 million in 2014). Cd is considered a tobacco contaminant. When tobacco is burned, Cd can exist as a fine aerosol and subsequent inhalation is linked to cancer. Tobacco root exudates enhance Cd uptake, even though the Cd concentration in NC soils is <0.1 mg/kg. Quantifying Cd concentrations in tobacco plants is crucial to understanding Cd bioavailability and implementing soil remediation efforts. The objective of this study was to develop a Cd mass balance for flue-cured tobacco grown under field conditions in NC. Whole plant samples were collected at transplanting and every 2 weeks thereafter until harvest. Individual plants were segregated into root, stalk and individual leaves (n = 15 whole plants/sampling date; composite samples were taken early in the growing season). After recording dry mass, samples were analyzed using ion-coupled plasma optical emission spectrometry or ion-coupled plasma mass spectrometry. Lower leaves contained the highest Cd concentrations ( 7-10 mg/kg). Leaves occupying the upper 50% of the plant had Cd concentrations of 2 mg/kg. Uptake rate was greatest from day 27 to 66 ( 21.5 μg Cd/day). Selective Cd uptake appears evident between day 27 and 43, but overall the relative rate of Cd uptake was similar to other trace metals and micronutrients. Cd distribution within the plants mirrored the distribution of calcium, a macronutrient. Of the 8 mg of soil extractable Cd (0.075 mg/kg) in the rooting zone, 15.0% (1203 μg) is removed by uptake. Of this 15%, 64.2% (772.2 μg) is exported at harvest, and 35.8% (430.8 μg; lower leaves, roots, stalks) is returned to the soil. This study must be replicated to account for seasonal and soil variations. These results do inform selection of tobacco strains that limit uptake of trace metals, particularly Cd.

Cadmium uptake by plants

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

Haghiri, F.

Absorption of /sup 115m/Cd by soybean (Gylcine max l.) plants via foliar and root systems and translocation into the seed was determined. The uptake of /sup 115m/Cd by soybeans via the root system was more efficient than that of the foliar placement. Growth and Cd concentrations of soybean and wheat (Triticum aestivum l.) tops were influenced by soil-applied Cd. In both crops, the Cd concentration of plant tops increased while yield decreased with increasing levels of applied Cd. Cadmium toxicitiy began to occur in both crops at the lowest level of soil applied Cd (2.5 ppM). With soybean plants, Cdmore » toxicity symptoms resembled fe chlorosis. For wheat plants there were no visual symptoms other than the studied growth. The relative concentration of Cd found in several vegetable crops varied depending on the plant species. The relative Cd concentration in descending order for various vegetables was lettuce (Lactuca sativa l.) > radish top (Raphanus sativus l.) > celery stalk (Apium graveolens l.) > celery leaves greater than or equal to green pepper (Capsicum frutescens l.) > radish roots.« less

Plant Regrowth as a Driver of Recent Enhancement of Terrestrial CO2 Uptake

NASA Astrophysics Data System (ADS)

Kondo, Masayuki; Ichii, Kazuhito; Patra, Prabir K.; Poulter, Benjamin; Calle, Leonardo; Koven, Charles; Pugh, Thomas A. M.; Kato, Etsushi; Harper, Anna; Zaehle, Sönke; Wiltshire, Andy

2018-05-01

The increasing strength of land CO2 uptake in the 2000s has been attributed to a stimulating effect of rising atmospheric CO2 on photosynthesis (CO2 fertilization). Using terrestrial biosphere models, we show that enhanced CO2 uptake is induced not only by CO2 fertilization but also an increasing uptake by plant regrowth (accounting for 0.33 ± 0.10 Pg C/year increase of CO2 uptake in the 2000s compared with the 1960s-1990s) with its effect most pronounced in eastern North America, southern-eastern Europe, and southeastern temperate Eurasia. Our analysis indicates that ecosystems in North America and Europe have established the current productive state through regrowth since the 1960s, and those in temperate Eurasia are still in a stage from regrowth following active afforestation in the 1980s-1990s. As the strength of model representation of CO2 fertilization is still in debate, plant regrowth might have a greater potential to sequester carbon than indicated by this study.

Plant Water Uptake in Drying Soils1

PubMed Central

Lobet, Guillaume; Couvreur, Valentin; Meunier, Félicien; Javaux, Mathieu; Draye, Xavier

2014-01-01

Over the last decade, investigations on root water uptake have evolved toward a deeper integration of the soil and roots compartment properties, with the goal of improving our understanding of water acquisition from drying soils. This evolution parallels the increasing attention of agronomists to suboptimal crop production environments. Recent results have led to the description of root system architectures that might contribute to deep-water extraction or to water-saving strategies. In addition, the manipulation of root hydraulic properties would provide further opportunities to improve water uptake. However, modeling studies highlight the role of soil hydraulics in the control of water uptake in drying soil and call for integrative soil-plant system approaches. PMID:24515834

Estimation of Cadmium uptake by tobacco plants from laboratory leaching tests.

PubMed

Marković, Jelena P; Jović, Mihajlo D; Smičiklas, Ivana D; Šljivić-Ivanović, Marija Z; Smiljanić, Slavko N; Onjia, Antonije E; Popović, Aleksandar R

2018-03-21

The objective of the present study was to determine the impact of cadmium (Cd) concentration in the soil on its uptake by tobacco plants, and to compare the ability of diverse extraction procedures for determining Cd bioavailability and predicting soil-to-plant transfer and Cd plant concentrations. The pseudo-total digestion procedure, modified Tessier sequential extraction and six standard single-extraction tests for estimation of metal mobility and bioavailability were used for the leaching of Cd from a native soil, as well as samples artificially contaminated over a wide range of Cd concentrations. The results of various leaching tests were compared between each other, as well as with the amounts of Cd taken up by tobacco plants in pot experiments. In the native soil sample, most of the Cd was found in fractions not readily available under natural conditions, but with increasing pollution level, Cd amounts in readily available forms increased. With increasing concentrations of Cd in the soil, the quantity of pollutant taken up in tobacco also increased, while the transfer factor (TF) decreased. Linear and non-linear empirical models were developed for predicting the uptake of Cd by tobacco plants based on the results of selected leaching tests. The non-linear equations for ISO 14870 (diethylenetriaminepentaacetic acid extraction - DTPA), ISO/TS 21268-2 (CaCl 2 leaching procedure), US EPA 1311 (toxicity characteristic leaching procedure - TCLP) single step extractions, and the sum of the first two fractions of the sequential extraction, exhibited the best correlation with the experimentally determined concentrations of Cd in plants over the entire range of pollutant concentrations. This approach can improve and facilitate the assessment of human exposure to Cd by tobacco smoking, but may also have wider applicability in predicting soil-to-plant transfer.

[Carbonyl compounds emission and uptake by plant: Research progress].

PubMed

Li, Jian; Cai, Jing; Yan, Liu-Shui; Li, Ling-Na; Tao, Min

2013-02-01

This paper reviewed the researches on the carbonyl compounds emission and uptake by plants, and discussed the compensation point of the bidirectional exchange of carbonyl compounds between plants and atmosphere. The uptake by leaf stomata and stratum corneum is the principal way for the purification of air aldehydes by plants. After entering into plant leaves, most parts of carbonyl compounds can be metabolized into organic acid, glucide, amino acid, and carbon dioxide, etc. , by the endoenzymes in leaves. The exchange direction of the carbonyl compounds between plants and atmosphere can be preliminarily predicted by the compensation point and the concentrations of ambient carbonyl compounds. This paper summarized the analytical methods such as DNPH/HPLC/UV and PFPH/GC/MS used for the determination of carbonyl compounds emitted from plants or in plant leaves. The main research interests in the future were pointed out, e. g. , to improve and optimize the analytical methods for the determination of carbonyl compounds emitted from plants and the researches on systems (e. g. , plant-soil system), to enlarge the detection species of carbonyl compounds emitted from plants, to screen the plant species which can effectively metabolize the pollutants, and to popularize the phytoremediation techniques for atmospheric

Foliar water uptake: a common water acquisition strategy for plants of the redwood forest.

PubMed

Limm, Emily Burns; Simonin, Kevin A; Bothman, Aron G; Dawson, Todd E

2009-09-01

Evaluations of plant water use in ecosystems around the world reveal a shared capacity by many different species to absorb rain, dew, or fog water directly into their leaves or plant crowns. This mode of water uptake provides an important water subsidy that relieves foliar water stress. Our study provides the first comparative evaluation of foliar uptake capacity among the dominant plant taxa from the coast redwood ecosystem of California where crown-wetting events by summertime fog frequently occur during an otherwise drought-prone season. Previous research demonstrated that the dominant overstory tree species, Sequoia sempervirens, takes up fog water by both its roots (via drip from the crown to the soil) and directly through its leaf surfaces. The present study adds to these early findings and shows that 80% of the dominant species from the redwood forest exhibit this foliar uptake water acquisition strategy. The plants studied include canopy trees, understory ferns, and shrubs. Our results also show that foliar uptake provides direct hydration to leaves, increasing leaf water content by 2-11%. In addition, 60% of redwood forest species investigated demonstrate nocturnal stomatal conductance to water vapor. Such findings indicate that even species unable to absorb water directly into their foliage may still receive indirect benefits from nocturnal leaf wetting through suppressed transpiration. For these species, leaf-wetting events enhance the efficacy of nighttime re-equilibration with available soil water and therefore also increase pre-dawn leaf water potentials.

Mapping the metal uptake in plants from Jasper Ridge Biological Preserve using synchrotron micro-focused X-ray fluorescence spectroscopy

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

Lo, Allison

2015-08-20

Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentine-tolerant plants. Rye grown onmore » potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.« less

[Study on the nitrogen and phosphorus uptake ability of four plants cultivated on floating-bed].

PubMed

Wu, Jian-Qiang; Wang, Min; Wu, Jian; Jiang, Yue; Sun, Cong-Jun; Cao, Yong

2011-04-01

Plant floating-bed tested engineering was constructed for eutrophication control in Dian-shan Lake, the characteristics and nutrient uptake abilities of Canna indica, Iris pseudacorus, Thalia dealbata and Lythrum salicaria were compared. It shows that using upper and lower nylon nets to fix the plants on the floating-bed is beneficial for them to grow and reproduce rapidly. Survival rates of Canna indica, lris pseudacorus, Thalia dealbata and Lythrum salicaria are 83.33%, 83.33%, 76.67% and 53.33% respectively. Ramets of Canna indica and Thalia dealbata are 64 and 78 respectively in November, and the biomass (fresh weight) of these two plants are 32.0 and 38.6 kg per individual plant. Nitrogen (N) and phosphorus (P) content in stems/leaves of Canna indica and Thalia dealbata are greater than those in roots. The ratio between stems/leaves and roots of N, P content in Canna indica are 1.40 and 1.21 respectively, while 1.59 and 1.08 in Thalia dealbata. The difference of cumulative N, P content in plants is mostly on account of different plant biomass. N uptake ability of Thalia dealbata is the highest, which is 457.11 g per square; Canna indica has the highest P uptake ability, which is 41.29 g per square. N, P uptake ability of stems/leaves in Canna indica are 2.17 and 1.86 times higher than that of roots, while 1.73 and 1.17 times higher respectively in Thalia dealbata. Thus, Canna indica and Thalia dealbata are recommended as the floating-bed plants to control the eutrophication in Dian-shan Lake.

Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

NASA Technical Reports Server (NTRS)

Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

1990-01-01

Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

Clipping and shading alter NH4+ uptake by plants in grazed and ungrazed Tibetan alpine grasslands

NASA Astrophysics Data System (ADS)

Sun, Yue; Schleuss, Per; Li, Qianru; Yang, Baijie; Xu, Xingliang; Kuzyakov, Yakov

2014-05-01

The Kobresia pastures are the most common and most important vegetation type on the Tibetan Plateau as it occupies more than 35% the plateau area. These pastures have been remained stable for about one million years, but have been strongly changed by increased grazing in the recent decades which led to serious grassland degradation. Previous studies on the N cycling in alpine grasslands showed that plant growth was limited by low N availability due to low N mineralization caused by low temperature. However, the effect of grazing on N turnover processes and plant N uptake remains unclear. To clarify the grazing effect for a better understanding N mineralization and plant N uptake in these alpine grasslands, we conducted a 15N experiment in grazed and ungraded plots in these alpine grasslands. Because ammonium was a dominant N form, we used 15N-labeled ammonium so that we can also measure gross N mineralization. To explore the effect of root exudates on 15NH4+ uptake by plants and gross N mineralization, three treatments such as clipping, shading and control were used. Initially, all treatments were labeled by 15NH4+, with blank treatments no 15N tracer addition. Plant and soil samples were collected 7, 14 and 28 days after the labelling. 15NH4+ uptake by alpine plants almost did not change after clipping in the grazed plots, but its uptake was lower under the clipping treatment than under the control treatment in the ungrazed plots. 15N recovery in plants under the shading treatment remained the lowest level in grazed and ungrazed plots. Although clipping removed a part of aboveground biomass, subsequent stimulation of plant growth increased N uptake by plants. Likely, moderate grazing removed a part of aboveground biomass, but 15N recovery in plants was still compared to that in the ungrazed plots, indicating moderate grazing stimulate N uptake by plants through compensatory growth. Gross N mineralization under the shading treatment was higher than under the

One way. Or another? Iron uptake in plants.

PubMed

Tsai, Huei-Hsuan; Schmidt, Wolfgang

2017-04-01

Iron (Fe) and phosphorus (P), the latter taken up by plants as phosphate (Pi), are two essential nutrients that determine species distribution and often limit crop yield as a result of their low availability in most soils. Pi-deficient plants improve the interception of Pi by increasing the density of root hairs, thereby expanding the volume of soil to be explored. The increase in root-hair frequency results mainly from attenuated primary root growth, a process that was shown to be dependent on the availability of external Fe. Recent data support a hypothesis in which cell elongation during Pi starvation is tuned by depositing Fe in the apoplast of cortical cells in the root elongation zone. Uptake of Fe under Pi starvation appears to proceed via an alternative, as yet unidentified, route that bypasses the default Fe transporter. Fe deposits acquired through this noncanonical Fe-uptake pathway compromises cell-to-cell communication that is critical for proper morphogenesis of epidermal cells and leads to shorter cells and higher root-hair density. An auxiliary Fe-uptake system might not only be crucial for recalibrating cell elongation in Pi-deficient plants but may also have general importance for growth on Pi- or Fe-poor soils by balancing the Pi and Fe supply. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Tree specific traits vs. stand level characteristics - assessing the source depths of plant water uptake in a mixed forest stand

NASA Astrophysics Data System (ADS)

Seeger, Stefan; Brinkmann, Nadine; Kahmen, Ansgar; Weiler, Markus

2017-04-01

Due to differences in fine root distributions, physiological root characteristics and plant plasticity, the spatial and temporal characteristics of plant water uptake are expected to vary between different tree species. This has implications on the overall water budget of a forest stand as well as on the drought sensitivity of particular trees. A four-year time series of climate data, soil moisture, and stable water isotopes in soil and tree xylem was used to investigate plant water uptake dynamics of four tree species (beech - Fagus sylvatica, spruce - Picea abies, ash - Fraxinus excelsior and maple - Acer pseudoplatanus) in a mixed forest stand. Modeling with a modified version of the soil hydrological model Hydrus-1D allowed us to simulate continuous time series of stable water isotopes in plant water uptake, which were compared to the measured values in tree xylem water and soil water. We found that different estimated species specific fine root distributions and root water uptake parameters lead to very similar simulated water balances and soil water isotope depth profiles for all four species. According to our simulations, differences in evaporative demand (i.e. LAI) had the biggest influence on water uptake and soil water distributions. Comparing the isotopic signatures of simulated root water uptake and measured xylem water, the simulations for beech were most suited to predict the observed signatures of all four species. This indicates that isolated, tree specific parametrized 1-D simulations are not suited to predict actual water uptake of different trees in a mixed stand. Due to overlapping root spaces dominant trees (in our case beeches with an LAI of around 5.5) may influence the soil water storage below accompanying trees (spruces, ashes and maples with LAIs between 1.8 and 3.1) in a degree that their actual water uptake cannot be predicted with 1-D simulations based on their smaller LAI values. Consequently, for a mixed forest stand the interplay of

How do microorganisms influence trace element uptake by plants? Screening in an agar model rhizosphere.

NASA Astrophysics Data System (ADS)

Marchetti, M.; Robinson, B. H.; Evangelou, M. W. H.; Vachey, A.; Schwitzguebel, J. P.; Bernier-Latmani, R.; Schulin, R.

2009-04-01

sterile, transparent plastic boxes, whose lid was equipped with a filter allowing gas exchanges without contamination by external microorganisms. The seed surface was sterilised and the plants grew one week in agar before their rhizosphere was inoculated with LB broth containing a pure bacterial strain or agar plugs colonized by fungal hyphae. We tested 14 strains, with 5 replicates per treatment and a control where the system was inoculated with sterile LB broth. The plants grew for 2 weeks in a climate chamber and their shoots were analysed for their TEs by ICP-OES. Samples of agar and roots were collected to confirm microbial colonization of the rhizosphere, respectively sterile conditions in the control treatments. Concerning the method development, the plants grew without visible toxicity in all the boxes, and the analysis of root and agar samples indicated that the controls were sterile and the strains inoculated were growing along the roots. More than 90% of the TE and nutrients added to the system were in the liquid fraction of the agar medium, thus available for root uptake. The screening showed that the microorganisms in general decreased TE uptake by wheat and sunflower, although some of them had an opposite effect on the plants. However, with the same plant species, the microorganisms had a consistent effect on all TE tested, i.e. a given single strain caused the same effect (increase or decrease of TE uptake) on all TE tested. In sunflower, 3 microorganisms (Paenibacillus polymyxa, Pythium ultimum and Rhizoctonia solani) decreased Cu and Zn uptake by 50% compared to the control treatment. These three species are common soil microorganisms. All three are known to exude auxin, a phytohormone. This hormone can modify root morphology and physiology and thus may affect TE uptake by plants. R. solani and P. ultimum are root pathogens. Their effect was opposite to what we expected. If roots are damaged, TE should have flooded into the plant and accumulate in the

Simultaneous Simulations of Uptake in Plants and Leaching to Groundwater of Cadmium and Lead for Arable Land Amended with Compost or Farmyard Manure

PubMed Central

Legind, Charlotte N.; Rein, Arno; Serre, Jeanne; Brochier, Violaine; Haudin, Claire-Sophie; Cambier, Philippe; Houot, Sabine; Trapp, Stefan

2012-01-01

The water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year experimental field study, where four organic amendments were applied every second year. Predicted concentrations slightly decreased (Cd) or stagnated (Pb) in control soils, but increased in amended soils by about 10% (Cd) and 6% to 18% (Pb). Estimated plant uptake was lower in amended plots, due to an increase of Kd (dry soil to water partition coefficient). Predicted concentrations in plants were close to measured levels in plant residues (straw), but higher than measured concentrations in grains. Initially, Pb was mainly predicted to deposit from air into plants (82% in 1998); the next years, uptake from soil became dominating (30% from air in 2006), because of decreasing levels in air. For Cd, predicted uptake from air into plants was negligible (1–5%). PMID:23056555

Regional investigations of soil and overburden analysis and plant uptake of metals

USGS Publications Warehouse

Gough, L.P.

1984-01-01

Regional studies on the bioavailability of metals at native and disturbed sites were conducted over the past seven years by the USGS. The work was concentrated in the Fort Union, Powder River, and Green River coal resource regions where measures of extractable metals in soils were found to have limited use in predicting metal levels in plants. Correlations between Cu, Fe, and Zn in plants and extractable (DTPA, EDTA, and oxalate) or total levels in native A- and C-horizons of soil were occasionally significant. A simple linear model is generally not adequate, however, in estimating element uptake by plants. Prediction capabilities were improved when a number of soil chemical and physical parameters were included as independent variables in a stepwise linear multiple regression analysis; however, never more than 54% of the total variability in the data was explained by the equations for these metals. Soil pH was the most important variable relating soil chemistry to plant chemistry. This relation was always positive and apparently a response to soil levels of metal carbonates and not Fe and Mn oxides. Studies that compared the metal uptake by rehabilitation species to extractable (DTPA) metal levels in mice soils produced similar results. ?? 1984 Science and Technology Letters.

Stable and radioactive cesium: A review about distribution in the environment, uptake and translocation in plants, plant reactions and plants' potential for bioremediation.

PubMed

Burger, Anna; Lichtscheidl, Irene

2018-03-15

Radiocesium in water, soil, and air represents a severe threat to human health and the environment. It either acts directly on living organisms from external sources, or it becomes incorporated through the food chain, or both. Plants are at the base of the food chain; it is therefore essential to understand the mechanisms of plants for cesium retention and uptake. In this review we summarize investigations about sources of stable and radioactive cesium in the environment and harmful effects caused by internal and external exposure of plants to radiocesium. Uptake of cesium into cells occurs through molecular mechanisms such as potassium and calcium transporters in the plasma membrane. In soil, bioavailability of cesium depends on the chemical composition of the soil and physical factors such as pH, temperature and tilling as well as on environmental factors such as soil microorganisms. Uptake of cesium occurs also from air through interception and absorption on leaves and from water through the whole submerged surface. We reviewed information about reducing cesium in the vegetation by loss processes, and we extracted transfer factors from the available literature and give an overview over the uptake capacities of 72 plants for cesium from the substratum to the biomass. Plants with high uptake potential could be used to remediate soil and water from radiocesium by accumulation and rhizofiltration. Inside plants, cesium distributes fast between the different plant organs and cells, but cesium in soil is extremely stable and remains for decades in the rhizosphere. Monitoring of contaminated soil therefore has to continue for many decades, and edible plants grown on such soil must continuously be monitored. Copyright © 2017 Elsevier B.V. All rights reserved.

Nitrogen and Phosphorous Uptake in Plant Biomass of Experimental Bioretention Systems in Utah

NASA Astrophysics Data System (ADS)

Sapkota, P.

2016-12-01

There is keen interest in implementing bioretention systems for stormwater management in an arid climate as they have proven to reduce toxicity from stormwater. Nitrogen is prevalent in urban stormwater, and plants and soil in bioretention treat stormwater before they enter natural waterways. A limited number of studies have focused on quantifying nutrient accumulation in plants. We quantified Total Nitrogen (TN), Total carbon (TC), and Total Phosphorous (TP) uptake in plants biomass of bioretention systems of semi-arid climate. The designed bioretention units housed at the University of Utah have three different vegetation types: Utah native plants (upland), no plants (control) and wetland plants (wetland grasses and reeds). The bioretention units are designed to capture 95% of the runoff from an impervious area of 220 m2. The soil is composed of 63% sand, 23% silt, and 14% clay. We compared TN, TC, and TP accumulation in plant biomass of upland and wetland systems. Two set of samples were taken for this study. For the first set, plants were completely destroyed in several upland and wetland bioretention units and TN and TP was quantified in their overall biomass. For the second set, TN and TP uptake were quantified in non-destructed samples on a monthly basis. To determine biomass of non-destructed samples, and TN, TP uptake, allometric equations were developed using plant height, crown diameter, and stem diameter measured each month from May 2015 to Dec 2015. Isotope ratio mass spectrometry (IRMS) was used to quantify TN and lachat colorimetry was used to quantify TP in all plant samples. TN, TC, and TP results for the destructed showed similar trends in three upland and wetland systems .i.e. when one increased other also increased. TN, TC analysis on plant samples over a seven months period showed that TN and TC decreased in summer, but it was significantly higher during winter. TN and TC on non-destructed samples spiked towards late spring, and woody plants

Variable effects of plant colonization on black slate uptake into microbial PLFAs

NASA Astrophysics Data System (ADS)

Seifert, Anne-Gret; Trumbore, Susan; Xu, Xiaomei; Zhang, Dachung; Gleixner, Gerd

2013-04-01

Microbial degradation of carbon derived from black shale and slate has been shown in vitro. However, in natural settings where other labile carbon sources are likely to exist, this has not been previously demonstrated. We investigated the uptake of ancient carbon derived from slate weathering and from recently photosynthesised organic matter by different groups of microorganisms. Therefore we isolated microbial biomarkers (phospholipid fatty acids, PLFAs) from black slates collected at a chronosequence of waste piles which differed in age and vegetation cover. We quantified the amount of PLFAs and performed stable isotope and radiocarbon measurements on individual or grouped PLFAs to quantify the fraction of slate derived carbon. We used black slate from a pile heaped in the 1950s with either uncovered black slate material (bare site) or material slightly colonized by small plants (greened site) and from a forested leaching pile (forested site) used for alum-mining in the 19th century. Colonization by plants influenced the amount and composition of the microbial community. Greater amounts of PLFAs (5410 ng PLFA/g dw) were extracted from slate sampled at the forested site as opposed to the bare site (960 ng PLFAs/g dw) or the greened (annual grasses and mosses) rock waste pile (1050 ng PLFAs/g dw). We found the highest proportion of PLFAs representing Gram-negative bacteria on the forested site and the highest proportion of PLFAs representing Gram-positive bacteria on the bare site. The fungal PLFA was most abundant at the greened site. Sites with less plant colonization (bare and greened site) tended to have more depleted δ13C values compared to the forested site. Radiocarbon measurements on PLFAs indicated that fungi and Gram-positive bacteria were best adapted to black slate carbon uptake. In the fungal PLFA (combined bare and greened waste pile sample) and in PLFAs of Gram-positive bacteria (greened site) we measured 39.7% and 28.9% ancient carbon uptake

Iron Requirement and Iron Uptake from Various Iron Compounds by Different Plant Species

PubMed Central

Christ, Rudolf A.

1974-01-01

The Fe requirements of four monocotyledonous plant species (Avena sativa L., Triticum aestivum L., Oryza sativa L., Zea mays L.) and of three dicotyledonous species (Lycopersicum esculentum Mill., Cucumis sativus L., Glycine maxima (L.) Merr.) in hydroponic cultures were ascertained. Fe was given as NaFe-EDDHA chelate (Fe ethylenediamine di (O-hydroxyphenylacetate). I found that the monocotyledonous species required a substantially higher Fe concentration in the nutrient solution in order to attain optimum growth than did the dicotyledonous species. Analyses showed that the process of iron uptake was less efficient with the monocotyledonous species. When the results obtained by using chelated Fe were compared with those using ionic Fe, it was shown that the inefficient species were equally inefficient in utilizing Fe3+ ions. However, the differences between the efficient and the inefficient species disappeared when Fe2+ was used. This confirms the work of others who postulated that Fe3+ is reduced before uptake of chelated iron by the root. In addition, it was shown that reduction also takes place when Fe is used in ionic form. The efficiency of Fe uptake seems to depend on the efficiency of the root system of the particular plant species in reducing Fe3+. The removal of Fe from the chelate complex after reduction to Fe2+ seems to present no difficulties to the various plant species. PMID:16658933

Native Plant Uptake Model for Radioactive Waste Disposal Areas at the Nevada Test Site

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

BROWN,THERESA J.; WIRTH,SHARON

1999-09-01

This report defines and defends the basic framework, methodology, and associated input parameters for modeling plant uptake of radionuclides for use in Performance Assessment (PA) activities of Radioactive Waste Management Sites (RWMS) at the Nevada Test Site (NTS). PAs are used to help determine whether waste disposal configurations meet applicable regulatory standards for the protection of human health, the environment, or both. Plants adapted to the arid climate of the NTS are able to rapidly capture infiltrating moisture. In addition to capturing soil moisture, plant roots absorb nutrients, minerals, and heavy metals, transporting them within the plant to the above-groundmore » biomass. In this fashion, plant uptake affects the movement of radionuclides. The plant uptake model presented reflects rooting characteristics important to plant uptake, biomass turnover rates, and the ability of plants to uptake radionuclides from the soil. Parameters are provided for modeling plant uptake and estimating surface contaminant flux due to plant uptake under both current and potential future climate conditions with increased effective soil moisture. The term ''effective moisture'' is used throughout this report to indicate the soil moisture that is available to plants and is intended to be inclusive of all the variables that control soil moisture at a site (e.g., precipitation, temperature, soil texture, and soil chemistry). Effective moisture is a concept used to simplify a number of complex, interrelated soil processes for which there are too little data to model actual plant available moisture. The PA simulates both the flux of radionuclides across the land surface and the potential dose to humans from that flux. Surface flux is modeled here as the amount of soil contamination that is transferred from the soil by roots and incorporated into aboveground biomass. Movement of contaminants to the surface is the only transport mechanism evaluated with the model presented

A series RCL circuit theory for analyzing non-steady-state water uptake of maize plants.

PubMed

Zhuang, Jie; Yu, Gui-Rui; Nakayama, Keiichi

2014-10-22

Understanding water uptake and transport through the soil-plant continuum is vital for ecosystem management and agricultural water use. Plant water uptake under natural conditions is a non-steady transient flow controlled by root distribution, plant configuration, soil hydraulics, and climatic conditions. Despite significant progress in model development, a mechanistic description of transient water uptake has not been developed or remains incomplete. Here, based on advanced electrical network theory (RLC circuit theory), we developed a non-steady state biophysical model to mechanistically analyze the fluctuations of uptake rates in response to water stress. We found that the non-steady-state model captures the nature of instantaneity and hysteresis of plant water uptake due to the considerations of water storage in plant xylem and coarse roots (capacitance effect), hydraulic architecture of leaf system (inductance effect), and soil-root contact (fuse effect). The model provides insights into the important role of plant configuration and hydraulic heterogeneity in helping plants survive an adverse environment. Our tests against field data suggest that the non-steady-state model has great potential for being used to interpret the smart water strategy of plants, which is intrinsically determined by stem size, leaf size/thickness and distribution, root system architecture, and the ratio of fine-to-coarse root lengths.

Selenium uptake, translocation, assimilation and metabolic fate in plants.

PubMed

Sors, T G; Ellis, D R; Salt, D E

2005-12-01

The chemical and physical resemblance between selenium (Se) and sulfur (S) establishes that both these elements share common metabolic pathways in plants. The presence of isologous Se and S compounds indicates that these elements compete in biochemical processes that affect uptake, translocation and assimilation throughout plant development. Yet, minor but crucial differences in reactivity and other metabolic interactions infer that some biochemical processes involving Se may be excluded from those relating to S. This review examines the current understanding of physiological and biochemical relationships between S and Se metabolism by highlighting their similarities and differences in relation to uptake, transport and assimilation pathways as observed in Se hyperaccumulator and non-accumulator plant species. The exploitation of genetic resources used in bioengineering strategies of plants is illuminating the function of sulfate transporters and key enzymes of the S assimilatory pathway in relation to Se accumulation and final metabolic fate. These strategies are providing the basic framework by which to resolve questions relating to the essentiality of Se in plants and the mechanisms utilized by Se hyperaccumulators to circumvent toxicity. In addition, such approaches may assist in the future application of genetically engineered Se accumulating plants for environmental renewal and human health objectives.

Utilization of a Model for Uptake of Cadmium by Plants as a Phytoremediation Assessment Tool

NASA Astrophysics Data System (ADS)

Takahashi, M.; Furbish, D. J.; Clarke, J.

2008-12-01

Some traditional methods of environmental remediation, such as removal and disposal of contaminated soil, are loosing economic favor and public acceptance, while others, such as in situ phytoremediation, are being carefully examined because of their attractiveness as environmentally friendly, low-cost solutions to site clean-up. The success of phytoremediation strategies, however, hinges on the ability of selected plants, or plant communities, to effectively uptake, accumulate and tolerate targeted contaminants. Heavy metals, specifically cadmium (Cd), are not essential nutrients to plants. However, chemically similar zinc (Zn) is a micronutrient and is actively taken up by hyperaccumulators. For this reason, the mechanisms involved in uptake of Cd parallel those of Zn. Ideally, Cd would be allocated to the stem, leaf, and/or flower, where it becomes harvestable. Our modeling work simulates the uptake and the storage of Cd in a growing hyperaccumulator. After uptake, Cd is partitioned between adsorption to plant tissue and upward movement to leaves driven by transpiration. Uptake, adsorption and transport are also regulated by phytotoxicity. Simulations suggest that a young plant with small biomass can quickly reach phytotoxicity, which shuts down the normal operation of the plant. Conversely, mature plants on a mildly contaminated site, if harvested before the plants die due to phytotoxicity or natural cause, not only survive but may occasionally thrive. The immediate aim is to estimate the effectiveness and limitations of Cd uptake by hyperaccumulators. The eventual goal of this study is to expand the model in spatial and temporal scales, from individual plants to the community scale, and from one harvest interval to several generations. Understanding the interface between physical and biological processes, specifically the uptake and release of contaminants, provides scientists and engineers tools to assess whether phytoremediation is a reasonable strategy for a

The effect of plant sterol-enriched turkey meat on cholesterol bio-accessibility during in vitro digestion and Caco-2 cell uptake.

PubMed

Grasso, S; Harrison, S M; Monahan, F J; Brayden, D; Brunton, N P

2018-03-01

This study evaluated the effect of a plant sterol-enriched turkey product on cholesterol bio-accessibility during in vitro digestion and cholesterol uptake by Caco-2 monolayers. Turkey products, one plant sterol-enriched (PS) and one plant sterol-free (C), were produced in an industrial pilot plant. Before simulated digestion, matrices were spiked with cholesterol (1:5 weight ratio of cholesterol to plant sterol). Plant sterols were included at a concentration equivalent to the minimum daily intake recommended by the European Food Safety Authority (EFSA) for cholesterol lowering. After simulated digestion, the percentage of cholesterol micellarization and uptake by Caco-2 cells in the presence of PS meat were measured. Compared to C meat, PS meat significantly inhibited cholesterol micellarization on average by 24% and Caco-2 cell accumulation by 10%. This study suggests that plant sterols in meat can reduce cholesterol uptake by intestinal epithelia and it encourages efforts to make new PS-based functional foods.

Ammonium and Nitrate Uptake by the Floating Plant Landoltia punctata

PubMed Central

Fang, Yun Ying; Babourina, Olga; Rengel, Zed; Yang, Xiao E.; Pu, Pei Min

2007-01-01

Background and Aims Plants from the family Lemnaceae are widely used in ecological engineering projects to purify wastewater and eutrophic water bodies. However, the biology of nutrient uptake mechanisms in plants of this family is still poorly understood. There is controversy over whether Lemnaceae roots are involved in nutrient uptake. No information is available on nitrogen (N) preferences and capacity of Landoltia punctata (dotted duckweed), one of the best prospective species in Lemnaceae for phytomelioration and biomass production. The aim of this study was to assess L. punctata plants for their ability to take up NH4+ and NO3− by both roots and fronds. Methods NO3− and NH4+ fluxes were estimated by a non-invasive ion-selective microelectrode technique. This technique allows direct measurements of ion fluxes across the root or frond surface of an intact plant. Key Results Landoltia punctata plants took up NH4+ and NO3− by both fronds and roots. Spatial distribution of NH4+ and NO3− fluxes demonstrated that, although ion fluxes at the most distal parts of the root were uneven, the mature part of the root was involved in N uptake. Despite the absolute flux values for NH4+ and NO3− being lower in roots than at the frond surface, the overall capacity of roots to take up ions was similar to that of fronds because the surface area of roots was larger. L. punctata plants preferred to take up NH4+ over NO3− when both N sources were available. Conclusions Landoltia punctata plants take up nitrogen by both roots and fronds. When both sources of N are available, plants prefer to take up NH4+, but will take up NO3− when it is the only N source. PMID:17204539

Phytate induced arsenic uptake and plant growth in arsenic-hyperaccumulator Pteris vittata.

PubMed

Liu, Xue; Fu, Jing-Wei; Tang, Ni; da Silva, E B; Cao, Yue; Turner, Benjamin L; Chen, Yanshan; Ma, Lena Q

2017-07-01

Phytate is abundant in soils, which is stable and unavailable for plant uptake. However, it occurs in root exudates of As-hyperaccumulator Pteris vittata (PV). To elucidate its effect on As uptake and growth, P. vittata were grown on agar media (63 μM P) containing 50 μM As and/or 50 or 500 μM phytate with non As-hyperaccumulator Pteris ensiformis (PE) as a congeneric control for 60 d. Phytate induced efficient As and P uptake, and enhanced growth in PV, but had little effects on PE. The As concentrations in PV fronds and roots were 157 and 31 mg kg -1 in As 50 +phytate 50 , 2.2- and 3.1-fold that of As 50 treatment. Phosphorus uptake by PV was reduced by 27% in As treatment than the control (P vs. P+As) but increased by 73% comparing phytate 500 to phytate 500 +As, indicating that PV effectively took up P from phytate. Neither As nor phytate affected Fe accumulation in PV, but phytate reduced root Fe concentration in PE (46-56%). As such, the increased As and P and the unsuppressed Fe uptake in PV probably promoted PV growth. Thus, supplying phytate to As-contaminated soils may promote As uptake and growth in PV and its phytoremediation ability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uptake and Metabolism of Phthalate Esters by Edible Plants.

PubMed

Sun, Jianqiang; Wu, Xiaoqin; Gan, Jay

2015-07-21

Phthalate esters (PAEs) are large-volume chemicals and are found ubiquitously in soil as a result of widespread plasticulture and waste disposal. Food plants such as vegetables may take up and accumulate PAEs from soil, potentially imposing human health risks through dietary intake. In this study, we carried out a cultivation study using lettuce, strawberry, and carrot plants to determine the potential of plant uptake, translocation, and metabolism of di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) and their primary metabolites mono-n-butyl phthalate (MnBP) and mono(2-ethylhexyl) phthalate (MEHP). All four compounds were detected in the plant tissues, with the bioconcentration factors (BCFs) ranging from 0.16 ± 0.01 to 4.78 ± 0.59. However, the test compounds were poorly translocated from roots to leaves, with a translocation factor below 1. Further, PAEs were readily transformed to their monoesters following uptake. Incubation of PAEs and monoalkyl phthalate esters (MPEs) in carrot cell culture showed that DnBP was hydrolyzed more rapidly than DEHP, while the monoesters were transformed more quickly than their parent precursors. Given the extensive metabolism of PAEs to monoesters in both whole plants and plant cells, metabolism intermediates such as MPEs should be considered when assessing human exposure via dietary intake of food produced from PAE-contaminated soils.

Uptake and translocation of plutonium in two plant species using hydroponics.

PubMed

Lee, J H; Hossner, L R; Attrep, M; Kung, K S

2002-01-01

This study presents determinations of the uptake and translocation of Pu in Indian mustard (Brassica juncea) and sunflower (Helianthus annuus) from Pu contaminated solution media. The initial activity levels of Pu were 18.50 and 37.00 Bq ml(-1), for Pu-nitrate [239Pu(NO3)4] and for Pu-citrate [239Pu(C6H5O7)+] in nutrient solution. Plutonium-diethylenetriaminepentaacetic acid (DTPA: [239Pu-C14H23O10N3] solution was prepared by adding 0, 5, 10, and 50 microg of DTPA ml(-1) with 239Pu(NO3)4 in nutrient solution. Concentration ratios (CR, Pu concentration in dry plant material/Pu concentration in nutrient solution) and transport indices (Tl, Pu content in the shoot/Pu content in the whole plant) were calculated to evaluate Pu uptake and translocation. All experiments were conducted in hydroponic solution in an environmental growth chamber. Plutonium concentration in the plant tissue was increased with increased Pu contamination. Plant tissue Pu concentration for Pu-nitrate and Pu-citrate application was not correlated and may be dependent on plant species. For plants receiving Pu-DTPA, the Pu concentration was increased in the shoots but decreased in the roots resulting in a negative correlation between the Pu concentrations in the plant shoots and roots. The Pu concentration in shoots of Indian mustard was increased for application rates up to 10 microg DTPA ml(-1) and up to 5 microg DTPA ml(-1) for sunflower. Similar trends were observed for the CR of plants compared to the Pu concentration in the shoots and roots, whereas the Tl was increased with increasing DTPA concentration. Plutonium in shoots of Indian mustard was up to 10 times higher than that in shoots of sunflower. The Pu concentration in the apparent free space (AFS) of plant root tissue of sunflower was more affected by concentration of DTPA than that of Indian mustard.

Composted biosolids and treated wastewater as sources of pharmaceuticals and personal care products for plant uptake: A case study with carbamazepine.

PubMed

Ben Mordechay, Evyatar; Tarchitzky, Jorge; Chen, Yona; Shenker, Moshe; Chefetz, Benny

2018-01-01

Irrigation with treated wastewater (TWW) and application of biosolids to arable land expose the agro-environment to pharmaceuticals and personal care products (PPCPs) which can be taken up by crops. In this project, we studied the effect of a carrier medium (e.g., biosolids and TWW) on plant (tomato, wheat and lettuce) uptake, translocation and metabolism of carbamazepine as a model for non-ionic PPCPs. Plant uptake and bioconcentration factors were significantly lower in soils amended with biosolids compared to soils irrigated with TWW. In soils amended with biosolids and irrigated with TWW, the bioavailability of carbamazepine for plant uptake was moderately decreased as compared to plants grown in soils irrigated with TWW alone. While TWW acts as a continuous source of PPCPs, biosolids act both as a source and a sink for these compounds. Moreover, it appears that decomposition of the biosolids in the soil after amendment enhances their adsorptive properties, which in turn reduces the bioavailability of PPCPs in the soil environment. In-plant metabolism of carbamazepine was found to be independent of environmental factors, such as soil type, carrier medium, and absolute amount implemented to the soil, but was controlled by the total amount taken up by the plant. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anomalous uptake and circulatory characteristics of the plant-based small RNA MIR2911.

PubMed

Yang, Jian; Hotz, Tremearne; Broadnax, LaCassidy; Yarmarkovich, Mark; Elbaz-Younes, Ismail; Hirschi, Kendal D

2016-06-02

Inconsistent detection of plant-based dietary small RNAs in circulation has thwarted the use of dietary RNA therapeutics. Here we demonstrate mice consuming diets rich in vegetables displayed enhanced serum levels of the plant specific small RNA MIR2911. Differential centrifugation, size-exclusion chromatography, and proteinase K treatment of plant extracts suggest this RNA resides within a proteinase K-sensitive complex. Plant derived MIR2911 was more bioavailable than the synthetic RNA. Furthermore, MIR2911 exhibited unusual digestive stability compared with other synthetic plant microRNAs. The characteristics of circulating MIR2911 were also unusual as it was not associated with exosomes and fractionated as a soluble complex that was insensitive to proteinase K treatment, consistent with MIR2911 being stabilized by modifications conferred by the host. These results indicate that intrinsic stability and plant-based modifications orchestrate consumer uptake of this anomalous plant based small RNA and invite revisiting plant-based microRNA therapeutic approaches.

Anomalous uptake and circulatory characteristics of the plant-based small RNA MIR2911

PubMed Central

Yang, Jian; Hotz, Tremearne; Broadnax, LaCassidy; Yarmarkovich, Mark; Elbaz-Younes, Ismail; Hirschi, Kendal D.

2016-01-01

Inconsistent detection of plant-based dietary small RNAs in circulation has thwarted the use of dietary RNA therapeutics. Here we demonstrate mice consuming diets rich in vegetables displayed enhanced serum levels of the plant specific small RNA MIR2911. Differential centrifugation, size-exclusion chromatography, and proteinase K treatment of plant extracts suggest this RNA resides within a proteinase K-sensitive complex. Plant derived MIR2911 was more bioavailable than the synthetic RNA. Furthermore, MIR2911 exhibited unusual digestive stability compared with other synthetic plant microRNAs. The characteristics of circulating MIR2911 were also unusual as it was not associated with exosomes and fractionated as a soluble complex that was insensitive to proteinase K treatment, consistent with MIR2911 being stabilized by modifications conferred by the host. These results indicate that intrinsic stability and plant-based modifications orchestrate consumer uptake of this anomalous plant based small RNA and invite revisiting plant-based microRNA therapeutic approaches. PMID:27251858

Impact of elemental uptake in the root chemistry of wetland plants.

PubMed

Aryal, Rupak; Nirola, Ramkrishna; Beecham, Simon; Kamruzzaman, Mohammad

2016-09-01

Plants play a key role in the accumulation of metals in contaminated environment. Ephemeral plants, such as cyperus vaginatus, from the family Cyperaceae have been used in constructed wetlands to alter the biogeochemistry of waterlogged soils. High elemental content in wetlands often induces chemical changes in the root, stem and leaf of wetland plants. Elemental uptake and possible chemical changes in the roots of Cyperus vaginatus was investigated and compared with plants grown away from the wetland. Among the 9 heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) and metalloid (As) measured, with the exception of Mn, all metals had higher content in the plant roots grown within the wetland. This was followed by plants grown near to the wetland that receive stormwater occasionally and then plants grown far from the wetland. The 3-D fluorescence spectra record showed notable differences in the chemical composition of roots grown in the three locations. The spectra combined with parallel factor analysis showed three dominant fluorescence components. Comparison of the fluorescence signatures showed a continuum of spectral properties constrained by the degree of metal contamination.

Effects of biochar on availability and plant uptake of heavy metals - A meta-analysis.

PubMed

Chen, De; Liu, Xiaoyu; Bian, Rongjun; Cheng, Kun; Zhang, Xuhui; Zheng, Jufeng; Joseph, Stephen; Crowley, David; Pan, Genxing; Li, Lianqing

2018-05-24

Biochar can be an effective amendment for immobilizing heavy metals in contaminated soils but has variable effects depending on its chemical and physical properties and those of the treated soil. To investigate the range of biochar's effects on heavy metal accumulation in plants in responses to the variation of soil, biochar and plant, we carried out a meta-analysis of the literature that was published before March 2016. A total of 1298 independent observations were collected from 74 published papers. Results showed that across all studies, biochar addition to soils resulted in average decreases of 38, 39, 25 and 17%, respectively, in the accumulation of Cd, Pb, Cu and Zn in plant tissues. The effect of biochar on heavy metal concentrations in plants varied depending on soil properties, biochar type, plant species, and metal contaminants. The largest decreases in plant heavy metal concentrations occurred in coarse-textured soils amended with biochar. Biochar had a relatively small effect on plant tissue Pb concentrations, but a large effect on plant Cu concentrations when applied to alkaline soils. Plant uptake of Pb, Cu and Zn was less in soils with higher organic carbon contents. Manure-derived biochar was the most effective for reducing Cd and Pb concentrations in plants as compared to biochars derived from other feedstock. Biochar having a high pH and used at high application rates resulted in greater decreases in plant heavy metal uptake. The meta-analysis provides useful guidelines on the range of effects that can be anticipated for different biochar materials in different plant-soil systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Natural colloidal P and its contribution to plant P uptake.

PubMed

Montalvo, Daniela; Degryse, Fien; McLaughlin, Mike J

2015-03-17

Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P.

Pentachlorophenol: Uptake/elimination kinetics and metabolism in an aquatic plant, Eichhornia crassipes

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

Roy, S.; Haenninen, O.

1994-05-01

Eichhornia crassipes [(Mart) Solms], an aquatic plant widely used for the treatment of wastewaters, was used to study uptake/elimination kinetics and metabolism of pentachlorophenol (PCP). PCP is a well-known industrial by-product and a major pollutant of the aquatic environment. The initial phase of PCP uptake by the plant was rapid and reached a nearly steady state between 24 and 48 h of exposure to PCP. The major by-products of PCP metabolisms in Eichhornia crassipes were identified as ortho- and para- substituted chlorohydroxyphenols (chlorocatechols and -hydroquiones), -anisoles, and -veratroles. Partially dechlorinated products of PCP were also detected. A major portion ofmore » the absorbed PCP and metabolites was found in bound/conjugated form. The response of the enzyme systems involved in the xenobiotic metabolism and antioxidative system were also studied following PCP exposure. A significant increase was observed in the activity of glutathione S-transferase (GST), a major conjugating enzyme, and in the activities of superoxide dismutase and ascorbate peroxidase of PCP exposed plants. Such responses of plant enzymes may be implemented as useful markers of aquatic pollution. The result related to the uptake and metabolism of PCP obtained from the present study suggests a crucial role of aquatic plants in determining the fate of environmental chemicals.« less

Uptake of Plutonium-238 into Solanum tuberosum L. (potato plants) in presence of complexing agent EDTA.

PubMed

Tawussi, Frank; Gupta, Dharmendra K; Mühr-Ebert, Elena L; Schneider, Stephanie; Bister, Stefan; Walther, Clemens

2017-11-01

Bioavailability and plant uptake of radionuclides depend on various factors. Transfer into different plant parts depends on chemical and physical processes, which need to be known for realistic ingestion dose modelling when these plants are used for food. Within the scope of the present work, the plutonium uptake by potato plants (Solanum tuberosum L.) was investigated in hydroponic solution of low concentration [Pu] = 10 -9  mol L -1 . Particular attention was paid to the speciation of radionuclides in the solution which was modelled by the speciation code PHREEQC. The speciation, the solubility and therefore the plant availability of radionuclides mainly depend on the pH value and the redox potential of the solution. During the contamination period, the redox potential did not change significantly. In contrast, the pH value showed characteristic changes depending on exudates excreted by the plants. Plant roots took up high amounts of plutonium (37%-50% of the added total amount). In addition to the uptake into the roots, the radionuclides can also adsorb to the exterior root surface. The solution-to-plant transfer factor showed values between 0.03 and 0.80 (Bq kg -1 / Bq L -1 ) for the potato tubers. By addition of the complexing agent EDTA (10 -4  mol L-1), the plutonium uptake from solution increased by 58% in tubers and by 155% in shoots/leaves. The results showed that excreted substances by plants affect bioavailability of radionuclides at low concentration, on the one hand. On the other hand, the uptake of plutonium by roots and the accumulation in different plant parts can lead to non-negligible ingestion doses, even at low concentration. We are aware of the limited transferability of data obtained in hydroponic solutions to plants growing in soil. However, the aim of this study is twofold: First we want to investigate the influence of Pu speciation on plant uptake in a rather well defined system which can be modelled using available thermodynamic data

Understanding nitrate uptake, signaling and remobilisation for improving plant nitrogen use efficiency.

PubMed

Kant, Surya

2018-02-01

The majority of terrestrial plants use nitrate as their main source of nitrogen. Nitrate also acts as an important signalling molecule in vital physiological processes required for optimum plant growth and development. Improving nitrate uptake and transport, through activation by nitrate sensing, signalling and regulatory processes, would enhance plant growth, resulting in improved crop yields. The increased remobilisation of nitrate, and assimilated nitrogenous compounds, from source to sink tissues further ensures higher yields and quality. An updated knowledge of various transporters, genes, activators, and microRNAs, involved in nitrate uptake, transport, remobilisation, and nitrate-mediated root growth, is presented. An enhanced understanding of these components will allow for their orchestrated fine tuning in efforts to improving nitrogen use efficiency in plants. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Selected Phytochemicals and Culinary Plant Extracts Inhibit Fructose Uptake in Caco-2 Cells.

PubMed

Lee, Yurim; Lim, Yeni; Kwon, Oran

2015-09-18

This study compared the ability of nine culinary plant extracts containing a wide array of phytochemicals to inhibit fructose uptake and then explored the involvement of intestinal fructose transporters and phytochemicals for selected samples. The chemical signature was characterized by high performance liquid chromatography with mass spectrometry. Inhibition of [(14)C]-fructose uptake was tested by using human intestinal Caco-2 cells. Then, the relative contribution of the two apical-facing intestinal fructose transporters, GLUT2 and GLUT5, and the signature components for fructose uptake inhibition was confirmed in naive, phloretin-treated and forskolin-treated Caco-2 cells. HPLC/MS analysis of the chemical signature revealed that guava leaf contained quercetin and catechin, and turmeric contained curcumin, bisdemethoxycurcumin and dimethoxycurcumin. Similar inhibition of fructose uptake (by ~50%) was observed with guava leaf and turmeric in Caco-2 cells, but with a higher contribution of GLUT2 for turmeric and that of GLUT5 for guava leaf. The data suggested that, in turmeric, demethoxycurcumin specifically contributed to GLUT2-mediated fructose uptake inhibition, and curcumin did the same to GLUT5-mediated fructose uptake inhibition, but GLUT2 inhibition was more potent. By contrast, in guava leaf, catechin specifically contributed to GLUT5-mediated fructose uptake inhibition, and quercetin affected both GLUT5- and GLUT2-mediated fructose uptake inhibition, resulting in the higher contribution of GLUT5. These results suggest that demethoxycurcumin is an important contributor to GLUT2-mediated fructose uptake inhibition for turmeric extract, and catechin is the same to GLUT5-mediated fructose uptake inhibition for guava leaf extract. Quercetin, curcumin and bisdemethoxycurcumin contributed to both GLUT5- and GLUT2-mediated fructose uptake inhibition, but the contribution to GLUT5 inhibition was higher than the contribution to GLUT2 inhibition.

Appraisal of available information on uptake by plants of transplutonium elements and neptunium

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

Thomas, R.L.; Healy, J.W.

1976-07-01

A critical review was made of reported information from laboratory studies of plant uptake of transplutonic elements plus neptunium. The available data are meager but indicate that the uptake of Np is the greatest followed by Am and Cm. The data are not sufficient to provide recommended values for use in hazard calculations but they do indicate that the actinides other than plutonium will be accumulated in plants to a greater degree than plutonium.

Impact of FGD gypsum on soil fertility and plant nutrient uptake

USDA-ARS?s Scientific Manuscript database

Use of FGD gypsum is thought to improve soil productivity and increase plant production. Thus, a study was conducted to evaluate the effects of FGD gypsum on yield, plant nutrient uptake and soil productivity. The study was conducted on an established bermudagrass pasture. Poultry litter was applied...

Water uptake by seminal and adventitious roots in relation to whole-plant water flow in barley (Hordeum vulgare L.).

PubMed

Knipfer, Thorsten; Fricke, Wieland

2011-01-01

Prior to an assessment of the role of aquaporins in root water uptake, the main path of water movement in different types of root and driving forces during day and night need to be known. In the present study on hydroponically grown barley (Hordeum vulgare L.) the two main root types of 14- to 17-d-old plants were analysed for hydraulic conductivity in dependence of the main driving force (hydrostatic, osmotic). Seminal roots contributed 92% and adventitious roots 8% to plant water uptake. The lower contribution of adventitious compared with seminal roots was associated with a smaller surface area and number of roots per plant and a lower axial hydraulic conductance, and occurred despite a less-developed endodermis. The radial hydraulic conductivity of the two types of root was similar and depended little on the prevailing driving force, suggesting that water uptake occurred along a pathway that involved crossing of membrane(s). Exudation experiments showed that osmotic forces were sufficient to support night-time transpiration, yet transpiration experiments and cuticle permeance data questioned the significance of osmotic forces. During the day, 90% of water uptake was driven by a tension of about -0.15 MPa.

Water uptake by seminal and adventitious roots in relation to whole-plant water flow in barley (Hordeum vulgare L.)

PubMed Central

Knipfer, Thorsten; Fricke, Wieland

2011-01-01

Prior to an assessment of the role of aquaporins in root water uptake, the main path of water movement in different types of root and driving forces during day and night need to be known. In the present study on hydroponically grown barley (Hordeum vulgare L.) the two main root types of 14- to 17-d-old plants were analysed for hydraulic conductivity in dependence of the main driving force (hydrostatic, osmotic). Seminal roots contributed 92% and adventitious roots 8% to plant water uptake. The lower contribution of adventitious compared with seminal roots was associated with a smaller surface area and number of roots per plant and a lower axial hydraulic conductance, and occurred despite a less-developed endodermis. The radial hydraulic conductivity of the two types of root was similar and depended little on the prevailing driving force, suggesting that water uptake occurred along a pathway that involved crossing of membrane(s). Exudation experiments showed that osmotic forces were sufficient to support night-time transpiration, yet transpiration experiments and cuticle permeance data questioned the significance of osmotic forces. During the day, 90% of water uptake was driven by a tension of about –0.15 MPa. PMID:20974734

Effect of arbuscular mycorrhizal (AM) fungi on 137Cs uptake by plants grown on different soils.

PubMed

Vinichuk, M; Mårtensson, A; Ericsson, T; Rosén, K

2013-01-01

The potential use of mycorrhiza as a bioremediation agent for soils contaminated by radiocesium was evaluated in a greenhouse experiment. The uptake of (137)Cs by cucumber, perennial ryegrass, and sunflower after inoculation with a commercial arbuscular mycorrhizal (AM) product in soils contaminated with (137)Cs was investigated, with non-mycorrhizal quinoa included as a "reference" plant. The effect of cucumber and ryegrass inoculation with AM fungi on (137)Cs uptake was inconsistent. The effect of AM fungi was most pronounced in sunflower: both plant biomass and (137)Cs uptake increased on loamy sand and loamy soils. The total (137)Cs activity accumulated within AM host sunflower on loamy sand and loamy soils was 2.4 and 3.2-fold higher than in non-inoculated plants. Although the enhanced uptake of (137)Cs by quinoa plants on loamy soil inoculated by the AM fungi was observed, the infection of the fungi to the plants was not confirmed. Copyright © 2012 Elsevier Ltd. All rights reserved.

NPKS uptake, sensing, and signaling and miRNAs in plant nutrient stress.

PubMed

Nath, Manoj; Tuteja, Narendra

2016-05-01

Sessile nature of higher plants consequently makes it highly adaptable for nutrient absorption and acquisition from soil. Plants require 17 essential elements for their growth and development which include 14 minerals (macronutrients: N, P, K, Mg, Ca, S; micronutrients: Cl, Fe, B, Mn, Zn, Cu, Ni, Mo) and 3 non-mineral (C, H, O) elements. The roots of higher plants must acquire these macronutrients and micronutrients from rhizosphere and further allocate to other plant parts for completing their life cycle. Plants evolved an intricate series of signaling and sensing cascades to maintain nutrient homeostasis and to cope with nutrient stress/availability. The specific receptors for nutrients in root, root system architecture, and internal signaling pathways help to develop plasticity in response to the nutrient starvation. Nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) are essential for various metabolic processes, and their deficiency negatively effects the plant growth and yield. Genes coding for transporters and receptors for nutrients as well as some small non-coding RNAs have been implicated in nutrient uptake and signaling. This review summarizes the N, P, K, and S uptake, sensing and signaling events in nutrient stress condition especially in model plant Arabidopsis thaliana and involvement of microRNAs in nutrient deficiency. This article also provides a framework of uptake, sensing, signaling and to highlight the microRNA as an emerging major players in nutrient stress condition. Nutrient-plant-miRNA cross talk may help plant to cope up nutrient stress, and understanding their precise mechanism(s) will be necessary to develop high yielding smart crop with low nutrient input.

Uptake of perfluorinated compounds by plants grown in nutrient solution.

PubMed

García-Valcárcel, A I; Molero, E; Escorial, M C; Chueca, M C; Tadeo, J L

2014-02-15

The uptake rates of three perfluorinated carboxylates and three perfluorinated sufonates by a grass (B diandrus) grown in nutrient solution at two different perfluorinated compounds (PFCs) concentrations were assessed. Grass can be ingested by grazing animals causing the PFCs to enter the food chain, which is a pathway of human exposure to these compounds. A rapid and miniaturized method was developed to determine PFCs in plants, based on a matrix solid-phase dispersion (MSPD) extraction procedure followed by quantitation by HPLC-MS/MS with an MQL in the range from 1 to 9 ng/g. An increase of PFCs levels in plant was observed along the exposure time. Differences in uptake for studied perfluorinated carboxylates were found, showing a decrease with carbon chain length (from 3027 to 1,167 ng/g at the end of assay), whereas no significant differences in absorption were obtained between perfluorinated sulfonates (about 1,700 ng/g). Initially, higher PFC transfer factors (ratio between concentration in plant and concentration in initial nutrient solution) were obtained for plants growing in the nutrient solution at the highest PFC concentration, but these factors became similar with time to plants exposed to the lowest concentration. © 2013 Elsevier B.V. All rights reserved.

Comparative study of Cd uptake and tolerance of two Italian ryegrass (Lolium multiflorum) cultivars

PubMed Central

Fang, Zhigang; Lou, Laiqing; Tai, Zhenglan; Wang, Yufeng; Yang, Lei

2017-01-01

Cadmium (Cd) is one of the most toxic heavy metals and is difficult to be removed from contaminated soil and water. Italian ryegrass (Lolium multiflorum), as an energy crop, exhibits a valuable potential to develop Cd polluted sites due to its use as a biofuel rather than as food and forage. Previously, via a screening for Cd-tolerant ryegrass, the two most extreme cultivars (IdyII and Harukaze) with high and low Cd tolerance during seed germination, respectively, were selected. However, the underlying mechanism for Cd tolerance was not well investigated. In this study, we comparatively investigated the growth, physiological responses, and Cd uptake and translocation of IdyII and Harukaze when the seedlings were exposed to a Cd (0–100 μM) solution for 12 days. As expected, excess Cd inhibited seedling growth and was accompanied by an accumulation of malondialdehyde (MDA) and reduced photosynthetic pigments in both cultivars. The effects of Cd on the uptake and translocation of other nutrient elements (Zn, Fe, Mn and Mg) were dependent on Cd concentrations, cultivars, plant tissues and elements. Compared with Harukaze, IdyII exhibited better performance with less MDA and higher pigment content. Furthermore, IdyII was less efficient in Cd uptake and translocation compared to Harukaze, which might be explained by the higher non-protein thiols content in its roots. Taken together, our data indicate that IdyII is more tolerant than Harukaze, which partially resulted from the differences in Cd uptake and translocation. PMID:29018594

Modeling the plant uptake of organic chemicals, including the soil-air-plant pathway.

PubMed

Collins, Chris D; Finnegan, Eilis

2010-02-01

The soil-air-plant pathway is potentially important in the vegetative accumulation of organic pollutants from contaminated soils. While a number of qualitative frameworks exist for the prediction of plant accumulation of organic chemicals by this pathway, there are few quantitative models that incorporate this pathway. The aim of the present study was to produce a model that included this pathway and could quantify its contribution to the total plant contamination for a range of organic pollutants. A new model was developed from three submodels for the processes controlling plant contamination via this pathway: aerial deposition, soil volatilization, and systemic translocation. Using the combined model, the soil-air-plant pathway was predicted to account for a significant proportion of the total shoot contamination for those compounds with log K(OA) > 9 and log K(AW) < -3. For those pollutants with log K(OA) < 9 and log K(AW) > -3 there was a higher deposition of pollutant via the soil-air-plant pathway than for those chemicals with log K(OA) > 9 and log K(AW) < -3, but this was an insignificant proportion of the total shoot contamination because of the higher mobility of these compounds via the soil-root-shoot pathway. The incorporation of the soil-air-plant pathway into the plant uptake model did not significantly improve the prediction of the contamination of vegetation from polluted soils when compared across a range of studies. This was a result of the high variability between the experimental studies where the bioconcentration factors varied by 2 orders of magnitude at an equivalent log K(OA). One potential reason for this is the background air concentration of the pollutants under study. It was found background air concentrations would dominate those from soil volatilization in many situations unless there was a soil hot spot of contamination, i.e., >100 mg kg(-1).

Predicting plant uptake of cadmium: validated with long-term contaminated soils.

PubMed

Lamb, Dane T; Kader, Mohammed; Ming, Hui; Wang, Liang; Abbasi, Sedigheh; Megharaj, Mallavarapu; Naidu, Ravi

2016-10-01

Cadmium accumulates in plant tissues at low soil loadings and is a concern for human health. Yet at higher levels it is also of concern for ecological receptors. We determined Cd partitioning constants for 41 soils to examine the role of soil properties controlling Cd partitioning and plant uptake. From a series of sorption and dose response studies, transfer functions were developed for predicting Cd uptake in Cucumis sativa L. (cucumber). The parameter log K f was predicted with soil pH ca , logCEC and log OC. Transfer of soil pore-water Cd 2+ to shoots was described with a power function (R 2  = 0.73). The dataset was validated with 13 long-term contaminated soils (plus 2 control soils) ranging in Cd concentration from 0.2 to 300 mg kg -1 . The series of equations predicting Cd shoot from pore-water Cd 2+ were able to predict the measured data in the independent dataset (root mean square error = 2.2). The good relationship indicated that Cd uptake to cucumber shoots could be predicted with Cd pore and Cd 2+ without other pore-water parameters such as pH or Ca 2+ . The approach may be adapted to a range of plant species.

Cyclic variations in nitrogen uptake rate of soybean plants: ammonium as a nitrogen source

NASA Technical Reports Server (NTRS)

Henry, L. T.; Raper, C. D. Jr

1989-01-01

When NO3- is the sole nitrogen source in flowing solution culture, the net rate of nitrogen uptake by nonnodulated soybean (Glycine max L. Merr. cv Ransom) plants cycles between maxima and minima with a periodicity of oscillation that corresponds with the interval of leaf emergence. Since soybean plants accumulate similar quantities of nitrogen when either NH4+ or NO3- is the sole source in solution culture controlled at pH 6.0, an experiment was conducted to determine if the oscillations in net rate of nitrogen uptake also occur when NH4+ is the nitrogen source. During a 21-day period of vegetative development, net uptake of NH4+ was measured daily by ion chromatography as depletion of NH4+ from a replenished nutrient solution containing 1.0 millimolar NH4+. The net rate of NH4+ uptake oscillated with a periodicity that was similar to the interval of leaf emergence. Instances of negative net rates of uptake indicate that the transition between maxima and minima involved changes in influx and efflux components of net NH4+ uptake.

Uptake of the natural radioactive gas radon by an epiphytic plant.

PubMed

Li, Peng; Zhang, Ruiwen; Gu, Mintian; Zheng, Guiling

2018-01-15

Radon ( 222 Rn) is a natural radioactive gas and the major radioactive contributor to human exposure. The present effective ways to control Rn contamination are ventilation and adsorption with activated carbon. Plants are believed to be negligible in reducing airborne Rn. Here, we found epiphytic Tillandsia brachycaulos (Bromeliaceae) was effective in reducing airborne Rn via the leaves. Rn concentrations in the Rn chamber after Tillandsia plant treatments decreased more than those in the natural situation. The specialized foliar trichomes densely covering Tillandsia leaves play a major role in the uptake of Rn because the amplified rough leaf surface area facilitates deposition of Rn progeny particles and the powdery epicuticular wax layer of foliar trichomes uptakes liposoluble Rn. The results provide us a new ecological strategy for Rn contamination control, and movable epiphytic Tillandsia plants can be applied widely in Rn removal systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Importance of plant species and external silicon concentration to active silicon uptake and transport.

PubMed

Liang, Yongchao; Hua, Haixia; Zhu, Yong-Guan; Zhang, Jie; Cheng, Chunmei; Römheld, Volker

2006-01-01

Here, we characterized silicon (Si) uptake and xylem loading in Oryza sativa, Zea mays, Helianthus annuus and Benincase hispida in a series of hydroponic experiments. Both active and passive Si-uptake components co-exist in all the plants tested. The active component is the major mechanism responsible for Si uptake in O. sativa and Z. mays. By contrast, passive uptake prevails in H. annuus and B. hispida at a higher external Si concentration (0.85 mM), while the active component constantly exists and contributes to the total Si uptake, especially at a lower external Si concentration (0.085 mM). Short experiments showed that Si uptake was significantly suppressed in O. sativa and Z. mays by metabolic inhibitors or low temperature, regardless of external Si concentrations. By contrast, Si uptake in H. annuus and B. hispida was inhibited more significantly by metabolic inhibitors or low temperature at lower (for example, 0.085 mM) than at higher (for example, 1.70 mM) external Si concentrations. It can be concluded that both active and passive Si-uptake components co-exist in O. sativa, Z. mays, H. annuus and B. hispida, with their relative contribution being dependent much upon both plant species and external Si concentrations.

Uptake Kinetics of Arsenic Species in Rice Plants

PubMed Central

Abedin, Mohammed Joinal; Feldmann, Jörg; Meharg, Andy A.

2002-01-01

Arsenic (As) finds its way into soils used for rice (Oryza sativa) cultivation through polluted irrigation water, and through historic contamination with As-based pesticides. As is known to be present as a number of chemical species in such soils, so we wished to investigate how these species were accumulated by rice. As species found in soil solution from a greenhouse experiment where rice was irrigated with arsenate contaminated water were arsenite, arsenate, dimethylarsinic acid, and monomethylarsonic acid. The short-term uptake kinetics for these four As species were determined in 7-d-old excised rice roots. High-affinity uptake (0–0.0532 mm) for arsenite and arsenate with eight rice varieties, covering two growing seasons, rice var. Boro (dry season) and rice var. Aman (wet season), showed that uptake of both arsenite and arsenate by Boro varieties was less than that of Aman varieties. Arsenite uptake was active, and was taken up at approximately the same rate as arsenate. Greater uptake of arsenite, compared with arsenate, was found at higher substrate concentration (low-affinity uptake system). Competitive inhibition of uptake with phosphate showed that arsenite and arsenate were taken up by different uptake systems because arsenate uptake was strongly suppressed in the presence of phosphate, whereas arsenite transport was not affected by phosphate. At a slow rate, there was a hyperbolic uptake of monomethylarsonic acid, and limited uptake of dimethylarsinic acid. PMID:11891266

Plant Uptake of Atmospheric Carbonyl Sulfide in Coast Redwood Forests

NASA Astrophysics Data System (ADS)

Campbell, J. E.; Whelan, M. E.; Berry, J. A.; Hilton, T. W.; Zumkehr, A.; Stinecipher, J.; Lu, Y.; Kornfeld, A.; Seibt, U.; Dawson, T. E.; Montzka, S. A.; Baker, I. T.; Kulkarni, S.; Wang, Y.; Herndon, S. C.; Zahniser, M. S.; Commane, R.; Loik, M. E.

2017-12-01

The future resilience of coast redwoods (Sequoia sempervirens) is now of critical concern due to the detection of a 33% decline in California coastal fog over the 20th century. However, ecosystem-scale measurements of photosynthesis and stomatal conductance are challenging in coast redwood forests, making it difficult to anticipate the impacts of future changes in fog. To address this methodological problem, we explore coastal variations in atmospheric carbonyl sulfide (COS or OCS), which could potentially be used as a tracer of these ecosystem processes. We conducted atmospheric flask campaigns in coast redwood sites, sampling at surface heights and in the canopy ( 70 m), at the University of California Landels-Hill Big Creek Reserve and Big Basin State Park. We simulated COS atmosphere-biosphere exchange with a high-resolution 3-D model to interpret these data. Flask measurements indicated a persistent daytime drawdown between the coast and the downwind forest (45 ± 6 ppt COS) that is consistent with the expected relationship between COS plant uptake, stomatal conductance, and gross primary production. Other sources and sinks of COS that could introduce noise to the COS tracer technique (soils, anthropogenic activity, nocturnal plant uptake, and surface hydrolysis on leaves) are likely to be small relative to daytime COS plant uptake. These results suggest that COS measurements may be useful for making ecosystem-scale estimates of carbon, water, and energy exchange in coast redwood forests.

Comparison and Intercalibration of Vegetation Indices from Different Sensors for Monitoring Above-Ground Plant Nitrogen Uptake in Winter Wheat

PubMed Central

Yao, Xinfeng; Yao, Xia; Jia, Wenqing; Tian, Yongchao; Ni, Jun; Cao, Weixing; Zhu, Yan

2013-01-01

Various sensors have been used to obtain the canopy spectral reflectance for monitoring above-ground plant nitrogen (N) uptake in winter wheat. Comparison and intercalibration of spectral reflectance and vegetation indices derived from different sensors are important for multi-sensor data fusion and utilization. In this study, the spectral reflectance and its derived vegetation indices from three ground-based sensors (ASD Field Spec Pro spectrometer, CropScan MSR 16 and GreenSeeker RT 100) in six winter wheat field experiments were compared. Then, the best sensor (ASD) and its normalized difference vegetation index (NDVI (807, 736)) for estimating above-ground plant N uptake were determined (R2 of 0.885 and RMSE of 1.440 g·N·m−2 for model calibration). In order to better utilize the spectral reflectance from the three sensors, intercalibration models for vegetation indices based on different sensors were developed. The results indicated that the vegetation indices from different sensors could be intercalibrated, which should promote application of data fusion and make monitoring of above-ground plant N uptake more precise and accurate. PMID:23462622

Characterization of Cadmium Uptake by Plant Tissue 12

PubMed Central

Cutler, Jay M.; Rains, Donald W.

1974-01-01

The uptake of cadmium by excised root tissue of barley (Hordeum vulgare L. cv. Arivat) was investigated with respect to kinetics, concentration, and interactions with various cations. The role of metabolism in Cd absorption was examined using a range of temperatures, anaerobic treatments, and chemical inhibitors. The uptake and distribution of Cd in intact barley plants was also determined. A large fraction of the Cd taken up by excised barley roots was apparently the result of exchange adsorption and was displaced by subsequent desorption with unlabeled Cd, Zn, Cu, or Hg. Another fraction of Cd which could not be displaced by desorption in unlabeled Cd was thought to result from strong irreversible binding of Cd, perhaps on sites of the cell wall. The fraction of the Cd taken up beyond that by exchange adsorption by fresh roots was a linear function of temperature, and inhibited by conditions of low oxygen and by the presence of 2,4-dinitrophenol. It was concluded that this fraction of Cd entered excised barley roots by diffusion. Diffusion, when followed by sequestering, probably accounts for the accumulation of Cd observed in intact barley plants. PMID:16658840

Investigating the Toxicity, Uptake, Nanoparticle Formation and Genetic Response of Plants to Gold

PubMed Central

Taylor, Andrew F.; Rylott, Elizabeth L.; Anderson, Christopher W. N.; Bruce, Neil C.

2014-01-01

We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis) to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold) were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa) to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake. PMID:24736522

Interaction of carbon nanohorns with plants: Uptake and biological effects

DOE PAGES

Lahiani, Mohamed H.; Chen, Jihua; Irin, Fahmida; ...

2014-10-07

Single-Walled Carbon Nanohorns (SWCNHs) are a unique carbon-based nanomaterial with promising application in different fields including, medicine, genetic engineering and horticulture. Here, we investigated the biological response of six crop species (barley, corn, rice, soybean, switchgrass, tomato) and tobacco cell culture to the exposure of SWCNHs. We found that SWCNHs can activate seed germination of selected crops and enhance growth of different organs of corn, tomato, rice and soybean. At cellular level, growth of tobacco cells was increased in response to exposure of SWCNHs (78% increase compared to control). Uptake of SWCNHs by exposed crops and tobacco cells was confirmedmore » by transmission electron microscopy (TEM) and quantified by microwave induced heating (MIH) technique. At genetic level, SWCNHs were able to affect expression of a number of tomato genes that are involved in stress responses, cellular responses and metabolic processes. Our conclusion is that SWCNHs can be used as plant growth regulators and have the potential for plant-related applications.« less

Approaches in the determination of plant nutrient uptake and distribution in space flight conditions

NASA Technical Reports Server (NTRS)

Heyenga, A. G.; Forsman, A.; Stodieck, L. S.; Hoehn, A.; Kliss, M.

2000-01-01

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the radionuclides calcium-45 and iron-59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Approaches in the Determination of Plant Nutrient Uptake and Distribution in Space Flight Conditions

NASA Technical Reports Server (NTRS)

Heyenga, A. G.; Forsman, A.; Stodieck, L. S.; Hoehn, A.; Kliss, Mark

1998-01-01

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which may impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the nuclides Ca45 and Fe59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Dynamics of Short-Term Phosphorus Uptake by Intact Mycorrhizal and Non-mycorrhizal Maize Plants Grown in a Circulatory Semi-Hydroponic Cultivation System.

PubMed

Garcés-Ruiz, Mónica; Calonne-Salmon, Maryline; Plouznikoff, Katia; Misson, Coralie; Navarrete-Mier, Micaela; Cranenbrouck, Sylvie; Declerck, Stéphane

2017-01-01

A non-destructive cultivation system was developed to study the dynamics of phosphorus (Pi) uptake by mycorrhizal and non-mycorrhizal maize plantlets. The system consisted of a plant container connected via silicon tubes to a glass bottle containing a nutrient solution supplemented with Pi. The nutrient solution is pumped with a peristaltic pump to the upper part of the container via the silicon tubes and the solution percolate through the plantlet container back into the glass bottle. Pi is sampled from the glass bottle at regular intervals and concentration evaluated. Maize plantlets were colonized by the AMF Rhizophagus irregularis MUCL 41833 and Pi uptake quantified at fixed intervals (9, 21, and 42 h) from the depletion of the Pi in the nutrient solution flowing through the plantlets containers. Plants and fungus grew well in the perlite substrate. The concentration of Pi in the bottles followed an almost linear decrease over time, demonstrating a depletion of Pi in the circulating solution and a concomitant uptake/immobilization by the plantlet-AMF associates in the containers. The Pi uptake rate was significantly increased in the AMF-colonized plantlets (at 9 and 21 h) as compared to non-colonized plantlets, although no correlation was noticed with plant growth or P accumulation in shoots. The circulatory semi-hydroponic cultivation system developed was adequate for measuring Pi depletion in a nutrient solution and by corollary Pi uptake/immobilization by the plant-AMF associates. The measurements were non-destructive so that the time course of Pi uptake could be monitored without disturbing the growth of the plant and its fungal associate. The system further opens the door to study the dynamics of other micro and macro-nutrients as well as their uptake under stressed growth conditions such as salinity, pollution by hydrocarbon contaminants or potential toxic elements.

A SIMPLE MODEL FOR THE UPTAKE, TRANSLOCATION, AND ACCUMULATION OF PERCHLORATE IN TOBACCO PLANTS

EPA Science Inventory

A simple mathematical model is being developed to describe the uptake, translocation, and accumulation of perchlorate in tobacco plants. The model defines a plant as a set of compartments, consisting of mass balance differential equations and plant-specific physiological paramet...

Arsenate and fluoride enhanced each other's uptake in As-sensitive plant Pteris ensiformis.

PubMed

Das, Suchismita; de Oliveira, Letuzia M; da Silva, Evandro; Ma, Lena Q

2017-08-01

We investigated the effects of arsenate (AsV) and fluoride (F) on each other's uptake in an As-sensitive plant Pteris ensiformis. Plants were exposed to 1) 0.1 × Hoagland solution control, 2) 3.75 mg L -1 As and 1.9, 3.8, or 7.6 mg L -1 F, or 3) 1 mg L -1 F and 3.75 mg L -1 or 7.5 mg L -1 As for 7 d in hydroponics. P. ensiformis accumulated 14.7-32.6 mg kg -1 As at 3.75 mg L -1 AsV, and 99-145 mg kg -1 F at 1 mg L -1 F. Our study revealed that AsV and F increased each other's uptake when co-present. At 1.9 mg L -1 , F increased frond As uptake from 14.7 to 40.3 mg kg -1 , while 7.5 mg L -1 As increased frond F uptake from 99 to 371 mg kg -1 . Although, AsV was the predominant As species in all tissues, F enhanced AsIII levels in the rhizomes and fronds, while the reverse was observed in the roots. Increasing As concentrations also enhanced TBARS and H 2 O 2 in tissues, indicating oxidative stress. However, F alleviated As stress by lowering their levels in the fronds. Frond and root membrane leakage were also evident due to As or F exposure. The results may facilitate better understanding of the mechanisms underlying the co-uptake of As and F in plants. However, the mechanisms of how they enhance each other's uptake in P. ensiformis need further investigation. Published by Elsevier Ltd.

Scoparia dulcis (SDF7) endowed with glucose uptake properties on L6 myotubes compared insulin.

PubMed

Beh, Joo Ee; Latip, Jalifah; Abdullah, Mohd Puad; Ismail, Amin; Hamid, Muhajir

2010-05-04

Insulin stimulates glucose uptake and promotes the translocation of glucose transporter 4 (Glut 4) to the plasma membrane on L6 myotubes. The aim of this study is to investigate affect of Scoparia dulcis Linn water extracts on glucose uptake activity and the Glut 4 translocation components (i.e., IRS-1, PI 3-kinase, PKB/Akt2, PKC and TC 10) in L6 myotubes compared to insulin. Extract from TLC fraction-7 (SDF7) was used in this study. The L6 myotubes were treated by various concentrations of SDF7 (1 to 50 microg/ml) and insulin (1 to 100 nM). The glucose uptake activities of L6 myotubes were evaluated using 2-Deoxy-D-glucose uptake assay in with or without fatty acid-induced medium. The Glut 4 translocation components in SDF7-treated L6 myotubes were detected using immunoblotting and quantified by densitometry compared to insulin. Plasma membrane lawn assay and glycogen colorimetry assay were carried out in SDF7- and insulin-treated L6 myotubes in this study. Here, our data clearly shows that SDF7 possesses glucose uptake properties on L6 myotubes that are dose-dependent, time-dependent and plasma membrane Glut 4 expression-dependent. SDF7 successfully stimulates glucose uptake activity as potent as insulin at a maximum concentration of 50 microg/ml at 480 min on L6 myotubes. Furthermore, SDF7 stimulates increased Glut 4 expression and translocation to plasma membranes at equivalent times. Even in the insulin resistance stage (free fatty acids-induced), SDF7-treated L6 myotubes were found to be more capable at glucose transport than insulin treatment. Thus, we suggested that Scoparia dulcis has the potential to be categorized as a hypoglycemic medicinal plant based on its good glucose transport properties. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Uptake of Uranium and Other Elements of Concern by Plants Growing on Uranium Mill Tailings Disposal Cells

NASA Astrophysics Data System (ADS)

Joseph, C. N.; Waugh, W.; Glenn, E.

2015-12-01

The U.S. Department of Energy (DOE) is responsible for long-term stewardship of disposal cells for uranium mill tailings throughout the United States. Rock-armored disposal cell covers create favorable habitat for deep-rooted plants by reducing soil evaporation, increasing soil water storage, and trapping windblown dust, thereby providing water and nutrients for plant germination and establishment. DOE is studying the tradeoffs of potential detrimental and beneficial effects of plants growing on disposal cell covers to develop a rational and consistent vegetation management policy. Plant roots often extend vertically through disposal cell covers into underlying tailings, therefore, uptake of tailings contaminants and dissemination through animals foraging on stems and leaves is a possible exposure pathway. The literature shows that plant uptake of contaminants in uranium mill tailings occurs, but levels can vary widely depending on plant species, tailings and soil chemistry, and cover soil hydrology. Our empirical field study measured concentrations of uranium, radium, thorium, molybdenum, selenium, manganese, lead, and arsenic in above ground tissues harvested from plants growing on disposal cells near Native American communities in western states that represent a range of climates, cover designs, cover soil types, and vegetation types. For risk screening, contaminant levels in above ground tissues harvested from plants on disposal cells were compared to Maximum Tolerance Levels (MTLs) set for livestock by the National Research Council, and to tissue levels in the same plant species growing in reference areas near disposal cells. Although tailings were covered with uncontaminated soils, for 14 of 46 comparisons, levels of uranium and other contaminants were higher in plants growing on disposal cells compared to reference area plants, indicating possible mobilization of these elements from the tailing into plant tissues. However, with one exception, all plant

UPTAKE AND PHYTOTRANSFORMATION OF ORGANOPHOSPHORUS PESTICIDES BY AXENICALLY CULTIVATED AQUATIC PLANTS

EPA Science Inventory

The uptake and phytotransformation of organophosphorus (OP) pesticides (malathion, demeton-S-methyl, and crufomate) was investigated in vitro using the axenically aquatic cultivated plants parrot feather (Myriophyllum aquaticum), duckweed (Spirodela oligorrhiza L.), and elodea (E...

Uptake of VOC by sunflower

NASA Astrophysics Data System (ADS)

Folkers, A.; Miebach, M.; Kleist, E.; Wildt, J.

2003-04-01

To study potential VOC uptake by plants we exposed sunflower (Helianthus annuus) to different VOC in continuously stirred tank reactors. For many VOC like methanol, ethanol, acetone, methylvinylketone, isoprene or limonene no uptake was detectable within the accuracy of our analytic set up. Other VOC like hexanal, octanal, (E)-3-hexenol and nopinone were taken up by sunflower. The uptake was related to stomatal aperture. Obviously, these VOC enter the plants through stomata. In case of hexanal, octanal, and (E)-3-hexenol the uptake was only limited by stomatal aperture implying that these VOC are rapidly metabolised. For nopinone the uptake seems to be limited by a slow metabolization. Estimations of deposition velocities showed that dry deposition of these compounds cannot be neglected as sink if diffusion through stomata is the limiting step for dry deposition. In such cases the lifetime with respect to dry deposiotion is comparable to the lifetime with respect to oxidation by hydroxyl radicals.

Nitrogen Cycling in the Mycorrhizosphere: Multipartite Interactions and Plant Nitrogen Uptake Vary with Fertilization Legacy

NASA Astrophysics Data System (ADS)

Hestrin, R.; Lehmann, J.

2017-12-01

Soil microbes play an important role in rhizosphere nutrient cycling and plant productivity. In this study, the contributions of soil microbes to organic matter mineralization and plant nitrogen uptake were investigated using incubation and microcosm experiments. Microbial inocula included arbuscular mycorrhizal fungi and microbial communities sampled across a long-term gradient of nitrogen fertilization. Stable isotopes, nanoSIMS imaging, and phospholipid fatty acid analysis were used to track carbon and nitrogen movement from organic matter into microbes, mycorrhizal fungi, and plants. Results show that multipartite relationships between plants and microbes increased plant growth and access to nitrogen from organic matter, and that nitrogen fertilization history had a lasting effect on microbial contributions to fungal and plant nitrogen uptake. This research links rhizosphere ecology and land management with terrestrial biogeochemistry.

Effect of plant growth-promoting rhizobacteria inoculation on cadmium (Cd) uptake by Eruca sativa.

PubMed

Kamran, Muhammad Aqeel; Syed, Jabir Hussain; Eqani, Syed Ali Musstjab Akber Shah; Munis, Muhammad Farooq Hussain; Chaudhary, Hassan Javed

2015-06-01

Microbe-assisted phyto-remediation approach is widely applied and appropriate choice to reduce the environmental risk of heavy metals originated from contaminated soils. The present study was designed to screen out the nested belongings of Eruca sativa plants and Pseudomonas putida (ATCC 39213) at varying cadmium (Cd) levels and their potential to deal with Cd uptake from soils. We carried out pot trial experiment by examining the soil containing E. sativa seedlings either treated with P. putida and/or untreated plants subjected to three different levels (ppm) of Cd (i.e., 150, 250, and 500). In all studied cases, we observed an increase in Cd uptake for E. sativa plants inoculated with P. putida than those of un-inoculated plants. Cd toxicity was assessed by recording different parameters including stunted shoot growth, poor rooting, and Cd residual levels in the plants that were not inoculated with P. putida. Significant difference (p < 0.05) of different growth parameters for inoculated vs non-inoculated plants was observed at all given treatments. However, among the different treatments, E. sativa exhibited increased values for different growth parameters (except proline contents) at lower Cd levels than those of their corresponding higher levels, shoot length (up to 27 %), root length (up to 32 %), whole fresh plant (up to 40 %), dry weight (up to 22 %), and chlorophyll contents (up to 26 %). Despite the hyperaccumulation of Cd in whole plant of E. sativa, P. putida improved the plant growth at varying levels of Cd supply than those of associated non-inoculated plants. Present results indicated that inoculation with P. putida enhanced the Cd uptake potential of E. sativa and favors the healthy growth under Cd stress.

Silicon in vascular plants: uptake, transport and its influence on mineral stress under acidic conditions.

PubMed

Pontigo, Sofía; Ribera, Alejandra; Gianfreda, Liliana; de la Luz Mora, María; Nikolic, Miroslav; Cartes, Paula

2015-07-01

So far, considerable advances have been achieved in understanding the mechanisms of Si uptake and transport in vascular plants. This review presents a comprehensive update about this issue, but also provides the new insights into the role of Si against mineral stresses that occur in acid soils. Such information could be helpful to understand both the differential Si uptake ability as well as the benefits of this mineral element on plants grown under acidic conditions. Silicon (Si) has been widely recognized as a beneficial element for many plant species, especially under stress conditions. In the last few years, great efforts have been made to elucidate the mechanisms involved in uptake and transport of Si by vascular plants and recently, different Si transporters have been identified. Several researches indicate that Si can alleviate various mineral stresses in plants growing under acidic conditions, including aluminium (Al) and manganese (Mn) toxicities as well as phosphorus (P) deficiency all of which are highly detrimental to crop production. This review presents recent findings concerning the influence of uptake and transport of Si on mineral stress under acidic conditions because a knowledge of this interaction provides the basis for understanding the role of Si in mitigating mineral stress in acid soils. Currently, only four Si transporters have been identified and there is little information concerning the response of Si transporters under stress conditions. More investigations are therefore needed to establish whether there is a relationship between Si transporters and the benefits of Si to plants subjected to mineral stress. Evidence presented suggests that Si supply and its subsequent accumulation in plant tissues could be exploited as a strategy to improve crop productivity on acid soils.

Uptake of explosives from contaminated soil by vegetation at the Joliet Army Ammunition Plant

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

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D.

1994-06-01

This study examines the uptake of explosives by vegetation growing on soils contaminated by 2,4,6-trinitrotoluene (TNT) in Group 61 at the Joliet Army Ammunition Plant (JAAP). Plant materials and soil from the root zone were sampled and analyzed to determine TNT uptake under natural field conditions. Standard USATHAMA methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. No- explosives were detected in the aboveground portion of any plant sample. However, results indicate that TNT, 2-aminodinitrotoluene (2-ADNT), and/or 4-ADNT were present in some root samples. The presence of 2-ADNT and 4-ADNT increases the likelihoodmore » that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.« less

Effect of nitrate on uptake of pertechnetate by tomato plants

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

Krijger, G.C.; Kolloeffel, C.; Wolterbeek, H.T.

Nitrate has been shown to affect the acquisition of the nuclear waste product technetium (Tc) by plants. The mechanism responsible for this phenomenon is unknown. The uptake of [{sup 99m}Tc]TcO{sub 4}{sup {minus}},[{sup 35}S] SO{sub 4}{sup 2{minus}} and H{sub 2}[{sup 32P}]PO{sub 4}{sup {minus}} was studied in tomato plants (Lycopersicon esculentum Mill., cv. Tiny Tim) with different growth rates due to culture at 0.5, 4.0, or 30 mM NO{sub 3}{sup {minus}}. In experiments lasting 24 h, net TcO{sub 4}{sup {minus}} uptake decreased at higher NO{sub 3}{sup {minus}} supplies. The inhibitory effect of NO{sub 3}{sup {minus}} on TcO{sub 4}{sup {minus}} uptake also wasmore » shown in TcO{sub 4}{sup {minus}} influx experiments (K{sub i} = 3.3 mM), although about 30% of the TcO{sub 4}{sup {minus}} influx is suggested to be insensitive to NO{sub 3}{sup {minus}}. In contrast, H{sub 2}PO{sub 4}{sup {minus}} (30 mM) did not inhibit TcO{sub 4}{sup {minus}} influx, whereas SO{sub 4}{sup 2{minus}} (30 mM) tended to increase TcO{sub 4}{sup {minus}} influx, probably due to the ionic strength of the uptake solution. Significant effects of the NO{sub 3}{sup {minus}} supply on Tc efflux were not found. Overall, this leads to the conclusion that TcO{sub 4}{sup {minus}} and NO{sub 3}{sup {minus}} share at least one transporter.« less

Plant uptake of elements in soil and pore water: field observations versus model assumptions.

PubMed

Raguž, Veronika; Jarsjö, Jerker; Grolander, Sara; Lindborg, Regina; Avila, Rodolfo

2013-09-15

Contaminant concentrations in various edible plant parts transfer hazardous substances from polluted areas to animals and humans. Thus, the accurate prediction of plant uptake of elements is of significant importance. The processes involved contain many interacting factors and are, as such, complex. In contrast, the most common way to currently quantify element transfer from soils into plants is relatively simple, using an empirical soil-to-plant transfer factor (TF). This practice is based on theoretical assumptions that have been previously shown to not generally be valid. Using field data on concentrations of 61 basic elements in spring barley, soil and pore water at four agricultural sites in mid-eastern Sweden, we quantify element-specific TFs. Our aim is to investigate to which extent observed element-specific uptake is consistent with TF model assumptions and to which extent TF's can be used to predict observed differences in concentrations between different plant parts (root, stem and ear). Results show that for most elements, plant-ear concentrations are not linearly related to bulk soil concentrations, which is congruent with previous studies. This behaviour violates a basic TF model assumption of linearity. However, substantially better linear correlations are found when weighted average element concentrations in whole plants are used for TF estimation. The highest number of linearly-behaving elements was found when relating average plant concentrations to soil pore-water concentrations. In contrast to other elements, essential elements (micronutrients and macronutrients) exhibited relatively small differences in concentration between different plant parts. Generally, the TF model was shown to work reasonably well for micronutrients, whereas it did not for macronutrients. The results also suggest that plant uptake of elements from sources other than the soil compartment (e.g. from air) may be non-negligible. Copyright © 2013 Elsevier Ltd. All rights

Effect of specific plant-growth-promoting rhizobacteria (PGPR) on growth and uptake of neonicotinoid insecticide thiamethoxam in corn (Zea mays L.) seedlings.

PubMed

Myresiotis, Charalampos K; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

2015-09-01

Corn (Zea mays L.) is one of the most important cereal crops in the world and is used for food, feed and energy. Inoculation with plant-growth-promoting rhizobacteria (PGPR) would reduce the use of chemical fertilisers and pesticides and could be suggested as an alternative practice for sustainable production of corn in modern agricultural systems. In this study, the effect of two Bacillus PGPR formulated products, Companion (B. subtilis GB03) and FZB24 (B. subtilis FZB24), on corn growth and root uptake of insecticide thiamethoxam was investigated. All bacterial treatments enhanced root biomass production by 38-65% compared with the uninoculated control, with no stimulatory effect of PGPR on above-ground biomass of corn. The uptake results revealed that, in plants inoculated with the PGPR B. subtilis FZB24 and B. subtilis GB03, singly or in combination, the uptake and/or systemic translocation of thiamethoxam in the above-ground corn parts was significantly higher at the different growth ages compared with the control receiving no bacterial treatment. The findings suggest that the PGPR-elicited enhanced uptake of thiamethoxam could lead to improved efficiency of thiamethoxam using reduced rates of pesticides in combination with PGPR as an alternative crop protection technique. © 2014 Society of Chemical Industry.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions.

PubMed

Gebremikael, Mesfin T; Steel, Hanne; Buchan, David; Bert, Wim; De Neve, Stefaan

2016-09-08

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions

NASA Astrophysics Data System (ADS)

Gebremikael, Mesfin T.; Steel, Hanne; Buchan, David; Bert, Wim; de Neve, Stefaan

2016-09-01

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Plant Uptake and Metabolism of Nitrofuran Antibiotics in Spring Onion Grown in Nitrofuran-Contaminated Soil.

PubMed

Wang, Yinan; Chan, K K Jason; Chan, Wan

2017-05-31

Environmental pollution caused by the discharge of mutagenic and carcinogenic nitrofurans to the aquatic and soil environment is an emerging public health concern because of the potential in producing drug-resistant microbes and being uptaken by food crops. Using liquid chromatography-tandem mass spectrometry analysis and with spring onion (Allium wakegi Araki) as the plant model, we investigated in this study the plant uptake and accumulation of nitrofuran from a contaminated environment. Our study revealed for the first time high uptake and accumulation rates of nitrofuran in the edible parts of the food crop. Furthermore, results indicated highly efficient plant metabolism of the absorbed nitrofuran within the plant, leading to the formation of genotoxic hydrazine-containing metabolites. The results from this study may disclose a previously unidentified human exposure pathway through contaminated food crops.

Hydraulic resistance of a plant root to water-uptake: A slender-body theory.

PubMed

Chen, Kang Ping

2016-05-07

A slender-body theory for calculating the hydraulic resistance of a single plant root is developed. The work provides an in-depth discussion on the procedure and the assumptions involved in calculating a root׳s internal hydraulic resistance as well as the physical and the mathematical aspects of the external three-dimensional flow around the tip of a root in a saturated soil and how this flow pattern enhances uptake and reduces hydraulic resistance. Analytical solutions for the flux density distribution on the stele-cortex interface, local water-uptake profile inside the stele core, the overall water-uptake at the base of the stele, and the total hydraulic resistance of a root are obtained in the slender-body limit. It is shown that a key parameter controlling a root's hydraulic resistance is the dimensionless axial conductivity in the stele, which depends on the permeabilities of the stele and the cortex as well as the root's radial and axial dimensions. Three-dimensional tip effect reduces a root's hydraulic resistance by as much as 36% when compared to the radial flow theory of Landsberg and Fowkes. In addition, the total hydraulic resistance cannot be generally decomposed into the direct sum of a radial resistance and an axial resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multiple Method Analysis of TiO2 Nanoparticle Uptake in Rice (Oryza sativa L.) Plants.

PubMed

Deng, Yingqing; Petersen, Elijah J; Challis, Katie E; Rabb, Savelas A; Holbrook, R David; Ranville, James F; Nelson, Bryant C; Xing, Baoshan

2017-09-19

Understanding the translocation of nanoparticles (NPs) into plants is challenging because qualitative and quantitative methods are still being developed and the comparability of results among different methods is unclear. In this study, uptake of titanium dioxide NPs and larger bulk particles (BPs) in rice plant (Oryza sativa L.) tissues was evaluated using three orthogonal techniques: electron microscopy, single-particle inductively coupled plasma mass spectroscopy (spICP-MS) with two different plant digestion approaches, and total elemental analysis using ICP optical emission spectroscopy. In agreement with electron microscopy results, total elemental analysis of plants exposed to TiO 2 NPs and BPs at 5 and 50 mg/L concentrations revealed that TiO 2 NPs penetrated into the plant root and resulted in Ti accumulation in above ground tissues at a higher level compared to BPs. spICP-MS analyses revealed that the size distributions of internalized particles differed between the NPs and BPs with the NPs showing a distribution with smaller particles. Acid digestion resulted in higher particle numbers and the detection of a broader range of particle sizes than the enzymatic digestion approach, highlighting the need for development of robust plant digestion procedures for NP analysis. Overall, there was agreement among the three techniques regarding NP and BP penetration into rice plant roots and spICP-MS showed its unique contribution to provide size distribution information.

Phytoextraction: simulating uptake and translocation of arsenic in a soil-plant system.

PubMed

Ouyang, Ying

2005-01-01

The uptake, transport, and accumulation of metals by plants are functions central to successful phytoextraction. This study investigates the uptake and translocation of arsenic from a contaminated sandy soil by a mature Chinese brake fern (Pteris vittata L.). An existing mathematical model for the coupled transport of water, heat, and solutes in the soil-plant-atmosphere continuum (CTSPAC) was modified to examine the flow of water as well as the uptake and translocation of total arsenic in the xylem of the fern. This model was calibrated using greenhouse measurements before its application. Simulation results showed that about 20% of the soil arsenic was removed by the fern in 10 d, of which about 90% of the arsenic was stored in the fronds and 10% in the roots. Although arsenic mass in the plant tissues increased consecutively with time, arsenic concentration in the xylem sap of the root tips has a typical diurnal distribution pattern: increasing during the day and decreasing at night, resulting from daily variations of frond surface water transpiration. The largest difference in simulated arsenic concentration in the root tips between the day and night was about 5%. This study also suggests that the use of transpiration stream concentration factor (TSCF), which is defined as the ratio of chemical concentration in the xylem sap to that in the external solution, to evaluate the translocation efficiency of arsenic for the hyperaccumulator Chinese brake fern (Pteris vittata L.) could be limited.

The impact of pH and calcium on the uptake of fluoride by tea plants (Camellia sinensis L.).

PubMed

Ruan, Jianyun; Ma, Lifeng; Shi, Yuanzhi; Han, Wenyan

2004-01-01

Tea plants (Camellia sinensis L.) accumulate large amounts of fluoride (F) from soils containing normal F concentrations. The present experiments examined the effects of pH and Ca on F uptake by this accumulating plant species. The effect of pH was assessed in two experiments, one using uptake solutions with different pHs, and the other using lime, as CaO, applied to the soil. The effect of Ca was examined by analysing F concentrations in plants supplied with varying amounts of Ca, as Ca(NO3)2, either in uptake solutions or through the soil. F uptake was highest at solution pH 5.5, and significantly lower at pH 4.0. In the soil experiment, leaf F decreased linearly with the amounts of lime, which raised the soil pH progressively from 4.32 to 4.91, 5.43, 5.89 and, finally, 6.55. Liming increased the water-soluble F content of the soil. Including Ca in the uptake solution or adding Ca to soil significantly decreased leaf F concentrations. The distribution pattern of F in tea plants was not altered by Ca treatment, with most F being allocated to leaves. The activity of F- in the uptake solution was unaffected and water-soluble F in the soil was sometimes increased by added Ca. F uptake by tea plants, which are inherently able to accumulate large quantities of F, was affected both by pH and by Ca levels in the medium. The reduced F uptake following Ca application appeared not to be due simply to the precipitation of CaF2 in solution and soil or to the complexing of Ca and F in roots, although these factors cannot be dismissed. It was more likely due to the effect of Ca on the properties of cell wall or membrane permeability in the solution experiments, and to alteration of F speciations and their quantities in soil solutions following Ca application.

Impact of soil water regime on degradation and plant uptake behaviour of the herbicide isoproturon in different soil types.

PubMed

Grundmann, Sabine; Doerfler, Ulrike; Munch, Jean Charles; Ruth, Bernhard; Schroll, Reiner

2011-03-01

The environmental fate of the worldwide used herbicide isoproturon was studied in four different, undisturbed lysimeters in the temperate zone of Middle Europe. To exclude climatic effects due to location, soils were collected at different regions in southern Germany and analyzed at a lysimeter station under identical environmental conditions. (14)C-isoproturon mineralization varied between 2.59% and 57.95% in the different soils. Barley plants grown on these lysimeters accumulated (14)C-pesticide residues from soil in partially high amounts and emitted (14)CO(2) in an extent between 2.01% and 13.65% of the applied (14)C-pesticide. Plant uptake and (14)CO(2) emissions from plants were inversely linked to the mineralization of the pesticide in the various soils: High isoproturon mineralization in soil resulted in low plant uptake whereas low isoproturon mineralization in soil resulted in high uptake of isoproturon residues in crop plants and high (14)CO(2) emission from plant surfaces. The soil water regime was identified as an essential factor that regulates degradation and plant uptake of isoproturon whereby the intensity of the impact of this factor is strongly dependent on the soil type. Copyright © 2010 Elsevier Ltd. All rights reserved.

K+ uptake in plant roots. The systems involved, their regulation and parallels in other organisms.

PubMed

Nieves-Cordones, Manuel; Alemán, Fernando; Martínez, Vicente; Rubio, Francisco

2014-05-15

Potassium (K(+)) is an essential macronutrient for plants. It is taken into the plant by the transport systems present in the plasma membranes of root epidermal and cortical cells. The identity of these systems and their regulation is beginning to be understood and the systems of K(+) transport in the model species Arabidopsis thaliana remain far better characterized than in any other plant species. Roots can activate different K(+) uptake systems to adapt to their environment, important to a sessile organism that needs to cope with a highly variable environment. The mechanisms of K(+) acquisition in the model species A. thaliana are the best characterized at the molecular level so far. According to the current model, non-selective channels are probably the main pathways for K(+) uptake at high concentrations (>10mM), while at intermediate concentrations (1mM), the inward rectifying channel AKT1 dominates K(+) uptake. Under lower concentrations of external K(+) (100μM), AKT1 channels, together with the high-affinity K(+) uptake system HAK5 contribute to K(+) acquisition, and at extremely low concentrations (<10μM) the only system capable of taking up K(+) is HAK5. Depending on the species the high-affinity system has been named HAK5 or HAK1, but in all cases it fulfills the same functions. The activation of these systems as a function of the K(+) availability is achieved by different mechanisms that include phosphorylation of AKT1 or induction of HAK5 transcription. Some of the characteristics of the systems for root K(+) uptake are shared by other organisms, whilst others are specific to plants. This indicates that some crucial properties of the ancestral of K(+) transport systems have been conserved through evolution while others have diverged among different kingdoms. Copyright © 2013 Elsevier GmbH. All rights reserved.

Compound Synthesis or Growth and Development of Roots/Stomata Regulate Plant Drought Tolerance or Water Use Efficiency/Water Uptake Efficiency.

PubMed

Meng, Lai-Sheng

2018-04-11

Water is crucial to plant growth and development because it serves as a medium for all cellular functions. Thus, the improvement of plant drought tolerance or water use efficiency/water uptake efficiency is important in modern agriculture. In this review, we mainly focus on new genetic factors for ameliorating drought tolerance or water use efficiency/water uptake efficiency of plants and explore the involvement of these genetic factors in the regulation of improving plant drought tolerance or water use efficiency/water uptake efficiency, which is a result of altered stomata density and improving root systems (primary root length, hair root growth, and lateral root number) and enhanced production of osmotic protectants, which is caused by transcription factors, proteinases, and phosphatases and protein kinases. These results will help guide the synthesis of a model for predicting how the signals of genetic and environmental stress are integrated at a few genetic determinants to control the establishment of either water use efficiency or water uptake efficiency. Collectively, these insights into the molecular mechanism underpinning the control of plant drought tolerance or water use efficiency/water uptake efficiency may aid future breeding or design strategies to increase crop yield.

Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review.

PubMed

Shahid, Muhammad; Shamshad, Saliha; Rafiq, Marina; Khalid, Sana; Bibi, Irshad; Niazi, Nabeel Khan; Dumat, Camille; Rashid, Muhammad Imtiaz

2017-07-01

Chromium (Cr) is a potentially toxic heavy metal which does not have any essential metabolic function in plants. Various past and recent studies highlight the biogeochemistry of Cr in the soil-plant system. This review traces a plausible link among Cr speciation, bioavailability, phytouptake, phytotoxicity and detoxification based on available data, especially published from 2010 to 2016. Chromium occurs in different chemical forms (primarily as chromite (Cr(III)) and chromate (Cr(VI)) in soil which vary markedly in term of their biogeochemical behavior. Chromium behavior in soil, its soil-plant transfer and accumulation in different plant parts vary with its chemical form, plant type and soil physico-chemical properties. Soil microbial community plays a key role in governing Cr speciation and behavior in soil. Chromium does not have any specific transporter for its uptake by plants and it primarily enters the plants through specific and non-specific channels of essential ions. Chromium accumulates predominantly in plant root tissues with very limited translocation to shoots. Inside plants, Cr provokes numerous deleterious effects to several physiological, morphological, and biochemical processes. Chromium induces phytotoxicity by interfering plant growth, nutrient uptake and photosynthesis, inducing enhanced generation of reactive oxygen species, causing lipid peroxidation and altering the antioxidant activities. Plants tolerate Cr toxicity via various defense mechanisms such as complexation by organic ligands, compartmentation into the vacuole, and scavenging ROS via antioxidative enzymes. Consumption of Cr-contaminated-food can cause human health risks by inducing severe clinical conditions. Therefore, there is a dire need to monitor biogeochemical behavior of Cr in soil-plant system. Copyright © 2017 Elsevier Ltd. All rights reserved.

EFFECTS OF SEWAGE SLUDGE ON DI-(2-ETHYLHEXYL) PHTHALATE UPTAKE BY PLANTS

EPA Science Inventory

Di-(2-ethylhexyl) phthalate (DEHP) is a priority organic pollutant frequently found in municipal sludges. reenhouse study was conducted to determine the effects of sludge on plant uptake of 14 C-DEHP (carbonyl labeled). lants grown included three food chain crops, lettuce (Lactuc...

Mercury uptake and accumulation by four species of aquatic plants.

PubMed

Skinner, Kathleen; Wright, Nicole; Porter-Goff, Emily

2007-01-01

The effectiveness of four aquatic plants including water hyacinth (Eichornia crassipes), water lettuce (Pistia stratiotes), zebra rush (Scirpus tabernaemontani) and taro (Colocasia esculenta) were evaluated for their capabilities in removing mercury from water. The plants were exposed to concentrations of 0 mg/L, 0.5 mg/L or 2 mg/L of mercury for 30 days. Assays were conducted using both Microtox (water) and cold vapor Atomic Absorption Spectroscopy (AAS) (roots and water). The Microtox results indicated that the mercury induced acute toxicity had been removed from the water. AAS confirmed an increase of mercury within the plant root tissue and a corresponding decrease of mercury in the water. All species of plants appeared to reduce mercury concentrations in the water via root uptake and accumulation. Water lettuce and water hyacinth appeared to be the most effective, followed by taro and zebra rush, respectively.

134Cs uptake by four plant species and Cs-K relations in the soil-plant system as affected by Ca(OH)2 application to an acid soil.

PubMed

Massas, I; Skarlou, V; Haidouti, C; Giannakopoulou, F

2010-03-01

Three rates of Ca(OH)(2) were applied to an acid soil and the (134)Cs uptake by radish, cucumber, soybean and sunflower plants was studied. The (134)Cs concentration in all plant species was reduced from 1.6-fold in the sunflower seeds to 6-fold in the soybean vegetative parts at the higher Ca(OH)(2) rate. Potassium (K) concentration in plants was also reduced, but less effectively. The significantly decreased (134)Cs-K soil to plant distribution factors (D.F.) clearly suggest a stronger effect of soil liming on (134)Cs than on K plant uptake. This observation was discussed in terms of ionic interactions in the soil matrix and within the plants. The results also indicated that the increased Ca(2+) concentration in the exchange phase and in the soil solution along with the improved root activity, due to the soil liming, enhanced the immobilization of (134)Cs in the soil matrix and consequently lowered the (134)Cs availability for plant uptake. 2009 Elsevier Ltd. All rights reserved.

Arsenic Uptake, Toxicity, Detoxification, and Speciation in Plants: Physiological, Biochemical, and Molecular Aspects

PubMed Central

Abbas, Ghulam; Murtaza, Behzad; Bibi, Irshad; Shahid, Muhammad; Khan, Muhammad Imran; Amjad, Muhammad; Hussain, Munawar; Natasha

2018-01-01

Environmental contamination with arsenic (As) is a global environmental, agricultural and health issue due to the highly toxic and carcinogenic nature of As. Exposure of plants to As, even at very low concentration, can cause many morphological, physiological, and biochemical changes. The recent research on As in the soil-plant system indicates that As toxicity to plants varies with its speciation in plants (e.g., arsenite, As(III); arsenate, As(V)), with the type of plant species, and with other soil factors controlling As accumulation in plants. Various plant species have different mechanisms of As(III) or As(V) uptake, toxicity, and detoxification. This review briefly describes the sources and global extent of As contamination and As speciation in soil. We discuss different mechanisms responsible for As(III) and As(V) uptake, toxicity, and detoxification in plants, at physiological, biochemical, and molecular levels. This review highlights the importance of the As-induced generation of reactive oxygen species (ROS), as well as their damaging impacts on plants at biochemical, genetic, and molecular levels. The role of different enzymatic (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (salicylic acid, proline, phytochelatins, glutathione, nitric oxide, and phosphorous) substances under As(III/V) stress have been delineated via conceptual models showing As translocation and toxicity pathways in plant species. Significantly, this review addresses the current, albeit partially understood, emerging aspects on (i) As-induced physiological, biochemical, and genotoxic mechanisms and responses in plants and (ii) the roles of different molecules in modulation of As-induced toxicities in plants. We also provide insight on some important research gaps that need to be filled to advance our scientific understanding in this area of research on As in soil-plant systems. PMID:29301332

Water uptake by growing cells: an assessment of the controlling roles of wall relaxation, solute uptake, and hydraulic conductance

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1993-01-01

Growing plant cells increase in volume principally by water uptake into the vacuole. There are only three general mechanisms by which a cell can modulate the process of water uptake: (a) by relaxing wall stress to reduce cell turgor pressure (thereby reducing cell water potential), (b) by modifying the solute content of the cell or its surroundings (likewise affecting water potential), and (c) by changing the hydraulic conductance of the water uptake pathway (this works only for cells remote from water potential equilibrium). Recent studies supporting each of these potential mechanisms are reviewed and critically assessed. The importance of solute uptake and hydraulic conductance is advocated by some recent studies, but the evidence is indirect and conclusions remain controversial. For most growing plant cells with substantial turgor pressure, it appears that reduction in cell turgor pressure, as a consequence of wall relaxation, serves as the major initiator and control point for plant cell enlargement. Two views of wall relaxation as a viscoelastic or a chemorheological process are compared and distinguished.

The Impact of pH and Calcium on the Uptake of Fluoride by Tea Plants (Camellia sinensis L.)

PubMed Central

RUAN, JIANYUN; MA, LIFENG; SHI, YUANZHI; HAN, WENYAN

2004-01-01

• Background and Aims Tea plants (Camellia sinensis L.) accumulate large amounts of fluoride (F) from soils containing normal F concentrations. The present experiments examined the effects of pH and Ca on F uptake by this accumulating plant species. • Methods The effect of pH was assessed in two experiments, one using uptake solutions with different pHs, and the other using lime, as CaO, applied to the soil. The effect of Ca was examined by analysing F concentrations in plants supplied with varying amounts of Ca, as Ca(NO3)2, either in uptake solutions or through the soil. • Key results F uptake was highest at solution pH 5·5, and significantly lower at pH 4·0. In the soil experiment, leaf F decreased linearly with the amounts of lime, which raised the soil pH progressively from 4·32 to 4·91, 5·43, 5·89 and, finally, 6·55. Liming increased the water‐soluble F content of the soil. Including Ca in the uptake solution or adding Ca to soil significantly decreased leaf F concentrations. The distribution pattern of F in tea plants was not altered by Ca treatment, with most F being allocated to leaves. The activity of F– in the uptake solution was unaffected and water‐soluble F in the soil was sometimes increased by added Ca. • Conclusions F uptake by tea plants, which are inherently able to accumulate large quantities of F, was affected both by pH and by Ca levels in the medium. The reduced F uptake following Ca application appeared not to be due simply to the precipitation of CaF2 in solution and soil or to the complexing of Ca and F in roots, although these factors cannot be dismissed. It was more likely due to the effect of Ca on the properties of cell wall or membrane permeability in the solution experiments, and to alteration of F speciations and their quantities in soil solutions following Ca application. PMID:14644914

Improving Lowland Rice (O. sativa L. cv. MR219) Plant Growth Variables, Nutrients Uptake, and Nutrients Recovery Using Crude Humic Substances.

PubMed

Palanivell, Perumal; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad; Jalloh, Mohamadu Boyie; Susilawati, Kasim

2015-01-01

High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A pot experiment was conducted to determine the effects of crude humic substances on rice plant growth, nutrients uptake, nutrients recovery, and soil chemical properties using an acid soil mixed with three rates of crude humic substances (20, 40, and 60 g pot(-1)). Standard procedures were used to evaluate rice plant dry matter production, nutrients uptake, nutrients recovery, and soil chemical properties. Application of crude humic substances increased ammonia volatilization. However, the lowest rate of crude humic substances (20 g pot(-1)) significantly improved total dry matter, nutrients uptake, nutrients recovery, and soil nutrients availability compared with crude humic substances (40 and 60 g pot(-1)) and the normal fertilization. Apart from improving growth of rice plants, crude humic substances can be used to ameliorate acid soils in rice cultivation. The findings of this study are being validated in our ongoing field trials.

Improving Lowland Rice (O. sativa L. cv. MR219) Plant Growth Variables, Nutrients Uptake, and Nutrients Recovery Using Crude Humic Substances

PubMed Central

Palanivell, Perumal; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad; Jalloh, Mohamadu Boyie; Susilawati, Kasim

2015-01-01

High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A pot experiment was conducted to determine the effects of crude humic substances on rice plant growth, nutrients uptake, nutrients recovery, and soil chemical properties using an acid soil mixed with three rates of crude humic substances (20, 40, and 60 g pot−1). Standard procedures were used to evaluate rice plant dry matter production, nutrients uptake, nutrients recovery, and soil chemical properties. Application of crude humic substances increased ammonia volatilization. However, the lowest rate of crude humic substances (20 g pot−1) significantly improved total dry matter, nutrients uptake, nutrients recovery, and soil nutrients availability compared with crude humic substances (40 and 60 g pot−1) and the normal fertilization. Apart from improving growth of rice plants, crude humic substances can be used to ameliorate acid soils in rice cultivation. The findings of this study are being validated in our ongoing field trials. PMID:25977938

Uptake and cellular distribution, in four plant species, of fluorescently labeled mesoporous silica nanoparticles.

PubMed

Sun, Dequan; Hussain, Hashmath I; Yi, Zhifeng; Siegele, Rainer; Cresswell, Tom; Kong, Lingxue; Cahill, David M

2014-08-01

We report the uptake of MSNs into the roots and their movement to the aerial parts of four plant species and their quantification using fluorescence, TEM and proton-induced x - ray emission (micro - PIXE) elemental analysis. Monodispersed mesoporous silica nanoparticles (MSNs) of optimal size and configuration were synthesized for uptake by plant organs, tissues and cells. These monodispersed nanoparticles have a size of 20 nm with interconnected pores with an approximate diameter of 2.58 nm. There were no negative effects of MSNs on seed germination or when transported to different organs of the four plant species tested in this study. Most importantly, for the first time, a combination of confocal laser scanning microscopy, transmission electron microscopy and proton-induced X-ray emission (micro-PIXE) elemental analysis allowed the location and quantification MSNs in tissues and in cellular and sub-cellular locations. Our results show that MSNs penetrated into the roots via symplastic and apoplastic pathways and then via the conducting tissues of the xylem to the aerial parts of the plants including the stems and leaves. The translocation and widescale distribution of MSNs in plants will enable them to be used as a new delivery means for the transport of different sized biomolecules into plants.

Uptake of explosives from contaminated soil by existing vegetation at the Iowa Army Ammunition Plant

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

Schneider, J.F.; Zellmer, S.D.; Tomczyk, N.A.

This study examines the uptake of explosives by existing vegetation growing in soils contaminated with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-3,5-triazine (RDX) in three areas at the Iowa Army Ammunition Plant (IAAP). To determine explosives uptake under natural environmental conditions, existing plant materials and soil from the root zone were sampled at different locations in each area, and plant materials were separated by species. Standard methods were used to determine the concentrations of explosives, their derivatives, and metabolites in the soil samples. Plant materials were also analyzed. The compound TNT was not detected in the aboveground portion of plants, and vegetation growingmore » on TNT-contaminated soils is not considered a health hazard. However, soil and plant roots may contain TNT degradation products that may be toxic; hence, their consumption is not advised. The compound RDX was found in the tops and roots of plants growing on RDX-contaminated soils at all surveyed sites. Although RDX is not a listed carcinogen, several of its potentially present degradation products are carcinogens. Therefore, the consumption of any plant tissues growing on RDX-contaminated sites should be considered a potential health hazard.« less

Cytochrome b5 Reductase 1 Triggers Serial Reactions that Lead to Iron Uptake in Plants.

PubMed

Oh, Young Jun; Kim, Hanul; Seo, Sung Hee; Hwang, Bae Geun; Chang, Yoon Seok; Lee, Junho; Lee, Dong Wook; Sohn, Eun Ju; Lee, Sang Joon; Lee, Youngsook; Hwang, Inhwan

2016-04-04

Rhizosphere acidification is essential for iron (Fe) uptake into plant roots. Plasma membrane (PM) H(+)-ATPases play key roles in rhizosphere acidification. However, it is not fully understood how PM H(+)-ATPase activity is regulated to enhance root Fe uptake under Fe-deficient conditions. Here, we present evidence that cytochrome b5 reductase 1 (CBR1) increases the levels of unsaturated fatty acids, which stimulate PM H(+)-ATPase activity and thus lead to rhizosphere acidification. CBR1-overexpressing (CBR1-OX) Arabidopsis thaliana plants had higher levels of unsaturated fatty acids (18:2 and 18:3), higher PM H(+)-ATPase activity, and lower rhizosphere pH than wild-type plants. By contrast, cbr1 loss-of-function mutant plants showed lower levels of unsaturated fatty acids and lower PM H(+)-ATPase activity but higher rhizosphere pH. Reduced PM H(+)-ATPase activity in cbr1 could be restored in vitro by addition of unsaturated fatty acids. Transcript levels of CBR1, fatty acids desaturase2 (FAD2), and fatty acids desaturase3 (FAD3) were increased under Fe-deficient conditions. We propose that CBR1 has a crucial role in increasing the levels of unsaturated fatty acids, which activate the PM H(+)-ATPase and thus reduce rhizosphere pH. This reaction cascade ultimately promotes root Fe uptake. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

Phytoremediation of Mercury and Organomercurials in Chloroplast Transgenic Plants: Enhanced Root Uptake, Translocation to Shoots, and Volatilization

PubMed Central

Hussein, Hussein S.; Ruiz, Oscar N.; Terry, Norman; Daniell, Henry

2008-01-01

Transgenic tobacco plants engineered with bacterial merA and merB genes via the chloroplast genome were investigated to study the uptake, translocation of different forms of mercury (Hg) from roots to shoots, and their volatilization. Untransformed plants, regardless of the form of Hg supplied, reached a saturation point at 200 µM of phenylmercuric acetate (PMA) or HgCl2, accumulating Hg concentrations up to 500 µg g−1 with significant reduction in growth. In contrast, chloroplast transgenic lines continued to grow well with Hg concentrations in root tissues up to 2000 µg g−1. Chloroplast transgenic lines accumulated both the organic and inorganic Hg forms to levels surpassing the concentrations found in the soil. The organic-Hg form was absorbed and translocated more efficiently than the inorganic-Hg form in transgenic lines, whereas no such difference was observed in untransformed plants. Chloroplast-transgenic lines showed about 100-fold increase in the efficiency of Hg accumulation in shoots compared to untransformed plants. This is the first report of such high levels of Hg accumulation in green leaves or tissues. Transgenic plants attained a maximum rate of elemental-Hg volatilization in two days when supplied with PMA and in three days when supplied with inorganic-Hg, attaining complete volatilization within a week. The combined expression of merAB via the chloroplast genome enhanced conversion of Hg2+ into Hg,0 conferred tolerance by rapid volatilization and increased uptake of different forms of mercury, surpassing the concentrations found in the soil. These investigations provide novel insights for improvement of plant tolerance and detoxification of mercury. PMID:18200876

Pharmacological and gene regulation properties point to the SlHAK5 K+ transporter as a system for high-affinity Cs+ uptake in tomato plants.

PubMed

Ródenas, Reyes; Nieves-Cordones, Manuel; Rivero, Rosa M; Martinez, Vicente; Rubio, Francisco

2018-04-01

Potassium (K + ) and cesium (Cs + ) are chemically similar but while K + is an essential nutrient, Cs + can be toxic for living organisms, plants included. Two different situations could lead to problems derived from the presence of Cs + in agricultural systems: (1) presence of Cs + at high concentrations that could produce toxic effects on plants, (2) presence of micromolar concentrations of radiocesium, which can be accumulated in the plant and affect animal and human health through the food chain. While K + uptake has been well described in tomato plants, information on molecular mechanisms involved in Cs + accumulation in this species is absent. Here, we show that in tomato plants, high concentrations of Cs + produce deficiency of K + but do not induce high-affinity K + uptake or the gene encoding the high-affinity K + transporter SlHAK5. At these concentrations, Cs + uptake takes place through a Ca 2+ -sensitive pathway, probably a non-selective cation channel. At micromolar concentrations, Cs + is accumulated by a high-affinity uptake system upregulated in K + -starved plants. This high-affinity Cs + uptake shares features with high-affinity K + uptake. It is sensitive to NH 4 + and insensitive to Ba 2+ and Ca 2+ and its presence parallels the pattern of SlHAK5 expression. Moreover, blockers of reactive oxygen species and ethylene action repress SlHAK5 and negatively regulate both high-affinity K + and Cs + uptake. Thus, we propose that SlHAK5 contributes to Cs + uptake from micromolar concentrations in tomato plants and can constitute a pathway for radiocesium transfer from contaminated areas to the food chain. © 2017 Scandinavian Plant Physiology Society.

Limited uptake, translocation and enhanced metabolic degradation contribute to glyphosate tolerance in Mucuna pruriens var. utilis plants.

PubMed

Rojano-Delgado, Antonia María; Cruz-Hipolito, Hugo; De Prado, Rafael; Luque de Castro, María Dolores; Franco, Antonio Rodríguez

2012-01-01

Velvet bean (Mucuna pruriens, Fabaceae) plants exhibits an innate, very high resistance (i.e., tolerance) to glyphosate similar to that of plants which have acquired resistance to this herbicide as a trait. We analyzed the uptake of [(14)C]-glyphosate by leaves and its translocation to meristematic tissues, and used scanning electron micrographs to further analyze the cuticle and 3D capillary electrophoresis to investigate a putative metabolism capable of degrading the herbicide. Velvet bean exhibited limited uptake of glyphosate and impaired translocation of the compound to meristematic tissues. Also, for the first time in a higher plant, two concurrent pathways capable of degrading glyphosate to AMPA, Pi, glyoxylate, sarcosine and formaldehyde as end products were identified. Based on the results, the innate tolerance of velvet bean to glyphosate is possibly a result of the combined action of the previous three traits, namely: limited uptake, impaired translocation and enhanced degradation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Transformation, Conjugation, and Sequestration Following the Uptake of Triclocarban by Jalapeno Pepper Plants.

PubMed

Huynh, Khang; Banach, Emily; Reinhold, Dawn

2018-04-25

Plant uptake and metabolism of emerging organic contaminants, such as personal-care products, pose potential risks to human health. In this study, jalapeno pepper ( Capsicum annuum) plants cultured in hydroponic media were exposed to both 14 C-labeled and unlabeled triclocarban (TCC) to investigate the accumulation, distribution, and metabolism of TCC following plant uptake. The results revealed that TCC was detected in all plant tissues; after 12 weeks, the TCC concentrations in root, stem, leaf, and fruit tissues were 19.74 ± 2.26, 0.26 ± 0.04, 0.11 ± 0.01, and 0.03 ± 0.01 mg/kg dry weight, respectively. More importantly, a substantial portion of the TCC taken up by plants was metabolized, especially in the stems, leaves, and fruits. Hydroxylated TCC (e.g., 2'-OH TCC and 6-OH TCC) and glycosylated OH-TCC were the main phase I and phase II metabolites in plant tissues, respectively. Bound (or nonextractable) residues of TCC accounted for approximately 44.6, 85.6, 69.0, and 47.5% of all TCC species that accumulated in roots, stems, leaves, and fruits, respectively. The concentrations of TCC metabolites were more than 20 times greater than the concentrations of TCC in the above-ground tissues of the jalapeno pepper plants after 12 weeks; crucially, approximately 95.6% of the TCC was present as metabolites in the fruits. Consequently, human exposure to TCC through the consumption of pepper fruits is expected to be substantially higher when phytometabolism is considered.

Improving prediction of metal uptake by Chinese cabbage (Brassica pekinensis L.) based on a soil-plant stepwise analysis.

PubMed

Zhang, Sha; Song, Jing; Gao, Hui; Zhang, Qiang; Lv, Ming-Chao; Wang, Shuang; Liu, Gan; Pan, Yun-Yu; Christie, Peter; Sun, Wenjie

2016-11-01

It is crucial to develop predictive soil-plant transfer (SPT) models to derive the threshold values of toxic metals in contaminated arable soils. The present study was designed to examine the heavy metal uptake pattern and to improve the prediction of metal uptake by Chinese cabbage grown in agricultural soils with multiple contamination by Cd, Cu, Ni, Pb, and Zn. Pot experiments were performed with 25 historically contaminated soils to determine metal accumulation in different parts of Chinese cabbage. Different soil bioavailable metal fractions were determined using different extractants (0.43M HNO3, 0.01M CaCl2, 0.005M DTPA, and 0.01M LWMOAs), soil moisture samplers, and diffusive gradients in thin films (DGT), and the fractions were compared with shoot metal uptake using both direct and stepwise multiple regression analysis. The stepwise approach significantly improved the prediction of metal uptake by cabbage over the direct approach. Strongly pH dependent or nonlinear relationships were found for the adsorption of root surfaces and in root-shoot uptake processes. Metals were linearly translocated from the root surface to the root. Therefore, the nonlinearity of uptake pattern is an important explanation for the inadequacy of the direct approach in some cases. The stepwise approach offers an alternative and robust method to study the pattern of metal uptake by Chinese cabbage (Brassica pekinensis L.). Copyright © 2016. Published by Elsevier B.V.

How does altered precipitation and annual grass invasion affect plant N uptake in a native semi-arid shrub community?

NASA Astrophysics Data System (ADS)

Mauritz, M.; Lipson, D.; Cleland, E. E.

2012-12-01

concentrations are more variable in grasses which could indicate higher plasticity in grass N uptake compared to shrubs. Resin N supports the 15N patterns. Resin N declined more rapidly under grasses and was lower than under shrubs, presumably due to high grass N uptake. Resin N was particularly high under shrubs in wetter conditions indicating that shrubs could not take advantage of high N supply. Together the 15N and resin N patterns indicate that grasses accumulate more N and begin N uptake earlier in the season than shrubs. Although 15N did not differ in response to rainfall, invasion alters the distribution of N in the system. Rain was only manipulated for one growing season; multiple years of altered precipitation may yield significant differences. Early season N uptake by grasses, the low variability in shrub 15N and low shrub 15N in wetter conditions, despite high resin N, indicates that N competition between invasive grasses and native shrubs is weak. If N supply is sufficient for shrub demands, invasive grasses and shrubs could coexist. This study contributes to a broader understanding of how changes in resource supply, plant phenology and functional type interact and respond to climate change.

Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

PubMed Central

Blankinship, Joseph C.; Marchus, Kenneth; Lucero, Delores M.; Sickman, James O.; Schimel, Joshua P.

2016-01-01

Nitric oxide (NO) is an important trace gas and regulator of atmospheric photochemistry. Theory suggests moist soils optimize NO emissions, whereas wet or dry soils constrain them. In drylands, however, NO emissions can be greatest in dry soils and when dry soils are rewet. To understand how aridity and vegetation interact to generate this pattern, we measured NO fluxes in a California grassland, where we manipulated vegetation cover and the length of the dry season and measured [δ15-N]NO and [δ18-O]NO following rewetting with 15N-labeled substrates. Plant N uptake reduced NO emissions by limiting N availability. In the absence of plants, soil N pools increased and NO emissions more than doubled. In dry soils, NO-producing substrates concentrated in hydrologically disconnected microsites. Upon rewetting, these concentrated N pools underwent rapid abiotic reaction, producing large NO pulses. Biological processes did not substantially contribute to the initial NO pulse but governed NO emissions within 24 h postwetting. Plants acted as an N sink, limiting NO emissions under optimal soil moisture. When soils were dry, however, the shutdown in plant N uptake, along with the activation of chemical mechanisms and the resuscitation of soil microbial processes upon rewetting, governed N loss. Aridity and vegetation interact to maintain a leaky N cycle during periods when plant N uptake is low, and hydrologically disconnected soils favor both microbial and abiotic NO-producing mechanisms. Under increasing rates of atmospheric N deposition and intensifying droughts, NO gas evasion may become an increasingly important pathway for ecosystem N loss in drylands. PMID:27114523

Phytotoxicity, uptake and metabolism of 1,4-dichlorobenzene by plant cells

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

Wang, M.J.; Bokern, M.; Boehme, C.

1996-07-01

Phytotoxicity, uptake, and metabolism of 1,4-dichlorobenzene (1,4-DCB) by carrot (Daucus carota L.), soybean (Glycine max. L.), tomato (Lycopersicon esculentum Mill.), and red goosefoot (Chenopodiun rubrum L.) cell suspension cultures were studied. Sealed glass systems were utilized for the investigation because 1,4-DCB is volatile. The sealed systems affect the growth of plant cells, but do not provide different results when testing xenobiotic uptake and metabolism. 1,4-Dichlorobenzene (40 {micro}g in 40 ml medium) was taken up by carrot (49%), soybean (50%), and red goosefoot (62%) cells. Only the soybean cell cultures provided evidence of the existence of metabolites of this compound, probablymore » conjugates of chlorophenols. Conditions for phytotoxicity tests were modified because the growth of cell cultures was affected when sealed for longer than 2 d. 1,4-Dichlorobenzene is toxic to cell cultures of the three tested plant species (tomato, soybean, and carrot). Concentrations of 0.5 mM caused 50% growth inhibition in carrot and soybean cultures. The tomato cultures were more sensitive, with 0.05 mM causing 50% growth inhibition.« less

Membrane transporters for nitrogen, phosphate and potassium uptake in plants.

PubMed

Chen, Yi-Fang; Wang, Yi; Wu, Wei-Hua

2008-07-01

Nitrogen, phosphorous and potassium are essential nutrients for plant growth and development. However, their contents in soils are limited so that crop production needs to invest a lot for fertilizer supply. To explore the genetic potentialities of crops (or plants) for their nutrient utilization efficiency has been an important research task for many years. In fact, a number of evidences have revealed that plants, during their evolution, have developed many morphological, physiological, biochemical and molecular adaptation mechanisms for acquiring nitrate, phosphate and potassium under stress conditions. Recent discoveries of many transporters and channels for nitrate, phosphate and potassium uptake have opened up opportunities to study the molecular regulatory mechanisms for acquisition of these nutrients. This review aims to briefly discuss the genes and gene families for these transporters and channels. In addition, the functions and regulation of some important transporters and channels are particularly emphasized.

Cross-ecosystem comparisons of in situ plant uptake of amino acid-N and NH4+

Treesearch

Jack W. McFarland; Roger W. Ruess; Knut Kielland; Kurt Pregitzer; Ronald Hendrick; Michael Allen

2010-01-01

Plant and microbial use of nitrogen (N) can be simultaneously mutualistic and competitive, particularly in ecosystems dominated by mycorrhizal fungi. Our goal was to quantify plant uptake of organic and inorganic N across a broad latitudinal gradient of forest ecosystems that varied with respect to overstory taxon, edaphic characteristics, and dominant mycorrhizal...

The foliar uptake and downward translocation of trichloroethylene and 1,2,3-trichlorobenzene in air-plant-water systems.

PubMed

Su, Yuhong; Liang, Yongchao

2013-05-15

The foliar uptake and downward translocation of trichloroethylene (TCE) and 1,2,3-trichlorobenzene (TCB) in wheat, corn, and tomato seedlings were investigated following 2-48-h exposure of the plant shoots to vapor-contaminated air. The results showed that both TCE and TCB could be rapidly transported from air to plant rhizosphere solution through the foliar uptake and downward transport; the TCE and TCB concentrations in rhizosphere solutions increased with exposure time and external contaminant concentration. Among the three plant species studied, the TCE and TCB downward transport followed the order of wheat>tomato>corn. The transport efficiency of TCE by the three plants was far greater than that of TCB. With a 24-h uptake time, the amounts of TCE transported into the rhizosphere solution by wheat, tomato, and corn seedlings were 2.39 ± 0.42, 1.50 ± 0.22 and 1.45 ± 0.08 μg TCE per gram of fresh weight biomass, respectively, when the initial external TCE concentration was set at 12 mg l(-1). In a 48-h uptake experiment with corn seedlings, the TCE concentration in the rhizosphere solutions was lower in the TCE-TCB mixture system than in the single TCE system, whereas there was no significant difference in TCB concentration between the single TCB and TCE-TCB mixture systems at 48 h. The downward transport processes of TCE were inhibited, while those of TCB were enhanced in the mixed contaminant system within a 48-h uptake time. Copyright © 2013 Elsevier B.V. All rights reserved.

Aquaporins and root water uptake

USDA-ARS?s Scientific Manuscript database

Water is one of the most critical resources limiting plant growth and crop productivity, and root water uptake is an important aspect of plant physiology governing plant water use and stress tolerance. Pathways of root water uptake are complex and are affected by root structure and physiological res...

Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity.

PubMed

Martínez-Ballesta, M Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

2016-06-08

Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWCNTs on growth in NaCl-treated plants was consequence of increased water uptake, promoted by more-favourable energetic forces driving this process, and enhanced net assimilation of CO2. MWCNTs induced changes in the lipid composition, rigidity and permeability of the root plasma membranes relative to salt-stressed plants. Also, enhanced aquaporin transduction occurred, which improved water uptake and transport, alleviating the negative effects of salt stress. Our work provides new evidences about the effect of MWCNTs on plasma membrane properties of the plant cell. The positive response to MWCNTs in broccoli plants opens novel perspectives for their technological uses in new agricultural practices, especially when 1plants are exposed to saline environments.

Influence of biologically-active substances on {sup 137}Cs and heavy metals uptake by Barley plant

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

Kruglov, Stanislav; Filipas, Alexander

2007-07-01

Available in abstract form only. Full text of publication follows: When solving the problem of contaminated agricultural lands rehabilitation, most of attention is concentrated on the effective means which allow the obtaining of ecologically safe production. The minimization of radionuclides and heavy metals (HM) content in farm products on the basis of their migration characteristics in agro-landscapes and with the regard for different factors influencing contaminants behavior in the soil-plant system is of great significance. Our investigation has shown that the effect of biologically active substances (BAS) using for seeds treatment on {sup 137}Cs transfer to barley grown on Cdmore » contaminated soil was dependent on their properties and dosage, characteristics of soil contamination and biological peculiarities of plants, including stage of plants development. Seeds treatment by plant growth regulator Zircon resulted in a significant increase in {sup 137}Cs activity in harvest (40- 50%), increase in K concentration and significant reduction in Ca concentration. Increased Cd content in soil reduced {sup 137}Cs transfer to barley plants by 30-60% (p<0,05) and Zircon application further reduced its concentration. Ambiol and El also reduced {sup 137}Cs uptake by roots and Cd and Pb phyto-toxicity. The experimental data do not make it possible to link the BAS effect on inhibition of {sup 137}Cs absorption by plants directly with their influence on HM phyto-toxicity. The dependence of Concentration Ratio of {sup 137}Cs on the Ambiol and El dose was not proportional and the most significant decrease in the radionuclide uptake by plants was reported with the use of dose showing the most pronounced stimulating effect on the barley growth and development. The pre-sowing seed treatment with Ambiol increased Pb absorption by 35-50% and, on the contrary, decreased Cd uptake by plants by 30-40%. (authors)« less

Screening for Bioactive Metabolites in Plant Extracts Modulating Glucose Uptake and Fat Accumulation

PubMed Central

El-Houri, Rime B.; Kotowska, Dorota; Olsen, Louise C. B.; Bhattacharya, Sumangala; Christensen, Lars P.; Oksbjerg, Niels; Færgeman, Nils; Kristiansen, Karsten; Christensen, Kathrine B.

2014-01-01

Dichloromethane and methanol extracts of seven different food and medicinal plants were tested in a screening platform for identification of extracts with potential bioactivity related to insulin-dependent glucose uptake and fat accumulation. The screening platform included a series of in vitro bioassays, peroxisome proliferator-activated receptor (PPAR) γ-mediated transactivation, adipocyte differentiation of 3T3-L1 cell cultures, and glucose uptake in both 3T3-L1 adipocytes and primary porcine myotubes, as well as one in vivo bioassay, fat accumulation in the nematode Caenorhabditis elegans. We found that dichloromethane extracts of aerial parts of golden root (Rhodiola rosea) and common elder (Sambucus nigra) as well as the dichloromethane extracts of thyme (Thymus vulgaris) and carrot (Daucus carota) were able to stimulate insulin-dependent glucose uptake in both adipocytes and myotubes while weekly activating PPARγ without promoting adipocyte differentiation. In addition, these extracts were able to decrease fat accumulation in C. elegans. Methanol extracts of summer savory (Satureja hortensis), common elder, and broccoli (Brassica oleracea) enhanced glucose uptake in myotubes but were not able to activate PPARγ, indicating a PPARγ-independent effect on glucose uptake. PMID:25254050

Effect of residue combinations on plant uptake of nutrients and potentially toxic elements.

PubMed

Brännvall, Evelina; Nilsson, Malin; Sjöblom, Rolf; Skoglund, Nils; Kumpiene, Jurate

2014-01-01

The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake. Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534 mg/l), Mg (184 mg/l), P (1.8 mg/l), S (760 mg/l), Cu (0.39 mg/l) and Zn (0.58 mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82 g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values. The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cadmium Sorption Characteristics of Soil Amendments and its Relationship with the Cadmium Uptake by Hyperaccumulator and Normal Plants in Amended Soils

PubMed Central

Sun, Yan; Wu, Qi-Tang; Lee, Charles C.C.; Li, Baoqin; Long, Xinxian

2013-01-01

In order to select appropriate amendments for cropping hyperaccumulator or normal plants on contaminated soils and establish the relationship between Cd sorption characteristics of soil amendments and their capacity to reduce Cd uptake by plants, batch sorption experiments with 11 different clay minerals and organic materials and a pot experiment with the same amendments were carried out. The pot experiment was conducted with Sedum alfredii and maize (Zea mays) in a co-cropping system. The results showed that the highest sorption amount was by montmorillonite at 40.82 mg/g, while mica was the lowest at only 1.83 mg/g. There was a significant negative correlation between the n value of Freundlich equation and Cd uptake by plants, and between the logarithm of the stability constant K of the Langmuir equation and plant uptake. Humic acids (HAs) and mushroom manure increased Cd uptake by S. alfredii, but not maize, thus they are suitable as soil amendments for the co-cropping S. alfredii and maize. The stability constant K in these cases was 0.14–0.16 L/mg and n values were 1.51–2.19. The alkaline zeolite and mica had the best fixation abilities and significantly decreased Cd uptake by the both plants, with K ≥ 1.49 L/mg and n ≥ 3.59. PMID:24912231

The effect of elevated CO2 and temperature on nutrient uptake by plants grown in basaltic soil

NASA Astrophysics Data System (ADS)

Villasenor Iribe, E.; Dontsova, K.; Juarez, S.; Le Galliard, J. F.; Chollet, S.; Llavata, M.; Massol, F.; Barré, P.; Gelabert, A.; Daval, D.; Troch, P.; Barron-Gafford, G.; Van Haren, J. L. M.; Ferrière, R.

2017-12-01

Mineral weathering is an important process in soil formation. The interactions between the hydrologic, geologic and atmospheric cycles often determine the rate at which weathering occurs. Elements and nutrients weathered from the soil by water can be removed from soils in the runoff and seepage, but they can also remain in situ as newly precipitated secondary minerals or in biomass as a result of plant uptake. Here we present data from an experiment that was conducted at the controlled environment facility, Ecotron Ile-de-France (Saint-Pierre-les-Nemours, France) that studied mineral weathering and plant growth in granular basaltic material with high glass content that is being used to simulate soil in large scale Biosphere 2 Landscape Evolution Observatory (LEO) project. The experiment used 3 plant types: velvet mesquite (Prosopis velutina), green spangletop (Leptochloa dubia), and alfalfa (Medicago sativa), which were grown under varying temperature and CO2 conditions. We hypothesized that plants grown under warmer, higher CO2 conditions would have larger nutrient concentrations as more mineral weathering would occur. Results of plant digestions and analysis showed that plant concentrations of lithogenic elements were significantly influenced by the plant type and were different between above- and below-ground parts of the plant. Temperature and CO2 treatment effects were less pronounced, but we observed significant temperature effect on plant uptake. A number of major and trace elements showed increase in concentration with increase in temperature at elevated atmospheric CO2. Effect was observed both in the shoots and in the roots, but more significant differences were observed in the shoots. Results presented here indicate that climate change would have strong effect on plant uptake and mobility of weathered elements during soil formation and give further evidence of interactions between abiotic and biological processes in terrestrial ecosystems.

Plant uptake of explosives from contaminated soil at the Joliet Army Ammunition Plant

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

Zellmer, S.D.; Schneider, J.F.; Tomczyk, N.A.

1995-04-01

Explosives and their degradation products may enter the animal and human food chains through plants grown on soils contaminated with explosives. Soil and plant samples were collected from the Group 61 area at the Joliet Army Ammunition Plant and analyzed to determine the extent to which 2,4,6-trinitrotoluene (TNT) and its degradation products are taken up by existing vegetation and crops growing on contaminated soils. Neither TNT nor its degradation products was detected in any of the aboveground plant organs of existing vegetation. Oat (Avena sativa L.) and perennial ryegrass (Lolium perenne L.) were planted on TNT-contaminated soils amended with threemore » levels of chopped grass hay. Extractable TNT concentrations in hay-amended soils were monitored for almost 1 year. Crop establishment and growth improved with increased levels of hay amendment, but TNT uptake was not affected or detected in any aboveground crop organs. Evidence was found to indicate that soil manipulation and hay addition may reduce extractable TNT concentration in soils, but the wide variations in TNT concentrations in these soils prevented development of conclusive evidence regarding reduction of extractable TNT concentrations. Results from this study suggest that vegetation grown on TNT-contaminated soils is not a major health concern because TNT and its degradation products were not detected in aboveground plant organs. However, low concentrations of TNT, 4-amino-2,6-dinitrotoluene, and 2-amino-4,6-dinitrotoluene were detected in or on some existing vegetation and crop roots. 21 refs., 10 figs., 26 tabs.« less

Evaluation of drug uptake and deactivation in plant: Fate of albendazole in ribwort plantain (Plantago laceolata) cells and regenerants.

PubMed

Stuchlíková Raisová, Lucie; Podlipná, Radka; Szotáková, Barbora; Syslová, Eliška; Skálová, Lenka

2017-07-01

Albendazole (ABZ) is a benzimidazole anthelmintic widely used especially in veterinary medicine. Along with other drugs, anthelmintics have become one of a new class of micro-pollutants that disturb the environment but the information about their fate in plants remains limited. The present study was designed to test the uptake and biotransformation of ABZ in the ribwort plantain (Plantago lancelota), a common meadow plant, which can come into contact with this anthelmintic through the excrements of treated animals in pastures. Two model systems were used and compared: cell suspensions and whole plant regenerants. In addition, time-dependent changes in occurrence of ABZ and its metabolites in roots, basal parts of the leaves and tops of the leaves were followed up. Ultrahigh-performance liquid chromatography coupled with high mass accuracy tandem mass spectrometry (UHPLC-MS/MS) led to the identification of 18 metabolites of ABZ formed in the ribwort. In both model systems, the same types of ABZ biotransformation reactions were found, but the spectrum and abundance of the ABZ metabolites detected in cell suspensions and regenerants differed significantly. Cell suspensions seem to be suitable only for qualitative estimations of drug biotransformation reactions while regenerants were shown to represent an adequate model for the qualitative as well as quantitative evaluation of drug uptake and metabolism in plants. Copyright © 2017. Published by Elsevier Inc.

Uptake of explosives from contaminated soil by existing vegetation at the Joliet Army Ammunition Plant

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

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D.

1994-01-01

This study examines the uptake of explosives by existing vegetation growing in TNT-contaminated soils on Group 61 at the Joliet Army Ammunition Plant (JAAP). The soils in this group were contaminated more than 40 years ago. In this study, existing plant materials and soil from the root zone were sampled from 15 locations and analyzed to determine TNT uptake by plants under natural field conditions. Plant materials were separated by species if more than one species was present at a sampling location. Standard methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. Plantmore » materials were also analyzed. No. explosives were detected in the aboveground portion of any plant sample. However, the results indicate that TNT, 2-amino DNT, and/or 4-amino DNT were found in some root samples of false boneset (Kuhnia eupatorioides), teasel (Dipsacus sylvestris), and bromegrass (Bromus inermis). It is possible that slight soil contamination remained on the roots, especially in the case of the very fine roots for species like bromegrass, where washing was difficult. The presence of 2-amino DNT and 4-amino DNT, which could be plant metabolites of TNT, increases the likelihood that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.« less

Soil- and plant- water uptake in saline environments and their consequences to plant adaptation in fluctuating climates

NASA Astrophysics Data System (ADS)

Volpe, V.; Albertson, J. D.; Katul, G. G.; Marani, M.

2010-12-01

Ecological processes determining plant colonization are quite peculiar and competition among different species is governed by a set of unique adaptations to stress conditions caused by drought, hypoxic or hyper-saline conditions. These adaptations and possible positive feedbacks often lead to the formation of patterns of vegetation colonization and spatial heterogeneity (zonation), and play a primary role in the stabilization of sediments. It is these issues that frame the scope of this study. The main objective of this work is to track one of the fundamental pathways between plant adaptation (quantified in terms of physiological and ecological attributes such as leaf area or root density profile) and feedbacks (quantified by plant-mediated alterations to water availability and salinity levels): root water uptake. Because root-water uptake is the main conduit connecting transpiring leaves to reservoirs of soil water, the means by which salinity modifies the processes governing its two end-points and any two-way interactions between them serves as a logical starting point. Salinity effects on leaf transpiration and photosynthesis are first explored via stomatal optimization principles that maximize carbon gain at a given water loss for autonomous leaves. Salinity directly affects leaf physiological attributes such as mesophyll conductance and photosynthetic parameters and hence over-all conductance to transpiration as well as different strategies to cope with the high salinity (e.g. through salt seclusion, compartmentation and osmotic adjustments). A coupled model of subsurface flow based on a modified Richards’ equation that accounts for the effects of increasing salinity, anaerobic conditions, water stress and compensation factors is developed. Plant water uptake is considered as a soil moisture sink term with a potential rate dictated by the carbon demands of the leaves, and an actual rate that accounts for both - hydraulic and salinity limitations. Using this

Plutonium-239 and americium-241 uptake by plants from soil. Final report

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

Brown, K.W.

1979-03-01

Alfalfa was grown in soil contaminated with plutonium-239 dioxide (239PuO2) at a concentration of 29.7 nanocuries per gram (nCi/g). In addition to alfalfa, radishes, wheat, rye, and tomatoes were grown in soils contaminated with americium-241 nitrate (241Am(NO3)3) at a concentration of 189 nCi/g. The length of exposure varied from 52 days for the radishes to 237 days for the alfalfa. The magnitude of plutonium incorporation by the alfalfa as indicated by the concentration ratio, 0.0000025, was similar to previously reported data using other chemical forms of plutonium. The results did indicate, however, that differences in the biological availability of plutoniummore » isotopes do exist. All of the species exposed to americium-241 assimilated and translocated this radioisotope to the stem, leaf, and fruiting structures. The magnitude of incorporation as signified by the concentration ratios varied from 0.00001 for the wheat grass to 0.0152 for the radishes. An increase in the uptake of americium also occurred as a function of time for four of the five plant species. Evidence indicates that the predominant factor in plutonium and americium uptake by plants may involve the chelation of these elements in soils by the action of compounds such as citric acid and/or other similar chelating agents released from plant roots.« less

Application of biosolids in mineral sands mine rehabilitation: use of stockpiled topsoil decreases trace element uptake by plants.

PubMed

Rate, Andrew W; Lee, Karen M; French, Peter A

2004-02-01

Mineral sands mining involves stripping topsoil to access heavy-mineral bearing deposits, which are then rehabilitated to their original state, commonly pasture in south-west Western Australia. Organic amendments such as biosolids (digested sewage sludge) can contribute organic carbon to the rehabilitating system and improve soil chemical fertility and physical conditions. Use of biosolids also introduces the risk of contamination of the soil-plant system with heavy metals, but may be a useful source of trace elements to plants if the concentrations of these elements are low in unamended soil. We expected that biosolids amendment of areas mined for mineral sands would result in increased concentrations of metals in soils and plants, and that metal uptake would be decreased by adding stockpiled topsoil or by liming. A glasshouse experiment growing a mixed annual ryegrass (Lolium rigidum)-subterranean clover (Trifolium subterraneum) sward was conducted using two soil materials (residue sand/clay and conserved topsoil) from a mineral sands mine amended with different rates of biosolids (0, 10, 20, 50 dry t/ha), and including a liming treatment (2 t/ha). Total concentrations of metals (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil increased with increasing rate of biosolids application. Metal uptake was generally lower where topsoil was present and was decreased by liming. With increasing biosolids application, plant metal concentrations increased for Cd, Ni and Zn but decreased or were erratic for other elements. In clover, biosolids application removed the Zn deficiency observed where biosolids were not applied. Plant uptake of all elements increased with increasing biosolids application, suggesting dilution by increased plant biomass was responsible for erratic metal concentration results. Despite the observed increases in uptake of metals by plants, metal concentrations in both species were low and below food standard thresholds. It is unlikely that a single

Electrophysiological approach to determine kinetic parameters of sucrose uptake by single sieve elements or phloem parenchyma cells in intact Vicia faba plants.

PubMed

Hafke, Jens B; Höll, Sabina-Roxana; Kühn, Christina; van Bel, Aart J E

2013-01-01

Apart from cut aphid stylets in combination with electrophysiology, no attempts have been made thus far to measure in vivo sucrose-uptake properties of sieve elements. We investigated the kinetics of sucrose uptake by single sieve elements and phloem parenchyma cells in Vicia faba plants. To this end, microelectrodes were inserted into free-lying phloem cells in the main vein of the youngest fully-expanded leaf, half-way along the stem, in the transition zone between the autotrophic and heterotrophic part of the stem, and in the root axis. A top-to-bottom membrane potential gradient of sieve elements was observed along the stem (-130 mV to -110 mV), while the membrane potential of the phloem parenchyma cells was stable (approx. -100 mV). In roots, the membrane potential of sieve elements dropped abruptly to -55 mV. Bathing solutions having various sucrose concentrations were administered and sucrose/H(+)-induced depolarizations were recorded. Data analysis by non-linear least-square data fittings as well as by linear Eadie-Hofstee (EH) -transformations pointed at biphasic Michaelis-Menten kinetics (2 MM, EH: K m1 1.2-1.8 mM, K m2 6.6-9.0 mM) of sucrose uptake by sieve elements. However, Akaike's Information Criterion (AIC) favored single MM kinetics. Using single MM as the best-fitting model, K m values for sucrose uptake by sieve elements decreased along the plant axis from 1 to 7 mM. For phloem parenchyma cells, higher K m values (EH: K m1 10 mM, K m2 70 mM) as compared to sieve elements were found. In preliminary patch-clamp experiments with sieve-element protoplasts, small sucrose-coupled proton currents (-0.1 to -0.3 pA/pF) were detected in the whole-cell mode. In conclusion (a) K m values for sucrose uptake measured by electrophysiology are similar to those obtained with heterologous systems, (b) electrophysiology provides a useful tool for in situ determination of K m values, (c) As yet, it remains unclear if one or two uptake systems are involved in sucrose

Electrophysiological approach to determine kinetic parameters of sucrose uptake by single sieve elements or phloem parenchyma cells in intact Vicia faba plants

PubMed Central

Hafke, Jens B.; Höll, Sabina-Roxana; Kühn, Christina; van Bel, Aart J. E.

2013-01-01

Apart from cut aphid stylets in combination with electrophysiology, no attempts have been made thus far to measure in vivo sucrose-uptake properties of sieve elements. We investigated the kinetics of sucrose uptake by single sieve elements and phloem parenchyma cells in Vicia faba plants. To this end, microelectrodes were inserted into free-lying phloem cells in the main vein of the youngest fully-expanded leaf, half-way along the stem, in the transition zone between the autotrophic and heterotrophic part of the stem, and in the root axis. A top-to-bottom membrane potential gradient of sieve elements was observed along the stem (−130 mV to −110 mV), while the membrane potential of the phloem parenchyma cells was stable (approx. −100 mV). In roots, the membrane potential of sieve elements dropped abruptly to −55 mV. Bathing solutions having various sucrose concentrations were administered and sucrose/H+-induced depolarizations were recorded. Data analysis by non-linear least-square data fittings as well as by linear Eadie–Hofstee (EH) -transformations pointed at biphasic Michaelis–Menten kinetics (2 MM, EH: Km1 1.2–1.8 mM, Km2 6.6–9.0 mM) of sucrose uptake by sieve elements. However, Akaike's Information Criterion (AIC) favored single MM kinetics. Using single MM as the best-fitting model, Km values for sucrose uptake by sieve elements decreased along the plant axis from 1 to 7 mM. For phloem parenchyma cells, higher Km values (EH: Km1 10 mM, Km2 70 mM) as compared to sieve elements were found. In preliminary patch-clamp experiments with sieve-element protoplasts, small sucrose-coupled proton currents (−0.1 to −0.3 pA/pF) were detected in the whole-cell mode. In conclusion (a) Km values for sucrose uptake measured by electrophysiology are similar to those obtained with heterologous systems, (b) electrophysiology provides a useful tool for in situ determination of Km values, (c) As yet, it remains unclear if one or two uptake systems are involved

Uptake of pharmaceutical and personal care products by soybean plants from soils applied with biosolids and irrigated with contaminated water.

PubMed

Wu, Chenxi; Spongberg, Alison L; Witter, Jason D; Fang, Min; Czajkowski, Kevin P

2010-08-15

Many pharmaceuticals and personal care products (PPCPs) are commonly found in biosolids and effluents from wastewater treatment plants. Land application of these biosolids and the reclamation of treated wastewater can transfer those PPCPs into the terrestrial and aquatic environments, giving rise to potential accumulation in plants. In this work, a greenhouse experiment was used to study the uptake of three pharmaceuticals (carbamazepine, diphenhydramine, and fluoxetine) and two personal care products (triclosan and triclocarban) by an agriculturally important species, soybean (Glycine max (L.) Merr.). Two treatments simulating biosolids application and wastewater irrigation were investigated. After growing for 60 and 110 days, plant tissues and soils were analyzed for target compounds. Carbamazepine, triclosan, and triclocarban were found to be concentrated in root tissues and translocated into above ground parts including beans, whereas accumulation and translocation for diphenhydramine and fluoxetine was limited. The uptake of selected compounds differed by treatment, with biosolids application resulting in higher plant concentrations, likely due to higher loading. However, compounds introduced by irrigation appeared to be more available for uptake and translocation. Degradation is the main mechanism for the dissipation of selected compounds in biosolids applied soils, and the presence of soybean plants had no significant effect on sorption. Data from two different harvests suggest that the uptake from soil to root and translocation from root to leaf may be rate limited for triclosan and triclocarban and metabolism may occur within the plant for carbamazepine.

Veterinary antibiotics in animal waste, its distribution in soil and uptake by plants: A review.

PubMed

Tasho, Reep Pandi; Cho, Jae Yong

2016-09-01

Therapeutic and sub-therapeutic use of antibiotics in livestock farming is and has been, a common practice worldwide. These bioactive organic compounds have short retention period and partial uptake into the animal system. The uptake effects of this pharmaceutics, with plants as the primary focus, has not been reviewed so far. This review addresses three main concerns 1) the extensive use of veterinary antibiotics in livestock farming, 2) disposal of animal waste containing active biosolids and 3) effects of veterinary antibiotics in plants. Depending upon the plant species and the antibiotic used, the response can be phytotoxic, hormetic as well as mutational. Additionally, the physiological interactions that make the uptake of these compounds relatively easy have also been discussed. High water solubility, longer half-lives, and continued introduction make them relatively persistent in the environment. Lastly, some prevention measures that can help limit their impact on the environment have been reviewed. There are three methods of control: treatment of animal manure before field application, an alternative bio-agent for disease treatment and a well targeted legalized use of antibiotics. Limiting the movement of these biosolids in the environment can be a challenge because of their varying physiological interactions. Electron irradiation and supervised inoculation of beneficial microorganisms can be effective remediation strategies. Thus, extensive future research should be focused in this area. Copyright © 2016 Elsevier B.V. All rights reserved.

Plant Nitrogen Acquisition Under Low Availability: Regulation of Uptake and Root Architecture

PubMed Central

Kiba, Takatoshi; Krapp, Anne

2016-01-01

Nitrogen availability is a major factor determining plant growth and productivity. Plants acquire nitrogen nutrients from the soil through their roots mostly in the form of ammonium and nitrate. Since these nutrients are scarce in natural soils, plants have evolved adaptive responses to cope with the environment. One of the most important responses is the regulation of nitrogen acquisition efficiency. This review provides an update on the molecular determinants of two major drivers of the nitrogen acquisition efficiency: (i) uptake activity (e.g. high-affinity nitrogen transporters) and (ii) root architecture (e.g. low-nitrogen-availability-specific regulators of primary and lateral root growth). Major emphasis is laid on the regulation of these determinants by nitrogen supply at the transcriptional and post-transcriptional levels, which enables plants to optimize nitrogen acquisition efficiency under low nitrogen availability. PMID:27025887

Nitrogen isotope fractionation during N uptake via arbuscular mycorrhizal and ectomycorrhizal fungi into grey alder.

PubMed

Schweiger, Peter F

2016-10-20

Arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi affect plant nitrogen (N) dynamics. Plant N isotope patterns have been used to characterise the contribution of ECM fungi to plant N uptake. By quantifying and comparing the effects of an AM and an ECM fungus on growth, N uptake and isotopic composition of one host plant grown at different relative N supply levels, the aim of this study was to improve the mechanistic understanding of natural 15 N abundance patterns in mycorrhizal plants and their underlying causes. Grey alders were inoculated with one ECM fungus or one AM fungus or left non-mycorrhizal. Plants were grown under semi-hydroponic conditions and were supplied with three rates of relative N supply ranging from deficient to luxurious. Neither mycorrhizal fungus increased plant growth or N uptake. AM root colonisation had no effect on whole plant δ 15 N and decreased foliar δ 15 N only under N deficiency. The roots of these plants were 15 N-enriched. ECM root colonisation consistently decreased foliar and whole plant δ 15 N. It is concluded, that both mycorrhizal fungi contributed to plant N uptake into the shoot. Nitrogen isotope fractionation during N assimilation and transformations in fungal mycelia is suggested to have resulted in plants receiving 15 N-depleted N via the mycorrhizal uptake pathways. Negative mycorrhizal growth effects are explained by symbiotic resource trade on carbon and N and decreased direct plant N uptake. Copyright © 2016 Elsevier GmbH. All rights reserved.

Plant Nitrogen Acquisition Under Low Availability: Regulation of Uptake and Root Architecture.

PubMed

Kiba, Takatoshi; Krapp, Anne

2016-04-01

Nitrogen availability is a major factor determining plant growth and productivity. Plants acquire nitrogen nutrients from the soil through their roots mostly in the form of ammonium and nitrate. Since these nutrients are scarce in natural soils, plants have evolved adaptive responses to cope with the environment. One of the most important responses is the regulation of nitrogen acquisition efficiency. This review provides an update on the molecular determinants of two major drivers of the nitrogen acquisition efficiency: (i) uptake activity (e.g. high-affinity nitrogen transporters) and (ii) root architecture (e.g. low-nitrogen-availability-specific regulators of primary and lateral root growth). Major emphasis is laid on the regulation of these determinants by nitrogen supply at the transcriptional and post-transcriptional levels, which enables plants to optimize nitrogen acquisition efficiency under low nitrogen availability. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

Uptake of 40K and 137Cs in native plants of the Marshall Islands.

PubMed

Simon, S L; Graham, J C; Terp, S D

2002-01-01

Uptake of 137Cs and 40K was studied in seven native plant species of the Marshall Islands. Plant and soil samples were obtained across a broad range of soil 137Cs concentrations (0.08-3900 Bq/kg) and a narrower range of 40K soil concentrations (2.3-55 Bq/kg), but with no systematic variation of 40K relative to 137Cs. Potassium-40 concentrations in plants varied little within the range of 40K soil concentrations observed. Unlike the case for 40K, 137Cs concentrations increased in plants with increasing 137Cs soil concentrations though not precisely in a proportionate manner. The best-fit relationship between soil and plant concentrations was P = aSb where a and b are regression coefficients and P and S are plant and soil concentrations, respectively. The exponent b for 40K was zero, implying plant concentrations were a single value, while b for 137Cs varied between 0.51 and 0.82, depending on the species. For both 40K and 137Cs, we observed a decreasing concentration ratio (where concentration ratio=plant concentration/soil concentration) with increasing soil concentrations. For the CR values, the best-fit relationship was of the form CR = aSb/S = aSb(-1). For the 40K CR functions, the exponent b - 1 was close to - 1 for all species. For the 137Cs CR functions, the exponent b - 1 varied from -0.19 to -0.48. The findings presented here, aswell as those by other investigators, collectively argue against the usefulness of simplistic ratio models to accurately predict uptake of either 40K or 137Cs in plants over wide ranges of soil concentration.

Alleviation of proton toxicity by nitrate uptake specifically depends on nitrate transporter 1.1 in Arabidopsis.

PubMed

Fang, Xian Zhi; Tian, Wen Hao; Liu, Xing Xing; Lin, Xian Yong; Jin, Chong Wei; Zheng, Shao Jian

2016-07-01

Protons in acid soil are highly rhizotoxic to plants, but the mechanism of tolerance of plants to protons is largely unknown. Nitrate uptake by root cells is accompanied by the uptake of protons. Therefore, nitrate uptake transporters (NRTs) may be involved in plant tolerance to proton toxicity. We investigated the root nitrate uptake response to proton stress in Arabidopsis and its association with proton tolerance using NRT-related mutants and pharmacological methods. Lack of NRT1.1 in knockout nrt1.1 mutants led to impaired proton tolerance in nitrate-sufficient growth medium, whereas no difference was seen between wild-type plants and NRT1.2-, NRT2.1-, NRT2.2-, and NRT2.4-null mutants. Another nrt1.1 point mutant, which is defective in nitrate uptake but has a normal nitrate-sensing function, also had impaired proton tolerance compared with the wild-type plant. Furthermore, proton stress induced NRT1.1-mediated nitrate uptake. These results indicate that NRT1.1-conferred proton tolerance depends on nitrate uptake activity. In addition, the rooting medium was alkalified by wild-type plants, but not by knockout nrt1.1 mutants, and in pH-buffered medium, there were no differences in proton tolerance between wild-type plants and knockout nrt1.1 mutants. We conclude that NRT1.1-mediated nitrate uptake plays a crucial role in plant proton tolerance by alkalifying the rhizosphere. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Silver Uptake, Distribution, and Effect on Calcium, Phosphorus, and Sulfur Uptake 1

PubMed Central

Koontz, Harold V.; Berle, Karen L.

1980-01-01

Bean, corn, and tomato plants were grown in a nutrient solution labeled with 32P, 45Ca, or 35S and varying concentrations of AgNO3. Following a 6-hour treatment period, plants were harvested and analyzed. A low Ag+ concentration (50 nanomolar) inhibited the shoot uptake of the ions investigated. In the roots, Ca uptake increased whereas P and S uptake decreased. Autoradiograms of bean and corn plants, using 110mAg, showed that Ag+ was uniformly deposited in the bean shoot, but corn shoots had regions of high activity along the leaf margins and at the tips where guttation had occurred. Roots were heavily labeled and shoots (especially the new growth) continued to accumulate Ag+ even after the intact plant was returned to Ag-free solution. Silver was believed to be phloem-mobile since it was exported from a treated leaf. Bean plants removed one-half the Ag+ from 4 liters of nutrient solution containing 50 nanomolar AgNO3 within 1.5 hours, but took 16 hours for 20 liters of solution. Images PMID:16661185

Phosphorus-loaded biochar changes soil heavy metals availability and uptake potential of maize (Zea mays L.) plants.

PubMed

Ahmad, Munir; Usman, Adel R A; Al-Faraj, Abdullah S; Ahmad, Mahtab; Sallam, Abdelazeem; Al-Wabel, Mohammad I

2018-03-01

Biochar (BC) was produced by pyrolyzing the date palm leaf waste at 600 °C and then loaded with phosphorus (P) via sorption process. Greenhouse pot experiment was conducted to investigate the application effects of BC and P-loaded biochar (BCP) on growth and availability of P and heavy metals to maize (Zea mays L.) plants grown in contaminated mining soil. The treatments consisted of BC and BCP (at application rates of 5, 10, 20, and 30 g kg -1 of soil), recommended NK and NPK, and a control (no amendment). Sorption experiment showed that Langmuir predicted maximum P sorption capacity of BC was 13.71 mg g -1 . Applying BCP increased the soil available P, while BC and BCP significantly decreased the soil labile heavy metals compared to control. Likewise, heavy metals in exchangeable and reducible fractions were transformed to more stable fraction with BC and BCP applications. The highest application rate of BCP (3%) was most effective treatment in enhancing plant growth parameters (shoot and root lengths and dry matter) and uptake of P and heavy metals by 2-3 folds. However, based on metal uptake and phytoextraction indices, total heavy metals extraction by maize plants was very small for practical application. It could be concluded that using P-loaded biochar as a soil additive may be considered a promising tool to immobilize heavy metals in contaminated mining areas, while positive effects on the biomass growth of plants may assist the stabilization of contaminated areas affected by wind and water erosion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Copper uptake by the water hyacinth. [Eichornia crassipes

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

Lee, T.A.; Hardy, J.K.

1987-01-01

Factors affecting Cu/sup +2/ uptake by the water hyacinth (Eichornia crassipes) were examined. Two phases of copper uptake were observed throughout the uptake range (1-1000 mg/1). An initial rapid uptake phase of 4 hours followed by a slower, near linear uptake phase extending past 48 hours was observed. Stirring the solution enhanced uptake, suggesting copper removal is partially diffusion limited. Variations in pH over the range of 3 to 10 did not significantly affect uptake. Increasing the root mass of the plant increased the amount of copper taken up. As solution volume was increased more copper was removed. The presencemore » of complexing agents during the uptake phase reduced copper uptake. The inability of complexing agents to recover all copper initially removed by a plant suggests a migration to sites within the plant.« less

Copper-resistant bacteria reduces oxidative stress and uptake of copper in lentil plants: potential for bacterial bioremediation.

PubMed

Islam, Faisal; Yasmeen, Tahira; Ali, Qasim; Mubin, Muhammad; Ali, Shafaqat; Arif, Muhammad Saleem; Hussain, Sabir; Riaz, Muhammad; Abbas, Farhat

2016-01-01

For effective microbe-assisted bioremediation, metal-resistant plant growth-promoting bacteria (PGPB) must facilitate plant growth by restricting excess metal uptake in plants, leading to prevent its bio-amplification in the ecosystem. The aims of our study were to isolate and characterize copper (Cu)-resistant PGPB from waste water receiving contaminated soil. In addition, we investigated the phytotoxic effect of copper on the lentil plants inoculated with copper-resistant bacteria Providencia vermicola, grown in copper-contaminated soil. Copper-resistant P. vermicola showed multiple plant growth promoting characteristics, when used as a seed inoculant. It protected the lentil plants from copper toxicity with a considerable increase in root and shoot length, plant dry weight and leaf area. A notable increase in different gas exchange characteristics such as A, E, C i , g s , and A/E, as well as increase in N and P accumulation were also recorded in inoculated plants as compared to un-inoculated copper stressed plants. In addition, leaf chlorophyll content, root nodulation, number of pods, 1,000 seed weight were also higher in inoculated plants as compared with non-inoculated ones. Anti-oxidative defense mechanism improved significantly via elevated expression of reactive oxygen species -scavenging enzymes including ascorbate peroxidase, superoxide dismutase, catalase, and guaiacol peroxidase with alternate decrease in malondialdehyde and H2O2 contents, reduced electrolyte leakage, proline, and total phenolic contents suggesting that inoculation of P. vermicola triggered heavy metals stress-related defense pathways under copper stress. Overall, the results demonstrated that the P. vermicola seed inoculation confer heavy metal stress tolerance in lentil plant which can be used as a potent biotechnological tool to cope with the problems of copper pollution in crop plants for better yield.

Soil and vegetation influence in plants natural radionuclides uptake at a uranium mining site

NASA Astrophysics Data System (ADS)

Charro, E.; Moyano, A.

2017-12-01

The main objective of this work is to investigate the uptake of several radionuclides by the vegetation characteristic of a dehesa ecosystem in uranium mining-impacted soils in Central-West of Spain. The activity concentration for 238U, 226Ra, 210Pb, 232Th, and 224Ra was measured in soil and vegetation samples using a Canberra n-type HPGe gamma-ray spectrometer. Transfer factors of natural radionuclides in different tissues (leaves, branches, twigs, and others) of native plants were evaluated. From these data, the influence of the mine, the physicochemical parameters of the soils and the type of vegetation were analyzed in order to explain the accumulation of radionuclides in the vegetation. A preferential uptake of 210Pb and 226Ra by plants, particularly by trees of the Quercus species (Quercus pyrenaica and Quercus ilex rotundifolia), has been observed, being the transfer factors for 226Ra and 210Pb in these tree species higher than those for other plants (like Pinus pinaster, Rubur ulmifolius and Populus sp.). The analysis of radionuclide contents and transfer factors in the vegetation showed no evidence of influence of the radionuclide concentration in soils, although it could be explained in terms of the type of plants and, in particular, of the tree's species, with special attention to the tree's rate of growth, being higher in slow growing species.

Uptake and metabolism of diclofenac in Typha latifolia--how plants cope with human pharmaceutical pollution.

PubMed

Bartha, Bernadett; Huber, Christian; Schröder, Peter

2014-10-01

The fate of pharmaceuticals in our environment is a very important issue for environmental and health research. Although these substances have been detected in environmental compartments in low concentration until now, they will pose considerable environmental risk to ecosystems, animals and human due to their biological activity. Alternative plant based removal technologies that make use of some potential wetland species like Phragmites or Typha within traditional wastewater treatment plants have to be established to cope with this "new generation" of pollutants. We investigated uptake and translocation of diclofenac (1mgl(-1)) in the macrophyte Typha latifolia L. during one week exposure in greenhouse experiments. Detoxification products and involved key enzymatic processes were identified. We also examined the oxidative stress induced by the treatment and the defense capacity of the plants. Rapid uptake and effective metabolism were observed, where glycoside and glutathione conjugates represent dominant metabolites. Up to seven-fold induction of glycosyltransferase activity was observed in roots, but not in shoots. Glutathione S-transferase activity was also induced, but to a lower extent. The activity changes of defense enzymes points to oxidative stress in the plants. Our results show that human pharmaceuticals can be metabolized by plants similar to xenobiotics, but that similarities to human metabolism are limited. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L.

PubMed

Kanwar, Mukesh Kumar; Bhardwaj, Renu; Arora, Priya; Chowdhary, Sikandar Pal; Sharma, Priyanka; Kumar, Subodh

2012-01-01

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management. Copyright © 2011 Elsevier Ltd. All rights reserved.

Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

PubMed Central

Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

2015-01-01

High concentrations of cesium (Cs+) inhibit plant growth but the detailed mechanisms of Cs+ uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs+, chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs+ tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs+ concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs+. Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs+ tolerance enhancer isolated here renders plants tolerant to Cs+ by inhibiting Cs+ entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland. PMID:25740624

Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake.

PubMed

Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

2015-03-05

High concentrations of cesium (Cs(+)) inhibit plant growth but the detailed mechanisms of Cs(+) uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs(+), chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs(+) tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs(+) concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs(+). Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs(+) tolerance enhancer isolated here renders plants tolerant to Cs(+) by inhibiting Cs(+) entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland.

Prediction of methyl mercury uptake by rice plants ( Oryza sativa L.) using the diffusive gradient in thin films technique.

PubMed

Liu, Jinling; Feng, Xinbin; Qiu, Guangle; Anderson, Christopher W N; Yao, Heng

2012-10-16

Rice consumption is the primary pathway for methyl mercury (MeHg) exposure at inland mercury (Hg) mining areas of SW China. Mechanistic information on MeHg accumulation in rice is, however, limited. The process of MeHg exchange between paddy soil and rice plants predominantly occurs in pore water. The detection of bioavailable MeHg in pore water is therefore important to predict MeHg uptake by rice plants ( Oryza sativa L.). This study investigated MeHg dynamics and spatial MeHg trends in pore water during the rice growing season using the diffusive gradient in thin films (DGT) technique and tested the ability of DGT to predict MeHg uptake by rice. The MeHg uptake flux from soil to rice plants via roots was significantly correlated with the DGT-measured MeHg flux (R = 0.853, p < 0.01). Our study implies that DGT can predict the bioavailability of MeHg in rice paddy soil and that the DGT method can provide quantitative description of the rate of uptake of this bioavailable MeHg. The DGT technique is demonstrated as a useful indicator of the likely ecotoxicological risk that might be apparent where paddy rice is grown in MeHg contaminated soil.

An overview on manufactured nanoparticles in plants: Uptake, translocation, accumulation and phytotoxicity.

PubMed

Tripathi, Durgesh Kumar; Shweta; Singh, Shweta; Singh, Swati; Pandey, Rishikesh; Singh, Vijay Pratap; Sharma, Nilesh C; Prasad, Sheo Mohan; Dubey, Nawal Kishore; Chauhan, Devendra Kumar

2017-01-01

The unprecedented capability to control and characterize materials on the nanometer scale has led to the rapid expansion of nanostructured materials. The expansion of nanotechnology, resulting into myriads of consumer and industrial products, causes a concern among the scientific community regarding risk associated with the release of nanomaterials in the environment. Bioavailability of excess nanomaterials ultimately threatens ecosystem and human health. Over the past few years, the field of nanotoxicology dealing with adverse effects and the probable risk associated with particulate structures <100 nm in size has emerged from the recognized understanding of toxic effects of fibrous and non-fibrous particles and their interactions with plants. The present review summarizes uptake, translocation and accumulation of nanomaterials and their recognized ways of phytotoxicity on morpho-anatomical, physiological, biochemical and molecular traits of plants. Besides this, the present review also examines the intrinsic detoxification mechanisms in plants in light of nanomaterial accumulation within plant cells or parts. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

pOsNAR2.1:OsNAR2.1 expression enhances nitrogen uptake efficiency and grain yield in transgenic rice plants.

PubMed

Chen, Jingguang; Fan, Xiaoru; Qian, Kaiyun; Zhang, Yong; Song, Miaoquan; Liu, Yu; Xu, Guohua; Fan, Xiaorong

2017-10-01

The nitrate (NO3-) transporter has been selected as an important gene maker in the process of environmental adoption in rice cultivars. In this work, we transferred another native OsNAR2.1 promoter with driving OsNAR2.1 gene into rice plants. The transgenic lines with exogenous pOsNAR2.1:OsNAR2.1 constructs showed enhanced OsNAR2.1 expression level, compared with wild type (WT), and 15 N influx in roots increased 21%-32% in response to 0.2 mm and 2.5 mm 15NO3- and 1.25 mm 15 NH 4 15 NO 3 . Under these three N conditions, the biomass of the pOsNAR2.1:OsNAR2.1 transgenic lines increased 143%, 129% and 51%, and total N content increased 161%, 242% and 69%, respectively, compared to WT. Furthermore in field experiments we found the grain yield, agricultural nitrogen use efficiency (ANUE), and dry matter transfer of pOsNAR2.1:OsNAR2.1 plants increased by about 21%, 22% and 21%, compared to WT. We also compared the phenotypes of pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines in the field, found that postanthesis N uptake differed significantly between them, and in comparison with the WT. Postanthesis N uptake (PANU) increased approximately 39% and 85%, in the pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines, respectively, possibly because OsNRT2.1 expression was less in the pOsNAR2.1:OsNAR2.1 lines than in the pOsNAR2.1:OsNRT2.1 lines during the late growth stage. These results show that rice NO 3 - uptake, yield and NUE were improved by increased OsNAR2.1 expression via its native promoter. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems.

PubMed

Blok, Chris; Jackson, Brian E; Guo, Xianfeng; de Visser, Pieter H B; Marcelis, Leo F M

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent

Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems

PubMed Central

Blok, Chris; Jackson, Brian E.; Guo, Xianfeng; de Visser, Pieter H. B.; Marcelis, Leo F. M.

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15–17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent

Comparison of MRI techniques and modelling with R-SWMS for determining solute distribution patterns and root water uptake of a white lupine plant (Lupinus Albus L.).

NASA Astrophysics Data System (ADS)

Koch, Axelle; Schröder, Natalie; Pohlmeier, Andreas; Garré, Sarah; Vanderborght, Jan; Javaux, Mathieu

2017-04-01

Measuring water extraction by plant would allow us to better understand root water uptake processes and how soil and plant properties affect them. Yet, direct measurement of root water uptake is still challenging and determining its distribution requires coupling experimentation and modelling. In this study, we investigated how the 3D monitoring of a tracer movement in a sand container with a lupine plant could inform us about root water uptake process. A sand column (10 cm height, 5 cm inner diameter) planted with an 18-day-old white lupine was subject to a tracer experiment with a chemically inert tracer (1 mmol/L Gd-DTPA2-) applied for 6 days. Then the tracer and water fluxes were stopped. The plume was monitored in 3-D for 7 days by Magnetic Resonance Imaging (Haber-Pohlmeier et al, unp). In addition the breakthrough curve at the outlet was also measured. We used a biophysical 3-D soil-plant model: R-SWMS (Javaux et al, 2008) to extract information from this experiment. First, we ran a virtual experiment to check the assumption that Gd concentration increase around roots is proportional to the extracted soil water during the same period. We also investigated whether this type of experiment helps discriminate different root hydraulic properties with a sensitivity analysis. Then, we compared the experimental and simulated Gd concentration patterns. A preliminary (qualitative) assessment showed that measured Gd distribution patterns were better represented by the model at day 7, where the main driver of the concentration distribution was root and not soil heterogeneity (which is not taken into account in the model). The main spatial and temporal features of the transport where adequately reproduced by the model in particular during the last day. The distribution of the tracer was shown to be sensitive to the root hydraulic properties. To conclude, information about root water uptake distributions and so about root hydraulic properties could be deduced from Gd

Abscisic acid triggers whole-plant and fruit-specific mechanisms to increase fruit calcium uptake and prevent blossom end rot development in tomato fruit.

PubMed

de Freitas, Sergio Tonetto; Shackel, Kenneth A; Mitcham, Elizabeth J

2011-05-01

Calcium (Ca) uptake into fruit and leaves is dependent on xylemic water movement, and hence presumably driven by transpiration and growth. High leaf transpiration is thought to restrict Ca movement to low-transpiring tomato fruit, which may increase fruit susceptibility to the Ca-deficiency disorder, blossom end rot (BER). The objective of this study was to analyse the effect of reduced leaf transpiration in abscisic acid (ABA)-treated plants on fruit and leaf Ca uptake and BER development. Tomato cultivars Ace 55 (Vf) and AB2 were grown in a greenhouse environment under Ca-deficit conditions and plants were treated weekly after pollination with water (control) or 500 mg l(-1) ABA. BER incidence was completely prevented in the ABA-treated plants and reached values of 30-45% in the water-treated controls. ABA-treated plants had higher stem water potential, lower leaf stomatal conductance, and lower whole-plant water loss than water-treated plants. ABA treatment increased total tissue and apoplastic water-soluble Ca concentrations in the fruit, and decreased Ca concentrations in leaves. In ABA-treated plants, fruit had a higher number of Safranin-O-stained xylem vessels at early stages of growth and development. ABA treatment reduced the phloem/xylem ratio of fruit sap uptake. The results indicate that ABA prevents BER development by increasing fruit Ca uptake, possibly by a combination of whole-plant and fruit-specific mechanisms.

Plant Comparative and Functional Genomics

DOE PAGES

Yang, Xiaohan; Leebens-Mack, Jim; Chen, Feng; ...

2015-01-01

Plants form the foundation for our global ecosystem and are essential for environmental and human health. An increasing number of available plant genomes and tractable experimental systems, comparative and functional plant genomics research is greatly expanding our knowledge of the molecular basis of economically and nutritionally important traits in crop plants. Inferences drawn from comparative genomics are motivating experimental investigations of gene function and gene interactions. In this special issue aims to highlight recent advances made in comparative and functional genomics research in plants. Nine original research articles in this special issue cover five important topics: (1) transcription factor genemore » families relevant to abiotic stress tolerance; (2) plant secondary metabolism; (3) transcriptomebased markers for quantitative trait locus; (4) epigenetic modifications in plant-microbe interactions; and (5) computational prediction of protein-protein interactions. Finally, we studied the plant species in these articles which include model species as well as nonmodel plant species of economic importance (e.g., food crops and medicinal plants).« less

Plant Comparative and Functional Genomics

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

Yang, Xiaohan; Leebens-Mack, Jim; Chen, Feng

Plants form the foundation for our global ecosystem and are essential for environmental and human health. An increasing number of available plant genomes and tractable experimental systems, comparative and functional plant genomics research is greatly expanding our knowledge of the molecular basis of economically and nutritionally important traits in crop plants. Inferences drawn from comparative genomics are motivating experimental investigations of gene function and gene interactions. In this special issue aims to highlight recent advances made in comparative and functional genomics research in plants. Nine original research articles in this special issue cover five important topics: (1) transcription factor genemore » families relevant to abiotic stress tolerance; (2) plant secondary metabolism; (3) transcriptomebased markers for quantitative trait locus; (4) epigenetic modifications in plant-microbe interactions; and (5) computational prediction of protein-protein interactions. Finally, we studied the plant species in these articles which include model species as well as nonmodel plant species of economic importance (e.g., food crops and medicinal plants).« less

Silver nanoparticles uptake by salt marsh plants - Implications for phytoremediation processes and effects in microbial community dynamics.

PubMed

Fernandes, Joana P; Mucha, Ana P; Francisco, Telmo; Gomes, Carlos Rocha; Almeida, C Marisa R

2017-06-15

This study investigated the uptake of silver nanoparticles (AgNPs) by a salt marsh plant, Phragmites australis, as well as AgNPs effects on rhizospheric microbial community, evaluating the implications for phytoremediation processes. Experiments were carried out with elutriate solution doped with Ag, either in ionic form or in NP form. Metal uptake was evaluated in plant tissues, elutriate solutions and sediments (by AAS) and microbial community was characterized in terms of bacterial community structure (evaluated by ARISA). Results showed Ag accumulation but only in plant belowground tissues and only in the absence of rhizosediment, the presence of sediment reducing Ag availability. But in plant roots Ag accumulation was higher when Ag was in NP form. Multivariate analysis of ARISA profiles showed significant effect of the absence/presence of Ag either in ionic or NP form on microbial community structure, although without significant differences among bacterial richness and diversity. Overall, P. australis can be useful for phytoremediation of medium contaminated with Ag, including with AgNPs. However, the presence of Ag in either forms affected the microbial community structure, which may cause disturbances in ecosystems function and compromise phytoremediation processes. Such considerations need to be address regarding environmental management strategies applied to the very important estuarine areas. The form in which the metal was added affected metal uptake by Phragmites australis and rhizosediment microbial community structure, which can affect phytoremediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

OsPT4 Contributes to Arsenate Uptake and Transport in Rice

PubMed Central

Ye, Ying; Li, Peng; Xu, Tangqian; Zeng, Liting; Cheng, Deng; Yang, Meng; Luo, Jie; Lian, Xingming

2017-01-01

Arsenic (As) is toxic to organisms, and elevated As accumulation in rice (Oryza sativa) grain may pose a significant health risk to humans. The predominant form of As in soil under aerobic conditions is As(V), which has a chemical structure similar to that of PO43-. Rice roots take up As(V) by phosphate (Pi) transporters, such as OsPT1 and OsPT8. In the present study, we investigated the contribution of OsPT4, belonging to the Pht1 family, on rice As(V) uptake and transport. We determined the mRNA amounts of OsPTs in rice seedlings, and expressions of OsPT1, OsPT4, and OsPT8 were up-regulated under As(V) conditions. OsPT4-overexpressing plants were obtained to examine the As (V) transport activity of OsPT4 in rice. When transgenic rice grew in hydroponic culture with 25 and 50 μM As(V), the plants showed sensitivity to As(V) stress with aboveground parts showing delayed growth and the roots stunted. The OsPT4 CRISPR lines showed the opposite phenotype. When plants were grown in 5 μM As(V) solution for 7 days, the As accumulation of OsPT4-overexpressing plants increased up to twice in roots and shoots. Furthermore, the arsenate uptake rates of OsPT4-overexpressing lines were higher compared with wild type. The Vmax of As(V) uptake in OsPT4-overexpressing plants increased 23–45% compared with Nipponbare. In the flooded soil, the As accumulation of OsPT4-overexpressing plants increased 40–66% and 22–30% in straw and grain, respectively. While in OsPT4-cr plants As accumulation in roots decreased 17–30% compared with Nipponbare. Therefore, the present study indicates that OsPT4 is involved in As(V) uptake and transport and could be a good candidate gene to generate low As-accumulating rice. PMID:29312424

Cadmium uptake and xylem loading are active processes in the hyperaccumulator Sedum alfredii.

PubMed

Lu, Ling-li; Tian, Sheng-ke; Yang, Xiao-e; Li, Ting-qiang; He, Zhen-li

2009-04-01

Sedum alfredii is a well known cadmium (Cd) hyperaccumulator native to China; however, the mechanism behind its hyperaccumulation of Cd is not fully understood. Through several hydroponic experiments, characteristics of Cd uptake and translocation were investigated in the hyperaccumulating ecotype (HE) of S. alfredii in comparison with its non-hyperaccumulating ecotype (NHE). The results showed that at Cd level of 10 microM measured Cd uptake in HE was 3-4 times higher than the implied Cd uptake calculated from transpiration rate. Furthermore, inhibition of transpiration rate in the HE has no essential effect on Cd accumulation in shoots of the plants. Low temperature treatment (4 degrees C) significantly inhibited Cd uptake and reduced upward translocation of Cd to shoots for 9 times in HE plants, whereas no such effect was observed in NHE. Cadmium concentration was 3-4-fold higher in xylem sap of HE, as compared with that in external uptake solution, whereas opposite results were obtained for NHE. Cadmium concentration in xylem sap of HE was significantly reduced by the addition of metabolic inhibitors, carbonyl cyanide m-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP), in the uptake solutions, whereas no such effect was noted in NHE. These results suggest that Cd uptake and translocation is an active process in plants of HE S. alfredii, symplastic pathway rather than apoplastic bypass contributes greatly to root uptake, xylem loading and translocation of Cd to the shoots of HE, in comparison with the NHE plants.

Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration

NASA Technical Reports Server (NTRS)

Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

1988-01-01

Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.

Nitrogen dioxide (NO2) uptake by vegetation controlled by atmospheric concentrations and plant stomatal aperture

NASA Astrophysics Data System (ADS)

Chaparro-Suarez, I. G.; Meixner, F. X.; Kesselmeier, J.

2011-10-01

Nitrogen dioxide (NO2) exchange between the atmosphere and five European tree species was investigated in the laboratory using a dynamic branch enclosure system (consisting of two cuvettes) and a highly specific NO2 analyzer. NO2 measurements were performed with a sensitive gas phase chemiluminescence NO detector combined with a NO2 specific (photolytic) converter, both from Eco-Physics (Switzerland). This highly specific detection system excluded bias from other nitrogen compounds. Investigations were performed at two light intensities (Photosynthetic Active Radiation, PAR, 450 and 900 μmol m-2 s-1) and NO2 concentrations between 0 and 5 ppb. Ambient parameters (air temperature and relative humidity) were held constant. The data showed dominant NO2 uptake by the respective tree species under all conditions. The results did not confirm the existence of a compensation point within a 95% confidence level, though we cannot completely exclude emission of NO2 under very low atmospheric concentrations. Induced stomatal stricture, or total closure, by changing light conditions, as well as by application of the plant hormone ABA (Abscisic Acid) caused a corresponding decrease of NO2 uptake. No loss of NO2 to plant surfaces was observed under stomatal closure and species dependent differences in uptake rates could be clearly related to stomatal behavior.

Use of gold nanoparticles to detect water uptake in vascular plants.

PubMed

Hwang, Bae Geun; Ahn, Sungsook; Lee, Sang Joon

2014-01-01

Direct visualization of water-conducting pathways and sap flows in xylem vessels is important for understanding the physiology of vascular plants and their sap ascent. Gold nanoparticles (AuNPs) combined with synchrotron X-ray imaging technique is a new promising tool for investigating plant hydraulics in opaque xylem vessels of vascular plants. However, in practical applications of AuNPs for real-time quantitative visualization of sap flows, their interaction with a vascular network needs to be verified in advance. In this study, the effect of AuNPs on the water-refilling function of xylem vessels is experimentally investigated with three monocot species. Discrepancy in the water uptakes starts to appear at about 20 min to 40 min after the supply of AuNP solution to the test plant by the possible gradual accumulation of AuNPs on the internal structures of vasculature. However conclusively, it is observed that the water-refilling speeds in individual xylem vessels are virtually unaffected by hydrophilically surface-modified AuNPs (diameter ∼20 nm). Therefore, the AuNPs can be effectively used as flow tracers in the xylem vessels in the first 20∼30 min without any physiological barrier. As a result, AuNPs are found to be useful for visualizing various fluid dynamic phenomena occurring in vascular plants.

Uptake of toluene and ethylbenzene by plants: removal of volatile indoor air contaminants.

PubMed

Sriprapat, Wararat; Suksabye, Parinda; Areephak, Sirintip; Klantup, Polawat; Waraha, Atcharaphan; Sawattan, Anuchit; Thiravetyan, Paitip

2014-04-01

Air borne uptake of toluene and ethylbenzene by twelve plant species was examined. Of the twelve plant species examined, the highest toluene removal was found in Sansevieria trifasciata, while the ethylbenzene removal from air was with Chlorophytum comosum. Toluene and ethylbenzene can penetrate the plant׳s cuticle. However, the removal rates do not appear to be correlated with numbers of stomata per plant. It was found that wax of S. trifasciata and Sansevieria hyacinthoides had greater absorption of toluene and ethylbenzene, and it contained high hexadecanoic acid. Hexadecanoic acid might be involved in toluene and ethylbenzene adsorption by cuticles wax of plants. Chlorophyll fluorescence analysis or the potential quantum yield of PSII (Fv/Fm) in toluene exposed plants showed no significant differences between the control and the treated plants, whereas plants exposed to ethylbenzene showed significant differences or those parameters, specifically in Dracaena deremensis (Lemon lime), Dracaena sanderiana, Kalanchoe blossfeldiana, and Cordyline fruticosa. The Fv/Fm ratio can give insight into the ability of plants to tolerate (indoor) air pollution by volatile organic chemicals (VOC). This index can be used for identification of suitable plants for treating/sequestering VOCs in contaminated air. Copyright © 2014 Elsevier Inc. All rights reserved.

Isolation and characterization of N2 -fixing bacteria from giant reed and switchgrass for plant growth promotion and nutrient uptake.

PubMed

Xu, Jia; Kloepper, Joseph W; Huang, Ping; McInroy, John A; Hu, Chia H

2018-05-01

The aims of this study were to isolate and characterize N 2 -fixing bacteria from giant reed and switchgrass and evaluate their plant growth promotion and nutrient uptake potential for use as biofertilizers. A total of 190 bacteria were obtained from rhizosphere soil and inside stems and roots of giant reed and switchgrass. All the isolates were confirmed to have nitrogenase activity, 96.9% produced auxin, and 85% produced siderophores. Then the top six strains, including Sphingomonas trueperi NNA-14, Sphingomonas trueperi NNA-19, Sphingomonas trueperi NNA-17, Sphingomonas trueperi NNA-20, Psychrobacillus psychrodurans NP-3, and Enterobacter oryzae NXU-38, based on nitrogenase activity, were inoculated on maize and wheat seeds in greenhouse tests to assess their potential benefits to plants. All the selected strains promoted plant growth by increasing at least one plant growth parameter or increasing the nutrient concentration of maize or wheat plants. NNA-14 outperformed others in promoting early growth and nutrient uptake by maize. Specifically, NNA-14 significantly increased root length, surface area, and fine roots of maize by 14%, 12%, and 17%, respectively, and enhanced N, Ca, S, B, Cu, and Zn in maize. NNA-19 and NXU-38 outperformed others in promoting both early growth and nutrient uptake by wheat. Specifically, NNA-19 significantly increased root dry weight and number of root tips of wheat by 25% and 96%, respectively, and enhanced Ca in wheat. NXU-38 significantly increased root length, surface area, and fine roots of wheat by 21%, 13%, and 26%, respectively, and enhanced levels of Ca and Mg in wheat. It is concluded that switchgrass and giant reed are colonized by N 2 -fixing bacteria that have the potential to contribute to plant growth and nutrient uptake by agricultural crops. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plant uptake of 238U, 235U, 232Th, 226Ra, 210Pb and 40K from a coal ash and slag disposal site and control soil under field conditions: A preliminary study.

PubMed

Skoko, Božena; Marović, Gordana; Babić, Dinko; Šoštarić, Marko; Jukić, Mirela

2017-06-01

The aim of this study was to investigate the uptake of 238 U, 235 U, 232 Th, 226 Ra, 210 Pb and 40 K by plants that grow on a coal ash and slag disposal site known for its higher content of naturally occurring radionuclides. Plant species that were sampled are common for the Mediterranean flora and can be divided as follows: grasses & herbs, shrubs and trees. To compare the activity concentrations and the resultant concentration ratios of the disposal site with those in natural conditions, we used control data specific for the research area, obtained for plants growing on untreated natural soil. Radionuclide activity concentrations were determined by high resolution gamma-ray spectrometry. Media parameters (pH, electrical conductivity and organic matter content) were also analysed. We confirmed significantly higher activity concentrations of 238 U, 235 U, 226 Ra and 210 Pb in ash and slag compared to control soil. However, a significant increase in the radionuclide activity concentration in the disposal site's vegetation was observed only for 226 Ra. On the contrary, a significantly smaller activity concentration of 40 K in ash and slag had no impact on its activity concentration in plant samples. The calculated plant uptake of 238 U, 235 U, 226 Ra and 210 Pb is significantly smaller in comparison with the uptake at the control site, while it is vice versa for 40 K. No significant difference was observed between the disposal site and the control site's plant uptake of 232 Th. These results can be the foundation for further radioecological assessment of this disposal site but also, globally, they can contribute to a better understanding of nature and long-term management of such disposal sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vanadium Uptake by Plants

PubMed Central

Welch, Ross M.

1973-01-01

The kinetics of vanadium absorption by excised barley (Hordeum vulgare L., cv. Eire) roots were investigated with respect to ionic species of V in solution, time and concentration dependence, Ca sensitivity, and interaction with various anions, cations, and pH levels. The role of metabolism in V absorption was also studied using anaerobic treatment (N2 gas) and chemical inhibitors (NaN3, KCN, or 2,4-dinitrophenol). Approximately one-third of the labeled V initially taken up by excised roots was desorbed to a constant level after 45 min in unlabeled V solutions. The rate of absorption of labeled V from 5 μm NH4VO3 solutions containing 0.5 mm CaSO4 was constant for at least 3 hours. Omission of Ca resulted in a 72% reduction in V uptake when compared to controls with 0.5 mm CaSO4. The rate of uptake of V was highest at pH 4 but dropped to a very low level at pH 10. It was relatively constant between the pH levels of 5 and 8 at which the VO3− ion is the predominant ionic species in solution. The rate of absorption of V was followed as a function of concentrations from 0.5 to 100 μm NH4VO3. It was found to be a linear function of concentration and did not follow saturation kinetics. Absorption experiments carried out with labeled V from either NaVO3 or NH4VO3 sources gave similar results. No anion studied (i.e. HPO42−, HAsO42−, MoO42−, SeO42−, SeO32−, CrO42−, BO33−, No3−, and Cl−) interfered appreciably (i.e. less than 30% inhibition) with the absorption of labeled V. Anaerobic treatment of absorption solution with N2 gas did not inhibit V absorption by excised roots. The results obtained using chemical inhibitors were not consistent. It was concluded that V is not actively absorbed by excised barley roots. PMID:16658421

Rhizosphere Microbial Community Composition Affects Cadmium and Zinc Uptake by the Metal-Hyperaccumulating Plant Arabidopsis halleri

PubMed Central

Muehe, E. Marie; Weigold, Pascal; Adaktylou, Irini J.; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas

2015-01-01

The remediation of metal-contaminated soils by phytoextraction depends on plant growth and plant metal accessibility. Soil microorganisms can affect the accumulation of metals by plants either by directly or indirectly stimulating plant growth and activity or by (im)mobilizing and/or complexing metals. Understanding the intricate interplay of metal-accumulating plants with their rhizosphere microbiome is an important step toward the application and optimization of phytoremediation. We compared the effects of a “native” and a strongly disturbed (gamma-irradiated) soil microbial communities on cadmium and zinc accumulation by the plant Arabidopsis halleri in soil microcosm experiments. A. halleri accumulated 100% more cadmium and 15% more zinc when grown on the untreated than on the gamma-irradiated soil. Gamma irradiation affected neither plant growth nor the 1 M HCl-extractable metal content of the soil. However, it strongly altered the soil microbial community composition and overall cell numbers. Pyrosequencing of 16S rRNA gene amplicons of DNA extracted from rhizosphere samples of A. halleri identified microbial taxa (Lysobacter, Streptomyces, Agromyces, Nitrospira, “Candidatus Chloracidobacterium”) of higher relative sequence abundance in the rhizospheres of A. halleri plants grown on untreated than on gamma-irradiated soil, leading to hypotheses on their potential effect on plant metal uptake. However, further experimental evidence is required, and wherefore we discuss different mechanisms of interaction of A. halleri with its rhizosphere microbiome that might have directly or indirectly affected plant metal accumulation. Deciphering the complex interactions between A. halleri and individual microbial taxa will help to further develop soil metal phytoextraction as an efficient and sustainable remediation strategy. PMID:25595759

UPTAKE AND PHYTOTRANSFORMATION OF O,P'-DDT AND P,P'-DDT BY AXENICALLY CULTIVATED AQUATIC PLANTS

EPA Science Inventory

The uptake and phytotransformation of o,p'-DDT and p,p'-DDT were investigated in vitro using three axenically cultivated aquatic plants: parrot feather (Mariophyllum aquaticum), duckweed (Spirodela oligorrhiza), and elodea (Elodea canadensis). The decay profile of DDT from the aq...

Seasonal variation in water uptake patterns of three plant species based on stable isotopes in the semi-arid Loess Plateau.

PubMed

Wang, Jian; Fu, Bojie; Lu, Nan; Zhang, Li

2017-12-31

Water is a limiting factor and significant driving force for ecosystem processes in arid and semi-arid areas. Knowledge of plant water uptake pattern is indispensable for understanding soil-plant interactions and species coexistence. The 'Grain for Green' project that started in 1999 in the Loess Plateau of China has led to large scale vegetation change. However, little is known about the water uptake patterns of the main plant species that inhabit in this region. In this study, the seasonal variations in water uptake patterns of three representative plant species, Stipa bungeana, Artemisia gmelinii and Vitex negundo, that are widely distributed in the semi-arid area of the Loess Plateau, were identified by using dual stable isotopes of δ 2 H and δ 18 O in plant and soil water coupled with a Bayesian mixing model MixSIAR. The soil water at the 0-120cm depth contributed 79.54±6.05% and 79.94±8.81% of the total water uptake of S. bungeana and A. gmelinii, respectively, in the growing season. The 0-40cm soil contributed the most water in July (74.20±15.20%), and the largest proportion of water (33.10±15.20%) was derived from 120-300cm soils in August for A. gmelinii. However, V. negundo obtained water predominantly from surface soil horizons (0-40cm) and then switched to deep soil layers (120-300cm) as the season progressed. This suggested that V. negundo has a greater degree of ecological plasticity as it could explore water sources from deeper soils as the water stress increased. This capacity can mainly be attributed to its functionally dimorphic root system. V. negundo may have a competitive advantage when encountering short-term drought. The ecological plasticity of plant water use needs to be considered in plant species selection and ecological management and restoration of the arid and semi-arid ecosystems in the Loess Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Fe plaque and organic acids on metal uptake by wetland plants under drained and waterlogged conditions.

PubMed

Li, W C; Deng, H; Wong, M H

2017-12-01

This study aims to assess the role of Fe plaque in metal uptake and translocation by different wetland plants and examine the effects of organic acids on metal detoxification in wetland plants. It was found that although exposed to a similar level of metals in rhizosphere soil solution, metal uptake by shoots of Cypercus flabelliformis and Panicum paludosum was greatly reduced, consequently leading to a better growth under flooded than under drained conditions. This may be related to the enhanced Fe plaque in the former, but due to the decreased root permeability in the latter under anoxic conditions. The Fe plaque on root surface has potential to sequester metals and then reduce metal concentrations and translocation in shoot tissues. However, whether the Fe plaque acts as a barrier to metal uptake and translocation may also be dependent on the root anatomy. Although metal tolerance in wetland plants mainly depends upon their metal exclusion ability, the higher-than-toxic-level of metal concentrations in some species indicates that internal metal detoxification might also exist. It was suggested that malic or citric acid in shoots of P. paludosum and C. flabelliformis may account for their internal detoxification for Zn. Copyright © 2017 Elsevier Ltd. All rights reserved.

Using Flux Site Observations to Calibrate Root System Architecture Stencils for Water Uptake of Plant Functional Types in Land Surface Models.

NASA Astrophysics Data System (ADS)

Bouda, M.

2017-12-01

Root system architecture (RSA) can significantly affect plant access to water, total transpiration, as well as its partitioning by soil depth, with implications for surface heat, water, and carbon budgets. Despite recent advances in land surface model (LSM) descriptions of plant hydraulics, RSA has not been included because of its three-dimensional complexity, which makes RSA modelling generally too computationally costly. This work builds upon the recently introduced "RSA stencil," a process-based 1D layered model that captures the dynamic shifts in water potential gradients of 3D RSA in response to heterogeneous soil moisture profiles. In validations using root systems calibrated to the rooting profiles of four plant functional types (PFT) of the Community Land Model, the RSA stencil predicts plant water potentials within 2% of the outputs of full 3D models, despite its trivial computational cost. In transient simulations, the RSA stencil yields improved predictions of water uptake and soil moisture profiles compared to a 1D model based on root fraction alone. Here I show how the RSA stencil can be calibrated to time-series observations of soil moisture and transpiration to yield a water uptake PFT definition for use in terrestrial models. This model-data integration exercise aims to improve LSM predictions of soil moisture dynamics and, under water-limiting conditions, surface fluxes. These improvements can be expected to significantly impact predictions of downstream variables, including surface fluxes, climate-vegetation feedbacks and soil nutrient cycling.

Mathematical modelling of the uptake and transport of salt in plant roots.

PubMed

Foster, Kylie J; Miklavcic, Stanley J

2013-11-07

In this paper, we present and discuss a mathematical model of ion uptake and transport in roots of plants. The underlying physical model of transport is based on the mechanisms of forced diffusion and convection. The model can take account of local variations in effective ion and water permeabilities across the major tissue regions of plant roots, represented through a discretized coupled system of governing equations including mass balance, forced diffusion, convection and electric potential. We present simulation results of an exploration of the consequent enormous parameter space. Among our findings we identify the electric potential as a major factor affecting ion transport across, and accumulation in, root tissues. We also find that under conditions of a constant but realistic level of bulk soil salt concentration and plant-soil hydraulic pressure, diffusion plays a significant role even when convection by the water transpiration stream is operating. Crown Copyright © 2013 Published by Elsevier Ltd. All rights reserved.

Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources.

PubMed

Keeping, Malcolm G

2017-01-01

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate

Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources

PubMed Central

Keeping, Malcolm G.

2017-01-01

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate

Dredged Illinois River Sediments: Plant Growth and Metal Uptake

USGS Publications Warehouse

Darmody, R.G.; Marlin, J.C.; Talbott, J.; Green, R.A.; Brewer, E.F.; Stohr, C.

2004-01-01

Sedimentation of the Illinois River in central Illinois has greatly diminished the utility and ecological value of the Peoria Lakes reach of the river. Consequently, a large dredging project has been proposed to improve its wildlife habitat and recreation potential, but disposal of the dredged sediment presents a challenge. Land placement is an attractive option. Previous work in Illinois has demonstrated that sediments are potentially capable of supporting agronomic crops due to their high natural fertility and water holding capacity. However, Illinois River sediments have elevated levels of heavy metals, which may be important if they are used as garden or agricultural soil. A greenhouse experiment was conducted to determine if these sediments could serve as a plant growth medium. A secondary objective was to determine if plants grown on sediments accumulated significant heavy metal concentrations. Our results indicated that lettuce (Lactuca sativa L.), barley (Hordeum vulgare L.), radish (Raphanus sativus L.), tomato (Lycopersicon lycopersicum L.), and snap bean (Phaseolus vulagaris L. var. humillis) grown in sediment and a reference topsoil did not show significant or consistent differences in germination or yields. In addition, there was not a consistent statistically significant difference in metal content among tomatoes grown in sediments, topsoil, or grown locally in gardens. In the other plants grown on sediments, while Cd and Cu in all cases and As in lettuce and snap bean were elevated, levels were below those considered excessive. Results indicate that properly managed, these relatively uncontaminated calcareous sediments can make productive soils and that metal uptake of plants grown in these sediments is generally not a concern.

Root traits explain observed tundra vegetation nitrogen uptake patterns: Implications for trait-based land models: Tundra N Uptake Model-Data Comparison

DOE PAGES

Zhu, Qing; Iversen, Colleen M.; Riley, William J.; ...

2016-12-23

Ongoing climate warming will likely perturb vertical distributions of nitrogen availability in tundra soils through enhancing nitrogen mineralization and releasing previously inaccessible nitrogen from frozen permafrost soil. But, arctic tundra responses to such changes are uncertain, because of a lack of vertically explicit nitrogen tracer experiments and untested hypotheses of root nitrogen uptake under the stress of microbial competition implemented in land models. We conducted a vertically explicit 15N tracer experiment for three dominant tundra species to quantify plant N uptake profiles. Then we applied a nutrient competition model (N-COM), which is being integrated into the ACME Land Model, tomore » explain the observations. Observations using an 15N tracer showed that plant N uptake profiles were not consistently related to root biomass density profiles, which challenges the prevailing hypothesis that root density always exerts first-order control on N uptake. By considering essential root traits (e.g., biomass distribution and nutrient uptake kinetics) with an appropriate plant-microbe nutrient competition framework, our model reasonably reproduced the observed patterns of plant N uptake. Additionally, we show that previously applied nutrient competition hypotheses in Earth System Land Models fail to explain the diverse plant N uptake profiles we observed. These results cast doubt on current climate-scale model predictions of arctic plant responses to elevated nitrogen supply under a changing climate and highlight the importance of considering essential root traits in large-scale land models. Finally, we provided suggestions and a short synthesis of data availability for future trait-based land model development.« less

Root traits explain observed tundra vegetation nitrogen uptake patterns: Implications for trait-based land models: Tundra N Uptake Model-Data Comparison

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

Zhu, Qing; Iversen, Colleen M.; Riley, William J.

Ongoing climate warming will likely perturb vertical distributions of nitrogen availability in tundra soils through enhancing nitrogen mineralization and releasing previously inaccessible nitrogen from frozen permafrost soil. But, arctic tundra responses to such changes are uncertain, because of a lack of vertically explicit nitrogen tracer experiments and untested hypotheses of root nitrogen uptake under the stress of microbial competition implemented in land models. We conducted a vertically explicit 15N tracer experiment for three dominant tundra species to quantify plant N uptake profiles. Then we applied a nutrient competition model (N-COM), which is being integrated into the ACME Land Model, tomore » explain the observations. Observations using an 15N tracer showed that plant N uptake profiles were not consistently related to root biomass density profiles, which challenges the prevailing hypothesis that root density always exerts first-order control on N uptake. By considering essential root traits (e.g., biomass distribution and nutrient uptake kinetics) with an appropriate plant-microbe nutrient competition framework, our model reasonably reproduced the observed patterns of plant N uptake. Additionally, we show that previously applied nutrient competition hypotheses in Earth System Land Models fail to explain the diverse plant N uptake profiles we observed. These results cast doubt on current climate-scale model predictions of arctic plant responses to elevated nitrogen supply under a changing climate and highlight the importance of considering essential root traits in large-scale land models. Finally, we provided suggestions and a short synthesis of data availability for future trait-based land model development.« less

Single particle ICP-MS method development for the determination of plant uptake and accumulation of CeO2 nanoparticles.

PubMed

Dan, Yongbo; Ma, Xingmao; Zhang, Weilan; Liu, Kun; Stephan, Chady; Shi, Honglan

2016-07-01

Cerium dioxide nanoparticles (CeO2NPs) are among the most broadly used engineered nanoparticles that will be increasingly released into the environment. Thus, understanding their uptake, transportation, and transformation in plants, especially food crops, is critical because it represents a potential pathway for human consumption. One of the primary challenges for the endeavor is the inadequacy of current analytical methodologies to characterize and quantify the nanomaterial in complex biological samples at environmentally relevant concentrations. Herein, a method was developed using single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) technology to simultaneously detect the size and size distribution of particulate Ce, particle concentration, and dissolved cerium in the shoots of four plant species including cucumber, tomato, soybean, and pumpkin. An enzymatic digestion method with Macerozyme R-10 enzyme previously used for gold nanoparticle extraction from the tomato plant was adapted successfully for CeO2NP extraction from all four plant species. This study is the first to report and demonstrate the presence of dissolved cerium in plant seedling shoots exposed to CeO2NPs hydroponically. The extent of plant uptake and accumulation appears to be dependent on the plant species, requiring further systematic investigation of the mechanisms.

Uptake of 17β-trenbolone and subsequent metabolite trendione by the pinto bean plant (Phaseolus vulgaris).

PubMed

Blackwell, B R; Karnjanapiboonwong, A; Anderson, T A; Smith, P N

2012-11-01

Manure from livestock feeding operations is commonly applied to agricultural fields as an alternative to commercial fertilizers. Trenbolone acetate (TbA) is a synthetic growth promoter frequently utilized in beef cattle feeding operations. Metabolites of TbA can be present in manure and subsequently applied to fields. Fate ofTbA metabolites 17β-trenbolone (17βTb), 17α-trenbolone (17αTb), and trendione (TbO) have been assessed in manure and soils, but plant uptake in agricultural fields is not fully understood. The objective of this study was to investigate potential plant uptake and biotransformation of 17βTb using the pinto bean plant (Phaseolus vulgaris). Vegetated (n=20) and control sands (n=16) were amended with 17βTb at a level of 1μg/g once per week for a total of four weeks. Sand, above-ground plant portion and below-ground plant portion were collected each week and then analyzed for 17βTb, 17αTb, and TbO. By week four, low concentrations of 17βTb (10±4.9μg/g fresh weight) were taken up into the roots of plants and, to a much lesser extent, translocated throughout the plant (0.04±0.02μg/g fresh weight). Extensive transformation of 17βTb to the metabolite trendione (TbO) occurred in vegetated sand, while minimal TbO was detected in control sand. These results suggest the biotransformation of 17βTb to TbO is predominantly through microbial degradation. Trenbolone (Tb) metabolites can then be taken up into plants but remain concentrated in the roots with only slight translocation to above ground portions of the plant. After four weeks, maximum observed concentrations of total Tb (parent+metabolites) in fresh plant tissues were 33.0μg/g in roots and 0.25μg/g in leaves. No phytotoxicity was observed to pinto bean plants throughout the four week study. Copyright © 2012 Elsevier Inc. All rights reserved.

Siderophores mediate reduced and increased uptake of cadmium by Streptomyces tendae F4 and sunflower (Helianthus annuus), respectively.

PubMed

Dimkpa, C O; Merten, D; Svatos, A; Büchel, G; Kothe, E

2009-11-01

As a toxic metal, cadmium (Cd) affects microbial and plant metabolic processes, thereby potentially reducing the efficiency of microbe or plant-mediated remediation of Cd-polluted soil. The role of siderophores produced by Streptomyces tendae F4 in the uptake of Cd by bacteria and plant was investigated to gain insight into the influence of siderophores on Cd availability to micro-organisms and plants. The bacterium was cultured under siderophore-inducing conditions in the presence of Cd. The kinetics of siderophore production and identification of the siderophores and their metal-bound forms were performed using electrospray ionization mass spectrometry. Inductively coupled plasma spectroscopy was used to measure iron (Fe) and Cd contents in the bacterium and in sunflower plant grown in Cd-amended soil. Siderophores significantly reduced the Cd uptake by the bacterium, while supplying it with iron. Bacterial culture filtrates containing three hydroxamate siderophores secreted by S. tendae F4 significantly promoted plant growth and enhanced uptake of Cd and Fe by the plant, relative to the control. Furthermore, application of siderophores caused slightly more Cd, but similar Fe uptake, compared with EDTA. Bioinoculation with Streptomyces caused a dramatic increase in plant Fe content, but resulted only in slight increase in plant Cd content. It is concluded that siderophores can help reduce toxic metal uptake in bacteria, while simultaneously facilitating the uptake of such metals by plants. Also, EDTA is not superior to hydroxamate siderophores in terms of metal solubilization for plant uptake. The study showed that microbial processes could indirectly influence the availability and amount of toxic metals taken up from the rhizosphere of plants. Furthermore, although EDTA is used for chelator-enhanced phytoremediation, microbial siderophores would be ideal for this purpose.

Phytoremediation of Metal Contaminated Soil Using Willow: Exploiting Plant-Associated Bacteria to Improve Biomass Production and Metal Uptake.

PubMed

Janssen, Jolien; Weyens, Nele; Croes, Sarah; Beckers, Bram; Meiresonne, Linda; Van Peteghem, Pierre; Carleer, Robert; Vangronsveld, Jaco

2015-01-01

Short rotation coppice (SRC) of willow and poplar is proposed for economic valorization and concurrently as remediation strategy for metal contaminated land in northeast-Belgium. However, metal phytoextraction appears insufficient to effectuate rapid reduction of soil metal contents. To increase both biomass production and metal accumulation of SRC, two strategies are proposed: (i) in situ selection of the best performing clones and (ii) bioaugmentation of these clones with beneficial plant-associated bacteria. Based on field data, two experimental willow clones, a Salix viminalis and a Salix alba x alba clone, were selected. Compared to the best performing commercial clones, considerable increases in stem metal extraction were achieved (up to 74% for Cd and 91% for Zn). From the selected clones, plant-associated bacteria were isolated and identified. All strains were subsequently screened for their plant growth-promoting and metal uptake enhancing traits. Five strains were selected for a greenhouse inoculation experiment with the selected clones planted in Cd-Zn-Pb contaminated soil. Extraction potential tended to increase after inoculation of S. viminalis plants with a Rahnella sp. strain due to a significantly increased twig biomass. However, although bacterial strains showing beneficial traits in vitro were used for inoculation, increments in extraction potential were not always observed.

Trace metal uptake by garden herbs and vegetables.

PubMed

Shariatpanahi, M; Anderson, A C; Mather, F

1986-12-01

In many regions of Iran, crops are irrigated with municipal and industrial wastewater that contain a variety of metals. The purpose of this study was to simulate the level of metals that may be presented to plants over a growing season in a controlled laboratory setting. Cadmium, lead, arsenic, chromium, mercury, nickel, copper, zinc, and selenium were applied to plants at the high rate of 200 g metal/ha/wk. The following plants were examined for metal accumulation and effects on yield: garden cress (Lipidium sativum), leek (Allium porrum L.), basil (Ocimum basilicum L.), mint (Mentha arvensis L.), onion (Allium capa L.), radish (Raphanus sativus L.), and tarragon (Artemisia draculus L.). All plants showed significant uptake of all metals when compared to control (p=0.05), and growth was significantly reduced (p=0.05). Cadmium and chromium levels of 85±7.4 and 47.6±8.9 μg/g); selenium levels were highest in tarragon (16.5±5.8 μg/g). Zinc levels were similar (p=0.05) in all species tested, as were mercury and lead. The remaining metals (nickel and copper) showed significant differences in uptake, depending on plant species.

Uptake of NO, NO 2 and O 3 by sunflower ( Helianthus annuus L.) and tobacco plants ( Nicotiana tabacum L.): dependence on stomatal conductivity

NASA Astrophysics Data System (ADS)

Neubert, A.; Kley, D.; Wildt, J.; Segschneider, H. J.; Förstel, H.

The uptake of NO, NO 2 and O 3 by sunflowers ( Helianthus annuus L. var. giganteus) and tobacco plants ( Nicotiana tabacum L. var. Bel W3), using concentrations representative for moderately polluted air, has been determined by gas exchange experiments. Conductivities for these trace gases were measured at different light fluxes ranging from 820 μEm -2s -1 to darkness. The conductivities to water vapor and the trace gases are highly correlated. It is concluded that the uptake of NO, NO 2 and O 3 by sunflowers and tobacco plants is linearly dependent on stomatal opening. While the uptake of NO is limited by the mesophyll resistance, the uptake of NO 2 is only by diffusion through the stomata. Loss processes by deposition to the leaf surfaces are more pronounced for O 3 than for NO and NO 2.

Comparative uptake of trace elements in vines and olive trees over calcareous soils in western La Mancha

NASA Astrophysics Data System (ADS)

Ángel Amorós, José; Higueras, Pablo; Pérez-de-los-Reyes, Caridad; Jesús García, Francisco; Villaseñor, Begoña; Bravo, Sandra; Losilla, María Luisa; María Moreno, Marta

2014-05-01

Grapevine (Vitis vinifera L.) and olive-tree (Olea europea L.) are very important cultures in Castilla-La Mancha for its extension and contribution to the regional economy. This study was carried out in the municipality of Carrión de Calatrava (Ciudad Real) where the variability of soils of different geological origin, with different evolutions giving a great diversity of soils. The metabolism of trace elements in plants has been extensively studied although each soil-plant system must be investigated, especially since small variations in composition can lead to marked differences. It can be stated that the composition of the plant reflects the environment where it is cultivated and the products of the plant (leaves, fruits, juices, etc…) will be influenced by the composition of the soil. The main aim of the work was to compare the uptake of 24 trace elements in grapevine and olive-tree cultivated in the same soil. Samples from surface soils and plant material (leaf) have been analyzed by X-ray fluorescence, obtaining trace elements in mg/kg. It can be concluded that the leaves of grapevines in the studied plots have shown content in elements: -Similar to the olive-tree in case of: Co, Ga, Y, Ta, Th, U y Nd. -Over to the olive-tree in: Sc, V, Cr, Ni, Rb, Sr, Zr, Nb, Ba, La, Ce, Hf y W. -Below to the olive-tree in: Cu, Zn, Cs y Pb. Keywords: woody culture soils, mineral nutrition, X-ray fluorescence.

Uptake, degradation and chiral discrimination of N-acyl-D/L-homoserine lactones by barley (Hordeum vulgare) and yam bean (Pachyrhizus erosus) plants.

PubMed

Götz, Christine; Fekete, Agnes; Gebefuegi, Istvan; Forczek, Sándor T; Fuksová, Kvetoslava; Li, Xiaojing; Englmann, Matthias; Gryndler, Milan; Hartmann, Anton; Matucha, Miroslav; Schmitt-Kopplin, Philippe; Schröder, Peter

2007-11-01

Bacterial intraspecies and interspecies communication in the rhizosphere is mediated by diffusible signal molecules. Many Gram-negative bacteria use N-acyl-homoserine lactones (AHLs) as autoinducers in the quorum sensing response. While bacterial signalling is well described, the fate of AHLs in contact with plants is much less known. Thus, adsorption, uptake and translocation of N-hexanoyl- (C6-HSL), N-octanoyl- (C8-HSL) and N-decanoyl-homoserine lactone (C10-HSL) were studied in axenic systems with barley (Hordeum vulgare L.) and the legume yam bean (Pachyrhizus erosus (L.) Urban) as model plants using ultra-performance liquid chromatography (UPLC), Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tritium-labelled AHLs. Decreases in AHL concentration due to abiotic adsorption or degradation were tolerable under the experimental conditions. The presence of plants enhanced AHL decline in media depending on the compounds' lipophilicity, whereby the legume caused stronger AHL decrease than barley. All tested AHLs were traceable in root extracts of both plants. While all AHLs except C10-HSL were detectable in barley shoots, only C6-HSL was found in shoots of yam bean. Furthermore, tritium-labelled AHLs were used to determine short-term uptake kinetics. Chiral separation by GC-MS revealed that both plants discriminated D-AHL stereoisomers to different extents. These results indicate substantial differences in uptake and degradation of different AHLs in the plants tested.

Phytotoxicity and uptake of roxarsone by wheat (Triticum aestivum L.) seedlings.

PubMed

Fu, Qing-Long; Blaney, Lee; Zhou, Dong-Mei

2016-12-01

Roxarsone (ROX), the primary aromatic arsenical additive (AAA) used in animal feeding operations, is of increasing concern to environmental and human health due to land application of ROX-laden animal manure. Few studies have investigated the phytotoxicity, uptake mechanisms, and speciation of AAA in crop plants. In this study, wheat seedlings were employed to address these issues under hydroponic conditions. Compared to inorganic arsenic, ROX was less toxic to wheat root elongation. Wheat roots were more sensitive to ROX stress than shoots. For the first time, metabolized inorganic arsenic was detected in plants, although ROX was the predominant detected arsenic species in wheat seedlings. ROX uptake and toxicity to roots were inhibited by humic acid at concentrations higher than 50 mg/L due to interaction with ROX. Phosphate enhanced ROX uptake, but no trends were observed for ROX uptake in the presence of glycerol at concentrations lower than 250 mM. In addition, ROX uptake was significantly decreased by silicate (Si(IV), 0.5-10 mM) and the metabolic inhibitor, 2,4-dinitrophenol (0.5-2 mM), indicating that ROX transport into wheat roots was actively mediated by Si(IV)-sensitive transporters. These findings provide important insights into the fate and speciation of AAA in soil-water-plant systems relevant to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Uptake coefficients for biosolids-amended dryland winter wheat

USDA-ARS?s Scientific Manuscript database

Biosolids regulations developed in the United States employed risk assessment impacts of trace element additions on plant uptake. The US Environmental Protection Agency adapted the uptake coefficient (ratio of plant concentration to quantity of element added) when developing limitations on selected...

Modelling water uptake efficiency of root systems

NASA Astrophysics Data System (ADS)

Leitner, Daniel; Tron, Stefania; Schröder, Natalie; Bodner, Gernot; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry; Schnepf, Andrea

2016-04-01

Water uptake is crucial for plant productivity. Trait based breeding for more water efficient crops will enable a sustainable agricultural management under specific pedoclimatic conditions, and can increase drought resistance of plants. Mathematical modelling can be used to find suitable root system traits for better water uptake efficiency defined as amount of water taken up per unit of root biomass. This approach requires large simulation times and large number of simulation runs, since we test different root systems under different pedoclimatic conditions. In this work, we model water movement by the 1-dimensional Richards equation with the soil hydraulic properties described according to the van Genuchten model. Climatic conditions serve as the upper boundary condition. The root system grows during the simulation period and water uptake is calculated via a sink term (after Tron et al. 2015). The goal of this work is to compare different free software tools based on different numerical schemes to solve the model. We compare implementations using DUMUX (based on finite volumes), Hydrus 1D (based on finite elements), and a Matlab implementation of Van Dam, J. C., & Feddes 2000 (based on finite differences). We analyse the methods for accuracy, speed and flexibility. Using this model case study, we can clearly show the impact of various root system traits on water uptake efficiency. Furthermore, we can quantify frequent simplifications that are introduced in the modelling step like considering a static root system instead of a growing one, or considering a sink term based on root density instead of considering the full root hydraulic model (Javaux et al. 2008). References Tron, S., Bodner, G., Laio, F., Ridolfi, L., & Leitner, D. (2015). Can diversity in root architecture explain plant water use efficiency? A modeling study. Ecological modelling, 312, 200-210. Van Dam, J. C., & Feddes, R. A. (2000). Numerical simulation of infiltration, evaporation and shallow

Toxicity of arsenic (III) and (V) on plant growth, element uptake, and total amylolytic activity of mesquite (Prosopis juliflora x P. velutina).

PubMed

Mokgalaka-Matlala, Ntebogeng S; Flores-Tavizón, Edith; Castillo-Michel, Hiram; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2008-01-01

The effects of arsenite [As(III)] and arsenate [As(V)] on the growth of roots, stems, and leaves and the uptake of arsenic (As), micro- and macronutrients, and total amylolytic activity were investigated to elucidate the phytotoxicity of As to the mesquite plant (Prosopis juliflora x P. velutina). The plant growth was evaluated by measuring the root and shoot length, and the element uptake was determined using inductively coupled plasma optical emission spectroscopy. The root and leaf elongation decreased significantly with increasing As(III) and As(V) concentrations; whereas, stem elongation remained unchanged. The As uptake increased with increasing As(III) or As(V) concentrations in the medium. Plants treated with 50 mg/L As(III) accumulated up to 920 mg/kg dry weight (d wt) in roots and 522 mg/kg d wt in leaves, while plants exposed to 50 mg/L As(V) accumulated 1980 and 210 mg/kg d wt in roots and leaves, respectively. Increasing the As(V) concentration up to 20 mg/L resulted in a decrease in the total amylolytic activity. On the contrary, total amylolytic activity in As(III)-treated plants increased with increasing As concentration up to 20 mg/L. The macro- and micronutrient concentrations changed in As-treated plants. In shoots, Mo and K were reduced but Ca was increased, while in roots Fe and Ca were increased but K was reduced. These changes reduced the size of the plants, mainly in the As(III)-treated plants; however, there were no visible sign of As toxicity.

Uptake and effects of a mixture of widely used therapeutic drugs in Eruca sativa L. and Zea mays L. plants.

PubMed

Marsoni, Milena; De Mattia, Fabrizio; Labra, Massimo; Bruno, Antonia; Bracale, Marcella; Vannini, Candida

2014-10-01

Pharmaceutically active compounds (PACs) are continuously dispersed into the environment due to human and veterinary use, giving rise to their potential accumulation in edible plants. In this study, Eruca sativa L. and Zea mays L. were selected to determine the potential uptake and accumulation of eight different PACs (Salbutamol, Atenolol, Lincomycin, Cyclophosphamide, Carbamazepine, Bezafibrate, Ofloxacin and Ranitidine) designed for human use. To mimic environmental conditions, the plants were grown in pots and irrigated with water spiked with a mixture of PACs at concentrations found in Italian wastewaters and rivers. Moreover, 10× and 100× concentrations of these pharmaceuticals were also tested. The presence of the pharmaceuticals was tested in the edible parts of the plants, namely leaves for E. sativa and grains for Z. mays. Quantification was performed by liquid chromatography mass spectroscopy (LC/MS/MS). In the grains of 100× treated Z. mays, only atenolol, lincomycin and carbamazepine were above the limit of detection (LOD). At the same concentration in E. sativa plants the uptake of all PACs was >LOD. Lincomycin and oflaxacin were above the limit of quantitation in all conditions tested in E. sativa. The results suggest that uptake of some pharmaceuticals from the soil may indeed be a potential transport route to plants and that these environmental pollutants can reach different edible parts of the selected crops. Measurements of the concentrations of these pharmaceuticals in plant materials were used to model potential adult human exposure to these compounds. The results indicate that under the current experimental conditions, crops exposed to the selected pharmaceutical mixture would not have any negative effects on human health. Moreover, no significant differences in the growth of E. sativa or Z. mays plants irrigated with PAC-spiked vs. non-spiked water were observed. Copyright © 2014 Elsevier Inc. All rights reserved.

Is there a strategy I iron uptake mechanism in maize?

PubMed

Li, Suzhen; Zhou, Xiaojin; Chen, Jingtang; Chen, Rumei

2018-04-03

Iron is a metal micronutrient that is essential for plant growth and development. Graminaceous and nongraminaceous plants have evolved different mechanisms to mediate Fe uptake. Generally, strategy I is used by nongraminaceous plants like Arabidopsis, while graminaceous plants, such as rice, barley, and maize, are considered to use strategy II Fe uptake. Upon the functional characterization of OsIRT1 and OsIRT2 in rice, it was suggested that rice, as an exceptional graminaceous plant, utilizes both strategy I and strategy II Fe uptake systems. Similarly, ZmIRT1 and ZmZIP3 were identified as functional zinc and iron transporters in the maize genome, along with the determination of several genes encoding Zn and Fe transporters, raising the possibility that strategy I Fe uptake also occurs in maize. This mini-review integrates previous reports and recent evidence to obtain a better understanding of the mechanisms of Fe uptake in maize.

Elevated CO2 plus chronic warming reduce nitrogen uptake and levels or activities of nitrogen-uptake and -assimilatory proteins in tomato roots.

PubMed

Jayawardena, Dileepa M; Heckathorn, Scott A; Bista, Deepesh R; Mishra, Sasmita; Boldt, Jennifer K; Krause, Charles R

2017-03-01

Atmospheric CO 2 enrichment is expected to often benefit plant growth, despite causing global warming and nitrogen (N) dilution in plants. Most plants primarily procure N as inorganic nitrate (NO 3 - ) or ammonium (NH 4 + ), using membrane-localized transport proteins in roots, which are key targets for improving N use. Although interactive effects of elevated CO 2 , chronic warming and N form on N relations are expected, these have not been studied. In this study, tomato (Solanum lycopersicum) plants were grown at two levels of CO 2 (400 or 700 ppm) and two temperature regimes (30 or 37°C), with NO 3 - or NH 4 + as the N source. Elevated CO 2 plus chronic warming severely inhibited plant growth, regardless of N form, while individually they had smaller effects on growth. Although %N in roots was similar among all treatments, elevated CO 2 plus warming decreased (1) N-uptake rate by roots, (2) total protein concentration in roots, indicating an inhibition of N assimilation and (3) shoot %N, indicating a potential inhibition of N translocation from roots to shoots. Under elevated CO 2 plus warming, reduced NO 3 - -uptake rate per g root was correlated with a decrease in the concentration of NO 3 - -uptake proteins per g root, reduced NH 4 + uptake was correlated with decreased activity of NH 4 + -uptake proteins and reduced N assimilation was correlated with decreased concentration of N-assimilatory proteins. These results indicate that elevated CO 2 and chronic warming can act synergistically to decrease plant N uptake and assimilation; hence, future global warming may decrease both plant growth and food quality (%N). © 2016 Scandinavian Plant Physiology Society.

Nucleic acids encoding metal uptake transporters and their uses

DOEpatents

Schroeder, Julian I.; Antosiewicz, Danuta M.; Schachtman, Daniel P.; Clemens, Stephan

1999-01-01

The invention provides LCT1 nucleic acids which encode metal ion uptake transporters. The invention also provides methods of modulating heavy metal and alkali metal uptake in plants. The methods involve producing transgenic plants comprising a recombinant expression cassette containing an LCT1 nucleic acid linked to a plant promoter.

Models for root water uptake under deficit irrigation

NASA Astrophysics Data System (ADS)

Lazarovitch, Naftali; Krounbi, Leilah; Simunek, Jirka

2010-05-01

Modern agriculture, with its dependence on irrigation, fertilizers, and pesticide application, contributes significantly to the water and solute influx through the soil into the groundwater, specifically in arid areas. The quality and quantity of this water as it passes through the vadose zone is influenced primarily by plant roots. Root water uptake is a function of both a physical root parameter, commonly referred to as the root length density, and the soil water status. The location of maximum water uptake in a homogenous soil profile of uniform water content and hydraulic conductivity occurs in the soil layer containing the largest root length density. Under field conditions, in a drying soil, plants are both subject to, and the source of, great spatial variability in the soil water content. The upper soil layers containing the bulk of the root zone are usually the most water depleted, while the deeper regions of the soil profile containing fewer roots are wetter. Changes in the physiological functioning of plants have been shown to result from extended periods of water stress, but the short term effects of water stress on root water uptake are less well understood. While plants can minimize transpiration and the resulting growth rates under limiting conditions to conserve water, many plants maintain a constant potential transpiration rate long after the commencement of the drying process. Compensatory uptake, whereby plants respond to non-uniform, limiting conditions by increasing water uptake from areas in the root zone characterized by more favorable conditions, is one such mechanism by which plants sustain potential transpiration rates in drying soils. The development of models which accurately characterize temporal and spatial root water uptake patterns is important for agricultural resource optimization, upon which subsequent management decisions affecting resource conservation and environmental pollution are based. Numerical simulations of root water

Impacts of industrial waste resources on maize (Zea mays L.) growth, yield, nutrients uptake and soil properties.

PubMed

Singh, Satnam; Young, Li-Sen; Shen, Fo-Ting; Young, Chiu-Chung

2014-10-01

Discharging untreated highly acidic (pH<4.0), organic and nutrients rich monosodium glutamate wastewater (MW), and highly alkaline (pH>10.0) paper-mill wastewater (PW) causes environmental pollution. When acidity of MW neutralized (pH 6.5±0.1) with PW and lime (treatments represented as MW+PW and MW+Lime), then MW may be utilized as a potential source of nutrients and organic carbon for sustainable food production. Objectives of this study were to compare the effects of PW and lime neutralized MW and chemical fertilizers on maize (Zea mays L. cv. Snow Jean) plant growth, yield, nutrients uptake, soil organic matter and humic substances. The field experiment was carried out on maize using MW at 6000 L ha(-1). Impacts of the MW application on maize crop and soil properties were evaluated at different stages. At harvest, plant height, and plant N and K uptake were higher in MW treatment. Leaf area index at 60 days after sowing, plant dry matter accumulation at harvest, and kernels ear(-1) and 100-kernel weight were higher in MW+Lime treatment. Kernel N, P, K, Mn, Fe and Zn, and plant Zn uptake were highest in MW+Lime. Plant Fe uptake, and soil organic matter and humic substances were highest in MW+PW. The MW+PW and MW+Lime treatments exhibited comparable results with chemically fertilized treatment. The MW acidity neutralized with lime showed positive impacts on growth, yield and nutrients uptake; nevertheless, when MW pH neutralized with PW has an additional benefit on increase in soil organic matter and humic substances. Copyright © 2014. Published by Elsevier Ltd.

Effects of sewage sludge on Di-(2-ethylhexyl) phthalate uptake by plants. [Lactuca sativa L. ; Daucus carota L. ; Capsicum annuum L. ; Festuca arundinacea Schreb

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

Aranda, J.M.; O'Connor, G.A.; Eiceman, G.A.

Di-(2-ethylhexyl) phthalate (DEHP) is a priority organic pollutant frequently found in municipal sludges. A greenhouse study was conducted to determine the effect of sludge on plant uptake of {sup 14}C-DEHP (carbonyl labeled). Plants grown included three food chain crops, lettuce (Lactuca sativa L.), carrot (Daucus carota L.) and chile pepper (Capsicum annuum L.) and tall fescue (Festuca arundinacea Schreb.). Net {sup 14}C concentration in plants grown in soil amended with {sup 14}C-DEHP-contaminated sludge was independent of sludge rate (at the same DEHP loading) for lettuce, chile fruit, and carrot roots. Net {sup 14}C concentration, however, was inversely related to sludgemore » rate in carrot tops, fescue, and chile plants. Intact DEHP was not detected in plants by gas chromatography/mass spectrometry analysis. Calculated plant DEHP concentrations (based on measured net {sup 14}C concentrations and DEHP specific activities) were generally correlated better with DEHP soil solution concentrations than with total DEHP soil concentrations. Net {sup 14}C-DEHP bioconcentration factors were calculated from initial soil DEHP concentration and plant fresh weights. Bioconcentration factors ranged from 0.01 to 0.03 for fescue, lettuce, carrots, and chile, suggesting little DEHP uptake. Additionally, because intact DEHP was not detected in any plants, DEHP uptake by plants was of minor importance and would not limit sludge additions to soils used to grow these crops.« less

Symptomatic rotator cuff tears show higher radioisotope uptake on bone scintigraphy compared with asymptomatic tears.

PubMed

Koike, Yoichi; Sano, Hirotaka; Kita, Atushi; Itoi, Eiji

2013-09-01

Some patients with rotator cuff tears complain of pain, whereas others are asymptomatic. Previous studies have pointed out the presence of active bone metabolism in the painful shoulder, identified with increased radioisotope uptake during bone scintigraphy. Shoulders with symptomatic rotator cuff tears will demonstrate higher radioisotope uptake than shoulders with asymptomatic tears with bone scintigraphy, reflecting active bone metabolism in symptomatic tears. Cross-sectional study; Level of evidence, 3. The study consisted of 3 groups: patients with symptomatic tears (symptomatic group), patients with asymptomatic tears (asymptomatic group), and controls (no tear group). The symptomatic group consisted of 28 shoulders from 28 patients with symptomatic rotator cuff tears (pain score ≤4 on the University of California, Los Angeles [UCLA] shoulder evaluation form) who underwent bone scintigraphy followed by rotator cuff repair. Of 70 volunteers who had previously undergone bone scintigraphy for diseases unrelated to their shoulder, 34 were selected for the asymptomatic group (pain score ≥8 on the UCLA shoulder form), and 32 were selected for the no tear group. The mean radioisotope uptake in the symptomatic group was significantly higher than that in the asymptomatic group (P = .02) and the no tear group (P = .02). Ten of 28 shoulders (36%) in the symptomatic group showed increased radioisotope uptake exceeding 2 standard deviations from the mean of the no tear group. This percentage was significantly higher when compared with the asymptomatic group (0%) (P < .01). Shoulders with a symptomatic rotator cuff tear showed higher radioisotope uptake on bone scintigraphy than those with an asymptomatic tear. The radioisotope uptake in shoulders with an asymptomatic tear was comparable with that in shoulders without a tear. Positive radioisotope uptake may be associated with pain in a subgroup of patients with rotator cuff tears.

Arabidopsis Transporter MGT6 Mediates Magnesium Uptake and Is Required for Growth under Magnesium Limitation[W

PubMed Central

Mao, Dandan; Chen, Jian; Tian, Lianfu; Liu, Zhenhua; Yang, Lei; Tang, Renjie; Li, Jian; Lu, Changqing; Yang, Yonghua; Shi, Jisen; Chen, Liangbi; Li, Dongping; Luan, Sheng

2014-01-01

Although magnesium (Mg2+) is the most abundant divalent cation in plant cells, little is known about the mechanism of Mg2+ uptake by plant roots. Here, we report a key function of Magnesium Transport6 (MGT6)/Mitochondrial RNA Splicing2-4 in Mg2+ uptake and low-Mg2+ tolerance in Arabidopsis thaliana. MGT6 is expressed mainly in plant aerial tissues when Mg2+ levels are high in the soil or growth medium. Its expression is highly induced in the roots during Mg2+ deficiency, suggesting a role for MGT6 in response to the low-Mg2+ status in roots. Silencing of MGT6 in transgenic plants by RNA interference (RNAi) resulted in growth retardation under the low-Mg2+ condition, and the phenotype was restored to normal growth after RNAi plants were transferred to Mg2+-sufficient medium. RNAi plants contained lower levels of Mg2+ compared with wild-type plants under low Mg2+ but not under Mg2+-sufficient conditions. Further analysis indicated that MGT6 was localized in the plasma membrane and played a key role in Mg2+ uptake by roots under Mg2+ limitation. We conclude that MGT6 mediates Mg2+ uptake in roots and is required for plant adaptation to a low-Mg2+ environment. PMID:24794135

Characterizing the Solid-Solution Coefficient and Plant Uptake Factor of As, Cd and Pb in California Croplands

USDA-ARS?s Scientific Manuscript database

In risk assessment models, the solid-solution partition coefficient (Kd), and plant uptake factor (PUF), are often employed to model the fate and transport of trace elements in soils. The trustworthiness of risk assessments depends on the reliability of the parameters used. In this study, we exami...

Development of accelerated net nitrate uptake. [Zea mays L

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

MacKown, C.T.; McClure, P.R.

1988-05-01

Upon initial nitrate exposure, net nitrate uptake rates in roots of a wide variety of plants accelerate within 6 to 8 hours to substantially greater rates. Effects of solution nitrate concentrations and short pulses of nitrate ({le}1 hour) upon nitrate-induced acceleration of nitrate uptake in maize (Zea mays L.) were determined. Root cultures of dark-grown seedlings, grown without nitrate, were exposed to 250 micromolar nitrate for 0.25 to 1 hour or to various solution nitrate concentration (10-250 micromolar) for 1 hour before returning them to a nitrate-free solution. Net nitrate uptake rates were assayed at various periods following nitrate exposuremore » and compared to rates of roots grown either in the absence of nitrate (CaSO{sub 4}-grown) or with continuous nitrate for at least 20 hours. Three hours after initial nitrate exposure, nitrate pulse treatments increased nitrate uptake rates three- to four-fold compared to the rates of CaSO{sub 4}-grown roots. When cycloheximide (5 micrograms per milliliter) was included during a 1-hour pulse with 250 micromolar nitrate, development of the accelerated nitrate uptake state was delayed. Otherwise, nitrate uptake rates reached maximum values within 6 hours before declining. Maximum rates, however, were significantly less than those of roots exposed continuously for 20, 32, or 44 hours. Pulsing for only 0.25 hour with 250 micromolar nitrate and for 1 hour with 10 micromolar caused acceleration of nitrate uptake, but the rates attained were either less than or not sustained for a duration comparable to those of roots pulsed for 1 hour with 250 micromolar nitrate. These results indicate that substantial development of nitrate-induced accelerated nitrate uptake state can be achieved by small endogenous accumulations of nitrate, which appear to moderate the activity or level of root nitrate uptake.« less

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

Ability of higenamine and related compounds to enhance glucose uptake in L6 cells.

PubMed

Kato, Eisuke; Kimura, Shunsuke; Kawabata, Jun

2017-12-15

β2-Adrenergic receptor (β2AR) agonists are employed as bronchodilators to treat pulmonary disorders, but are attracting attention for their modulation of glucose handling and energy expenditure. Higenamine is a tetrahydroisoquinoline present in several plant species and has β2AR agonist activity, but the involvement of each functional groups in β2AR agonist activity and its effectiveness compared with endogenous catecholamines (dopamine, epinephrine, and norepinephrine) has rarely been studied. Glucose uptake of muscle cells are known to be induced through β2AR activation. Here, the ability to enhance glucose uptake of higenamine was compared with that of several methylated derivatives of higenamine or endogenous catecholamines. We found that: (i) the functional groups of higenamine except for the 4'-hydroxy group are required to enhance glucose uptake; (ii) higenamine shows a comparable ability to enhance glucose uptake with that of epinephrine and norepinephrine; (iii) the S-isomer shows a greater ability to enhance glucose uptake compared with that of the R-isomer. Copyright © 2017 Elsevier Ltd. All rights reserved.

NO3- , PO43- and SO42- deprivation reduced LKT1-mediated low-affinity K+ uptake and SKOR-mediated K+ translocation in tomato and Arabidopsis plants.

PubMed

Ródenas, Reyes; García-Legaz, Manuel Francisco; López-Gómez, Elvira; Martínez, Vicente; Rubio, Francisco; Ángeles Botella, M

2017-08-01

Regulation of essential macronutrients acquisition by plants in response to their availability is a key process for plant adaptation to changing environments. Here we show in tomato and Arabidopsis plants that when they are subjected to NO 3 - , PO 4 3 - and SO 4 2 - deprivation, low-affinity K + uptake and K + translocation to the shoot are reduced. In parallel, these nutritional deficiencies produce reductions in the messenger levels of the genes encoding the main systems for low-affinity K + uptake and K + translocation, i.e. AKT1 and SKOR in Arabidopsis and LKT1 and the tomato homolog of SKOR, SlSKOR in tomato, respectively. The results suggest that the shortage of one nutrient produces a general downregulation of the acquisition of other nutrients. In the case of K + nutrient, one of the mechanisms for such a response resides in the transcriptional repression of the genes encoding the systems for K + uptake and translocation. © 2017 Scandinavian Plant Physiology Society.

Differences in uptake of immunisations and health examinations among refugee children compared to Danish-born children: a cohort study.

PubMed

Moller, Sanne Pagh; Hjern, Anders; Andersen, Anne-Marie Nybo; Norredam, Marie

2016-04-01

Refugee children and their families constitute a vulnerable group regarding health and access to care. In a register-based cohort design, we examined differences in uptake of immunisations and child health examinations between refugee children and Danish-born children, including predictors of uptake among refugee children. Refugee children (n = 16,701) who, between January 1993 and December 2010, obtained residency permits in Denmark were included and matched in a 1:6 ratio on age and sex with Danish-born children (n = 100,206). Personal identification numbers were cross-linked to the National Danish Health Service Register, identifying all contacts for immunisation and child health examinations. We estimated hazard ratios (HR) of uptake. Refugee children had a lower uptake of all immunisations compared to Danish-born children. The lowest uptake was found for immunisation against diphtheria, tetanus, pertussis and polio (HR = 0.50; 95 % confidence interval (CI) 0.48-0.51). Participation in child health examinations was also lower among refugee children with the lowest at the last child health examination at age 5 (HR = 0.48; 95 % CI 0.47-0.50). Adjusting the analysis for parental income increased the HRs by 10-20 %. This Danish register-based study using nationwide data revealed a lower uptake of routine immunisations and child health examinations among refugee children compared to Danish-born children. •Uptake of immunisation and child health examination is associated with low household income, unemployment and low educational status among the parents. •Uptake may be even lower among refugee families as they constitute a vulnerable group regarding access to healthcare. What is New: •Refugee children had lower uptake of immunisations and child health examinations compared to Danish-born children. •Several predictors of uptake were identified including region of origin and duration of residence.

Mannitol alleviates chromium toxicity in wheat plants in relation to growth, yield, stimulation of anti-oxidative enzymes, oxidative stress and Cr uptake in sand and soil media.

PubMed

Adrees, Muhammad; Ali, Shafaqat; Iqbal, Muhammad; Aslam Bharwana, Saima; Siddiqi, Zeenat; Farid, Mujahid; Ali, Qasim; Saeed, Rashid; Rizwan, Muhammad

2015-12-01

Chromium (Cr) is one of the most phytotoxic metals in the agricultural soils and its concentration is continuously increasing mainly through anthropogenic activities. Little is known on the role of mannitol (M) on plant growth and physiology under metal stress. The aim of this study was to investigate the mechanism of growth amelioration and antioxidant enzyme activities in Cr-stressed wheat (Triticum aestivum L. cv. Lasani 2008) by exogenously applied mannitol. For this, wheat seedlings were sown in pots containing soil or sand and subjected to increasing Cr concentration (0, 0.25 and 0.5mM) in the form of of K2Cr2O7 with and without foliar application of 100mM mannitol. Plants were harvested after four months and data regarding growth characteristics, biomass, photosynthetic pigments, and antioxidant enzymes were recorded. Mannitol application increased plant biomass, photosynthetic pigments and antioxidant enzymes while decreased Cr uptake and accumulation in plants as compared to Cr treatments alone. In this study, we observed that M applied exogenously to Cr-stressed wheat plants, which normally cannot synthesize M, improved their Cr tolerance by increasing growth, photosynthetic pigments and enhancing activities of antioxidant enzymes and by decreasing Cr uptake and translocation in wheat plants. From this study, it can be concluded that M could be used to grow crops on marginally contaminated soils for which separate remediation techniques are time consuming and not cost effective. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of elevated CO2 on soil organic matter turnover and plant nitrogen uptake: First results from a dual labeling mesocosm experiment

NASA Astrophysics Data System (ADS)

Eder, Lucia Muriel; Weber, Enrico; Schrumpf, Marion; Zaehle, Sönke

2017-04-01

The response of plant growth to elevated concentrations of CO2 (eCO2) is often constrained by plant nitrogen (N) uptake. To overcome potential N limitation, plants may invest photosynthetically fixed carbon (C) into N acquiring strategies, including fine root biomass, root exudation, or C allocation to mycorrhizal fungi. In turn, these strategies may affect the decomposition of soil organic matter, leading to uncertainties in net effects of eCO2 on C storage. To gain more insight into these plant-soil C-N-interactions, we combined C and N stable isotope labeling in a mesocosm experiment. Saplings of Fagus sylvatica L. were exposed to a 13CO2 enriched atmosphere at near ambient (380 ppm) or elevated (550 ppm) CO2 concentrations for four months of the vegetation period in 2016. Aboveground and belowground net CO2 fluxes were measured separately and the 13C label enabled partitioning of total soil CO2 efflux into old, soil derived and new, plant-derived C. We used ingrowth cores to assess effects of eCO2on belowground C allocation and plant N uptake in more detail and in particular we evaluated the relative importance of ectomycorrhizal associations. In the soil of each sapling, ingrowth cores with different mesh sizes allowed fine roots or only mycorrhizal hyphae to penetrate. In one type of ingrowth core each, we incorporated fine root litter that was enriched in 15N. Additionally, total N uptake was estimated by using 15N enriched saplings and unlabeled control plants. We found that eCO2 increased aboveground net CO2 exchange rates by 19% and total soil respiration by 11%. The eCO2 effect for GPP and also for NPP was positive (+23% and +11%, respectively). By combining gaseous C fluxes with data on new and old C stocks in bulk soil and plants through destructive harvesting in late autumn 2016, we will be able to infer net effects of eCO2 on the fate of C in these mesocosms. Biomass allocation patterns can reveal physiological responses to high C availability under

Uptake, Translocation, Metabolism, and Distribution of Glyphosate in Nontarget Tea Plant (Camellia sinensis L.).

PubMed

Tong, Mengmeng; Gao, Wanjun; Jiao, Weiting; Zhou, Jie; Li, Yeyun; He, Lili; Hou, Ruyan

2017-09-06

The uptake, translocation, metabolism, and distribution behavior of glyphosate in nontarget tea plant were investigated. The negative effects appeared to grown tea saplings when the nutrient solution contained glyphosate above 200 mg L -1 . Glyphosate was highest in the roots of the tea plant, where it was also metabolized to aminomethyl phosphonic acid (AMPA). The glyphosate and AMPA in the roots were transported through the xylem or phloem to the stems and leaves. The amount of AMPA in the entire tea plant was less than 6.0% of the amount of glyphosate. The glyphosate level in fresh tea shoots was less than that in mature leaves at each day. These results indicated that free glyphosate in the soil can be continuously absorbed by, metabolized in, and transported from the roots of the tea tree into edible leaves, and therefore, free glyphosate residues in the soil should be controlled to produce teas free of glyphosate.

Absence of plant uptake and translocation of polybrominated biphenyls (PBBs).

PubMed

Chou, S F; Jacobs, L W; Penner, D; Tiedje, J M

1978-04-01

Studies of polybrominated biphenyl (PBB) uptake by plants have been conducted in hydroponic solutions and in greenhouse experiments with soil. Autoradiograms of corn and soybean seedlings grown in hydroponic solutions showed no translocation of 14C-PBB from 14C-PBB-treated solutions to plant tops or within the leaf from 14C-PBB-treated spots on the upper leaf surface. A significant portion of the 14C-PBB associated with the roots was removed when the roots were dipped in acetone. Three root crops (radishes, carrots, and onions) were grown in two soils, each treated with a mixture of FireMaster BP-6 (PBB) and 14C-PBB to achieve final concentrations of 100 ppm and 100 ppb. All roots showed more PBB when grown in the soil with the lower clay and organic matter content than they did when grown in the soil with more clay and organic matter. In the latter soil (clay loam) no PBB was detected in any roots from the 100 ppb treatment. More PBB was associated with roots of carrot than of radish or onion. Corn leaf whorls containing dust from a PBB contamination soil and washed radishes from a heavily contaminated garden showed no PBB.

Significance of the concentration of chelating ligands on Fe3+-solubility, bioavailability, and uptake in rice plant.

PubMed

Hasegawa, Hiroshi; Rahman, M Mamunur; Kadohashi, Kouta; Takasugi, Yui; Tate, Yousuke; Maki, Teruya; Rahman, M Azizur

2012-09-01

Present study investigated the significance of the concentration of chelating ligand on Fe(3+)-solubility in growth medium and its influence on Fe bioavailability and uptake in rice plant. Rice seedlings were grown in modified Murashige and Skoog (MS) hydroponic growth medium with moderate (250 μM) and high (500 μM) concentrations of ethylenediaminetetraacetate (EDTA) and hydroxyiminodisuccinate (HIDS) under sterile and non-sterile conditions. Concentrations of soluble Fe in the growth medium increased with increasing ligand concentrations, and the growth of rice seedlings was higher at moderate ligand concentration than at control (without chelant) and high ligand concentration. This explains the relationship between Fe solubility and bioavailability in the growth medium, and its effect on Fe uptake in rice plant. Fe exists in the growth medium predominantly as particulate (insoluble) forms at low ligand concentration, and as soluble [Fe(OH)(2+), Fe(OH)(2)(+), Fe-L complex] and apparently soluble (colloidal) forms at moderate ligand concentration. At high ligand concentration, most of the Fe(3+) in the growth medium forms soluble Fe-L complex, however, the bioavailability of Fe from Fe-L complex decreased due to lopsided complex formation equilibrium reaction (CFER) between Fe and the ligands. Also, Fe is solubilized forming stable and soluble Fe-L complex, which is then detached as less stable, but soluble and bioavailable substance(s) after (time-dependent) biodegradation. Therefore- i) ligand concentration and stability constant of Fe-L complex (K(Fe-L)) influence Fe bioavailability and uptake in rice plant, and ii) the biodegradable ligands (e.g., HIDS) would be more effective Fe fertilizer than the environmentally persistent and less biodegradable ligands (e.g., EDTA). Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Mercury uptake and phytotoxicity in terrestrial plants grown naturally in the Gumuskoy (Kutahya) mining area, Turkey.

PubMed

Sasmaz, Merve; Akgül, Bunyamin; Yıldırım, Derya; Sasmaz, Ahmet

2016-01-01

This study investigated mercury (Hg) uptake and transport from the soil to different plant parts by documenting the distribution and accumulation of Hg in the roots and shoots of 12 terrestrial plant species, all of which grow naturally in surface soils of the Gumuskoy Pb-Ag mining area. Plant samples and their associated soils were collected and analyzed for Hg content by ICP-MS. Mean Hg values in the soils, roots, and shoots of all plants were 6.914, 460, and 206 µg kg(-1), respectively and lower than 1. The mean enrichment factors for the roots (ECR) and shoots (ECS) of these plants were 0.06 and 0.09, respectively and lower than 1. These results show that the roots of the studied plants prevented Hg from reaching the aerial parts of the plants. The mean translocation factor (TLF) was 1.29 and higher than 1. The mean TLF values indicated that all 12 plant species had the ability to transfer Hg from the roots to the shoots but that transfer was more efficient in plants with higher ECR and ECS. Therefore, these plants could be useful for the biomonitoring of environmental pollution and for rehabilitating areas contaminated by Hg.

‘And then there were three’: highly efficient uptake of potassium by foliar trichomes of epiphytic bromeliads

PubMed Central

Winkler, Uwe; Zotz, Gerhard

2010-01-01

Background and Aims Vascular epiphytes have to acquire nutrients from atmospheric wash out, stem-flow, canopy soils and trapped litter. Physiological studies on the adaptations to nutrient acquisition and plant utilization of nutrients have focused on phosphorus and nitrogen; potassium, as a third highly abundant nutrient element, has received minor attention. In the present study, potassium uptake kinetics by leaves, within-plant distribution and nutrient accumulation were analysed to gain an improved understanding of physiological adaptations to non-terrestrial nutrient supply of plants. Methods Radioactively labelled 86RbCl was used as an analogue to study uptake kinetics of potassium absorbed from tanks of epiphytes, its plant distribution and the correlation between uptake efficiency and abundance of trichomes, functioning as uptake organs of leaves. Potassium in leaves was additionally analysed by atomic absorption spectroscopy to assess plant responses to potassium deficiency. Key Results Labelled rubidium was taken up from tanks over a wide range of concentrations, 0·01–90 mm, which was achieved by two uptake systems. In four tank epiphytes, the high-affinity transporters had average Km values of 41·2 µm, and the low-affinity transporters average Km values of 44·8 mm. Further analysis in Vriesea splenriet showed that high-affinity uptake of rubidium was an ATP-dependent process, while low-affinity uptake was mediated by a K+-channel. The kinetic properties of both types of transporters are comparable with those of potassium transporters in roots of terrestrial plants. Specific differences in uptake velocities of epiphytes are correlated with the abundance of trichomes on their leaf surfaces. The main sinks for potassium were fully grown leaves. These leaves thus function as internal potassium sources, which allow growth to be maintained during periods of low external potassium availability. Conclusions Vascular epiphytes possess effective mechanisms

Nitrogen uptake by the shoots of smooth cordgrass Spartina alterniflora

USGS Publications Warehouse

Mozdzer, T.J.; Kirwan, M.; McGlathery, K.J.; Zieman, J.C.

2011-01-01

The smooth cordgrass Spartina alterniflora is the foundation species in intertidal salt marshes of the North American Atlantic coast. Depending on its elevation within the marsh, S. alterniflora may be submerged for several hours per day. Previous ecosystem-level studies have demonstrated that S. alterniflora marshes are a net sink for nitrogen (N), and that removal of N from flooding tidal water can provide enough N to support the aboveground biomass. However, studies have not specifically investigated whether S. alterniflora plants assimilate nutrients through their aboveground tissue. We determined in situ foliar and stem N uptake kinetics for 15NH4, 15NO3, and 15N-glycine by artificially flooding plants in a mid-Atlantic salt marsh. To determine the ecological importance of shoot uptake, a model was created to estimate the time of inundation of S. alterniflora in 20 cm height intervals during the growing season. Estimates of inundation time, shoot mass, N uptake rates, and N availability from long-term data sets were used to model seasonal shoot N uptake. Rates of aboveground N uptake rates (leaves + stems) were ranked as follows: NH4 + > glycine > NO3 -. Our model suggests that shoot N uptake may satisfy up to 15% of the growing season N demand in mid-Atlantic salt marshes, with variation depending on plant elevation and water column N availability. However, in eutrophic estuaries, our model indicates the potential of the plant canopy as a nutrient filter, with shoot uptake contributing 66 to 100% of plant N demand. ?? 2011 Inter-Research.

Nitrogen uptake by the shoots of smooth cordgrass Spartina alterniflora

USGS Publications Warehouse

Mozdzer, T.J.; Kirwan, M.; McGlathery, K.J.; Zieman, J.C.

2011-01-01

The smooth cordgrass Spartina alterniflora is the foundation species in intertidal salt marshes of the North American Atlantic coast. Depending on its elevation within the marsh, S. alterniflora may be submerged for several hours per day. Previous ecosystem-level studies have demonstrated that S. alterniflora marshes are a net sink for nitrogen (N), and that removal of N from flooding tidal water can provide enough N to support the aboveground biomass. However, studies have not specifically investigated whether S. alterniflora plants assimilate nutrients through their aboveground tissue. We determined in situ foliar and stem N uptake kinetics for 15NH4, 15NO3, and 15N-glycine by artificially flooding plants in a mid-Atlantic salt marsh. To determine the ecological importance of shoot uptake, a model was created to estimate the time of inundation of S. alterniflora in 20 cm height intervals during the growing season. Estimates of inundation time, shoot mass, N uptake rates, and N availability from long-term data sets were used to model seasonal shoot N uptake. Rates of aboveground N uptake rates (leaves + stems) were ranked as follows: NH4+ > glycine > NO3–. Our model suggests that shoot N uptake may satisfy up to 15% of the growing season N demand in mid-Atlantic salt marshes, with variation depending on plant elevation and water column N availability. However, in eutrophic estuaries, our model indicates the potential of the plant canopy as a nutrient filter, with shoot uptake contributing 66 to 100% of plant N demand.

Foliar uptake of cesium from the water column by aquatic macrophytes.

PubMed

Pinder, J E; Hinton, T G; Whicker, F W

2006-01-01

The probable occurrence and rate of foliar absorption of stable cesium (133Cs) from the water column by aquatic macrophyte species was analyzed following the addition of 133Cs into a small reservoir near Aiken, South Carolina, USA. An uptake parameter u (10(3)Lkg(-1)d(-1)) and a loss rate parameter k (d(-1)) were estimated for each species using time series of 133Cs concentrations in the water and plant tissues. Foliar uptake, as indicated by rapid increases in plant concentrations following the 133Cs addition, occurred in two floating-leaf species, Brasenia schreberi and Nymphaea odorata, and two submerged species, Myriophyllum spicatum and Utricularia inflata. These species had values of u> or =0.75 x 10(3)Lkg(-1)d(-1). Less evidence for foliar uptake was observed in three emergent species, including Typha latifolia. Ratios of u to k for B. schreberi, M. spicatum, N. odorata and U. inflata can be used to estimate concentration ratios (CR) at equilibrium, and these estimates were generally within a factor of 2 of the CR for 137Cs for these species in the same reservoir. This correspondence suggests that foliar uptake of Cs was the principal absorption mechanism for these species. Assessments of: (1) the prevalence of foliar uptake of potassium, rubidium and Cs isotopes by aquatic macrophytes and (2) the possible importance of foliar uptake of Cs in other lentic systems are made from a review of foliar uptake studies and estimation of comparable u and k values from lake studies involving Cs releases.

Root Uptake of Lipophilic Zinc−Rhamnolipid Complexes

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

Stacey, Samuel P.; McLaughlin, Michael J.; Cakmak, Ismail

This study investigated the formation and plant uptake of lipophilic metal-rhamnolipid complexes. Monorhamnosyl and dirhamnosyl rhamnolipids formed lipophilic complexes with copper (Cu), manganese (Mn), and zinc (Zn). Rhamnolipids significantly increased Zn absorption by Brassica napus var. Pinnacle roots in {sup 65}Zn-spiked ice-cold solutions, compared with ZnSO{sub 4} alone. Therefore, rhamnolipid appeared to facilitate Zn absorption via a nonmetabolically mediated pathway. Synchrotron XRF and XAS showed that Zn was present in roots as Zn-phytate-like compounds when roots were treated with Zn-free solutions, ZnSO{sub 4}, or Zn-EDTA. With rhamnolipid application, Zn was predominantly found in roots as the Zn-rhamnolipid complex. When appliedmore » to a calcareous soil, rhamnolipids increased dry matter production and Zn concentrations in durum (Triticum durum L. cv. Balcali-2000) and bread wheat (Triticum aestivum L. cv. BDME-10) shoots. Rhamnolipids either increased total plant uptake of Zn from the soil or increased Zn translocation by reducing the prevalence of insoluble Zn-phytate-like compounds in roots.« less

A comparison of chelator-facilitated metal uptake by a halophyte and a glycophyte.

PubMed

Jordan, Fiona L; Robin-Abbott, Molly; Maier, Raina M; Glenn, Edward P

2002-12-01

Phytoextraction is the use of plants to remove contaminants, in particular metals, from soil via root uptake and translocation to the shoots. Efficient phytoextraction requires high-biomass plants with efficient translocating properties. Halophytes characteristically accumulate large quantities of salts in above ground tissue material and can have high biomass production. It has been speculated that salt-tolerant plants may also be heavy metal tolerant and, further, may be able to accumulate metals. This study compared growth and metal uptake by a halophyte, Atriplex nummularia, and a common glycophyte, Zea mays, in a mine-tailing contaminated soil:mulch mixture. Two chelators, ethylenediaminetetraacetic acid (EDTA) and rhamnolipid, were used to facilitate plant metal uptake. Despite a lower growth rate (2% growth/d) in the contaminated soil, the halophyte accumulated roughly the same amount of metals as the glycophyte on a mass basis (30-40 mg/kg dry wt). Neither plant, however, hyperaccumulated any of the metals tested. When treated with EDTA, specific differences in patterns of metal uptake between the two plants emerged. The halophyte accumulated significantly more Cu (2x) and Pb (1x) in the shoots than the glycophyte, but root metal concentrations were generally higher for the glycophyte, indicating that the halophyte translocated more metal from the root to the shoot than the glycophyte. For example, Zn shoot-to-root ratios ranged from 1.4 to 2.1 for Atriplex and from 0.5 to 0.6 for Z. mays. The biodegradable chelator rhamnolipid was not effective at enhancing shoot metal concentrations, even though radiolabeled chelator was found in the shoot material of both plants. Our results suggest that halophytes, despite their slower growth rates, may have greater potential to selectively phytoextract metals from contaminated soils than glycophytes.

Plant uptake/bioavailability of heavy metals from the contaminated soil after treatment with humus soil and hydroxyapatite.

PubMed

Misra, Virendra; Chaturvedi, Pranav Kumar

2007-10-01

Uptake /bioavailability study using the Indian mustard plant (Brassica juncea) was undertaken at the interval of 7, 14 and 21 days to test the immobilization of heavy metals from contaminated soil that were amended with humus soil and/or hydroxyapatite. For this, four sets consisting of non-humus soil + metals (Cd, Cr, Ni and Pb), humus soil + metals, non-humus and humus soil in the ratio of 1:3 + metals and non-humus soil: humus soil in the ratio of 1:3 + metals + 1% hydroxyapatite were prepared. The bioavailability of Pb, Cd, Cr and Ni in non-humus soil system was 58%, 67%, 65% and 63%, respectively in 7 days, more than 80% in 14 days and more than 90% in 21 days. Use of non-humus, humus soil in the ratio of 1:3 and addition of 1% hydroxyapatite decreased the bioavailability of lead around 21 to 22.5%, Cd 35 to 36%, Cr 25.5 to 26.9%, Ni 34 to 39% in 7, 14 and 21 days. Apart from this increase in the fresh weight of the plant was also noticed during the experiment. The data showed that addition of 1% hydroxyapatite in the non-humus-humus soil system caused the increase in the fresh weight around 90% in 7, 14 and 21 days as compared to plant grown in non-humus and metal soil system.

Sustainable measures for sewage sludge treatment - evaluating the effects on P reaction in soils and plant P uptake

NASA Astrophysics Data System (ADS)

Shenker, Moshe; Einhoren, Hana

2016-04-01

Wastewater treatment, whether for water reusing or for releasing into the environment, results in sewage sludge rich in organic matter and nutrients. If free of pathogens and pollutants, this waste material is a widely used as soil amendment and source of valuable nutrients for agronomic use. Nevertheless, its P/N ratio largely exceeds plant P/N demand. Limiting its application rates according to the P demand of crops will largely limit its application rates and its beneficial effect as a soil amendment and as a source for other nutrients. An alternative approach, in which P is stabilized before application, was evaluated in this study. Anaerobically digested fresh sewage sludge (FSS) was stabilized by aluminum sulfate, ferrous sulfate, and calcium oxide (CaO), as well as by composting with shredded woody yard-waste to produce Al-FSS, Fe-FSS, CaO-FSS, and FSS-compost, respectively. Defined organic-P sources (glucose-1-phosphate and inositol-hexa-phosphate) and a P fertilizer (KH2PO4) were included as well and a control with no P amendments was included as a reference. Each material was applied at a fixed P load of 50 mg kg-1 to each of three soils and P speciation and plants P uptake were tested along 112 days of incubation at moderate (near field capacity) water content. Tomato seedlings were used for the P uptake test. The large set of data was used to evaluate the effect of each treatment on P reactions and mechanisms of retention in the tested soils and to correlate various P indices to P availability for plants. Plant P uptake was highly correlated to Olsen-P as well as to water-soluble inorganic-P, but not to water-soluble organic-P and not to total P or other experimentally-defined stable P fractions. We conclude that the P stabilization in the sludge will allow beneficial and sustainable use of sewage sludge as a soil amendment and source of nutrients, but the stabilization method should be selected in accordance with the target soil properties.

Phytozome Comparative Plant Genomics Portal

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

Goodstein, David; Batra, Sajeev; Carlson, Joseph

2014-09-09

The Dept. of Energy Joint Genome Institute is a genomics user facility supporting DOE mission science in the areas of Bioenergy, Carbon Cycling, and Biogeochemistry. The Plant Program at the JGI applies genomic, analytical, computational and informatics platforms and methods to: 1. Understand and accelerate the improvement (domestication) of bioenergy crops 2. Characterize and moderate plant response to climate change 3. Use comparative genomics to identify constrained elements and infer gene function 4. Build high quality genomic resource platforms of JGI Plant Flagship genomes for functional and experimental work 5. Expand functional genomic resources for Plant Flagship genomes

A meta-analysis of arbuscular mycorrhizal effects on plants grown under salt stress.

PubMed

Chandrasekaran, Murugesan; Boughattas, Sonia; Hu, Shuijin; Oh, Sang-Hyon; Sa, Tongmin

2014-11-01

Salt stress limits crop yield and sustainable agriculture in most arid and semiarid regions of the world. Arbuscular mycorrhizal fungi (AMF) are considered bio-ameliorators of soil salinity tolerance in plants. In evaluating AMF as significant predictors of mycorrhizal ecology, precise quantifiable changes in plant biomass and nutrient uptake under salt stress are crucial factors. Therefore, the objective of the present study was to analyze the magnitude of the effects of AMF inoculation on growth and nutrient uptake of plants under salt stress through meta-analyses. For this, data were compared in the context of mycorrhizal host plant species, plant family and functional group, herbaceous vs. woody plants, annual vs. perennial plants, and the level of salinity across 43 studies. Results indicate that, under saline conditions, AMF inoculation significantly increased total, shoot, and root biomass as well as phosphorous (P), nitrogen (N), and potassium (K) uptake. Activities of the antioxidant enzymes superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase also increased significantly in mycorrhizal compared to nonmycorrhizal plants growing under salt stress. In addition, sodium (Na) uptake decreased significantly in mycorrhizal plants, while changes in proline accumulation were not significant. Across most subsets of the data analysis, identities of AMF (Glomus fasciculatum) and host plants (Acacia nilotica, herbs, woody and perennial) were found to be essential in understanding plant responses to salinity stress. For the analyzed dataset, it is concluded that under salt stress, mycorrhizal plants have extensive root traits and mycorrhizal morphological traits which help the uptake of more P and K, together with the enhanced production of antioxidant enzymes resulting in salt stress alleviation and increased plant biomass.

Using a plant hormone and a thioligand to improve phytoremediation of Hg-contaminated soil from a petrochemical plant.

PubMed

Cassina, L; Tassi, E; Pedron, F; Petruzzelli, G; Ambrosini, P; Barbafieri, M

2012-09-15

Mercury-contaminated soils from a petrochemical plant in southern Italy were investigated to assess the phytoextraction efficiency of crop plants treated with the phytohormone, cytokinine (CK foliar treatment), and with the thioligand, ammonium thiosulfate (TS, soil application). Plant biomass, evapotranspiration, Hg uptake and distribution in plant tissues following treatment were compared. Results indicate the effectiveness of CK in increasing plant biomass and the evapotranspiration rate while TS treatment promoted soil Hg solubility and availability. The simultaneous addition of CK and TS treatments increased Hg uptake and translocation in both tested plants with up to 248 and 232% in Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) respectively. B. juncea was more effective in Hg uptake, whereas H. annuus gave better response regarding plant biomass production. The effectiveness of the treatments was confirmed by the calculation of Hg phytoextraction and evaluation of labile-Hg residue in the soil after plant growth. In one growing cycle the plants subject to simultaneous CK and TS treatment significantly reduced labile-Hg pools that were characterized by the soil sequential extraction, but did not significantly affect the pseudototal metal content in the soil. Results support the use of plant growth regulators in the assisted phytoextraction process for Hg-contaminated soils. Copyright © 2012 Elsevier B.V. All rights reserved.

MIPSPlantsDB—plant database resource for integrative and comparative plant genome research

PubMed Central

Spannagl, Manuel; Noubibou, Octave; Haase, Dirk; Yang, Li; Gundlach, Heidrun; Hindemitt, Tobias; Klee, Kathrin; Haberer, Georg; Schoof, Heiko; Mayer, Klaus F. X.

2007-01-01

Genome-oriented plant research delivers rapidly increasing amount of plant genome data. Comprehensive and structured information resources are required to structure and communicate genome and associated analytical data for model organisms as well as for crops. The increase in available plant genomic data enables powerful comparative analysis and integrative approaches. PlantsDB aims to provide data and information resources for individual plant species and in addition to build a platform for integrative and comparative plant genome research. PlantsDB is constituted from genome databases for Arabidopsis, Medicago, Lotus, rice, maize and tomato. Complementary data resources for cis elements, repetive elements and extensive cross-species comparisons are implemented. The PlantsDB portal can be reached at . PMID:17202173

Quantification of root water uptake in soil using X-ray computed tomography and image-based modelling.

PubMed

Daly, Keith R; Tracy, Saoirse R; Crout, Neil M J; Mairhofer, Stefan; Pridmore, Tony P; Mooney, Sacha J; Roose, Tiina

2018-01-01

Spatially averaged models of root-soil interactions are often used to calculate plant water uptake. Using a combination of X-ray computed tomography (CT) and image-based modelling, we tested the accuracy of this spatial averaging by directly calculating plant water uptake for young wheat plants in two soil types. The root system was imaged using X-ray CT at 2, 4, 6, 8 and 12 d after transplanting. The roots were segmented using semi-automated root tracking for speed and reproducibility. The segmented geometries were converted to a mesh suitable for the numerical solution of Richards' equation. Richards' equation was parameterized using existing pore scale studies of soil hydraulic properties in the rhizosphere of wheat plants. Image-based modelling allows the spatial distribution of water around the root to be visualized and the fluxes into the root to be calculated. By comparing the results obtained through image-based modelling to spatially averaged models, the impact of root architecture and geometry in water uptake was quantified. We observed that the spatially averaged models performed well in comparison to the image-based models with <2% difference in uptake. However, the spatial averaging loses important information regarding the spatial distribution of water near the root system. © 2017 John Wiley & Sons Ltd.

Foliar uptake of fog in coastal California shrub species.

PubMed

Emery, Nathan C

2016-11-01

Understanding plant water uptake is important in ecosystems that experience periodic drought. In many Mediterranean-type climates like coastal California, plants are subject to significant drought and wildfire disturbance. During the dry summer months, coastal shrub species are often exposed to leaf wetting from overnight fog events. This study sought to determine whether foliar uptake of fog occurs in shrub species and how this uptake affects physiology and fuel condition. In a controlled greenhouse experiment, dominant California shrub species were exposed to isotopically labeled fog water and plant responses were measured. Potted plants were covered at the base to prevent root uptake. The deuterium label was detected in the leaves of four out of five species and in the stems of two of the species. While there was a minimal effect of foliar water uptake on live fuel moisture, several species had lower xylem tension and greater photosynthetic rates after overnight fog treatments, especially Salvia leucophylla. Coastal fog may provide a moisture source for many species during the summer drought, but the utilization of this water source may vary based on foliar morphology, phenology and plant water balance. From this study, it appears that drought-deciduous species (Artemisia californica and Salvia leucophylla) benefit more from overnight fog events than evergreen species (Adenostoma fasciculatum, Baccharis pilularis and Ceanothus megacarpus). This differential response to fog exposure among California shrub species may affect species distributions and physiological tolerances under future climate scenarios.

Dependence of Plant Uptake and Diffusion of Polycyclic Aromatic Hydrocarbons on the Leaf Surface Morphology and Micro-structures of Cuticular Waxes

NASA Astrophysics Data System (ADS)

Li, Qingqing; Li, Yungui; Zhu, Lizhong; Xing, Baoshan; Chen, Baoliang

2017-04-01

The uptake of organic chemicals by plants is considered of great significance as it impacts their environmental transport and fate and threatens crop growth and food safety. Herein, the dependence of the uptake, penetration, and distribution of sixteen polycyclic aromatic hydrocarbons (PAHs) on the morphology and micro-structures of cuticular waxes on leaf surfaces was investigated. Plant surface morphologies and wax micro-structures were examined by scanning emission microscopy, and hydrophobicities of plant surfaces were monitored through contact angle measurements. PAHs in the cuticles and inner tissues were distinguished by sequential extraction, and the cuticle was verified to be the dominant reservoir for the accumulation of lipophilic pollutants. The interspecies differences in PAH concentrations cannot be explained by normalizing them to the plant lipid content. PAHs in the inner tissues became concentrated with the increase of tissue lipid content, while a generally negative correlation between the PAH concentration in cuticles and the epicuticular wax content was found. PAHs on the adaxial and abaxial sides of a leaf were differentiated for the first time, and the divergence between these two sides can be ascribed to the variations in surface morphologies. The role of leaf lipids was redefined and differentiated.

Total and Bioaccessible Soil Arsenic and Lead Levels and Plant Uptake in Three Urban Community Gardens in Puerto Rico

EPA Science Inventory

Arsenic (As) and lead (Pb) are two contaminants of concern associated with urban gardening. In Puerto Rico, data currently is limited on As and Pb levels in urban garden soils, soil metal (loid) bioaccessibility, and uptake of As and Pb in soil by edible plants grown in the regio...

Fe uptake from meso and D,L-racemic Fe(o,o-EDDHA) isomers by strategy I and II plants.

PubMed

Cerdán, Mar; Alcañiz, Sara; Juárez, Margarita; Jordá, Juana D; Bermúdez, Dolores

2006-02-22

One of the most efficient fertilizers to correct Fe deficiency in calcareous soils and waters with high bicarbonate content is based on ferric ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid [Fe(o,o-EDDHA)]. Fe(o,o-EDDHA) forms two groups of geometric isomers known as meso and D,L-racemic. To determine the Fe uptake from meso and D,L-racemic Fe(o,o-EDDHA), four iron-efficient plants, two plants representative of strategy I (tomato and pepper) and two plants representative of strategy II (wheat and oats), were grown in hydroponic culture. Results indicated that strategy II plants took up iron from both Fe(o,o-EDDHA) isomers equally. However, strategy I plants took mainly the iron associated with the meso form (the lowest stability isomer).

The roles of nematodes in nitrogen and phosphorous availability, plant uptake and growth in organically amended soils

NASA Astrophysics Data System (ADS)

Gebremikael, Mesfin; Buchan, David; De Neve, Stefaan

2017-04-01

Several studies have shown that soil biota contributes significantly to the crucial ecosystem functions and services such as organic matter decomposition and nutrient cycling. The contribution of each group of soil organisms may vary depending primarily on their feeding behavior. The magnitude of the ecosystem services by the biota may also depend on the interactions amongst the soil biota groups and their surrounding environment, for instance, biochemical characteristics of the externally added organic material. However, only a few studies considered these interactions concurrently. Here, we investigated the effects of fauna-microbe-plant interactions on organic matter decomposition and nutrient cycling by applying different organic materials spanning a range of C:N ratios and presumed N availability. Nematodes were selected as model fauna because they are the most abundant soil metazoans that have a diversified feeding strategy and interact very intimately with microbes, other fauna, and plants. A series of incubation experiments were conducted in bare and planted microcosms under controlled conditions using fresh soil collected from an agricultural field and defaunated by gamma irradiation. In the first experiment without plants, the defaunated soil cores were either left unamended (UNA) or received lignin-rich low N compost (COI), N-rich compost (COV), fresh manure (MAN) or chopped clover (CLO). The entire free-living soil nematode community was extracted from unirradiated fresh soil and reinoculated into half of the soil cores that had been defaunated by gamma irradiation. Two treatments: with (+Nem) and without (-Nem) nematodes were compared for soil nitrogen and phosphorus availability, plant uptake, and PLFA signatures over time during a 105-days incubation. The same experimental setup was used to investigate further the CLO amendment in the presence of plants (rye grass was used as a model plant). Nematodes were extracted and assigned to feeding groups

Arbuscular mycorrhizal fungal hyphae contribute to the uptake of polycyclic aromatic hydrocarbons by plant roots.

PubMed

Gao, Yanzheng; Cheng, Zhaoxia; Ling, Wanting; Huang, Jing

2010-09-01

The arbuscular mycorrhizal (AM) hyphae-mediated uptake of polycyclic aromatic hydrocarbons (PAHs) by the roots of ryegrass (Lolium multiflorum Lam.) was investigated using three-compartment systems. Glomus mosseae and Glomus etunicatum were chosen, and fluorene and phenanthrene were used as representative PAHs. When roots were grown in un-spiked soils, AM hyphae extended into PAH-spiked soil and clearly absorbed and transported PAHs to roots, resulting in high concentrations of fluorene and phenanthrene in roots. This was further confirmed by the batch equilibration experiment, which revealed that the partition coefficients (K(d)) of tested PAHs by mycorrhizal hyphae were 270-356% greater than those by roots, suggesting the great potential of hyphae to absorb PAHs. Because of fluorene's lower molecular weight and higher water solubility, its translocation by hyphae was greater than that of phenanthrene. These results provide new perspectives on the AM hyphae-mediated uptake by plants of organic contaminants from soil. Copyright 2010 Elsevier Ltd. All rights reserved.

Assessment of plant-driven uptake and translocation of clofibric acid by Scirpus validus.

PubMed

Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Ng, Wun Jern; Tan, Soon Keat

2013-07-01

Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L(-1). At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4-26.8 μg g(-1) (fresh weight) were detected in the roots and 7.2-34.6 μg g(-1) (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6-13% for the roots and 22-49% for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground

Growth, cadmium uptake and accumulation of maize (Zea mays L.) under the effects of arbuscular mycorrhizal fungi.

PubMed

Liu, Lingzhi; Gong, Zongqiang; Zhang, Yulong; Li, Peijun

2014-12-01

The effects of three arbuscular mycorrhizal fungi isolates on Cd uptake and accumulation by maize (Zea mays L.) were investigated in a planted pot experiment. Plants were inoculated with Glomus intraradices, Glomus constrictum and Glomus mosseae at three different Cd concentrations. The results showed that root colonization increased with Cd addition during a 6-week growth period, however, the fungal density on roots decreased after 9-week growth in the treatments with G. constrictum and G. mosseae isolates. The percentage of mycorrhizal colonization by the three arbuscular mycorrhizal fungi isolates ranged from 22.7 to 72.3%. Arbuscular mycorrhizal fungi inoculations decreased maize biomass especially during the first 6-week growth before Cd addition, and this inhibitory effect was less significant with Cd addition and growth time. Cd concentrations and uptake in maize plants increased with arbuscular mycorrhizal fungi colonization at low Cd concentration (0.02 mM): nonetheless, it decreased at high Cd concentration (0.20 mM) after 6-week growth period. Inoculation with G. constrictum isolates enhanced the root Cd concentrations and uptake, but G. mosseae isolates showed the opposite results at high Cd concentration level after 9 week growth period, as compared to non-mycorrhizal plants. In conclusion, maize plants inoculated with arbuscular mycorrhizal fungi were less sensitive to Cd stress than uninoculated plants. G. constrictum isolates enhanced Cd phytostabilization and G. mosseae isolates reduced Cd uptake in maize (Z. mays L.).

Grass species influence on plant N uptake - Determination of atmospheric N deposition to a semi-natural peat bog site using a 15N labelling approach

NASA Astrophysics Data System (ADS)

Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

2014-05-01

Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. Our study site - a moderately drained raised bog - is surrounded by highly fertilized agricultural land and livestock production. In this study, we used a 15N pool dilution technique called 'Integrated Total Nitrogen Input' (ITNI) to quantify annual deposition of atmospheric N into biomonitoring pots over a two-year period. Since it considers direct N uptake by plants, it was expected to result in higher N input than conventional methods for determination of N deposition (e.g. micrometeorological approaches, bulk N samplers). Using Lolium multiflorum and Eriophorum vaginatum as monitor plants and low, medium and high levels of fertilization, we aimed to simulate increasing N deposition to planted pots and to allocate airborne N after its uptake by the soil-plant system in aboveground biomass, roots and soil. Increasing N fertilization was positively correlated with biomass production of Eriophorum vaginatum, whereas atmospheric plant N uptake decreased and highest airborne N input of 899.8 ± 67.4 µg N d-1 pot-1 was found for low N fertilization. In contrast, Lolium multiflorum showed a clear dependency of N supply on plant N uptake and was highest (688.7 ± 41.4 µg N d-1 pot-1) for highly fertilized vegetation pots. Our results suggest that grass species respond differently to increasing N input. While crop grasses such as Lolium multiflorum take up N according to N availability, species adopted to nutrient-limited conditions like Eriophorum vaginatum show N saturation effects with increasing N supply. Total airborne N input ranged from about 24 to 66 kg N ha-1 yr-1 dependent on the used indicator plant and the amount of added fertilizer. Parallel determination of atmospheric N deposition using a micrometeorological approach

Total and Bioaccessible Soil Arsenic and Lead Levels and Plant Uptake in Three Urban Community Gardens in Puerto Rico.

PubMed

Misenheimer, John; Nelson, Clay; Huertas, Evelyn; Medina-Vera, Myriam; Prevatte, Alex; Bradham, Karen

2018-01-01

Arsenic (As) and lead (Pb) are two contaminants of concern associated with urban gardening. In Puerto Rico, data currently is limited on As and Pb levels in urban garden soils, soil metal (loid) bioaccessibility, and uptake of As and Pb in soil by edible plants grown in the region. This study examined total and bioaccessible soil As and Pb concentrations and accumulation in 10 commonly grown garden plants collected from three urban community gardens in Puerto Rico. Bioavailability values were predicted using bioaccessibility data to compare site-specific bioavailability estimates to commonly used default exposure assumptions. Total and bioaccessible As levels in study soils ranged from 2 to 55 mg/kg and 1 to 18 mg/kg, respectively. Total and bioaccessible Pb levels ranged from 19 to 172 mg/kg and 17 to 97 mg/kg, respectively. Measured bioaccessibility values corresponded to 19 to 42% bioaccessible As and 61 to 100% bioaccessible Pb when expressed as a percent of total As and Pb respectively. Predicted relative percent bioavailability of soil As and Pb based on measured bioaccessibility values ranged from 18 to 36% and 51 to 85% for As and Pb respectively. Transfer factors (TFs) measuring uptake of As in plants from soil ranged from 0 to 0.073 in the edible flesh (fruit or vegetable) of plant tissues analyzed and 0.073 to 0.444 in edible leaves. Pb TFs ranged from 0.002 to 0.012 in flesh and 0.023 to 0.204 in leaves. Consistent with TF values, leaves accumulated higher concentrations of As and Pb than the flesh, with the highest tissue concentrations observed in the culantro leaf (3.2 mg/kg dw of As and 8.9 mg/kg dw of Pb). Leaves showed a general but not statistically-significant (α = 0.05) trend of increased As and Pb concentration with increased soil levels, while no trend was observed for flesh tissues. These findings provide critical data that can improve accuracy and reduce uncertainty when conducting site-specific risk determination of potential As and Pb

Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species.

PubMed

Greger, Maria; Wang, Yaodong; Neuschütz, Clara

2005-03-01

In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 microg L(-1) Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected.

Influence of low air humidity and low root temperature on water uptake, growth and aquaporin expression in rice plants.

PubMed

Kuwagata, Tsuneo; Ishikawa-Sakurai, Junko; Hayashi, Hidehiro; Nagasuga, Kiyoshi; Fukushi, Keiko; Ahamed, Arifa; Takasugi, Katsuko; Katsuhara, Maki; Murai-Hatano, Mari

2012-08-01

The effects of low air humidity and low root temperature (LRT) on water uptake, growth and aquaporin gene expression were investigated in rice plants. The daily transpiration of the plants grown at low humidity was 1.5- to 2-fold higher than that at high humidity. LRT at 13°C reduced transpiration, and the extent was larger at lower humidity. LRT also reduced total dry matter production and leaf area expansion, and the extent was again larger at lower humidity. These observations suggest that the suppression of plant growth by LRT is associated with water stress due to decreased water uptake ability of the root. On the other hand, the net assimilation rate was not affected by low humidity and LRT, and water use efficiency was larger for LRT. We found that low humidity induced coordinated up-regulation of many PIP and TIP aquaporin genes in both the leaves and the roots. Expression levels of two root-specific aquaporin genes, OsPIP2;4 and OsPIP2;5, were increased significantly after 6 and 13 d of LRT exposure. Taken together, we discuss the possibility that aquaporins are part of an integrated response of this crop to low air humidity and LRT.

Direct uptake of soil nitrogen by mosses

PubMed Central

Ayres, Edward; van der Wal, René; Sommerkorn, Martin; Bardgett, Richard D

2006-01-01

Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques (15N). Both species exhibited increased concentrations of shoot 15N when exposed to either soil- or wet deposition-derived 15N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated. PMID:17148384

Direct uptake of soil nitrogen by mosses.

PubMed

Ayres, Edward; van der Wal, René; Sommerkorn, Martin; Bardgett, Richard D

2006-06-22

Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques (15N). Both species exhibited increased concentrations of shoot 15N when exposed to either soil- or wet deposition-derived 15N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated.

Cyclic variations in nitrogen uptake rate of soybean plants: effects of pH and mixed nitrogen sources

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.; Chaillou, S.

1991-01-01

To determine if the daily pattern of NO3- and NH4+ uptake is affected by acidity or NO3- : NH4+ ratio of the nutrient solution, non-nodulated soybean plants (Glycine max) were exposed for 21 days to replenished, complete nutrient solutions at pH 6.0, 5.5, 5.0, and 4.5 which contained either 1.0 mM NH4+, 1.0 mM NO3- [correction of NO3+], 0.67 mM NH4+ plus 0.33 mM NO3- (2:1 NH4+ : NO3-) [correction of (2:1 NH3+ : NO4-)], or 0.33 mM NH4+ plus 0.67 mM NO3- (1:2 NH4+ : NO3-). Net uptake rates of NH4+ and NO3- were measured daily by ion chromatography as depletion from the replenished solutions. When NH4+ and NO3- were supplied together, cumulative uptake of total nitrogen was not affected by pH or solution NH4+ : NO3- ratio. The cumulative proportion of nitrogen absorbed as NH4+ decreased with increasing acidity; however, the proportional uptake of NH4+ and NO3- was not constant, but varied day-to-day. This day-to-day variation in relative proportions of NH4+ and NO3- absorbed when NH4+ : NO3- ratio and pH of solution were constant indicates that the regulatory mechanism is not directly competitive. Regardless of the effect of pH on cumulative uptake of NH4+, the specific nitrogen uptake rates from mixed and from individual NH4+ and NO3- sources oscillated between maxima and minima at each pH with average periodicities similar to the expected interval of leaf emergence.

Uptake, translocation, and toxicity of gold nanorods in maize

NASA Astrophysics Data System (ADS)

Moradi Shahmansouri, Nastaran

Nanomaterials are widely used in many different products, such as electronics, cosmetics, industrial goods, biomedical uses, and other material applications. The heavy emission of nanomaterials into the environment has motived increasing concern regarding the effects on ecosystems, food chains, and, human health. Plants can tolerate a certain amount of natural nanomaterials, but large amounts of ENMs released from a variety of industries could be toxic to plants and possibly threaten the ecosystem. Employing phytoremediation as a contamination treatment method may show promise. However a pre-requisite to successful treatment is a better understanding of the behavior and effects of nanomaterials within plant systems. This study is designed to investigate the uptake, translocation, bioavailability, and toxicity of gold nanorods in maize plants. Maize is an important food and feed crop that can be used to understand the potential hazardous effects of nanoparticle uptake and distribution in the food chain. The findings could be an important contribution to the fields of phytoremediation, agri-nanotechnology, and nanoparticle toxicity on plants. In the first experiment, hydroponically grown maize seedlings were exposed to similar doses of commercial non-coated gold nanorods in three sizes, 10x34 nm, 20x75 nm, and 40x96 nm. The three nanorod species were suspended in solutions at concentrations of 350 mg/l, 5.8 mg/l, and 14 mg/l, respectively. Maize plants were exposed to all three solutions resulting in considerably lower transpiration and wet biomass than control plants. Likewise, dry biomass was reduced, but the effect is less pronounced than that of transpiration and wet biomass. The reduced transpiration and water content, which eventually proved fatal to exposed plants, were most likely a result of toxic effect of gold nanorod, which appeared to physically hinder the root system. TEM images proved that maize plants can uptake gold particles and accumulate them in

Increase in nitrate uptake by soybean plants during interruption of the dark period with low intensity light

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.

1991-01-01

Diurnal patterns of net NO3- uptake by nonnodulated soybean [Glycine max (L.) Merr. cv. Ransom] plants growing in flowing hydroponic culture at 26 and 16 degrees C root temperatures were measured at hourly intervals during alternate days of a 12-day growth period. Ion chromatography was used to determine removal of NO3- from the culture solution. Day and night periods of 9 and 15 h were used during growth. The night period included two 6-h dark periods and an intervening 3-h period of night interruption by incandescent lamps to effect a long-day photoperiod and repress floral initiation. At both root temperatures, the average specific rates of NO3- uptake were twice as great during the night interruption period as during the day period; they were greater during the day period than during the dark periods; and they were greater during the dark period immediately following the day period than during the later dark period that followed the night interruption. While these average patterns were repetitious among days, measured rates of uptake varied hourly and included intervals of net efflux scattered through the day period and more frequently through the 2 dark periods. Root temperature did not affect the average daily specific rates of uptake or the qualitative relationships among day, dark and night interruption periods of the diurnal cycle.

Manipulating stomatal density enhances drought tolerance without deleterious effect on nutrient uptake.

PubMed

Hepworth, Christopher; Doheny-Adams, Timothy; Hunt, Lee; Cameron, Duncan D; Gray, Julie E

2015-10-01

Manipulation of stomatal density was investigated as a potential tool for enhancing drought tolerance or nutrient uptake. Drought tolerance and soil water retention were assessed using Arabidopsis epidermal patterning factor mutants manipulated to have increased or decreased stomatal density. Root nutrient uptake via mass flow was monitored under differing plant watering regimes using nitrogen-15 ((15) N) isotope and mass spectrometry. Plants with less than half of their normal complement of stomata, and correspondingly reduced levels of transpiration, conserve soil moisture and are highly drought tolerant but show little or no reduction in shoot nitrogen concentrations especially when water availability is restricted. By contrast, plants with over twice the normal density of stomata have a greater capacity for nitrogen uptake, except when water availability is restricted. We demonstrate the possibility of producing plants with reduced transpiration which have increased drought tolerance, with little or no loss of nutrient uptake. We demonstrate that increasing transpiration can enhance nutrient uptake when water is plentiful. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

A portion of plant airborne communication is endorsed by uptake and metabolism of volatile organic compounds.

PubMed

Matsui, Kenji

2016-08-01

Plants have the ability to sense volatile organic compounds (VOCs) so as to efficiently adapt to their environment. The mechanisms underlying such plant 'olfactory' systems are largely unknown. Here I would like to propose that the metabolism of VOCs in plant tissues is one of the mechanisms by which plants sense VOCs. During the gas-exchange that is essential for photosynthesis, VOCs in the atmosphere are taken into the intercellular spaces of leaves. Each VOC is partitioned between the gas phase (intercellular space) and liquid phase (cell wall) at a certain ratio determined by Henry's law. The VOCs in the cell wall diffuse through the plasma membrane to the cytosol depending on their oil/water partition coefficients. Plants detoxify some VOCs, especially those that are oxidized, through glycosylation, glutathionylation, and reduction. These metabolic processes lower the concentration of VOCs in the cytosol, which facilitates further cytosolic uptake. As a result, vigorous metabolism of VOCs in the cytosol can lead to a substantial accumulation of VOC metabolites and the depletion of glutathione or NADPH. One such metabolite (a VOC glycoside) is known to mount a direct defense against herbivores, whilst deprivation of glutathione and NADPH can fortify plants with responses similar to the oxidative stress response. Copyright © 2016 Elsevier Ltd. All rights reserved.

Environmental variation between habitats and uptake of heavy metals by Urtica dioica.

PubMed

Otte, M L; Wijte, A H

1993-12-01

The observation from previous surveys, that Urtica dioica plants that had grown in metal contaminated soil in the floodplains of the former Rhine estuary in different habitats, but at comparable total soil metal concentrations, showed significant differences in tissue metal concentrations, led to the hypothesis that variation in other environmental characteristics than soil composition and chemical speciation of metals between habitats is also important in determining uptake and translocation of metals in plants. A field survey indicated that differences in root Cd, Cu and Zn concentrations might partly be explained by variation in speciation of metals in different habitats. However, shoot concentrations showed a different pattern that did not relate to variation in soil metal concentrations. In a habitat experiment Urtica dioica plants were grown in artificially contaminated soil in pots that were placed in the four habitats (grassland, pure reed, mixed reed, osier bed) that were also included in the field survey. After seven weeks the plants showed significant differences in Cu and Zn concentrations in roots and aboveground plant parts and in distribution of the metals in the plants between habitats. It was concluded that variation between habitats in environmental characteristics other than soil composition can explain as much variation in plants as can variation in soil metal concentrations and/or speciation. The implications for assessment of soil metal contamination and uptake by plants are discussed.

Quantification of water uptake by arbuscular mycorrhizal hyphae and its significance for leaf growth, water relations, and gas exchange of barley subjected to drought stress.

PubMed

Khalvati, M A; Hu, Y; Mozafar, A; Schmidhalter, U

2005-11-01

Arbuscular mycorrhizal fungi alleviate drought stress in their host plants via the direct uptake and transfer of water and nutrients through the fungal hyphae to the host plants. To quantify the contribution of the hyphae to plant water uptake, a new split-root hyphae system was designed and employed on barley grown in loamy soil inoculated with Glomus intraradices under well-watered and drought conditions in a growth chamber with a 14-h light period and a constant temperature (15 degrees C; day/night). Drought conditions were initiated 21 days after sowing, with a total of eight 7-day drying cycles applied. Leaf water relations, net photosynthesis rates, and stomatal conductance were measured at the end of each drying cycle. Plants were harvested 90 days after sowing. Compared to the control treatment, the leaf elongation rate and the dry weight of the shoots and roots were reduced in all plants under drought conditions. However, drought resistance was comparatively increased in the mycorrhizal host plants, which suffered smaller decreases in leaf elongation, net photosynthetic rate, stomatal conductance, and turgor pressure compared to the non-mycorrhizal plants. Quantification of the contribution of the arbuscular mycorrhizal hyphae to root water uptake showed that, compared to the non-mycorrhizal treatment, 4 % of water in the hyphal compartment was transferred to the root compartment through the arbuscular mycorrhizal hyphae under drought conditions. This indicates that there is indeed transport of water by the arbuscular mycorrhizal hyphae under drought conditions. Although only a small amount of water transport from the hyphal compartment was detected, the much higher hyphal density found in the root compartment than in the hyphal compartment suggests that a larger amount of water uptake by the arbuscular mycorrhizal hyphae may occur in the root compartment.

Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies.

PubMed

Jensen, Frank B; Rohde, Sabina

2010-04-01

Nitrite uptake into red blood cells (RBCs) precedes its intracellular reactions with hemoglobin (Hb) that forms nitric oxide (NO) during hypoxia. We investigated the uptake of nitrite and its reactions with Hb at different oxygen saturations (So(2)), using RBCs with (carp and rabbit) and without (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO(2) diffusion and AE1-mediated facilitated NO(2)(-) diffusion. Participation of HNO(2) diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled by intracellular reaction rates. Changes in nitrite uptake with So(2), pH, or species were accordingly explained by corresponding changes in reaction rates. In carp, nitrite uptake rates increased linearly with decreasing So(2) over the entire So(2) range. In rabbit, nitrite uptake rates were highest at intermediate So(2), producing a bell-shaped relationship with So(2). Nitrite consumption increased approximately 10-fold with a 1 unit decrease in pH, as expected from the involvement of protons in the reactions with Hb. The reaction of nitrite with deoxyhemoglobin was favored over that with oxyhemoglobin at intermediate So(2). We propose a model for RBC nitrite uptake that involves both HNO(2) diffusion and AE1-mediated transport and that explains both the present and previous (sometimes puzzling) results.

Numerical model for the uptake of groundwater contaminants by phreatophytes

USGS Publications Warehouse

Widdowson, M.A.; El-Sayed, A.; Landmeyer, J.E.

2008-01-01

Conventional solute transport models do not adequately account for the effects of phreatophytic plant systems on contaminant concentrations in shallow groundwater systems. A numerical model was developed and tested to simulate threedimensional reactive solute transport in a heterogeneous porous medium. Advective-dispersive transport is coupled to biodegradation, sorption, and plantbased attenuation processes including plant uptake and sorption by plant roots. The latter effects are a function of the physical-chemical properties of the individual solutes and plant species. Models for plant uptake were tested and evaluated using the experimental data collected at a field site comprised of hybrid poplar trees. A non-linear equilibrium isotherm model best represented site conditions.

Biochar application to a contaminated soil reduces the availability and plant uptake of zinc, lead and cadmium.

PubMed

Puga, A P; Abreu, C A; Melo, L C A; Beesley, L

2015-08-15

Heavy metals in soil are naturally occurring but may be enhanced by anthropogenic activities such as mining. Bio-accumulation of heavy metals in the food chain, following their uptake to plants can increase the ecotoxicological risks associated with remediation of contaminated soils using plants. In the current experiment sugar cane straw-derived biochar (BC), produced at 700 °C, was applied to a heavy metal contaminated mine soil at 1.5%, 3.0% and 5.0% (w/w). Jack bean (Canavalia ensiformis) and Mucuna aterrima were grown in pots containing soil and biochar mixtures, and control pots without biochar. Pore water was sampled from each pot to confirm the effects of biochar on metal solubility, whilst soils were analyzed by DTPA extraction to confirm available metal concentrations. Leaves were sampled for SEM analysis to detect possible morphological and anatomical changes. The application of BC decreased the available concentrations of Cd, Pb and Zn in 56, 50 and 54% respectively, in the mine contaminated soil leading to a consistent reduction in the concentration of Zn in the pore water (1st collect: 99 to 39 μg L(-1), 2nd: 97 to 57 μg L(-1) and 3rd: 71 to 12 μg L(-1)). The application of BC reduced the uptake of Cd, Pb and Zn by plants with the jack bean translocating high proportions of metals (especially Cd) to shoots. Metals were also taken up by Mucuna aterrima but translocation to shoot was more limited than for jack bean. There were no differences in the internal structures of leaves observed by scanning electron microscopy. This study indicates that biochar application during mine soil remediation reduce plant concentrations of potential toxic metals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Arsenic-induced nutrient uptake in As-hyperaccumulator Pteris vittata and their potential role to enhance plant growth.

PubMed

Liu, Xue; Feng, Hua-Yuan; Fu, Jing-Wei; Chen, Yanshan; Liu, Yungen; Ma, Lena Q

2018-05-01

It is known that arsenic (As) promotes growth of As-hyperaccumulator Pteris vittata (PV), however, the associated mechanisms are unclear. Here we examined As-induced nutrient uptake in P. vittata and their potential role to enhance plant growth in sterile agar by excluding microbial effects. As-hyperaccumulator P. multifida (PM) and non-hyperaccumulator P. ensiformis (PE) belonging to the Pteris genus were used as comparisons. The results showed that, after 40 d of growth, As induced biomass increase in hyperaccumulators PV and PM by 5.2-9.4 fold whereas it caused 63% decline in PE. The data suggested that As played a beneficial role in promoting hyperaccumulator growth. In addition, hyperaccumulators PV and PM accumulated 7.5-13, 1.4-3.6, and 1.8-4.4 fold more As, Fe, and P than the non-hyperaccumulator PE. In addition, nutrient contents such as K and Zn were also increased while Ca, Mg, and Mn decreased or unaffected under As treatment. This study demonstrated that As promoted growth in hyperaccumulators and enhanced Fe, P, K, and Zn uptake. Different plant growth responses to As among hyperaccumulators PV and PM and non-hyperaccumulator PE may help to better understand why hyperaccumulators grow better under As-stress. Published by Elsevier Ltd.

Uptake and Bioaccumulation of Pentachlorophenol by Emergent Wetland Plant Phragmites australis (Common Reed) in Cadmium Co-contaminated Soil.

PubMed

Hechmi, Nejla; Ben Aissa, Nadhira; Abdenaceur, Hassen; Jedidi, Naceur

2015-01-01

Despite many studies on phytoremediation of soils contaminated with either heavy metals or organics, little information is available on the effectiveness of phytoremediation of co-occurring metal and organic pollutants especially by using wetland species. Phragmites australis is a common wetland plant and its potential for phytoremediation of cadmium pentachlorophenol (Cd-PCP) co-contaminated soil was investigated. A greenhouse study was executed to elucidate the effects of Cd (0, 10, and 20 mg kg(-1)) without or with PCP (0, 50, and 250 mg kg(-1)) on the growth of the wetland plant P. australis and its uptake, accumulation and removal of pollutant from soils. After 75 days, plant biomass was significantly influenced by interaction of Cd and PCP and the effect of Cd on plant growth being stronger than that of PCP. Coexistence of PCP at low level lessened Cd toxicity to plants, resulting in improved plant growth and increased Cd accumulation in plant tissues. The dissipation of PCP in soils was significantly influenced by interactions of Cd, PCP and plant presence or absence. As an evaluation of soil biological activities after remediation soil enzyme was measured.

Effects of elemental sulphur on heavy metal uptake by plants growing on municipal sewage sludge.

PubMed

Dede, Gulgun; Ozdemir, Saim

2016-01-15

In this study experiment was carried out to determine the phytoextraction potential of six plant species (Conium maculatum, Brassica oleraceae var. oleraceae, Brassica juncea, Datura stramonium, Pelargonium hortorum and Conyza canadensis) grown in a sewage sludge medium amended with metal uptake promoters. The solubility of Cu, Cd and Pb was significantly increased with the application of elemental S due to decrease of pH. Faecal coliform number was markedly decreased by addition of elemental sulphur. The extraction of Cu, Cr and Pb from sewage sludge by using B. juncea plant was observed as 65%, 65% and 54% respectively that is statistically similar to EDTA as sulphur. The bioaccumulation factors were found higher (>1) in the plants tested for Cu and Pb like B. juncea. Translocation index (TI) calculated values for Cd and Pb were greater than one (>1) in both C. maculatum and B. oleraceae var. oleraceae. The results cleared that the amendment of sludge with elemental sulphur showed potential to solubilize heavy metals in phytoremediation as much as EDTA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Foliar water uptake of Tamarix ramosissima from an atmosphere of high humidity.

PubMed

Li, Shuang; Xiao, Hong-lang; Zhao, Liang; Zhou, Mao-Xian; Wang, Fang

2014-01-01

Many species have been found to be capable of foliar water uptake, but little research has focused on this in desert plants. Tamarix ramosissima was investigated to determine whether its leaves can directly absorb water from high humidity atmosphere and, if they can, to understand the magnitude and importance of foliar water uptake. Various techniques were adopted to demonstrate foliar water uptake under submergence or high atmospheric humidity. The mean increase in leaf water content after submergence was 29.38% and 20.93% for mature and tender leaves, respectively. In the chamber experiment, obvious reverse sap flow occurred when relative humidity (RH) was persistently above 90%. Reverse flow was recorded first in twigs, then in branches and stems. For the stem, the percentage of negative sap flow rate accounting for the maximum value of sap flow reached 10.71%, and its amount accounted for 7.54% of diurnal sap flow. Small rainfall can not only compensate water loss of plant by foliar uptake, but also suppress transpiration. Foliar uptake can appear in the daytime under certain rainfall events. High atmospheric humidity is beneficial for enhancing the water status of plants. Foliar uptake should be an important strategy of water acquisition for desert plants.

Foliar Water Uptake of Tamarix ramosissima from an Atmosphere of High Humidity

PubMed Central

Li, Shuang; Xiao, Hong-lang; Zhao, Liang; Zhou, Mao-Xian; Wang, Fang

2014-01-01

Many species have been found to be capable of foliar water uptake, but little research has focused on this in desert plants. Tamarix ramosissima was investigated to determine whether its leaves can directly absorb water from high humidity atmosphere and, if they can, to understand the magnitude and importance of foliar water uptake. Various techniques were adopted to demonstrate foliar water uptake under submergence or high atmospheric humidity. The mean increase in leaf water content after submergence was 29.38% and 20.93% for mature and tender leaves, respectively. In the chamber experiment, obvious reverse sap flow occurred when relative humidity (RH) was persistently above 90%. Reverse flow was recorded first in twigs, then in branches and stems. For the stem, the percentage of negative sap flow rate accounting for the maximum value of sap flow reached 10.71%, and its amount accounted for 7.54% of diurnal sap flow. Small rainfall can not only compensate water loss of plant by foliar uptake, but also suppress transpiration. Foliar uptake can appear in the daytime under certain rainfall events. High atmospheric humidity is beneficial for enhancing the water status of plants. Foliar uptake should be an important strategy of water acquisition for desert plants. PMID:24982964

Factors affecting the availability of americium-241 to the rice plant

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

Adriano, D.C.

1979-11-01

Since there has been no published transuranic uptake data on the rice plant (Oryza sativa L.), greenhouse experiments were conducted to determine the effects of some factors on the uptake of /sup 241/Am by this crop. Results indicate that chelated /sup 241/Am (in the form of americium-241-diethylenetriaminepentaacetic acid) applied to the flood water was markedly taken up by the rice plant, compared to the nonchelated form. However, most of the accumulation of /sup 241/Am occurred in the vegetative parts and only trace amounts, if any, were translocated to the grain. Soil application of /sup 241/Am resulted in much lower uptake.more » Soil amendment with either diethylenetriaminepentaacetic acid (DTPA) or organic matter did not produce a discernible uptake pattern. A synthesis of published data on plant uptake of /sup 241/Am indicates that the concentration ratio (CR, a measure of availability of /sup 241/Am to the plants) values for /sup 241/Am for agricultural crops ranged from 10-/sup 6/ to 10/sup 1/ (from lowest to highest availability). Some factors that appear to influence /sup 241/Am uptake are as follows: plant parts (grain usually having lower CR), chelating agents (DTPA usually increasing the CR), organic matter (inconsistent effects although generally decreasing the CR), and lime (usually decreasing the CR).« less

Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

DOE PAGES

Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; ...

2016-03-21

Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO 2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States foundmore » soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, >800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. Furthermore, while COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.« less

INFLUENCE OF GROWTH REGULATORS ON PESTICIDE UPTAKE

EPA Science Inventory

The purpose of this study was to significantly reduce the amounts of herbicides necessary to control certain noxious weeds. In laboratory and field studies herbicides were applied with certain plant hormones to accelerate their uptake and translocation in plants. Treatment of red...

Comparison of radiocesium concentration changes in leguminous and non-leguminous herbaceous plants observed after the Fukushima Dai-ichi Nuclear Power Plant accident.

PubMed

Uchida, Shigeo; Tagami, Keiko

2018-06-01

Transfer of radiocesium from soil to crops is an important pathway for human intake. In the period from one to two years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, food monitoring results showed that radiocesium concentrations in soybean (a legume) were higher than those in other annual agricultural crops; in these crops, root uptake is the major pathway of radiocesium from soil to plant. However, it was not clear whether or not leguminous and non-leguminous herbaceous plants have different Cs uptake abilities from the same soil because crop sample collection fields were different. In this study, therefore, we compared the concentrations of 137 Cs in seven herbaceous plant species including two leguminous plants (Trifolium pratense L. and Vicia sativa L.) collected in 2012-2016 from the same sampling field in Chiba, Japan that had been affected by the FDNPP accident fallout. Among these species, Petasites japonicus (Siebold & Zucc.) Maxim. showed the highest 137 Cs concentration in 2012-2016. The correlation factor between all concentration data for 137 Cs and those for 40 K in these seven plants was R = 0.54 (p < 0.001) by t-test, thus potassium uptake ability by species would affect radiocesium uptake; however, for each species, no correlation between 137 Cs and 40 K was found. Interestingly, 40 K concentrations in T. pratense, V. sativa and Poaceae family plants did not differ significantly, but 137 Cs data in the Poaceae family plants were significantly lower than those in T. pratense (p < 0.001) and V. sativa (p = 0.017). The results indicated that leguminous species would have higher 137 Cs uptake ability than Poaceae family plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uptake and translocation of hexachlorobenzene: Oilpumpkin and sunflower

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

NONE

1993-10-01

The uptake of hexachlorobenzene (HCB) and its translocation to seeds were studied with oil pumpkin and sunflower plants. Open air pot experiments were conducted with soil treated with different amounts of HCB. 14C-labelled HCB was used in solution culture experiments with young plants to investigate the distribution of HCB within the plants. During the experiments the contaminant was taken up by the root system of pumkin plant and translocated intensity to the reproductive organs. Autoradiographic pictures of crossections of stems and young fruits confirm this. Such translocation mechanism was not found in sunflower. Nevertheless it can be assumed that undermore » field conditions the uptake of vaporized HCB from contamination soil by foliage and fruits of oil pumpkin is the main pathway of contamination.« less

Sputnik: a database platform for comparative plant genomics.

PubMed

Rudd, Stephen; Mewes, Hans-Werner; Mayer, Klaus F X

2003-01-01

Two million plant ESTs, from 20 different plant species, and totalling more than one 1000 Mbp of DNA sequence, represents a formidable transcriptomic resource. Sputnik uses the potential of this sequence resource to fill some of the information gap in the un-sequenced plant genomes and to serve as the foundation for in silicio comparative plant genomics. The complexity of the individual EST collections has been reduced using optimised EST clustering techniques. Annotation of cluster sequences is performed by exploiting and transferring information from the comprehensive knowledgebase already produced for the completed model plant genome (Arabidopsis thaliana) and by performing additional state of-the-art sequence analyses relevant to today's plant biologist. Functional predictions, comparative analyses and associative annotations for 500 000 plant EST derived peptides make Sputnik (http://mips.gsf.de/proj/sputnik/) a valid platform for contemporary plant genomics.

Sputnik: a database platform for comparative plant genomics

PubMed Central

Rudd, Stephen; Mewes, Hans-Werner; Mayer, Klaus F.X.

2003-01-01

Two million plant ESTs, from 20 different plant species, and totalling more than one 1000 Mbp of DNA sequence, represents a formidable transcriptomic resource. Sputnik uses the potential of this sequence resource to fill some of the information gap in the un-sequenced plant genomes and to serve as the foundation for in silicio comparative plant genomics. The complexity of the individual EST collections has been reduced using optimised EST clustering techniques. Annotation of cluster sequences is performed by exploiting and transferring information from the comprehensive knowledgebase already produced for the completed model plant genome (Arabidopsis thaliana) and by performing additional state of-the-art sequence analyses relevant to today's plant biologist. Functional predictions, comparative analyses and associative annotations for 500 000 plant EST derived peptides make Sputnik (http://mips.gsf.de/proj/sputnik/) a valid platform for contemporary plant genomics. PMID:12519965

Towards a universal model for carbon dioxide uptake by plants

DOE PAGES

Wang, Han; Prentice, I. Colin; Keenan, Trevor F.; ...

2017-09-04

Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

Towards a universal model for carbon dioxide uptake by plants

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

Wang, Han; Prentice, I. Colin; Keenan, Trevor F.

Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

Effect of arbuscular mycorrhizal fungi on trace metal uptake by sunflower plants grown on cadmium contaminated soil.

PubMed

Hassan, Saad Eldin; Hijri, Mohamed; St-Arnaud, Marc

2013-09-25

Trace metal (TM) pollution of soil is a worldwide problem that threatens the quality of human and environmental health. Phytoremediation using plants and their associated microbes has been increasingly used as a green technology for cleaning up TM-polluted soils. In this study, we investigated the effect of inoculating two arbuscular mycorrhizal fungal isolates, Rhizophagus irregularis and Funneliformis mosseae, on trace metal uptake by sunflower plants grown in soils contaminated with three different Cd concentrations in a greenhouse trial. Root colonization, plant dry mass, and plant tissue cadmium (Cd), zinc (Zn), and copper (Cu) concentrations in roots and shoots were determined after sunflower harvesting. We found that root mycorrhizal colonization rates were not significantly affected by Cd treatments. At low soil Cd concentration, R. irregularis-inoculated plants had significantly higher shoot Cd and Zn concentrations than plants inoculated with F. mosseae and non-inoculated plants. However, at high soil Cd concentrations, F. mosseae-inoculated plants had significantly lower shoot Cd and Zn concentrations and biological concentration factor (BCF) values than plants inoculated with R. irregularis and non-inoculated plants. Cadmium was mainly translocated in shoot tissues of R. irregularis-inoculated plants and sequestered in the rhizosphere of F. mosseae-inoculated plants. The results indicate that these AMF strains mediate different tolerance strategies to alleviate TM toxicity in their host plants and that inoculation with the R. irregularis strain can be used for Cd phytoextraction, whereas this F. mosseae strain can be useful for Cd and Zn phytostabilization of contaminated soil. Copyright © 2013 Elsevier B.V. All rights reserved.

Ammonium and nitrate uptake by soybean during recovery from nitrogen deprivation

NASA Technical Reports Server (NTRS)

Rideout, J. W.; Chaillou, S.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1994-01-01

Soybean [Glycine max (L.) Merrill] plants that had been subjected to 15 d of nitrogen deprivation were resupplied for 10 d with 1.0 mol m-3 nitrogen provided as NO3-, NH4+, or NH4(+) + NO3- in flowing hydroponic culture. Plants in a fourth hydroponic system received 1.0 mol m-3 NO3- during both stress and resupply periods. Concentrations of soluble carbohydrates and organic acids in roots increased 210 and 370%, respectively, during stress. For the first day of resupply, however, specific uptake rates of nitrogen, determined by ion chromatography as depletion from solution, were lower for stressed than for non-stressed plants by 43% for NO3- resupply, by 32% for NH4(+) + NO3- resupply, and 86% for NH4+ resupply. When specific uptake of nitrogen for stressed plants recovered to rates for non-stressed plants at 6 to 8 d after nitrogen resupply, carbohydrates and organic acids in their roots had declined to concentrations lower than those of non-stressed plants. Recovery of nitrogen uptake capacity of roots thus does not appear to be regulated simply by the content of soluble carbon compounds within roots. Solution concentrations of NH4+ and NO3- were monitored at 62.5 min intervals during the first 3 d of resupply. Intermittent 'hourly' intervals of net influx and net efflux occurred. Rates of uptake during influx intervals were greater for the NH4(+)-resupplied than for the NO3(-)-resupplied plants. For NH4(+)-resupplied plants, however, the hourly intervals of efflux were more numerous than for NO3(-)-resupplied plants. It thus is possible that, instead of repressing NH4+ influx, increased accumulation of amino acids and NH4+ in NH4(+)-resupplied plants inhibited net uptake by stimulation of efflux on NH4+ absorbed in excess of availability of carbon skeletons for assimilation. Entry of NH4+ into root cytoplasm appeared to be less restricted than translocation of amino acids from the cytoplasm into the xylem.

Foliar application of microbial and plant based biostimulants increases growth and potassium uptake in almond (Prunus dulcis [Mill.] D. A. Webb).

PubMed

Saa, Sebastian; Olivos-Del Rio, Andres; Castro, Sebastian; Brown, Patrick H

2015-01-01

The use of biostimulants has become a common practice in agriculture. However, there is little peer-reviewed research on this topic. In this study we tested, under controlled and replicated conditions, the effect of one biostimulant derived from seaweed extraction (Bio-1) and another biostimulant derived from microbial fermentation (Bio-2). This experiment utilized 2-years-old almond plants over two growing seasons in a randomized complete design with a full 2 × 4 factorial structure with two soil potassium treatments (125 μg g(-1) of K vs. 5 μg g(-1)) and four foliar treatments (No spray, Foliar-K, Bio-1, Bio-2). Rubidium was utilized as a surrogate for short-term potassium uptake and plant growth, nutrient concentration, and final plant biomass were evaluated. There was a substantial positive effect of both biostimulant treatments on total shoot leaf area, and significant increases in shoot length and biomass under adequate soil potassium supply with a positive effect of Bio-1 only under low K supply. Rubidium uptake was increased by Bio-1 application an effect that was greater under the low soil K treatment. Though significant beneficial effects of the biostimulants used on plant growth were observed, it is not possible to determine the mode of action of these materials. The results presented here illustrate the promise and complexity of research involving biostimulants.

Foliar application of microbial and plant based biostimulants increases growth and potassium uptake in almond (Prunus dulcis [Mill.] D. A. Webb)

PubMed Central

Saa, Sebastian; Olivos-Del Rio, Andres; Castro, Sebastian; Brown, Patrick H.

2015-01-01

The use of biostimulants has become a common practice in agriculture. However, there is little peer-reviewed research on this topic. In this study we tested, under controlled and replicated conditions, the effect of one biostimulant derived from seaweed extraction (Bio-1) and another biostimulant derived from microbial fermentation (Bio-2). This experiment utilized 2-years-old almond plants over two growing seasons in a randomized complete design with a full 2 × 4 factorial structure with two soil potassium treatments (125 μg g-1 of K vs. 5 μg g-1) and four foliar treatments (No spray, Foliar-K, Bio-1, Bio-2). Rubidium was utilized as a surrogate for short-term potassium uptake and plant growth, nutrient concentration, and final plant biomass were evaluated. There was a substantial positive effect of both biostimulant treatments on total shoot leaf area, and significant increases in shoot length and biomass under adequate soil potassium supply with a positive effect of Bio-1 only under low K supply. Rubidium uptake was increased by Bio-1 application an effect that was greater under the low soil K treatment. Though significant beneficial effects of the biostimulants used on plant growth were observed, it is not possible to determine the mode of action of these materials. The results presented here illustrate the promise and complexity of research involving biostimulants. PMID:25755660

Screening of medicinal plants for PPPAR-alpha and PPAR-gamma activation and evaluation of their effects on glucose uptake and 3T3-L1 adipogenesis

USDA-ARS?s Scientific Manuscript database

Medicinal plants are a rich source of ligands for nuclear receptors. The present study was aimed to screen a collection of plant extracts for PPAR-alpha/gamma activating properties and identify the active extract that can stimulate cellular glucose uptake without enhancing the adipogenesis. A report...

Using thermodynamics to assess biotic and abiotic impediments to root water uptake

NASA Astrophysics Data System (ADS)

Bechmann, Marcel; Hildebrandt, Anke; Kleidon, Axel

2016-04-01

Root water uptake has been the subject of extensive research, dealing with understanding the processes limiting transpiration and understanding strategies of plants to avoid water stress. Many of those studies use models of water flow from the soil through the plant into the atmosphere to learn about biotic and abiotic factors affecting plant water relations. One important question in this context is to identify those processes that are most limiting to water transport, and specifically whether these processes lie within the plant or the soil? Here, we propose to use a thermodynamic formulation of root water uptake to answer this question. The method allows us to separate the energy exported at the root collar into a sum of energy fluxes related to all processes along the flow path, notably including the effect of increasing water retention in drier soils. Evaluation of the several contributions allows us to identify and rank the processes by how much these impede water flow from the soil to the atmosphere. The application of this approach to a complex 3-dimensional root water uptake model reveals insights on the role of root versus soil resistances to limit water flow. We investigate the efficiency of root water uptake in an ensemble of root systems with varying root hydraulic properties. While root morphology is kept the same, root radial and axial resistances are artificially varied. Starting with entirely young systems (uptake roots, high radial, low axial conductance) we increasingly add older roots (transport roots, high axial, low radial conductance) to improve transport within root systems. This yields a range of root hydraulic architectures, where the extremes are limited either by radial uptake capacity or low capacity to transport water along the root system. We model root water uptake in this range of root systems with a 3-dimensional root water uptake model in two different soils, applying constant flux boundary conditions in a dry down experiment and

Soil moisture variations affect short-term plant-microbial competition for ammonium, glycine, and glutamate

PubMed Central

Månsson, Katarina F; Olsson, Magnus O; Falkengren-Grerup, Ursula; Bengtsson, Göran

2014-01-01

We tested whether the presence of plant roots would impair the uptake of ammonium (), glycine, and glutamate by microorganisms in a deciduous forest soil exposed to constant or variable moisture in a short-term (24-h) experiment. The uptake of 15NH4 and dual labeled amino acids by the grass Festuca gigantea L. and soil microorganisms was determined in planted and unplanted soils maintained at 60% WHC (water holding capacity) or subject to drying and rewetting. The experiment used a design by which competition was tested in soils that were primed by plant roots to the same extent in the planted and unplanted treatments. Festuca gigantea had no effect on microbial N uptake in the constant moist soil, but its presence doubled the microbial uptake in the dried and rewetted soil compared with the constant moist. The drying and rewetting reduced by half or more the uptake by F. gigantea, despite more than 60% increase in the soil concentration of . At the same time, the amino acid and -N became equally valued in the plant uptake, suggesting that plants used amino acids to compensate for the lower acquisition. Our results demonstrate the flexibility in plant-microbial use of different N sources in response to soil moisture fluctuations and emphasize the importance of including transient soil conditions in experiments on resource competition between plants and soil microorganisms. Competition between plants and microorganisms for N is demonstrated by a combination of removal of one of the potential competitors, the plant, and subsequent observations of the uptake of N in the organisms in soils that differ only in the physical presence and absence of the plant during a short assay. Those conditions are necessary to unequivocally test for competition. PMID:24772283

Soil moisture variations affect short-term plant-microbial competition for ammonium, glycine, and glutamate.

PubMed

Månsson, Katarina F; Olsson, Magnus O; Falkengren-Grerup, Ursula; Bengtsson, Göran

2014-04-01

We tested whether the presence of plant roots would impair the uptake of ammonium ([Formula: see text]), glycine, and glutamate by microorganisms in a deciduous forest soil exposed to constant or variable moisture in a short-term (24-h) experiment. The uptake of (15)NH4 and dual labeled amino acids by the grass Festuca gigantea L. and soil microorganisms was determined in planted and unplanted soils maintained at 60% WHC (water holding capacity) or subject to drying and rewetting. The experiment used a design by which competition was tested in soils that were primed by plant roots to the same extent in the planted and unplanted treatments. Festuca gigantea had no effect on microbial N uptake in the constant moist soil, but its presence doubled the microbial [Formula: see text] uptake in the dried and rewetted soil compared with the constant moist. The drying and rewetting reduced by half or more the [Formula: see text] uptake by F. gigantea, despite more than 60% increase in the soil concentration of [Formula: see text]. At the same time, the amino acid and [Formula: see text]-N became equally valued in the plant uptake, suggesting that plants used amino acids to compensate for the lower [Formula: see text] acquisition. Our results demonstrate the flexibility in plant-microbial use of different N sources in response to soil moisture fluctuations and emphasize the importance of including transient soil conditions in experiments on resource competition between plants and soil microorganisms. Competition between plants and microorganisms for N is demonstrated by a combination of removal of one of the potential competitors, the plant, and subsequent observations of the uptake of N in the organisms in soils that differ only in the physical presence and absence of the plant during a short assay. Those conditions are necessary to unequivocally test for competition.

Leaf and Stem CO2 Uptake in the Three Subfamilies of the Cactaceae 1

PubMed Central

Nobel, Park S.; Hartsock, Terry L.

1986-01-01

Net CO2 uptake over 24-hour periods was examined for the leaves and for the stems of 11 species of cacti representing all three subfamilies. For Pereskia aculeata, Pereskia grandifolia, and Maihuenia poeppigii (subfamily Pereskioideae), all the net shoot CO2 uptake was by the leaves and during the daytime. In contrast, for the leafless species Carnegiea gigantea, Ferocactus acanthodes, Coryphantha vivipara, and Mammillaria dioica (subfamily Cactoideae), all the shoot net CO2 uptake was by the stems and at night. Similarly, for leafless Opuntia ficus-indica (subfamily Opuntioideae), all net CO2 uptake occurred at night. For leafy members of the Opuntioideae (Pereskiopsis porteri, Quiabentia chacoensis, Austrocylindropuntia subulata), at least 88% of the shoot CO2 uptake over 24 hours was by the leaves and some CO2 uptake occurred at night. Leaves responded to the instantaneous level of photosynthetically active radiation (PAR) during the daytime, as occurs for C3 plants, whereas nocturnal CO2 uptake by stems of O. ficus-indica and F. acanthodes responded to the total daily PAR, as occurs for Crassulacean acid metabolism (CAM) plants. Thus, under the well-watered conditions employed, the Pereskioideae behaved as C3 plants, the Cactoideae behaved as CAM plants, and the Opuntioideae exhibited characteristics of both pathways. PMID:16664741

Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

PubMed

Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

2016-07-01

The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Uptake of heavy metals by Typha capensis from wetland sites polluted by effluent from mineral processing plants: implications of metal-metal interactions.

PubMed

Zaranyika, M F; Nyati, W

2017-10-01

The aim of the present work was to demonstrate the existence of metal-metal interactions in plants and their implications for the absorption of toxic elements like Cr. Typha capensis , a good accumulator of heavy metals, was chosen for the study. Levels of Fe, Cr, Ni, Cd, Pb, Cu and Zn were determined in the soil and roots, rhizomes, stems and leaves of T. capensis from three Sites A, B and C polluted by effluent from a chrome ore processing plant, a gold ore processing plant, and a nickel ore processing plant, respectively. The levels of Cr were extremely high at Site A at 5415 and 786-16,047 μg g -1 dry weight in the soil and the plant, respectively, while the levels of Ni were high at Site C at 176 and 24-891 μg g -1 in the soil and the plant, respectively. The levels of Fe were high at all three sites at 2502-7500 and 906-13,833 μg g -1 in the soil and plant, respectively. For the rest of the metals, levels were modest at 8.5-148 and 2-264 μg g -1 in the soil and plant, respectively. Pearson's correlation analysis confirmed mutual synergistic metal-metal interactions in the uptake of Zn, Cu, Co, Ni, Fe, and Cr, which are attributed to the similarity in the radii and coordination geometry of the cations of these elements. The implications of such metal-metal interactions (or effects of one metal on the behaviour of another) on the uptake of Cr, a toxic element, and possible Cr detoxification mechanism within the plant, are discussed.

Inferring foliar water uptake using stable isotopes of water.

PubMed

Goldsmith, Gregory R; Lehmann, Marco M; Cernusak, Lucas A; Arend, Matthias; Siegwolf, Rolf T W

2017-08-01

A growing number of studies have described the direct absorption of water into leaves, a phenomenon known as foliar water uptake. The resultant increase in the amount of water in the leaf can be important for plant function. Exposing leaves to isotopically enriched or depleted water sources has become a common method for establishing whether or not a plant is capable of carrying out foliar water uptake. However, a careful inspection of our understanding of the fluxes of water isotopes between leaves and the atmosphere under high humidity conditions shows that there can clearly be isotopic exchange between the two pools even in the absence of a change in the mass of water in the leaf. We provide experimental evidence that while leaf water isotope ratios may change following exposure to a fog event using water with a depleted oxygen isotope ratio, leaf mass only changes when leaves are experiencing a water deficit that creates a driving gradient for the uptake of water by the leaf. Studies that rely on stable isotopes of water as a means of studying plant water use, particularly with respect to foliar water uptake, must consider the effects of these isotopic exchange processes.

Xenobiotic-metabolizing enzymes in plants and their role in uptake and biotransformation of veterinary drugs in the environment.

PubMed

Bártíková, Hana; Skálová, Lenka; Stuchlíková, Lucie; Vokřál, Ivan; Vaněk, Tomáš; Podlipná, Radka

2015-08-01

Many various xenobiotics permanently enter plants and represent potential danger for their organism. For that reason, plants have evolved extremely sophisticated detoxification systems including a battery of xenobiotic-metabolizing enzymes. Some of them are similar to those in humans and animals, but there are several plant-specific ones. This review briefly introduces xenobiotic-metabolizing enzymes in plants and summarizes present information about their action toward veterinary drugs. Veterinary drugs are used worldwide to treat diseases and protect animal health. However, veterinary drugs are also unwantedly introduced into environment mostly via animal excrements, they persist in the environment for a long time and may impact on the non-target organisms. Plants are able to uptake, transform the veterinary drugs to non- or less-toxic compounds and store them in the vacuoles and cell walls. This ability may protect not only plant themselves but also other organisms, predominantly invertebrates and wild herbivores. The aim of this review is to emphasize the importance of plants in detoxification of veterinary drugs in the environment. The results of studies, which dealt with transport and biotransformation of veterinary drugs in plants, are summarized and evaluated. In conclusion, the risks and consequences of veterinary drugs in the environment and the possibilities of phytoremediation technologies are considered and future perspectives are outlined.

Uptake of 17α-ethynylestradiol and triclosan in pinto bean, Phaseolus vulgaris.

PubMed

Karnjanapiboonwong, Adcharee; Chase, Darcy A; Cañas, Jaclyn E; Jackson, William A; Maul, Jonathan D; Morse, Audra N; Anderson, Todd A

2011-07-01

Pharmaceuticals and personal care products (PPCPs) have emerged as a group of potential environmental contaminants of concern. PPCPs in soil may enter terrestrial food webs via plant uptake. We evaluated uptake of 17α-ethynylestradiol (EE2) and triclosan in bean plants (Phaseolus vulgaris) grown in sand and soil. The extent of uptake and accumulation of EE2 and triclosan in plants grown in sand was higher than in plants grown in soil. In sand (conditions of maximum contaminant bioavailability), bioconcentration factors (BCFs) of EE2 and triclosan in roots (based on dry weights) were 1424 and 16,364, respectively, whereas BCFs in leaves were 55 for EE2 and 85 for triclosan. In soil, the BCF of EE2 decreased from 154 in the first week to 32 in the fourth week while it fluctuated in leaves from 18 to 20. The BCF for triclosan in plants grown in soil increased over time to 12 in roots and 8 in leaves. These results indicate that the potential for uptake and accumulation of PPCPs in plants exists. This trophic transfer pathway should be considered when assessing exposure to certain PPCPs, particularly with the use of recycled wastewater for irrigation. Copyright © 2011 Elsevier Inc. All rights reserved.

Cadmium, lead, and zinc mobility and plant uptake in a mine soil amended with sugarcane straw biochar.

PubMed

Puga, A P; Abreu, C A; Melo, L C A; Paz-Ferreiro, J; Beesley, L

2015-11-01

Accumulation of heavy metals in unconsolidated soils can prove toxic to proximal environments, if measures are not taken to stabilize soils. One way to minimize the toxicity of metals in soils is the use of materials capable of immobilizing these contaminants by sorption. Biochar (BC) can retain large amounts of heavy metals due to, among other characteristics, its large surface area. In the current experiment, sugarcane-straw-derived biochar, produced at 700 °C, was applied to a heavy-metal-contaminated mine soil at 1.5, 3.0, and 5.0% (w/w). Jack bean and Mucuna aterrima were grown in pots containing a mine contaminated soil and soil mixed with BC. Pore water was sampled to assess the effects of biochar on zinc solubility, while soils were analyzed by DTPA extraction to confirm available metal concentrations. The application of BC decreased the available concentrations of Cd, Pb, and Zn in the mine contaminated soil leading to a consistent reduction in the concentration of Zn in the pore water. Amendment with BC reduced plant uptake of Cd, Pb, and Zn with the jack bean uptaking higher amounts of Cd and Pb than M. aterrima. This study indicates that biochar application during mine soil remediation could reduce plant concentrations of heavy metals. Coupled with this, symptoms of heavy metal toxicity were absent only in plants growing in pots amended with biochar. The reduction in metal bioavailability and other modifications to the substrate induced by the application of biochar may be beneficial to the establishment of a green cover on top of mine soil to aid remediation and reduce risks.

Rhizobial symbiosis effect on the growth, metal uptake, and antioxidant responses of Medicago lupulina under copper stress.

PubMed

Kong, Zhaoyu; Mohamad, Osama Abdalla; Deng, Zhenshan; Liu, Xiaodong; Glick, Bernard R; Wei, Gehong

2015-08-01

The effects of rhizobial symbiosis on the growth, metal uptake, and antioxidant responses of Medicago lupulina in the presence of 200 mg kg(-1) Cu(2+) throughout different stages of symbiosis development were studied. The symbiosis with Sinorhizobium meliloti CCNWSX0020 induced an increase in plant growth and nitrogen content irrespective of the presence of Cu(2+). The total amount of Cu uptake of inoculated plants significantly increased by 34.0 and 120.4% in shoots and roots, respectively, compared with non-inoculated plants. However, although the rhizobial symbiosis promoted Cu accumulation both in shoots and roots, the increase in roots was much higher than in shoots, thus decreasing the translocation factor and helping Cu phytostabilization. The rate of lipid peroxidation was significantly decreased in both shoots and roots of inoculated vs. non-inoculated plants when measured either 8, 13, or 18 days post-inoculation. In comparison with non-inoculated plants, the activities of superoxide dismutase and ascorbate peroxidase of shoots of inoculated plants exposed to excess Cu were significantly elevated at different stages of symbiosis development; similar increases occurred in the activities of superoxide dismutase, catalase, and glutathione reductase of inoculated roots. The symbiosis with S. meliloti CCNWSX0020 also upregulated the corresponding genes involved in antioxidant responses in the plants treated with excess Cu. The results indicated that the rhizobial symbiosis with S. meliloti CCNWSX0020 not only enhanced plant growth and metal uptake but also improved the responses of plant antioxidant defense to excess Cu stress.

Impact of phosphate on glyphosate uptake and toxicity in willow.

PubMed

Gomes, Marcelo Pedrosa; Le Manac'h, Sarah Gingras; Moingt, Matthieu; Smedbol, Elise; Paquet, Serge; Labrecque, Michel; Lucotte, Marc; Juneau, Philippe

2016-03-05

Phosphate (PO4(3-)) has been shown to increase glyphosate uptake by willow, a plant species known for its phytoremediation potential. However, it remains unclear if this stimulation of glyphosate uptake can result in an elevated glyphosate toxicity to plants (which could prevent the use of willows in glyphosate-remediation programs). Consequently, we studied the effects of PO4(3-) on glyphosate uptake and toxicity in a fast growing willow cultivar (Salix miyabeana SX64). Plants were grown in hydroponic solution with a combination of glyphosate (0, 0.001, 0.065 and 1 mg l(-1)) and PO4(3-) (0, 200 and 400 mg l(-1)). We demonstrated that PO4(3-) fertilization greatly increased glyphosate uptake by roots and its translocation to leaves, which resulted in increased shikimate concentration in leaves. In addition to its deleterious effects in photosynthesis, glyphosate induced oxidative stress through hydrogen peroxide accumulation. Although it has increased glyphosate accumulation, PO4(3-) fertilization attenuated the herbicide's deleterious effects by increasing the activity of antioxidant systems and alleviating glyphosate-induced oxidative stress. Our results indicate that in addition to the glyphosate uptake, PO4(3-) is involved in glyphosate toxicity in willow by preventing glyphosate induced oxidative stress. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydroponic Uptake of Atrazine and Lambda-cyhalothrin in Aquatic Macrophytes

NASA Astrophysics Data System (ADS)

Bouldin, J. L.; Farris, J. L.; Moore, M. T.; Smith, S.; Cooper, C. M.

2005-05-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to soil geochemical modifications and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48 h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8 d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that the seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Assessing cadmium exposure risks of vegetables with plant uptake factor and soil property.

PubMed

Yang, Yang; Chang, Andrew C; Wang, Meie; Chen, Weiping; Peng, Chi

2018-07-01

Plant uptake factors (PUFs) are of great importance in human cadmium (Cd) exposure risk assessment while it has been often treated in a generic way. We collected 1077 pairs of vegetable-soil samples from production fields to characterize Cd PUFs and demonstrated their utility in assessing Cd exposure risks to consumers of locally grown vegetables. The Cd PUFs varied with plant species and pH and organic matter content of soils. Once normalized PUFs against soil parameters, the PUFs distributions were log-normal in nature. In this manner, the PUFs were represented by definable probability distributions instead of a deterministic figure. The Cd exposure risks were then assessed using the normalized PUF based on the Monte Carlo simulation algorithm. Factors affecting the extent of Cd exposures were isolated through sensitivity analyses. Normalized PUF would illustrate the outcomes for uncontaminated and slightly contaminated soils. Among the vegetables, lettuce was potentially hazardous for residents due to its high Cd accumulation but low Zn concentration. To protect 95% of the lettuce production from causing excessive Cd exposure risks, pH of soils needed to be 5.9 and above. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative effects of aluminum and ouabain on synaptosomal choline uptake, acetylcholine release and (Na+/K+)ATPase.

PubMed

Silva, Virgília S; Nunes, M Alexandra; Cordeiro, J Miguel; Calejo, Ana I; Santos, Sofia; Neves, Paulo; Sykes, António; Morgado, Fernando; Dunant, Yves; Gonçalves, Paula P

2007-07-17

Closing the gap between adverse health effects of aluminum and its mechanisms of action still represents a huge challenge. Cholinergic dysfunction has been implicated in neuronal injury induced by aluminum. Previously reported data also indicate that in vivo and in vitro exposure to aluminum inhibits the mammalian (Na(+)/K(+))ATPase, an ubiquitous plasma membrane pump. This study was undertaken with the specific aim of determining whether in vitro exposure to AlCl(3) and ouabain, the foremost utilized selective inhibitor of (Na(+)/K(+))ATPase, induce similar functional modifications of cholinergic presynaptic nerve terminals, by comparing their effects on choline uptake, acetylcholine release and (Na(+)/K(+))ATPase activity, on subcellular fractions enriched in synaptic nerve endings isolated from rat brain, cuttlefish optic lobe and torpedo electric organ. Results obtained show that choline uptake by rat synaptosomes was inhibited by submillimolar AlCl(3), whereas the amount of choline taken up by synaptosomes isolated from cuttlefish and torpedo remained unchanged. Conversely, choline uptake was reduced by ouabain to a large extent in all synaptosomal preparations analyzed. In contrast to ouabain, which modified the K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions, AlCl(3) induced reduction of stimulated acetylcholine release was only observed when rat synaptosomes were challenged. Finally, it was observed that the aluminum effect on cuttlefish and torpedo synaptosomal (Na(+)/K(+))ATPase activity was slight when compared to its inhibitory action on mammalian (Na(+)/K(+))ATPase. In conclusion, inhibition of (Na(+)/K(+))ATPase by AlCl(3) and ouabain jeopardized the high-affinity (Na(+)-dependent, hemicholinium-3 sensitive) uptake of choline and the Ca(2+)-dependent, K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions. The effects of submillimolar AlCl(3

Sphagnum Mosses - Masters of Efficient N-Uptake while Avoiding Intoxication

PubMed Central

Fritz, Christian; Lamers, Leon P. M.; Riaz, Muhammad; van den Berg, Leon J. L.; Elzenga, Theo J. T. M.

2014-01-01

Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form (15N - ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5–6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands

Sphagnum mosses--masters of efficient N-uptake while avoiding intoxication.

PubMed

Fritz, Christian; Lamers, Leon P M; Riaz, Muhammad; van den Berg, Leon J L; Elzenga, Theo J T M

2014-01-01

Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form ((15)N-ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5-6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands.

Molecular mechanisms of foliar water uptake in a desert tree

PubMed Central

Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

2015-01-01

Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. PMID:26567212

Local and distal effects of arbuscular mycorrhizal colonization on direct pathway Pi uptake and root growth in Medicago truncatula

PubMed Central

Watts-Williams, Stephanie J.; Jakobsen, Iver; Cavagnaro, Timothy R.; Grønlund, Mette

2015-01-01

Two pathways exist for plant Pi uptake from soil: via root epidermal cells (direct pathway) or via associations with arbuscular mycorrhizal (AM) fungi, and the two pathways interact in a complex manner. This study investigated distal and local effects of AM colonization on direct root Pi uptake and root growth, at different soil P levels. Medicago truncatula was grown at three soil P levels in split-pots with or without AM fungal inoculation and where one root half grew into soil labelled with 33P. Plant genotypes included the A17 wild type and the mtpt4 mutant. The mtpt4 mutant, colonized by AM fungi, but with no functional mycorrhizal pathway for Pi uptake, was included to better understand effects of AM colonization per se. Colonization by AM fungi decreased expression of direct Pi transporter genes locally, but not distally in the wild type. In mtpt4 mutant plants, direct Pi transporter genes and the Pi starvation-induced gene Mt4 were more highly expressed than in wild-type roots. In wild-type plants, less Pi was taken up via the direct pathway by non-colonized roots when the other root half was colonized by AM fungi, compared with non-mycorrhizal plants. Colonization by AM fungi strongly influenced root growth locally and distally, and direct root Pi uptake activity locally, but had only a weak influence on distal direct pathway activity. The responses to AM colonization in the mtpt4 mutant suggested that in the wild type, the increased P concentration of colonized roots was a major factor driving the effects of AM colonization on direct root Pi uptake. PMID:25944927

Gramene database: navigating plant comparative genomics resources

USDA-ARS?s Scientific Manuscript database

Gramene (http://www.gramene.org) is an online, open source, curated resource for plant comparative genomics and pathway analysis designed to support researchers working in plant genomics, breeding, evolutionary biology, system biology, and metabolic engineering. It exploits phylogenetic relationship...

An updated model for nitrate uptake modelling in plants. I. Functional component: cross-combination of flow–force interpretation of nitrate uptake isotherms, and environmental and in planta regulation of nitrate influx

PubMed Central

Le Deunff, Erwan; Malagoli, Philippe

2014-01-01

Background and Aims In spite of major breakthroughs in the last three decades in the identification of root nitrate uptake transporters in plants and the associated regulation of nitrate transport activities, a simplified and operational modelling approach for nitrate uptake is still lacking. This is due mainly to the difficulty in linking the various regulations of nitrate transport that act at different levels of time and on different spatial scales. Methods A cross-combination of a Flow–Force approach applied to nitrate influx isotherms and experimentally determined environmental and in planta regulation is used to model nitrate in oilseed rape, Brassica napus. In contrast to ‘Enzyme–Substrate’ interpretations, a Flow–Force modelling approach considers the root as a single catalytic structure and does not infer hypothetical cellular processes among nitrate transporter activities across cellular layers in the mature roots. In addition, this approach accounts for the driving force on ion transport based on the gradient of electrochemical potential, which is more appropriate from a thermodynamic viewpoint. Key Results and Conclusions Use of a Flow–Force formalism on nitrate influx isotherms leads to the development of a new conceptual mechanistic basis to model more accurately N uptake by a winter oilseed rape crop under field conditions during the whole growth cycle. This forms the functional component of a proposed new structure–function mechanistic model of N uptake. PMID:24638820

Gramene 2016: comparative plant genomics and pathway resources

PubMed Central

Tello-Ruiz, Marcela K.; Stein, Joshua; Wei, Sharon; Preece, Justin; Olson, Andrew; Naithani, Sushma; Amarasinghe, Vindhya; Dharmawardhana, Palitha; Jiao, Yinping; Mulvaney, Joseph; Kumari, Sunita; Chougule, Kapeel; Elser, Justin; Wang, Bo; Thomason, James; Bolser, Daniel M.; Kerhornou, Arnaud; Walts, Brandon; Fonseca, Nuno A.; Huerta, Laura; Keays, Maria; Tang, Y. Amy; Parkinson, Helen; Fabregat, Antonio; McKay, Sheldon; Weiser, Joel; D'Eustachio, Peter; Stein, Lincoln; Petryszak, Robert; Kersey, Paul J.; Jaiswal, Pankaj; Ware, Doreen

2016-01-01

Gramene (http://www.gramene.org) is an online resource for comparative functional genomics in crops and model plant species. Its two main frameworks are genomes (collaboration with Ensembl Plants) and pathways (The Plant Reactome and archival BioCyc databases). Since our last NAR update, the database website adopted a new Drupal management platform. The genomes section features 39 fully assembled reference genomes that are integrated using ontology-based annotation and comparative analyses, and accessed through both visual and programmatic interfaces. Additional community data, such as genetic variation, expression and methylation, are also mapped for a subset of genomes. The Plant Reactome pathway portal (http://plantreactome.gramene.org) provides a reference resource for analyzing plant metabolic and regulatory pathways. In addition to ∼200 curated rice reference pathways, the portal hosts gene homology-based pathway projections for 33 plant species. Both the genome and pathway browsers interface with the EMBL-EBI's Expression Atlas to enable the projection of baseline and differential expression data from curated expression studies in plants. Gramene's archive website (http://archive.gramene.org) continues to provide previously reported resources on comparative maps, markers and QTL. To further aid our users, we have also introduced a live monthly educational webinar series and a Gramene YouTube channel carrying video tutorials. PMID:26553803

Increasing uptake of comparative effectiveness and patient-centered outcomes research among stakeholders: insights from conference discussion.

PubMed

Law, Ernest; Harrington, Rachel; Alexander, G Caleb; Saha, Soumi; Oehrlein, Elisabeth; Perfetto, Eleanor M

2018-02-01

The goal of comparative effectiveness research (CER) and patient-centered outcomes research (PCOR) is to improve health outcomes by providing stakeholders with evidence directly relevant to decision making. In January 2017, the Pharmaceutical Research and Manufacturers Association Foundation, alongside the Academy for Managed Care Pharmacy, organized a conference aimed at engaging experts and opinion leaders representing clinicians, patients and payers to identify and discuss barriers and strategies to enhancing uptake and use of CER/PCOR. This report summarizes the conference discussion in the following sections: preconference survey; summary of barriers and strategies to the uptake of CER/PCOR identified by conference attendees; and future perspectives on the field.

Effect of water extracts from edible Myrtaceae plants on uptake of 2-(n-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose in TNF-α-treated FL83B mouse hepatocytes.

PubMed

Chang, Wen-Chang; Shen, Szu-Chuan

2013-02-01

This study investigated the glucose uptake activity of the water extracts from the leaves and fruit of edible Myrtaceae plants, including guava (Psidium guajava Linn.), wax apples [Syzygium samarangense (Blume) Merr. and L.M. Perry], Pu-Tau [Syzygium jambo (L.) Alston], and Kan-Shi Pu-Tau (Syzygium cumini Linn.) in FL83B mouse hepatocytes. The fluorescent dye 2-(n-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose was used to estimate the uptake ability of the cells. Glucose uptake test showed that pink wax apple fruit extract (PWFE) exhibits the highest glucose uptake activity, at an increment of 21% in the insulin-resistant FL83B mouse hepatocytes as compared with the TNF-α-treated control group. Vescalagin was isolated using column chromatography of PWFE. This compound, at the concentration of 6.25 µg/mL, exhibits the same glucose uptake improvement in insulin-resistant cells as PWFE at a 100-µg/mL dose. We postulate that vescalagin is an active component in PWFE that may alleviate the insulin resistance in mouse hepatocytes. Copyright © 2012 John Wiley & Sons, Ltd.

Inoculation with arbuscular mycorrhizae does not improve 137Cs uptake in crops grown in the Chernobyl region.

PubMed

Vinichuk, M; Mårtensson, A; Rosén, K

2013-12-01

Methods for cleaning up radioactive contaminated soils are urgently needed. In this study we investigated whether the use of arbuscular mycorrhizal (AM) fungi can improve (137)Cs uptake by crops. Barley, cucumber, perennial ryegrass, and sunflower were inoculated with AM fungi and grown in low-level radionuclide contaminated soils in a field experiment 70 km southwest of Chernobyl, Ukraine, during two successive years (2009-2010). Roots of barley, cucumber and sunflower plants were slightly or moderately infected with AM fungus and root infection frequency was negatively or non-correlated with (137)Cs uptake by plants. Roots of ryegrass were moderately infected with AM fungus and infection frequency was moderately correlated with (137)Cs uptake by ryegrass. The application of AM fungi to soil in situ did not enhance radionuclide plant uptake or biomass. The responsiveness of host plants and AM fungus combination to (137)Cs uptake varied depending on the soil, although mycorrhization of soil in the field was conditional and did not facilitate the uptake of radiocesium. The total amount of (137)Cs uptake by plants growing on inoculated soil was equal to amounts in plant cultivated on non-inoculated soil. Thus, the use of AM fungi in situ for bioremediation of soil contaminated with a low concentration of (137)Cs could not be recommended. Copyright © 2013 Elsevier Ltd. All rights reserved.

PLUTONIUM UPTAKE AND BEHAVIOR IN PLANTS OF THE DESERT SOUTHWEST: A PRELIMINARY ASSESSMENT

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

Caldwell, E.; Duff, M.; Ferguson, C.

2011-03-01

Eight species of desert vegetation and associated soils were collected from the Nevada National Security Site (N2S2) and analyzed for 238Pu and 239+240Pu concentrations. Amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. The diversity of growth strategies provided insight into the geochemical behavior and bio-availability of Pu at the N2S2. The highest concentrations of Pu were measured in the onion moss (24.27 Bq kg-1 238Pu and 52.78 Bq kg-1 239+240Pu) followed by the rimmed navel lichen (8.18 Bq kg-1 and 18.4 Bqmore » kg-1 respectively), pointing to the importance of eolian transport of Pu. Brome and desert globemallow accumulated between 3 and 9 times higher concentrations of Pu than creosote and sage brush species. These results support the importance of species specific elemental accumulation strategies rather than exposure duration as the dominant variable influencing Pu concentrations in these plants. Total vegetation elemental concentrations of Ce, Fe, Al, Sm and others were also analyzed. Strong correlations were observed between Fe and Pu. This supports the conclusion that Pu was accumulated as a consequence of the active accumulation of Fe and other plant required nutrients. Cerium and Pu are considered to be chemical analogs. Strong correlations observed in plants support the conclusion that these elements displayed similar geochemical behavior in the environment as it related to the biochemical uptake process of vegetation. Soils were also sampled in association with vegetation samples. This allowed for the calculation of a concentration ratio (CR). The CR values for Pu in plants were highly influenced by the heterogeneity of Pu distribution among sites. Results from the naturally occurring elements of concern were more evenly distributed between sample sites. This allowed for the development of a pattern

Effect of mineral sulphur availability on nitrogen and sulphur uptake and remobilization during the vegetative growth of Brassica napus L.

PubMed Central

Abdallah, M.; Dubousset, L.; Meuriot, F.; Etienne, P.; Avice, J-C.; Ourry, A.

2010-01-01

Because it has a high demand for sulphur (S), oilseed rape is particularly sensitive to S limitation. However, the physiological effects of S limitation remain unclear, especially during the rosette stage. For this reason a study was conducted to determine the effects of mineral S limitation on nitrogen (N) and S uptake and remobilization during vegetative growth of oilseed rape at both the whole-plant and leaf rank level for plants grown during 35 d with 300 μM 34SO42– (control plants; +S) or with 15 μM 34SO42– (S-limited plants; –S). The results highlight that S-limited plants showed no significant differences either in whole-plant and leaf biomas or in N uptake, when compared with control plants. However, total S and 34S (i.e. deriving from S uptake) contents were greatly reduced for the whole plant and leaf after 35 d, and a greater redistribution of endogenous S from leaves to the benefit of roots was observed. The relative expression of tonoplast and plasmalemma sulphate transporters was also strongly induced in the roots. In conclusion, although S-limited plants had 20 times less mineral S than control plants, their development remained surprisingly unchanged. During S limitation, oilseed rape is able to recycle endogenous S compounds (mostly sulphate) from leaves to roots. However, this physiological adaptation may be effective only over a short time scale (i.e. vegetative growth). PMID:20403880

Effect of water management and silicon on germination, growth, phosphorus and arsenic uptake in rice.

PubMed

Zia, Zahida; Bakhat, Hafiz Faiq; Saqib, Zulfiqar Ahmad; Shah, Ghulam Mustafa; Fahad, Shah; Ashraf, Muhammad Rizwan; Hammad, Hafiz Mohkum; Naseem, Wajid; Shahid, Muhammad

2017-10-01

Silicon (Si) is the 2nd most abundant element in soil which is known to enhance stress tolerance in wide variety of crops. Arsenic (As), a toxic metalloid enters into the human food chain through contaminated water and food or feed. To alleviate the deleterious effect of As on human health, it is a need of time to find out an effective strategy to reduce the As accumulation in the food chain. The experiments were conducted during September-December 2014, and 2016 to optimize Si concentration for rice (Oryza sativa L.) exposed to As stress. Further experiment were carried out to evaluate the effect of optimum Si on rice seed germination, seedling growth, phosphorus and As uptake in rice plant. During laboratory experiment, rice seeds were exposed to 150 and 300µM As with and without 3mM Si supplementation. Results revealed that As application, decreased the germination up to 40-50% as compared to control treatment. Arsenic stress also significantly (P < 0.05) reduced the seedling length but Si supplementation enhanced the seedlings length. Maximum seedling length (4.94cm) was recorded for 3mM Si treatment while, minimum seedling length (0.60cm) was observed at day7 by the application of 300µM As. Silicon application resulted in 10% higher seedling length than the control treatment. In soil culture experiment, plants were exposed to same concentrations of As and Si under aerobic and anaerobic conditions. Irrigation water management, significantly (P˂0.05) affected the plant growth, Si and As concentrations in the plant. Arsenic uptake was relatively less under aerobic conditions. The maximum As concentration (9.34 and 27.70mgkg DW -1 in shoot and root, respectively) was found in plant treated with 300µM As in absence of Si under anaerobic condition. Similarly, anaerobic condition resulted in higher As uptake in the plants. The study demonstrated that aerobic cultivation is suitable to decrease the As uptake and in rice exogenous Si supply is beneficial to

Predicting human papillomavirus vaccine uptake in young adult women: Comparing the Health Belief Model and Theory of Planned Behavior

PubMed Central

Gerend, Mary A.; Shepherd, Janet E.

2012-01-01

Background Although theories of health behavior have guided thousands of studies, relatively few studies have compared these theories against one another. Purpose The purpose of the current study was to compare two classic theories of health behavior—the Health Belief Model (HBM) and the Theory of Planned Behavior (TPB)—in their prediction of human papillomavirus (HPV) vaccination. Methods After watching a gain-framed, loss-framed, or control video, women (N=739) ages 18–26 completed a survey assessing HBM and TPB constructs. HPV vaccine uptake was assessed ten months later. Results Although the message framing intervention had no effect on vaccine uptake, support was observed for both the TPB and HBM. Nevertheless, the TPB consistently outperformed the HBM. Key predictors of uptake included subjective norms, self-efficacy, and vaccine cost. Conclusions Despite the observed advantage of the TPB, findings revealed considerable overlap between the two theories and highlighted the importance of proximal versus distal predictors of health behavior. PMID:22547155

Global uptake of carbonyl sulfide (COS) by terrestrial vegetation: Estimates corrected by deposition velocities normalized to the uptake of carbon dioxide (CO2)

NASA Astrophysics Data System (ADS)

Sandoval-Soto, L.; Stanimirov, M.; von Hobe, M.; Schmitt, V.; Valdes, J.; Wild, A.; Kesselmeier, J.

2005-01-01

COS uptake by trees, as observed under dark/light changes and under application of the plant hormone abscisic acid, exhibited a strong correlation with the CO2 assimilation rate and the stomatal conductance. As the uptake of COS occurred exclusively through the stomata we compared experimentally derived and re-evaluated deposition velocities (Vd for COS and CO2). We show that Vd of COS is generally significantly larger than that of CO2. We therefore introduced this attribute into a new global estimate of COS fluxes into vegetation. The global COS uptake by vegetation as estimated by the new model ranges between 0.69-1.40 Tg a-1, based on the Net Primary Productivity (NPP). Taking into account Gross Primary Productivity (GPP) the deposition estimate ranges between 1.37-2.81 Tg a-1 (0.73-1.50 Tg S a-1). We believe that in order to obtain accurate and reliable global NPP-based estimates for the COS flux into vegetation, the different deposition velocities of COS and CO2 must be taken into account.

[Mechanism Study of the Smectite-OR-SH Compound for Reducing Cadmium Uptake by Plants in Contaminated Soils].

PubMed

Zeng, Yan-jun; Zhou, Zhi-jun; Zhao, Qiu-xiang

2015-06-01

Adsorption and desorption experiments, pot experiments and characterization test were performed to investigate the immobilization effect and mechanism of the smectite-OR-SH compound for reducing cadmium uptake by plants in contaminated soils. The results showed that the saturated adsorption capacity for the adsorption of Cd2+ on smectite raised distinctly after functionalized. The adsorption of Cd2+ on smectite-OR-SH compound was very stable and it was difficult for Cd2+ to be desorbed from it. Crop yields promoted differently in original soil, Cd 3 mg x kg(-1) soil and Cd 10 mg x kg(-1) soil after adding the smectite-OR-SH compound. And the cadmium content of the cabbage reduced 61.00%, 62.10% and 83.73% respectively compare with the control. Characterization test analysis showed that Cd was adsorbed by the compound successfully and ligand interaction occurred between Cd and the thiol group. Floc amount on the compound surface increased correspondingly. In addition to electrostatic adsorption, ion exchange and hydroxyl ligand adsorption, the reaction mechanism of smectite-OR-SH compound with Cd was mainly sulfhydryl ligand adsorption.

Seasonal plant water uptake patterns in the saline southeast Everglades ecotone.

PubMed

Ewe, Sharon M L; Sternberg, Leonel da S L; Childers, Daniel L

2007-07-01

The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (delta(18)O) was enriched (4.8 +/- 0.2 per thousand) in the DS relative to the WS (0.0 +/- 0.1 per thousand), but groundwater delta(18)O remained constant between seasons (DS: 2.2 +/- 0.4 per thousand; WS: 2.1 +/- 0.1 per thousand). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil-groundwater mix (delta 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on delta(18)O data, the roots of R. mangle roots were exposed to salinities of 25.4 +/- 1.4 PSU, less saline than either C. jamaicense (39.1 +/- 2.2 PSU) or S. portulacastrum (38.6 +/- 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to

Comparison between Arabidopsis and Rice for Main Pathways of K(+) and Na(+) Uptake by Roots.

PubMed

Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco

2016-01-01

K(+) is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K(+) in the soil solution are widely variable, K(+) nutrition is secured by uptake systems that exhibit different affinities for K(+). Two main systems have been described for root K(+) uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K(+) uptake, although they only seem to operate when K(+) is not limiting. The use of knock-out lines has allowed demonstrating their role in root K(+) uptake in Arabidopsis and rice. Plant adaptation to the different K(+) supplies relies on the finely tuned regulation of these systems. Low K(+)-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant's adaptation to low K(+). Na(+) is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na(+) improves growth, especially under K(+) deficiency. Thus, high-affinity Na(+) uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na(+) accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K(+) deficiency. Data concerning pathways for Na(+) uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na(+) uptake in rice grown under salinity

Accumulation of phenanthrene by roots of intact wheat (Triticum acstivnm L.) seedlings: passive or active uptake?

PubMed Central

2010-01-01

Background Polycyclic aromatic hydrocarbons (PAHs) are of particular concern due to their hydrophobic, recalcitrant, persistent, potentially carcinogenic, mutagenic and toxic properties, and their ubiquitous occurrence in the environment. Most of the PAHs in the environment are present in surface soil. Plants grown in PAH-contaminated soils or water can become contaminated with PAHs because of their uptake. Therefore, they may threaten human and animal health. However, the mechanism for PAHs uptake by crop roots is little understood. It is important to understand exactly how PAHs are transported into the plant root system and into the human food chain, since it is beneficial in governing crop contamination by PAHs, remedying soils or waters polluted by PAHs with plants, and modeling potential uptake for risk assessment. Results The possibility that plant roots may take up phenanthrene (PHE), a representative of PAHs, via active process was investigated using intact wheat (Triticum acstivnm L.) seedlings in a series of hydroponic experiments. The time course for PHE uptake into wheat roots grown in Hoagland solution containing 5.62 μM PHE for 36 h could be separated into two periods: a fast uptake process during the initial 2 h and a slow uptake component thereafter. Concentration-dependent PHE uptake was characterized by a smooth, saturable curve with an apparent Km of 23.7 μM and a Vmax of 208 nmol g-1 fresh weight h-1, suggesting a carrier-mediated uptake system. Competition between PHE and naphthalene for their uptake by the roots further supported the carrier-mediated uptake system. Low temperature and 2,4-dinitrophenol (DNP) could inhibit PHE uptake equally, indicating that metabolism plays a role in PHE uptake. The inhibitions by low temperature and DNP were strengthened with increasing concentration of PHE in external solution within PHE water solubility (7.3 μM). The contribution of active uptake to total absorption was almost 40% within PHE water

Mycorrhizal Controls on Nitrogen Uptake Drive Carbon Cycling at the Global Scale

NASA Astrophysics Data System (ADS)

Shi, M.; Fisher, J. B.; Brzostek, E. R.; Phillips, R.

2015-12-01

Nearly all plants form symbiotic relationships with one of two types of mycorrhizal fungi—arbuscular mycorrhizae (AM) and ectomycorrhizal (ECM) fungi, which are essential to global biogeochemical cycling of nutrient elements. In soils with higher rates of nitrogen and phosphorus mineralization from organic matter, AM-associated plants can be better adapted than ECM-associated plants. Importantly, the photosynthate costs of nutrient uptake for AM-associated plants are usually lower than that for ECM-associated plants. Thus, the global carbon cycle is closely coupled with mycorrhizal controls on N uptake. To investigate the potential climate dependence of terrestrial environments from AM- and ECM-associated plants, this study uses the Community Atmosphere Model (CAM) with a plant productivity-optimized N acquisition model—the Fixation and Uptake of Nitrogen (FUN) model—integrated into its land model—the Community Land Model (CLM). This latest version of CLM coupled with FUN allows for the assessment of mycorrhizal controls on global biogeochemical cycling. Here, we show how the historical evolution of AM- and ECM-associations altered regional and global biogeochemical cycling and climate, and future projections over the next century.

Gramene 2016: comparative plant genomics and pathway resources

USDA-ARS?s Scientific Manuscript database

Gramene (http://www.gramene.org) is an online resource for comparative functional genomics in crops and model plant species. Its two main frameworks are genomes (collaboration with Ensembl Plants) and pathways (The Plant Reactome and archival BioCyc databases). Since our last NAR update, the data...

Cadmium dynamics in the rhizosphere and Cd uptake of different plant species evaluated by a mechanistic model.

PubMed

Stritsis, Christos; Steingrobe, Bernd; Claassen, Norbert

2014-01-01

Maize, sunflower,flax, and spinach differed in the accumulation of Cd when grown on a Cd contaminated soil. This was mainly due to the different Cd net influx, In, that varied among species by a factor of up to 30. The objective of this study was to find possible reasons for the different Cd In by using a mechanistic model. After 14 days of Cd uptake the model calculated only a small Cd depletion at the root surface, e.g. from 0.22 mumol L(-1) down to 0.19 mumol L(-1) for maize and from 0.48 mumol L(-1) down to 0.35 mumol L(-1)for spinach. Even so the model always overestimated the Cd I(n), for spinach by a factor of 1.5 and for maize by a factor of 10. Only simulating a decrease of C(Li) or the root absorbing power, alpha, by 40% to 90% gave an agreement of calculated and measured I(n),. This may be interpreted as that about 40% in the case of spinach and 90% in the case of maize of the Cd in soil solution were not accessible for plant uptake. The high sensitivity to alpha also shows that not the Cd transport to the root but alpha was limiting the step for Cd uptake.

Global uptake of carbonyl sulfide (COS) by terrestrial vegetation: Estimates corrected by deposition velocities normalized to the uptake of carbon dioxide (CO2)

NASA Astrophysics Data System (ADS)

Sandoval-Soto, L.; Stanimirov, M.; von Hobe, M.; Schmitt, V.; Valdes, J.; Wild, A.; Kesselmeier, J.

2005-06-01

COS uptake by trees, as observed under dark/light changes and under application of the plant hormone abscisic acid, exhibited a strong correlation with the CO2 assimilation rate and the stomatal conductance. As the uptake of COS occurred exclusively through the stomata we compared experimentally derived and re-evaluated deposition velocities (Vd; related to stomatal conductance) for COS and CO2. We show that Vd of COS is generally significantly larger than that of CO2. We therefore introduced this attribute into a new global estimate of COS fluxes into vegetation. The new global estimate of the COS uptake based on available net primary productivity data (NPP) ranges between 0.69-1.40 Tga-1. However, as a COS molecule is irreversibly split in contrast to CO2 which is released again by respiration processes, we took into account the Gross Primary Productivity (GPP) representing the true CO2 leaf flux the COS uptake has to be related to. Such a GPP based deposition estimate ranged between 1.4--2.8 Tga-1 (0.73-1.50 TgSa-1). We believe that in order to obtain accurate global COS sink estimates such a GPP-based estimate corrected by the different deposition velocities of COS and CO2 must be taken into account.

Molecular mechanisms of foliar water uptake in a desert tree.

PubMed

Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

2015-11-12

Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. Published by Oxford University Press on behalf of the Annals of Botany Company.

Growth and (137)Cs uptake of four Brassica species influenced by inoculation with a plant growth-promoting rhizobacterium Bacillus pumilus in three contaminated farmlands in Fukushima prefecture, Japan.

PubMed

Aung, Han Phyo; Djedidi, Salem; Oo, Aung Zaw; Aye, Yi Swe; Yokoyama, Tadashi; Suzuki, Sohzoh; Sekimoto, Hitoshi; Bellingrath-Kimura, Sonoko Dorothea

2015-07-15

The effectiveness of the plant growth-promoting rhizobacterium Bacillus pumilus regarding growth promotion and radiocesium ((137)Cs) uptake was evaluated in four Brassica species grown on different (137)Cs contaminated farmlands at Fukushima prefecture in Japan from June to August 2012. B. pumilus inoculation did not enhance growth in any of the plants, although it resulted in a significant increase of (137)Cs concentration and higher (137)Cs transfer from the soil to plants. The Brassica species exhibited different (137)Cs uptake abilities in the order Komatsuna>turnip>mustard>radish. TF values of (137)Cs ranged from 0.018 to 0.069 for all vegetables. Komatsuna possessed the largest root surface area and root volume, and showed a higher (137)Cs concentration in plant tissue and higher (137)Cs TF values (0.060) than the other vegetables. Higher (137)Cs transfer to plants was prominent in soil with a high amount of organic matter and an Al-vermiculite clay mineral type. Copyright © 2015 Elsevier B.V. All rights reserved.

Plant–Water Relations (1): Uptake and Transport

PubMed Central

2014-01-01

Summary Plants, like all living things, are mostly water. Water is the matrix of life, and its availability determines the distribution and productivity of plants on earth. Vascular plants evolved structures that enable them to transport water long distances with little input of energy, but the hollow tracheary elements are just one of many adaptations that enable plants to cope with a very dry atmosphere. This lecture examines the physical laws that govern water uptake and transport, the biological properties of cells and plant tissues that facilitate it, and the strategies that enable plants to survive in diverse environments

Traffic-related heavy metals uptake by wild plants grow along two main highways in Hunan Province, China: effects of soil factors, accumulation ability, and biological indication potential.

PubMed

Zhai, Yunbo; Dai, Qingyun; Jiang, Kang; Zhu, Yun; Xu, Bibo; Peng, Chuan; Wang, Tengfei; Zeng, Guangming

2016-07-01

This study was performed to investigate pollution of traffic-related heavy metals (HMs-Zn, Pb, Cu, Cr, and Cd) in roadside soils and their uptake by wild plants growing along highways in Hunan Province, China. For this, we analyzed the concentration and chemical fractionation of HMs in soils and plants. Soil samples were collected with different depths in the profile and different distances from highway edge. And leaves and barks of six high-frequency plants were collected. Results of the modified European Community Bureau of Reference (BCR) showed that the mobile fraction of these HMs was in the order of Cd > Pb > Zn > Cu > Cr. A high percentage of the mobile fraction indicates Cd, Pb, and Zn were labile and available for uptake by wild plants. The total concentration and values of risk assessment code (RAC) showed that Cd was the main risk factor, which were in the range high to very high risk. The accumulation ability of HMs in plants was evaluated by the biological accumulation factor (BAF) and the metal accumulation index (MAI), and the results showed that all those plant species have good phyto-extraction ability, while accumulation capacity for most HMs plants tissues was bark > leaf. The highest MAI value (5.99) in Cinnamomum camphora (L) Presl indicates the potential for bio-monitoring and a good choice for planting along highways where there is contamination with HMs.

Explaining variation in Down's syndrome screening uptake: comparing the Netherlands with England and Denmark using documentary analysis and expert stakeholder interviews.

PubMed

Crombag, Neeltje M T H; Vellinga, Ynke E; Kluijfhout, Sandra A; Bryant, Louise D; Ward, Pat A; Iedema-Kuiper, Rita; Schielen, Peter C J I; Bensing, Jozien M; Visser, Gerard H A; Tabor, Ann; Hirst, Janet

2014-09-25

The offer of prenatal Down's syndrome screening is part of routine antenatal care in most of Europe; however screening uptake varies significantly across countries. Although a decision to accept or reject screening is a personal choice, it is unlikely that the widely differing uptake rates across countries can be explained by variation in individual values alone.The aim of this study was to compare Down's syndrome screening policies and programmes in the Netherlands, where uptake is relatively low (<30%) with England and Denmark where uptake is higher (74 and > 90% respectively), in an attempt to explain the observed variation in national uptake rates. We used a mixed methods approach with an embedded design: a) documentary analysis and b) expert stakeholder analysis. National central statistical offices and legal documents were studied first to gain insight in demographic characteristics, cultural background, organization and structure of healthcare followed by documentary analysis of primary and secondary sources on relevant documents on DSS policies and programme. To enhance interpretation of these findings we performed in-depth interviews with relevant expert stakeholders. There were many similarities in the demographics, healthcare systems, government abortion legislation and Down's syndrome screening policy across the studied countries. However, the additional cost for Down's syndrome screening over and above standard antenatal care in the Netherlands and an emphasis on the 'right not to know' about screening in this country were identified as potential explanations for the 'low' uptake rates of Down's syndrome screening in the Netherlands. The social context and positive framing of the offer at the service delivery level may play a role in the relatively high uptake rates in Denmark. This paper makes an important contribution to understanding how macro-level demographic, social and healthcare delivery factors may have an impact on national uptake rates for

Gramene 2016: comparative plant genomics and pathway resources.

PubMed

Tello-Ruiz, Marcela K; Stein, Joshua; Wei, Sharon; Preece, Justin; Olson, Andrew; Naithani, Sushma; Amarasinghe, Vindhya; Dharmawardhana, Palitha; Jiao, Yinping; Mulvaney, Joseph; Kumari, Sunita; Chougule, Kapeel; Elser, Justin; Wang, Bo; Thomason, James; Bolser, Daniel M; Kerhornou, Arnaud; Walts, Brandon; Fonseca, Nuno A; Huerta, Laura; Keays, Maria; Tang, Y Amy; Parkinson, Helen; Fabregat, Antonio; McKay, Sheldon; Weiser, Joel; D'Eustachio, Peter; Stein, Lincoln; Petryszak, Robert; Kersey, Paul J; Jaiswal, Pankaj; Ware, Doreen

2016-01-04

Gramene (http://www.gramene.org) is an online resource for comparative functional genomics in crops and model plant species. Its two main frameworks are genomes (collaboration with Ensembl Plants) and pathways (The Plant Reactome and archival BioCyc databases). Since our last NAR update, the database website adopted a new Drupal management platform. The genomes section features 39 fully assembled reference genomes that are integrated using ontology-based annotation and comparative analyses, and accessed through both visual and programmatic interfaces. Additional community data, such as genetic variation, expression and methylation, are also mapped for a subset of genomes. The Plant Reactome pathway portal (http://plantreactome.gramene.org) provides a reference resource for analyzing plant metabolic and regulatory pathways. In addition to ∼ 200 curated rice reference pathways, the portal hosts gene homology-based pathway projections for 33 plant species. Both the genome and pathway browsers interface with the EMBL-EBI's Expression Atlas to enable the projection of baseline and differential expression data from curated expression studies in plants. Gramene's archive website (http://archive.gramene.org) continues to provide previously reported resources on comparative maps, markers and QTL. To further aid our users, we have also introduced a live monthly educational webinar series and a Gramene YouTube channel carrying video tutorials. Published by Oxford University Press on behalf of Nucleic Acids Research 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Imaging and modelling root water uptake

NASA Astrophysics Data System (ADS)

Zarebanadkouki, M.; Meunier, F.; Javaux, M.; Kaestner, A.; Carminati, A.

2017-12-01

Spatially resolved measurement and modelling of root water uptake is urgently needed to identify root traits that can improve capture of water from the soil. However, measuring water fluxes into roots of transpiring plants growing in soil remains challenging. Here, we describe an in-situ technique to measure local fluxes of water into roots. The technique consists of tracing the transport of deuterated water (D2O) in soil and roots using time series neutron radiography and tomography. A diffusion-convection model was used to model the transport of D2O in roots. The model includes root features such as the endodermis, xylem and the composite flow of water in the apoplastic and symplastic pathways. Diffusion permeability of root cells and of the endodermis were estimated by fitting the experiment during the night, when transpiration was negligible. The water fluxes at different position of the root system were obtained by fitting the experiments at daytime. The results showed that root water uptake was not uniform along root system and varied among different root types. The measured profiles of root water uptake into roots were used to estimate the radial and axial hydraulic of the roots. A three-dimensional model of root water uptake was used to fit the measured water fluxes by adjusting the root radial and axial hydraulic conductivities. We found that the estimated radial conductivities decreased with root age, while the axial conducances increased, and they are different among root types. The significance of this study is the development of a method to estimate 1) water uptake and 2) the radial and axial hydraulic conductivities of roots of transpiring plants growing in the soil.

Drivers of Phosphorus Uptake by Barley Following Secondary Resource Application

PubMed Central

Brod, Eva; Øgaard, Anne Falk; Krogstad, Tore; Haraldsen, Trond Knapp; Frossard, Emmanuel; Oberson, Astrid

2016-01-01

Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake is still poorly understood. Using radioactive-labeling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal, and wood ash were studied as P uptake by barley after 44 days and compared with those of water-soluble mineral P (MinP) and an unfertilized control (NoP) in a pot experiment with an agricultural soil containing little available P at two soil pH levels, approximately pH 5.3 (unlimed soil) and pH 6.2 (limed soil). In a parallel incubation experiment, the effects of the secondary resources on physicochemical and microbial soil processes were studied. The results showed that the relative agronomic efficiency compared with MinP decreased in the order: manure ≥fish sludge ≥wood ash ≥meat bone meal. The solubility of inorganic P in secondary resources was the main driver for P uptake by barley (Hordeum vulgare). The effects of secondary resources on physicochemical and microbial soil processes were of little overall importance. Application of organic carbon with manure resulted in microbial P immobilization and decreased uptake by barley of P derived from the soil. On both soils, P uptake by barley was best explained by a positive linear relationship with the H2O + NaHCO3-soluble inorganic P fraction in fertilizers or by a linear negative relationship with the HCl-soluble inorganic P fraction in fertilizers. PMID:27243015

Plant-driven removal of heavy metals from soil: uptake, translocation, tolerance mechanism, challenges, and future perspectives.

PubMed

Thakur, Sveta; Singh, Lakhveer; Wahid, Zularisam Ab; Siddiqui, Muhammad Faisal; Atnaw, Samson Mekbib; Din, Mohd Fadhil Md

2016-04-01

Increasing heavy metal (HM) concentrations in the soil have become a significant problem in the modern industrialized world due to several anthropogenic activities. Heavy metals (HMs) are non-biodegradable and have long biological half lives; thus, once entered in food chain, their concentrations keep on increasing through biomagnification. The increased concentrations of heavy metals ultimately pose threat on human life also. The one captivating solution for this problem is to use green plants for HM removal from soil and render it harmless and reusable. Although this green technology called phytoremediation has many advantages over conventional methods of HM removal from soils, there are also many challenges that need to be addressed before making this technique practically feasible and useful on a large scale. In this review, we discuss the mechanisms of HM uptake, transport, and plant tolerance mechanisms to cope with increased HM concentrations. This review article also comprehensively discusses the advantages, major challenges, and future perspectives of phytoremediation of heavy metals from the soil.

Plutonium, curium, and other radionuclide uptake by the rice plant from a naturally weathered, contaminated soil

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

Adriano, D.C.; McLeod, K.W.; Ciravolo, T.G.

1981-07-01

A greenhouse study using three United States rice varieties (Belle Patna, Nato, and Starbonnet) varying in maturity period and a widely used Asian variety (IR-1561) indicates that, with the exception of /sup 137/Cs, no significant differences were obtained among varieties in the foliage uptake of selected gamma-emitters. On the average, /sup 137/Cs and /sup 40/K were translocated less to the grain than to the foliage. The concentration ratio (CR) values for the gamma-emitters, with the exception of /sup 40/K, were approximately one order of magnitude higher than those for subterranean crops grown in experimental plots adjacent to a chemical separationsmore » facility at the Savannah River Plant. The CR values for /sup 238/Pu and /sup 244/Cm are within the range of values published in the open literature. The CR values for /sup 239/ /sup 240/Pu, however, were higher than the normally reported values for plants grown in nonamended soils.« less

Direct observation of organic contaminant uptake, storage, and metabolism within plant roots.

PubMed

Wild, Edward; Dent, John; Thomas, Gareth O; Jones, Kevin C

2005-05-15

Two-photon excitation microscopy (TPEM) is used to visualize and track the uptake and movement of anthracene and phenanthrene from a contaminated growth medium into living unmodified roots of maize and wheat over a 56-day period. The degradation of anthracene was also directly observed within the cortex cells of both species. The power of this technique is that neither the plant nor the compound require altering (staining or sectioning) to visualize them, meaning they are in their natural form throughout the experiment. Initially both compounds bound to the epidermis along the zone of elongation, passing through the epidermal cells to reach the cortex within the root hair, and branching zones of the root. The PAHs entered the epidermis radially; however, once within the cortex cells this movement was dominated by slow lateral movement of both compounds toward the shoot. Highly focused "streams" of compound were observed to form over time; zones where phenanthrene concentrated extended up to 1500 microm in length over a 56-day period, for example, passing through several adjoining cells, and were detectable in cell walls and cell vacuoles. Radial movement was not observed to extend beyond the cortex cells to reach the vascular tissues of the plant. The longitudinal movement of both compounds was not observed to extend beyond the root base into the stem or vegetative parts of the plant. The lateral movement of both compounds within the cortex cells was dominated by movement within the cell walls, suggesting apoplastic flow through multiple cell walls, but with a low level of symplastic movement to transport compound into the cellular vacuoles. Degradation of anthracene to the partial breakdown products anthrone, anthraquinone, and hydroxyanthraquinone was observed directly in the zones of root elongation and branching. The technique and observations have important applications to the fields of agrochemistry and phytoremediation.

Plant growth inhibitory activity of p-hydroxyacetophenones and tremetones from Chilean endemic Baccharis species and some analogous: a comparative study.

PubMed

Céspedes, Carlos L; Uchoa, Adjaci; Salazar, Juan R; Perich, Fernando; Pardo, Fernando

2002-04-10

Plant growth inhibitory effects of acetophenones 1-6, tremetones 7-12, and MeOH and CH(2)Cl(2) extracts from the aerial parts of Baccharis linnearis, Baccharis magellanica, and Baccharis umbelliformis collected in Chile were assayed as growth inhibitory activity in ranges of 10-500 microM and 0.1-150 ppm, respectively. The effects on seedling growth, germination, and respiration of ryegrass, lettuce, green tomato, and red clover weedy target species were measured. In addition to the inhibitory activity on bleaching of crocin induced by alkoxyl radicals, these compounds also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl in thin-layer chromatography autographic and spectrophotometric assays. In addition, acetophenones and tremetones also showed inhibition of H(+) uptake and oxygen uptake respiration in isolated chloroplasts and mitochondria, respectively. Our results indicate that 1, 4, 7-12, and CH(2)Cl(2) extracts interfere with the dicot preemergence properties, mainly energy metabolism of the seeds at the level of respiration. These compounds appear to have selective effects on the radicle more than shoot growth of dicot seeds. Also, the levels of radicle inhibition obtained with some compounds on Physalis ixocarpa and Trifolium pratense are totally comparable to those of ovatifolin, a known natural growth inhibitor. This behavior might be responsible for its plant growth inhibitory properties and its possible role as an allelopathic agent.

Comparison between Arabidopsis and Rice for Main Pathways of K+ and Na+ Uptake by Roots

PubMed Central

Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco

2016-01-01

K+ is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K+ in the soil solution are widely variable, K+ nutrition is secured by uptake systems that exhibit different affinities for K+. Two main systems have been described for root K+ uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K+ uptake, although they only seem to operate when K+ is not limiting. The use of knock-out lines has allowed demonstrating their role in root K+ uptake in Arabidopsis and rice. Plant adaptation to the different K+ supplies relies on the finely tuned regulation of these systems. Low K+-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant’s adaptation to low K+. Na+ is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na+ improves growth, especially under K+ deficiency. Thus, high-affinity Na+ uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na+ accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K+ deficiency. Data concerning pathways for Na+ uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na+ uptake in rice grown under salinity conditions, but in other plant species

Iodine uptake by spinach (Spinacia oleracea L.) plants grown in solution culture: effects of iodine species and solution concentrations.

PubMed

Zhu, Y-G; Huang, Y-Z; Hu, Y; Liu, Y-X

2003-04-01

A hydroponic experiment was carried out to investigate the effects of iodine species and solution concentrations on iodine uptake by spinach (Spinacia oleracea L.). Five iodine concentrations (0, 1, 10, 50 and 100 microM) for iodate (IO(3)(-)) and iodide (I(-)) were used. Results show that higher concentrations of I(-) (> or =10 microM) had some detrimental effect on plant growth, while IO(3)(-) had little effect on the biomass production of spinach plants. Increases in iodine concentration in the growth solution significantly enhanced I concentrations in plant tissues. The detrimental effect of I(-) on plant growth was probably due to the excessively high accumulation of I in plant tissues. The solution-to-spinach leaf transfer factors (TF(leaf), fresh weight basis) for plants treated with iodide were between 14.2 and 20.7 at different solution concentrations of iodide; TF(leaf) for plants treated with iodate decreased gradually from 23.7 to 2.2 with increasing solution concentrations of iodate. The distribution coefficients (DCs) of I between leaves and roots were constantly higher for plants treated with iodate than those treated with iodide. DCs for plants treated with iodide increased with increasing solution concentrations of iodide, while DCs for plants treated with iodate (around 5.5) were similar across the range of solution concentrations of iodate used in this experiment. The implications of iodine accumulation in leafy vegetables in human iodine nutrition are also discussed. Copyright 2002 Elsevier Science Ltd.

Speciation And Uptake of Arsenic Accumulated By Corn Seedlings Using XAS And DRC-ICP-MS

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

Parsons, J.G.; Martinez-Martinez, A.; Peralta-Videa, J.R.

ICP-MS was used to investigate the uptake of As(III) and As(V) from hydroponics growth media by corn seedlings. It was found that arsenic uptake by the plant roots for the arsenic(V) and arsenic(III) treatments were 95 and 112 ppm, respectively. However, in the shoots of the arsenic (V) treatments had 18 ppm whereas arsenic(III) treatments had 12 ppm. XANES studies showed that As for both treatments arsenic was present as a mixture of an As(III) sulfur complex and an As(V) oxygen complex. The XANES data was corroborated by the EXAFS studies showing the presence of both oxygen and sulfur ligandsmore » coordinated to the arsenic. Iron concentrations were found to increase by 4 fold in the As(V) contaminated growth media and 7 fold in the As(III) treatment compared to the control iron concentration of 500 ppm. Whereas, the total iron concentration in the shoots was found to decrease by approximately the same amount for both treatments from 360 ppm in the control to approximately 125 ppm in both arsenic treatments. Phosphorus concentrations were found to decrease in both the roots and shoots compared to the control plants. The total sulfur in the roots was found to increase in the arsenic(III) and arsenic(V) treatments to 560 ppm and 800 ppm, respectively, compared to the control plants 358 ppm. In addition, the total sulfur in shoots of the plants was found to remain relatively constant at approximately 1080 ppm. The potassium concentrations in the plants were found to increase in the roots and decrease in the shoots.« less

Mercury uptake and distribution in Lavandula stoechas plants grown in soil from Almadén mining district (Spain).

PubMed

Sierra, M J; Millán, R; Esteban, E

2009-11-01

This work studies mercury root uptake by Lavandula stoechas var. Kew Red (lavender) and the distribution of this metal through the plant under greenhouse conditions along three consecutive seasons. Mercury concentration in plant tissues and in the different products obtained from lavender plants (essential oil, toilet water and in lavender tea) was assessed in order to evaluate the possible cultivation of lavender as a profitable alternative land use to mercury mining in the Almadén area once the mine had been closed down. Mercury concentration in useful parts of the plant was low (0.03-0.55 mg kg(-1)). Likewise, the essential oil, toilet water and tea obtained from these plants presented very low mercury levels, below the detection limit of the used equipment (<0.5 microg kg(-1)). In the case of the obtained tea, according to the recommendations given by the World Health Organization, the maximum daily intake of it without intoxication risk would be 85.2l. So, although other sources of mercury intake should also be considered in order to elaborate a complete toxicological risk assessment. Lavender data, obtained under this greenhouse working conditions, shows that lavender cultivation could be an alternative crop in the Almadén area.

Influence of exogenously applied abscisic acid on carotenoid content and water uptake in flowers of the tea plant (Camellia sinensis).

PubMed

Baldermann, Susanne; Yang, Ziyin; Sakai, Miwa; Fleischmann, Peter; Morita, Akio; Todoroki, Yasushi; Watanabe, Naoharu

2013-05-01

Carotenoids are a major class of plant pigments and fulfill many functions in different organisms that either produce or consume them. Although the color of the stamina of tea (Camellia sinensis) flowers is clearly due to the presence of carotenoids, the carotenoid profile and content remain to be discovered. We investigated the carotenoid profile of tea flowers and determined changes in concentrations over the floral development. The flowers contained oxygenated xanthophylls such as neoxanthin, lutein and zeaxanthin, as well as the hydrocarbons β-carotene and α-carotene. Flowers of the tea plant contain to vegetables comparable amounts of carotenoids. The content of 9'-cis-epoxycarotenoids, which serve as abscisic acid precursors, as well as changes in concentration of abscisic acid were studied. The concentrations of carotenoids decreased whereas the abscisic acid content increased over the floral development. Exogenously applied S-abscisic acid affected water uptake, flower opening and carotenoid accumulation. In summary, this paper reports, for the first time, the carotenoid profile and content of tea flowers. The study revealed that carotenoids in tea flowers are an interesting target in respect of possible applications of tea flower extracts as well as biological functions of abscisic acid during floral development. © 2012 Society of Chemical Industry.

Studies on uptake of trivalent and hexavalent chromium by maize (Zea mays).

PubMed

Mishra, S; Singh, V; Srivastava, S; Srivastava, R; Srivastava, M M; Dass, S; Satsangi, G P; Prakash, S

1995-05-01

Pot culture experiments were carried out to study the uptake and translocation of chromium from irrigation water when supplied in its trivalent and hexavalent states to maize plants grown in soil and sand culture. The uptake of chromium was observed to increase with increase in the concentration for both oxidation states of chromium. For the root, the observed order of uptake was CrIII sand > CrVI sand > CrIII soil > CrVI soil, whereas in the lower shoot, upper shoot and fruit the order was CrVI sand > CrVI soil > CrIII sand > CrIII soil. Significantly high uptake of chromium by roots in the sand culture (CrIII treatment) is attributed to the effect of root exudates and degradation products on the mobilization of CrIII. In aerial parts of the plants a higher uptake was observed when the initial supply was CrVI. The trends observed are explained on the basis of the redox behaviour of chromium.

Spatial 2D distribution of the proportion of soil phosphorus uptake by maize and soybean caused by tillage and fertilization

NASA Astrophysics Data System (ADS)

Li, Haixiao; Mollier, Alain; Ziadi, Noura; Messiga, Aimé Jean; Parent, Leon-Étienne; Morel, Christian

2017-04-01

Plant-available soil phosphorus (P) accumulates primarily in the topsoil due to P fertilization and P released from crop residues. In contrast with conventional tillage (moldboard plough, MP), conservation tillage [e.g. no-till, (NT)] often leads to higher P concentrations in the topsoil mainly due to the absence of mixing between soil, fertilizer, and crop residues. Our objective was to estimate the proportion of P uptake from a given soil mass across the soil profile under maize and soybean as the product of root surface density proportions and local plant-available soil P. This study was conducted on a long-term field experiment initiated in 1992 in southern Quebec, Canada, and established on a clay-loam soil under MP and NT systems. The experiment was factorially treated with three P doses (0, 17.5 and 35 kg P ha-1 applied as triple superphosphate on maize at 5 cm depth and at 5 cm on one side of the crop row). Soil was sampled at flowering stage at five depths (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and three horizontal distances perpendicular to the crop row (5, 15 and 25 cm) in 2014 and 2015 to map a grid soil P availability to plants, e.g. phosphate ion concentrations in solution and the time-dependent amount of phosphate ions that can equilibrate- solution by diffusion, root distribution, and consequently crop P uptake, which was calculated as the fraction of plant-available soil P intercepted by surface roots. In general, NT tended to have higher soil P status in the upper soil layer and lower soil P status in the deeper soil layer compared to MP ; confirming previous results obtained from the same experimental site. This variation along the soil profile was significantly affected by sampling distance to crop row with higher concentration observed at 5-cm distance mainly because of the placement of P fertilizers. The 2D distribution of P uptake depended on tillage practice and P fertilization. There was higher proportions of P uptake from the 0-10 and 0

Improving representation of nitrogen uptake, allocation, and carbon assimilation in the Community Land Model

NASA Astrophysics Data System (ADS)

Ghimire, B.; Riley, W. J.; Koven, C.

2013-12-01

Nitrogen is the most important nutrient limiting plant carbon assimilation and growth, and is required for production of photosynthetic enzymes, growth and maintenance respiration, and maintaining cell structure. The forecasted rise in plant available nitrogen through atmospheric nitrogen deposition and the release of locked soil nitrogen by permafrost thaw in high latitude ecosystems is likely to result in an increase in plant productivity. However a mechanistic representation of plant nitrogen dynamics is lacking in earth system models. Most earth system models ignore the dynamic nature of plant nutrient uptake and allocation, and further lack tight coupling of below- and above-ground processes. In these models, the increase in nitrogen uptake does not translate to a corresponding increase in photosynthesis parameters, such as maximum Rubisco capacity and electron transfer rate. We present an improved modeling framework implemented in the Community Land Model version 4.5 (CLM4.5) for dynamic plant nutrient uptake, and allocation to different plant parts, including leaf enzymes. This modeling framework relies on imposing a more realistic flexible carbon to nitrogen stoichiometric ratio for different plant parts. The model mechanistically responds to plant nitrogen uptake and leaf allocation though changes in photosynthesis parameters. We produce global simulations, and examine the impacts of the improved nitrogen cycling. The improved model is evaluated against multiple observations including TRY database of global plant traits, nitrogen fertilization observations and 15N tracer studies. Global simulations with this new version of CLM4.5 showed better agreement with the observations than the default CLM4.5-CN model, and captured the underlying mechanisms associated with plant nitrogen cycle.

Comparison of PAHs uptake by selected Monocotyledones and Dicotyledones from municipal and industrial sewage sludge.

PubMed

Gworek, Barbara; Klimczak, Katarzyna; Kijeńska, Marta; Gozdowski, Dariusz

2016-10-01

The study was focused on two goals: (i) the confirmation of the existence of a general relation between the content of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge and in plants growing in it, regardless of the type and content of sewage sludge, and (ii) if so, the answer to the question whether the uptake of PAHs by plants depends on their type. To realize the set aims, the contents of PAHs in four differentiated plant species were measured, two belonging to the Monocotyledones and two belonging to Dicotyledones group, growing in municipal and industrial sewage sludge in two locations. All the investigations were carried out during the period of 3 years. The results clearly demonstrated that the uptake of PAHs by a plant depended on polyaromatic hydrocarbon concentration in the sewage sludge. The relation between accumulation coefficient of PAHs in plant material vs. the content of PAH in sewage sludge was of exponential character. The results indicate that in case of four- and five-ring PAHs, the root uptake mechanism from soil solution occurs, regardless of the type and origin of sewage sludge and the type of plant. For three-ring PAHs, we can assume for Monocotyledones that the root uptake mechanism occurs because we observe a significant correlation between the content of fluorene, phenanthrene, and anthracene in plant material and in the sewage sludge. For Dicotyledones, the correlation is insignificant, and in this case probably two mechanisms occur-the uptake by roots and by leaves.

Electrokinetic enhancement on phytoremediation in Zn, Pb, Cu and Cd contaminated soil using potato plants.

PubMed

Aboughalma, Hanssan; Bi, Ran; Schlaak, Michael

2008-07-01

The use of a combination of electrokinetic remediation and phytoremediation to decontaminate soil polluted with heavy metals has been demonstrated in a laboratory-scale experiment. Potato tubers were planted in plastic vessels filled with Zn, Pb, Cu and Cd contaminated soil and grown in a greenhouse. Three of these vessels were treated with direct current electric field (DC), three with alternative current (AC) and three remained untreated as control vessels. The soil pH varied from anode to cathode with a minimum of pH 3 near the anode and a maximum of pH 8 near the cathode in the DC treated soil profile. There was an accumulation of Zn, Cu and Cd at about 12 cm distance from anode when soil pH was 5 in the DC treated soil profile. There was no significant metal redistribution and pH variation between anode and cathode in the AC soil profile. The biomass production of the plants was 72% higher under AC treatment and 27% lower under DC treatment compared to the control. Metal accumulation was generally higher in the plant roots treated with electrical fields than the control. The overall metal uptake in plant shoots was lower under DC treatment compared to AC treatment and control, although there was a higher accumulation of Zn and Cu in the plant roots treated with electrical fields. The Zn uptake in plant shoots under AC treatment was higher compared to the control and DC treatment. Zn and Cu accumulation in the plant roots under AC and DC treatment was similar, and both were higher comparing to control. Cd content in plant roots under all three treatments was found to be higher than that in the soil. The Pb accumulation in the roots and the uptake into the shoots was lower compared to its content in the soil.

Soil respiration and photosynthetic uptake of carbon dioxide by ground-cover plants in four ages of jack pine forest

USGS Publications Warehouse

Striegl, Robert G.; Wickland, K.P.

2001-01-01

Soil carbon dioxide (CO2) emission (soil respiration), net CO2 exchange after photosynthetic uptake by ground-cover plants, and soil CO2 concentration versus depth below land surface were measured at four ages of jack pine (Pinus banksiana Lamb.) forest in central Saskatchewan. Soil respiration was smallest at a clear-cut site, largest in an 8-year-old stand, and decreased with stand age in 20-year-old and mature (60-75 years old) stands during May-September 1994 (12.1, 34.6, 31.5, and 24.9 mol C??m-2, respectively). Simulations of soil respiration at each stand based on continuously recorded soil temperature were within one standard deviation of measured flux for 48 of 52 measurement periods, but were 10%-30% less than linear interpolations of measured flux for the season. This was probably due to decreased soil respiration at night modeled by the temperature-flux relationships, but not documented by daytime chamber measurements. CO2 uptake by ground-cover plants ranged from 0 at the clear-cut site to 29, 25, and 9% of total growing season soil respiration at the 8-year, 20-year, and mature stands. CO2 concentrations were as great as 7150 ppmv in the upper 1 m of unsaturated zone and were proportional to measured soil respiration.

Comparative evaluation of SUV, tumor-to-blood standard uptake ratio (SUR), and dual time point measurements for assessment of the metabolic uptake rate in FDG PET.

PubMed

Hofheinz, Frank; Hoff, Jörg van den; Steffen, Ingo G; Lougovski, Alexandr; Ego, Kilian; Amthauer, Holger; Apostolova, Ivayla

2016-12-01

We have demonstrated recently that the tumor-to-blood standard uptake ratio (SUR) is superior to tumor standardized uptake value (SUV) as a surrogate of the metabolic uptake rate K m of fluorodeoxyglucose (FDG), overcoming several of the known shortcomings of the SUV approach: excellent linear correlation of SUR and K m from Patlak analysis was found using dynamic imaging of liver metastases. However, due to the perfectly standardized uptake period used for SUR determination and the comparatively short uptake period, these results are not automatically valid and applicable for clinical whole-body examinations in which the uptake periods (T) are distinctly longer and can vary considerably. Therefore, the aim of this work was to investigate the correlation between SUR derived from clinical static whole-body scans and K m-surrogate derived from dual time point (DTP) measurements. DTP (18)F-FDG PET/CT was performed in 90 consecutive patients with histologically proven non-small cell lung cancer (NSCLC). In the PET images, the primary tumor was delineated with an adaptive threshold method. For determination of the blood SUV, an aorta region of interest (ROI) was delineated manually in the attenuation CT and transferred to the PET image. Blood SUV was computed as the mean value of the aorta ROI. SUR values were computed as ratio of tumor SUV and blood SUV. SUR values from the early time point of each DTP measurement were scan time corrected to 75 min postinjection (SURtc). As surrogate of K m, we used the SUR(T) slope, K slope, derived from DTP measurements since it is proportional to the latter under the given circumstances. The correlation of SUV and SURtc with K slope was investigated. The prognostic value of SUV, SURtc, and K slope for overall survival (OS) and progression-free survival (PFS) was investigated with univariate Cox regression in a homogeneous subgroup (N=31) treated with primary chemoradiation. Correlation analysis revealed for both, SUV and SURtc, a

Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

PubMed Central

Brackin, Richard; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Schmidt, Susanne; Inselsbacher, Erich

2015-01-01

Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots’ uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed. PMID:26496834

The pitcher plant Sarracenia purpurea can directly acquire organic nitrogen and short-circuit the inorganic nitrogen cycle.

PubMed

Karagatzides, Jim D; Butler, Jessica L; Ellison, Aaron M

2009-07-07

Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture.

The Pitcher Plant Sarracenia purpurea Can Directly Acquire Organic Nitrogen and Short-Circuit the Inorganic Nitrogen Cycle

PubMed Central

Karagatzides, Jim D.; Butler, Jessica L.; Ellison, Aaron M.

2009-01-01

Background Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. Methodology and Principal Findings At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. Conclusions and Significance By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on

Root Uptake Of Lipophilic Zinc-Rhamnolipid Complexes

EPA Science Inventory

This study investigated the formation and plant uptake of lipophilic metal-rhamnolipid complexes. Monorhamnosyl and dirhamnosyl rhamnolipids formed lipophilic complexes with copper (Cu), manganese (Mn), and zinc (Zn). Rhamnolipids significantly increased Zn absorption by Bra...