The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Norman Terry - One of the best experts on this subject based on the ideXlab platform.
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Rhizosphere Bacteria mobilize Zn for hyperaccumulation by Thlaspi caerulescens.
Environmental science & technology, 2001Co-Authors: Steven N Whiting, M P De Souza, Norman TerryAbstract:Thlaspi caerulescens has a remarkable ability to hyperaccumulate Zn from soils containing mostly nonlabile Zn. The present study shows that Rhizosphere microbes play an important role in increasing the availability of water-soluble Zn in soil, thus enhancing Zn accumulation by T. caerulescens. The addition of Bacteria to surface-sterilized seeds of T. caerulescens sown in autoclaved soil increased the Zn concentration in shoots 2-fold as compared to axenic controls; the total accumulation of Zn was enhanced 4-fold. When the same experiment was conducted with Thlaspi arvense, a nonaccumulator, Bacteria had no effect on shoot Zn accumulation although they increased water-soluble Zn concentrations available to both Thlaspi species by 22-67% as compared to the axenic controls. Further evidence that Bacteria increase the availability of water-soluble Zn in soil was obtained when liquid media that had supported Bacterial growth mobilized 1.3-1.8-fold more Zn from soil as compared to axenic media. Other experiments with agar media showed that Bacteria did not facilitate an increase in the rate of soluble Zn transport into the root nor did they enlarge the surface area of the roots of either Thlaspi species. Thus, the Bacterially mediated increase in the dissolution of Zn from the nonlabile phase in soil may enhance Zn accumulation in T. caerulescens shoots.
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Rhizosphere Bacteria mobilize zn for hyperaccumulation by thlaspi caerulescens
Environmental Science & Technology, 2001Co-Authors: Steven N Whiting, M P De Souza, Norman TerryAbstract:Thlaspi caerulescens has a remarkable ability to hyperaccumulate Zn from soils containing mostly nonlabile Zn. The present study shows that Rhizosphere microbes play an important role in increasing the availability of water-soluble Zn in soil, thus enhancing Zn accumulation by T. caerulescens. The addition of Bacteria to surface-sterilized seeds of T. caerulescens sown in autoclaved soil increased the Zn concentration in shoots 2-fold as compared to axenic controls; the total accumulation of Zn was enhanced 4-fold. When the same experiment was conducted with Thlaspi arvense, a nonaccumulator, Bacteria had no effect on shoot Zn accumulation although they increased water-soluble Zn concentrations available to both Thlaspi species by 22−67% as compared to the axenic controls. Further evidence that Bacteria increase the availability of water-soluble Zn in soil was obtained when liquid media that had supported Bacterial growth mobilized 1.3−1.8-fold more Zn from soil as compared to axenic media. Other experime...
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Rhizosphere Bacteria enhance the accumulation of selenium and mercury in wetland plants
Planta, 1999Co-Authors: M P De Souza, C P A Huang, N Chee, Norman TerryAbstract:The role of Rhizosphere Bacteria in facilitating Se and Hg accumulation in two wetland plants, saltmarsh bulrush (Scirpus robustus Pursh) and rabbitfoot grass (Polypogon monspeliensis (L.) Desf.), was studied. Ampicillin-amended plants (i.e., with inhibited Rhizosphere Bacteria) supplied with Na2SeO4 or HgCl2 had significantly lower concentrations of Se and Hg, respectively, in roots than plants without ampicillin. These results were confirmed by inoculating axenic saltmarsh bulrush plants with Bacteria isolated from the Rhizosphere of plants collected from the field; these plants accumulated significantly more Se and Hg compared to axenic controls. Therefore, Rhizosphere Bacteria can increase the efficiency of Se and Hg phytoremediation by promoting the accumulation of Se and Hg in tissues of wetland plants.
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Rhizosphere Bacteria enhance selenium accumulation and volatilization by indian mustard
Plant Physiology, 1999Co-Authors: Mark P De Souza, May Zhao, Steven E Ruzin, Denise Schichnes, Amro Zayed, Norman TerryAbstract:Indian mustard (Brassica juncea L.) accumulates high tissue Se concentrations and volatilizes Se in relatively nontoxic forms, such as dimethylselenide. This study showed that the presence of Bacteria in the Rhizosphere of Indian mustard was necessary to achieve the best rates of plant Se accumulation and volatilization of selenate. Experiments with the antibiotic ampicillin showed that Bacteria facilitated 35% of plant Se volatilization and 70% of plant tissue accumulation. These results were confirmed by inoculating axenic plants with Rhizosphere Bacteria. Compared with axenic controls, plants inoculated with Rhizosphere Bacteria had 5-fold higher Se concentrations in roots (the site of volatilization) and 4-fold higher rates of Se volatilization. Plants with Bacteria contained a heat-labile compound in their root exudate; when this compound was added to the Rhizosphere of axenic plants, Se accumulation in plant tissues increased. Plants with Bacteria had an increased root surface area compared with axenic plants; the increased area was unlikely to have caused their increased tissue Se accumulation because they did not accumulate more Se when supplied with selenite or selenomethionine. Rhizosphere Bacteria also possibly increased plant Se volatilization because they enabled plants to overcome a rate-limiting step in the Se volatilization pathway, i.e. Se accumulation in plant tissues.
Sasha N Jenkins - One of the best experts on this subject based on the ideXlab platform.
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Soil disturbance and water stress interact to influence arbuscular mycorrhizal fungi, Rhizosphere Bacteria and potential for N and C cycling in an agricultural soil
Biology and Fertility of Soils, 2018Co-Authors: Bede S Mickan, L K Abbott, Kadambot H M Siddique, Zakaria M Solaiman, Falko Mathes, Sasha N JenkinsAbstract:The objective of this study was to determine how soil disturbance and soil water deficit alter colonisation of roots by naturally occurring arbuscular mycorrhizal (AM) fungi and Rhizosphere Bacteria. Soil cores were collected at the end of summer from a cropped paddock with a 5-year history of no-tillage in south-western Australia which has a Mediterranean climate. Well-watered and water-stressed treatments were maintained at 70 and 35% field capacity, respectively. AM fungal colonisation was determined using microscopy, Rhizosphere Bacterial community composition was assessed using barcoded PCR-amplified Bacterial 16S rRNA genes, and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis of functional gene prediction was used to characterise the Rhizosphere functionality for some nitrogen (N) cycling and soil carbon (C) degradation. Mycorrhizal colonisation and plant growth were reduced by disturbance under water stress but not for well-watered soil cores. The Rhizosphere Bacterial community composition shifted with both soil disturbance and soil moisture, and there was an interaction between them. Disturbance decreased the relative abundance of ProteoBacteria and AcidoBacteria and increased the relative abundance of ActinoBacteria and Firmicutes in water-stressed soil. The predicted abundance of some genes involved in N reactions was negatively influenced by both disturbance and soil moisture, but the predicted abundance of C degrading predicted genes was only marginally affected. This study highlighted how soil disturbance prior to seeding can alter soil biological processes that influence plant growth and that this could be most pronounced when water is limiting.
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application of compost and clay under water stressed conditions influences functional diversity of Rhizosphere Bacteria
Biology and Fertility of Soils, 2018Co-Authors: Bede S Mickan, L K Abbott, Jingwei Fan, Miranda M Hart, Kadambot H M Siddique, Zakaria M Solaiman, Sasha N JenkinsAbstract:Applications of compost and clay to ameliorate soil constraints such as water stress are potential management strategies for sandy agricultural soils. Water repellent sandy soils in rain-fed agricultural systems limit production and have negative environmental effects associated with leaching and soil erosion. The aim was to determine whether compost and clay amendments in a sandy agricultural soil influenced the Rhizosphere microbiome of Trifolium subterraneum under differing water regimes. Soil was amended with compost (2% w/w), clay (5% w/w) and a combination of both, in a glasshouse experiment with well-watered and water-stressed (70 and 35% field capacity) treatments. Ion Torrent 16S rRNA sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis of functional gene prediction were used to characterise the Rhizosphere Bacterial community and its functional component involved in nitrogen (N) cycling and soil carbon (C) degradation. Compost soil treatments increased the relative abundance of copiotrophic Bacteria, decreased labile C and increased the abundance of recalcitrant C degrading genes. Predicted N cycling genes increased with the addition of clay (N2 fixation, nitrification, denitrification) and compost + clay (N2 fixation, denitrification) and decreased with compost (for denitrification) amendment. Water stress did not alter the relative abundance of phylum level taxa in the presence of compost, although copiotrophic ActinoBacteria increased in relative abundance with addition of clay and with compost + clay. A significant role of compost and clay under water stress in influencing the composition of Rhizosphere Bacteria and their implications for N cycling and C degradation was demonstrated.
Bede S Mickan - One of the best experts on this subject based on the ideXlab platform.
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Soil disturbance and water stress interact to influence arbuscular mycorrhizal fungi, Rhizosphere Bacteria and potential for N and C cycling in an agricultural soil
Biology and Fertility of Soils, 2018Co-Authors: Bede S Mickan, L K Abbott, Kadambot H M Siddique, Zakaria M Solaiman, Falko Mathes, Sasha N JenkinsAbstract:The objective of this study was to determine how soil disturbance and soil water deficit alter colonisation of roots by naturally occurring arbuscular mycorrhizal (AM) fungi and Rhizosphere Bacteria. Soil cores were collected at the end of summer from a cropped paddock with a 5-year history of no-tillage in south-western Australia which has a Mediterranean climate. Well-watered and water-stressed treatments were maintained at 70 and 35% field capacity, respectively. AM fungal colonisation was determined using microscopy, Rhizosphere Bacterial community composition was assessed using barcoded PCR-amplified Bacterial 16S rRNA genes, and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis of functional gene prediction was used to characterise the Rhizosphere functionality for some nitrogen (N) cycling and soil carbon (C) degradation. Mycorrhizal colonisation and plant growth were reduced by disturbance under water stress but not for well-watered soil cores. The Rhizosphere Bacterial community composition shifted with both soil disturbance and soil moisture, and there was an interaction between them. Disturbance decreased the relative abundance of ProteoBacteria and AcidoBacteria and increased the relative abundance of ActinoBacteria and Firmicutes in water-stressed soil. The predicted abundance of some genes involved in N reactions was negatively influenced by both disturbance and soil moisture, but the predicted abundance of C degrading predicted genes was only marginally affected. This study highlighted how soil disturbance prior to seeding can alter soil biological processes that influence plant growth and that this could be most pronounced when water is limiting.
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application of compost and clay under water stressed conditions influences functional diversity of Rhizosphere Bacteria
Biology and Fertility of Soils, 2018Co-Authors: Bede S Mickan, L K Abbott, Jingwei Fan, Miranda M Hart, Kadambot H M Siddique, Zakaria M Solaiman, Sasha N JenkinsAbstract:Applications of compost and clay to ameliorate soil constraints such as water stress are potential management strategies for sandy agricultural soils. Water repellent sandy soils in rain-fed agricultural systems limit production and have negative environmental effects associated with leaching and soil erosion. The aim was to determine whether compost and clay amendments in a sandy agricultural soil influenced the Rhizosphere microbiome of Trifolium subterraneum under differing water regimes. Soil was amended with compost (2% w/w), clay (5% w/w) and a combination of both, in a glasshouse experiment with well-watered and water-stressed (70 and 35% field capacity) treatments. Ion Torrent 16S rRNA sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis of functional gene prediction were used to characterise the Rhizosphere Bacterial community and its functional component involved in nitrogen (N) cycling and soil carbon (C) degradation. Compost soil treatments increased the relative abundance of copiotrophic Bacteria, decreased labile C and increased the abundance of recalcitrant C degrading genes. Predicted N cycling genes increased with the addition of clay (N2 fixation, nitrification, denitrification) and compost + clay (N2 fixation, denitrification) and decreased with compost (for denitrification) amendment. Water stress did not alter the relative abundance of phylum level taxa in the presence of compost, although copiotrophic ActinoBacteria increased in relative abundance with addition of clay and with compost + clay. A significant role of compost and clay under water stress in influencing the composition of Rhizosphere Bacteria and their implications for N cycling and C degradation was demonstrated.
M P De Souza - One of the best experts on this subject based on the ideXlab platform.
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Rhizosphere Bacteria mobilize Zn for hyperaccumulation by Thlaspi caerulescens.
Environmental science & technology, 2001Co-Authors: Steven N Whiting, M P De Souza, Norman TerryAbstract:Thlaspi caerulescens has a remarkable ability to hyperaccumulate Zn from soils containing mostly nonlabile Zn. The present study shows that Rhizosphere microbes play an important role in increasing the availability of water-soluble Zn in soil, thus enhancing Zn accumulation by T. caerulescens. The addition of Bacteria to surface-sterilized seeds of T. caerulescens sown in autoclaved soil increased the Zn concentration in shoots 2-fold as compared to axenic controls; the total accumulation of Zn was enhanced 4-fold. When the same experiment was conducted with Thlaspi arvense, a nonaccumulator, Bacteria had no effect on shoot Zn accumulation although they increased water-soluble Zn concentrations available to both Thlaspi species by 22-67% as compared to the axenic controls. Further evidence that Bacteria increase the availability of water-soluble Zn in soil was obtained when liquid media that had supported Bacterial growth mobilized 1.3-1.8-fold more Zn from soil as compared to axenic media. Other experiments with agar media showed that Bacteria did not facilitate an increase in the rate of soluble Zn transport into the root nor did they enlarge the surface area of the roots of either Thlaspi species. Thus, the Bacterially mediated increase in the dissolution of Zn from the nonlabile phase in soil may enhance Zn accumulation in T. caerulescens shoots.
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Rhizosphere Bacteria mobilize zn for hyperaccumulation by thlaspi caerulescens
Environmental Science & Technology, 2001Co-Authors: Steven N Whiting, M P De Souza, Norman TerryAbstract:Thlaspi caerulescens has a remarkable ability to hyperaccumulate Zn from soils containing mostly nonlabile Zn. The present study shows that Rhizosphere microbes play an important role in increasing the availability of water-soluble Zn in soil, thus enhancing Zn accumulation by T. caerulescens. The addition of Bacteria to surface-sterilized seeds of T. caerulescens sown in autoclaved soil increased the Zn concentration in shoots 2-fold as compared to axenic controls; the total accumulation of Zn was enhanced 4-fold. When the same experiment was conducted with Thlaspi arvense, a nonaccumulator, Bacteria had no effect on shoot Zn accumulation although they increased water-soluble Zn concentrations available to both Thlaspi species by 22−67% as compared to the axenic controls. Further evidence that Bacteria increase the availability of water-soluble Zn in soil was obtained when liquid media that had supported Bacterial growth mobilized 1.3−1.8-fold more Zn from soil as compared to axenic media. Other experime...
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Rhizosphere Bacteria enhance the accumulation of selenium and mercury in wetland plants
Planta, 1999Co-Authors: M P De Souza, C P A Huang, N Chee, Norman TerryAbstract:The role of Rhizosphere Bacteria in facilitating Se and Hg accumulation in two wetland plants, saltmarsh bulrush (Scirpus robustus Pursh) and rabbitfoot grass (Polypogon monspeliensis (L.) Desf.), was studied. Ampicillin-amended plants (i.e., with inhibited Rhizosphere Bacteria) supplied with Na2SeO4 or HgCl2 had significantly lower concentrations of Se and Hg, respectively, in roots than plants without ampicillin. These results were confirmed by inoculating axenic saltmarsh bulrush plants with Bacteria isolated from the Rhizosphere of plants collected from the field; these plants accumulated significantly more Se and Hg compared to axenic controls. Therefore, Rhizosphere Bacteria can increase the efficiency of Se and Hg phytoremediation by promoting the accumulation of Se and Hg in tissues of wetland plants.
Marc Starnaud - One of the best experts on this subject based on the ideXlab platform.
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the Bacterial community of tomato Rhizosphere is modified by inoculation with arbuscular mycorrhizal fungi but unaffected by soil enrichment with mycorrhizal root exudates or inoculation with phytophthora nicotianae
Soil Biology & Biochemistry, 2010Co-Authors: Laetitia Lioussanne, Francois Perreault, Mario Jolicoeur, Marc StarnaudAbstract:Arbuscular mycorrhizal (AM) fungi have been shown to induce the biocontrol of soilborne diseases, to change the composition of root exudates and to modify the Bacterial community structure of the Rhizosphere, leading to the formation of the mycorRhizosphere. Tomato plants were grown in a compartmentalized soil system and were either submitted to direct mycorrhizal colonization or to enrichment of the soil with exudates collected from mycorrhizal tomato plants, with the corresponding negative controls. Three weeks after planting, the plants were inoculated or not with the soilborne pathogen Phytophthora nicotianae growing through a membrane from an adjacent infected compartment. At harvest, a PCR-Denaturing gradient gel electrophoresis analysis of 16S rRNA gene fragments amplified from the total DNA extracted from each plant Rhizosphere was performed. Root colonization with the AM fungi Glomus intraradices or Glomus mosseae induced significant changes in the Bacterial community structure of tomato Rhizosphere, compared to non-mycorrhizal plants, while enrichment with root exudates collected from mycorrhizal or non-mycorrhizal plants had no effect. Our results support that the effect of AM fungi on Rhizosphere Bacteria would not be mediated by compounds present in root exudates of mycorrhizal plants but rather by physical or chemical factors associated with the mycelium, volatiles and/or root surface bound substrates. Moreover, infection of mycorrhizal or non-mycorrhizal plants with P. nicotianae did not significantly affect the Bacterial community structure suggesting that Rhizosphere Bacteria would be less sensitive to the pathogen invasion than to mycorrhizal colonization. Of 96 unique sequences detected in the tomato Rhizosphere, eight were specific to mycorrhizal fungi, including two Pseudomonas, a Bacillus simplex, an Herbaspirilium and an Acidobacterium. One Verrucomicrobium was common to Rhizospheres of mycorrhizal plants and of plants watered with mycorrhizal root exudates.