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A J M Baker - One of the best experts on this subject based on the ideXlab platform.

  • the effect of nitrogen form on rhizosphere soil ph and zinc phytoextraction by Thlaspi caerulescens
    Chemosphere, 2008
    Co-Authors: Alison Carol. Monsant, Caixian Tang, A J M Baker
    Abstract:

    Abstract The phytoextraction of Zn may be improved by applying N fertilizers to increase the biomass and Zn content of shoots. Rhizosphere-pH change from uptake of different N forms will affect Zn phyto-availability in the rhizosphere and Zn phytoextraction. This glasshouse study examined the effect of N form on Zn phytoextraction by Thlaspi caerulescens (Prayon). The plants were grown in a Zn-contaminated soil (total Zn 250 mg kg−1 soil; pHwater 5.7) and supplied with (NH4)2SO4, Ca(NO3)2 or urea [(NH2)2CO]. The NH 4 + form was maintained by applying the nitrification inhibitor dicyandiamide. A biodegradable chelator ethylenediaminedisuccinic acid (EDDS) was included for comparison. The addition of N doubled the shoot biomass. The highest shoot Zn content occurred in the Ca(NO3)2 treatment and was associated with the highest rhizosphere pH. The lowest shoot dry weight occurred in the EDDS treatment. The Zn concentration in the shoots increased as the rhizosphere pH increased. A significant correlation occurred between Ca and Zn concentrations in the shoots. This study demonstrated that Ca(NO3)2 is a more effective treatment than NH 4 + , urea or EDDS for enhancing Zn phytoextraction in a mildly acidic soil.

  • a comparison of the Thlaspi caerulescens and Thlaspi arvense shoot transcriptomes
    New Phytologist, 2006
    Co-Authors: A J M Baker, Victoria Mills, Steven N Whiting, Philip J. White, John P Hammond, Helen C Bowen, Kevin A Pyke, Martin R. Broadley
    Abstract:

    Summary • Whole-genome transcriptome profiling is revealing how biological systems are regulated at the transcriptional level. This study reports the development of a robust method to profile and compare the transcriptomes of two nonmodel plant species, Thlaspi caerulescens, a zinc (Zn) hyperaccumulator, and Thlaspi arvense, a nonhyperaccumulator, using Affymetrix Arabidopsis thaliana ATH1-121501 GeneChip® arrays (Affymetrix, Santa Clara, CA, USA). • Transcript abundance was quantified in the shoots of agar- and compost-grown plants of both species. Analyses were optimized using a genomic DNA (gDNA)-based probe-selection strategy based on the hybridization efficiency of Thlaspi gDNA with corresponding A. thaliana probes. In silico alignments of GeneChip® probes with Thlaspi gene sequences, and quantitative real-time PCR, confirmed the validity of this approach. • Approximately 5000 genes were differentially expressed in the shoots of T. caerulescens compared with T. arvense, including genes involved in Zn transport and compartmentalization. • Future functional analyses of genes identified as differentially expressed in the shoots of these closely related species will improve our understanding of the molecular mechanisms of Zn hyperaccumulation.

  • nickel and zinc hyperaccumulation by alyssum murale and Thlaspi caerulescens brassicaceae do not enhance survival and whole plant growth under drought stress
    Plant Cell and Environment, 2003
    Co-Authors: Steven N Whiting, Peter M Neumann, A J M Baker
    Abstract:

    Nickel and Zn hyperaccumulation by Alyssum murale and Thlaspi caerulescens bear substantial energetic costs and should confer benefits to the plant. This research determined whether metal hyperaccumulation can increase osmotic adjustment and resistance to water stress (drought). Alyssum murale and Thlaspi caerulescens treated with low or high concentrations of Ni or Zn were exposed to moderate (−0·4 MPa) and severe (−1·0 MPa) water stresses using aqueous polyethylene glycol. In the absence of metals both water deficits inhibited shoot growth. Nickel and Zn hyperaccumulation did not ameliorate growth inhibition by either level of water stress. The water stress did not induce major changes in shoot metal concentrations of these constitutive hyperaccumulators. Moreover, metal hyperaccumulation had minimal effects on the osmolality of leaf-sap extracts, relative water content of the shoots, or rate of evapotranspiration. It is concluded that Ni or Zn hyperaccumulation does not augment whole-plant capacity for drought resistance in A. murale and T. caerulescens.

  • assessment of zn mobilization in the rhizosphere of Thlaspi caerulescens by bioassay with non accumulator plants and soil extraction
    Plant and Soil, 2001
    Co-Authors: Steven N Whiting, Jonathan R Leake, Stephen P Mcgrath, A J M Baker
    Abstract:

    This study used co-cultivated plants as a bioassay to test the hypothesis that the roots of the zinc-hyperaccumulating plant Thlaspi caerulescensmobilize Zn from less-available pools in the soil. Thlaspi caerulescens was grown in uncompartmentalised pots, or pots that were divided by solid or mesh barriers to limit the extent of root intermingling (rhizosphere interaction) with co-cultivated Thlaspi arvense or Festuca rubra. Thlaspi caerulescens did not increase the concentration of Zn in either indicator species, suggesting that T. caerulescens does not strongly mobilize Zn in its rhizosphere. The increase in the shoot mass of T. arvense when its roots were permitted to intermingle with those of T. caerulescens was explained by greater intensity of competition of T. arvense compared to T. caerulescens.

  • hyperaccumulation of zn by Thlaspi caerulescens can ameliorate zn toxicity in the rhizosphere of cocropped Thlaspi arvense
    Environmental Science & Technology, 2001
    Co-Authors: Steven N Whiting, S P Mcgrath, Jonathan R Leake, A J M Baker
    Abstract:

    The metal hyperaccumulating plant Thlaspi caerulescens is effective in depleting plant-available metals from the soil. We hypothesized that this reduction of toxic metals in the rhizosphere of T. caerulescens would increase the growth of less metal-tolerant plants with their roots permitted to intermingle and develop coincident rhizospheres. The extent of rhizosphere interaction between T. caerulescens and a coplanted nonaccumulator species, Thlaspi arvense, was controlled using barriers. Two media with elevated concentrations of water-extractable Zn were prepared by enriching one soil with zinc oxide (ZnO) or zinc sulfide (ZnS). The shoot mass of T. arvense was increased by 30% when its roots were permitted to intermingle with those of T. caerulescens in the ZnO treatment. The concomitant 2−3-fold reduction in shoot Zn concentration in T. arvense confirmed that its improved growth was associated with reduced uptake and phytotoxicity of Zn. Thlaspi arvense also showed increased growth and reduced metal up...

S P Mcgrath - One of the best experts on this subject based on the ideXlab platform.

  • Physiological evidence for a high‐affinity cadmium transporter highly expressed in a Thlaspi caerulescens ecotype
    New Phytologist, 2020
    Co-Authors: Enzo Lombi, Fang-jie Zhao, S.d. Young, S P Mcgrath, Gian Attilio Sacchi
    Abstract:

    • Uptake kinetics and translocation characteristics of cadmium and zinc are presented for two contrasting ecotypes of the Cd/Zn hyperaccumulator Thlaspi caerulescens, Ganges (southern France) and Prayon (Belgium). • Experiments using radioactive isotopes were designed to investigate the physiology of Cd and Zn uptake, and a pressure-chamber system was employed to collect xylem sap. • In contrast to similar Zn uptake and translocation, measurements of concentration-dependent influx of Cd revealed marked differences between ecotypes. Ganges alone showed a clear saturable component in the low Cd concentration range; maximum influx Vmax for Cd was fivefold higher in Ganges; and there was a fivefold difference in the Cd concentration in xylem sap. Addition of Zn to the uptake solution at equimolar concentration to Cd did not decrease Cd uptake by Ganges, but caused a 35% decrease in Prayon. • There is strong physiological evidence for a high-affinity, highly expressed Cd transporter in the root cell plasma membranes of the Ganges ecotype of T. caerulescens. This raises evolutionary questions about specific transporters for non-essential metals. The results also show the considerable scope for selecting hyperaccumulator ecotypes to achieve higher phytoextraction efficiencies.

  • variation in root to shoot translocation of cadmium and zinc among different accessions of the hyperaccumulators Thlaspi caerulescens and Thlaspi praecox
    New Phytologist, 2008
    Co-Authors: Henk Schat, S P Mcgrath, Jian Feng, Daisei Ueno, J P Xing, Rongfeng Jiang, Fang-jie Zhao
    Abstract:

    • Efficient root-to-shoot translocation is a key trait of the zinc/cadmium hyperaccumulators Thlaspi caerulescens and Thlaspi praecox, but the extent of variation among different accessions and the underlying mechanisms remain unclear. • Root-to-shoot translocation of Cd and Zn and apoplastic bypass flow were determined in 10 accessions of T. caerulescens and one of T. praecox, using radiolabels

  • does cadmium play a physiological role in the hyperaccumulator Thlaspi caerulescens
    Chemosphere, 2008
    Co-Authors: Junta Yanai, S P Mcgrath, Rongfeng Jiang, Fusuo Zhang, Fang-jie Zhao
    Abstract:

    Abstract The southern French (Ganges) ecotype of Thlaspi caerulescens J & C Presl is able to hyperaccumulate several thousand mg Cd kg −1 shoot dry weight without suffering from phytotoxicity. We investigated the effect of Cd on growth and the activity of carbonic anhydrase (CA), a typical Zn-requiring enzyme, of T. caerulescens in soil and hydroponic experiments. In one of the hydroponic experiments, T. caerulescens was compared to the non-accumulator Thlaspi ferganense N. Busch. In the soil experiment, additions of Cd at 5–500 mg kg −1 soil increased the growth of T. caerulescens significantly. In the hydroponic experiments, exposure to Cd at 1–50 μM for three weeks had no significant effect on the growth of T. caerulescens , but decreased the growth of T. ferganense markedly even at the lowest concentration of Cd (1 μM). Cadmium exposure significantly increased the CA activity in T. caerulescens , but decreased it in T. ferganense . The CA activity in T. caerulescens correlated positively with the Cd concentration in the shoots up to 6000 mg kg −1 , even though shoot Zn concentration was decreased by the Cd treatments. For comparison, Cd treatments had no consistent effect on the activity of superoxide dismutase in T. caerulescens . The results suggest that Cd may play a physiological role in the Cd-hyperaccumulating ecotype of T. caerulescens by enhancing the activities of some enzymes such as CA. Further research is needed to establish whether a Cd-requiring CA exists in T. caerulescens .

  • synthesis of low molecular weight thiols in response to cd exposure in Thlaspi caerulescens
    Plant Cell and Environment, 2006
    Co-Authors: Javier Hernandezallica, Fang-jie Zhao, Carlos Garbisu, J M Becerril, Oihana Barrutia, Jose Ignacio Garciaplazaola, S P Mcgrath
    Abstract:

    In this study, we investigated the accumulation of phytochelatins (PCs) and other low molecular weight (LMW) thiols in response to Cd exposure in two contrasting ecotypes differing in Cd accumulation. Using a root elongation test, we found that the highly accumulating ecotype Ganges was more tolerant to Cd than the low Cd-accumulation ecotype Prayon. l-buthionine-(S,R)-sulphoximine (BSO), a potent inhibitor of the γ-glutamylcysteine synthetase (γ-ECS) (an enzyme involved in the PC biosynthetic pathway), increased the Cd sensitivity of Prayon, but had no effect on Ganges. Although PC accumulation increased in response to Cd exposure, no significant differences were observed between the two ecotypes. Cd exposure induced a dose-dependent accumulation of both Cys and a still unidentified LMW thiol in roots of both ecotypes. Root accumulation of Cys and this thiol was higher in Ganges than in Prayon; the ecotypic differences were more pronounced when the plants were treated with BSO. These findings suggest that PCs do not contribute to the Cd hypertolerance displayed by the Ganges ecotype of Thlaspi caerulescens, whereas Cys and other LMW thiols might be involved.

  • field evaluation of cd and zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and arabidopsis halleri
    Environmental Pollution, 2006
    Co-Authors: S P Mcgrath, Enzo Lombi, S J Dunham, C W Gray, N Caille, Fang-jie Zhao
    Abstract:

    Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd.

Henk Schat - One of the best experts on this subject based on the ideXlab platform.

  • isolation and characterization of arabidopsis halleri and Thlaspi caerulescens phytochelatin synthases
    Planta, 2011
    Co-Authors: Clairelise Meyer, Henk Schat, Daniel Peisker, M Courbot, Adrian Radu Craciun, Anneclaire Cazale, Denis Desgain, Stephan Clemens
    Abstract:

    The synthesis of phytochelatins (PC) represents a major metal and metalloid detoxification mechanism in various species. PC most likely play a role in the distribution and accumulation of Cd and possibly other metals. However, to date, no studies have investigated the phytochelatin synthase (PCS) genes and their expression in the Cd-hyperaccumulating species. We used functional screens in two yeast species to identify genes expressed by two Cd hyperaccumulators (Arabidopsis halleri and Thlaspi caerulescens) and involved in cellular Cd tolerance. As a result of these screens, PCS genes were identified for both species. PCS1 was in each case the dominating cDNA isolated. The deduced sequences of AhPCS1 and TcPCS1 are very similar to AtPCS1 and their identity is particularly high in the proposed catalytic N-terminal domain. We also identified in A. halleri and T. caerulescens orthologues of AtPCS2 that encode functional PCS. As compared to A. halleri and A. thaliana, T. caerulescens showed the lowest PCS expression. Furthermore, concentrations of PC in Cd-treated roots were the highest in A. thaliana, intermediate in A. halleri and the lowest in T. caerulescens. This mirrors the known capacity of these species to translocate Cd to the shoot, with T. caerulescens being the best translocator. Very low or undetectable concentrations of PC were measured in A. halleri and T. caerulescens shoots, contrary to A. thaliana. These results suggest that extremely efficient alternative Cd sequestration pathways in leaves of Cd hyperaccumulators prevent activation of PC synthase by Cd2+ ions.

  • Identification and functional analysis of two ZIP metal transporters of the hyperaccumulator Thlaspi caerulescens
    Plant and Soil, 2009
    Co-Authors: Jian Wu, Artak Ghandilyan, Barbara Logoteta, Myriam Olortegui Guzman, Fang-jie Zhao, Xiaowu Wang, Henk Schat, Mark G M Aarts
    Abstract:

    The heavy metal hyperaccumulator Thlaspi caerulescens expresses several ZIP-like genes at higher levels than their orthologues in non-hyperaccumulator species, but it is not clear why. To elucidate the function of the T. caerulescens orthologues of the Arabidopsis thaliana ZIP5 and ZIP6 genes, full-length cDNAs of TcZNT5-LC and TcZNT6-LC were cloned, their expression was examined and genes were expressed in A. thaliana. Transcript level analysis revealed the constitutively high expression of these two genes in T. caerulescens compared to AtZIP5 and AtZIP6 genes and differential expression of both genes when comparing two accessions of T. caerulescens with different metal accumulation properties. Expression of TcZNT5-LC in A. thaliana did not modify Cd or Zn tolerance, but mildly affected the root and shoot Zn concentrations towards a hyperaccumulator shoot to root concentration ratio. A. thaliana zip5 knock-out mutants showed increased tolerance to Cd and decreased seed mineral concentrations. Expression of TcZNT6-LC enhanced the Cd sensitivity of A. thaliana, but no phenotype was observed for the zip6 mutant. In conclusion, the changes in expression of TcZNT5-LC and TcZNT6-LC upon changes in Zn or Cd exposure indicate both genes act in metal homeostasis, but their CaMV 35S-mediated expression in A. thaliana does not create T. caerulescens hyperaccumulator phenotypes.

  • intraspecific variation of nickel and zinc accumulation and tolerance in the hyperaccumulator Thlaspi caerulescens
    Plant and Soil, 2009
    Co-Authors: Kerstin H. Richau, Henk Schat
    Abstract:

    Plants from two contrasting populations of the hyperaccumulator Thlaspi caerulescens, one from the serpentine area of Monte Prinzera (MP) in northern Italy and a Belgian calamine population, La Calamine (LC), were crossed to study the genetic correlation of Ni and Zn accumulation as well as Ni accumulation and Ni tolerance. Parental populations and F3 and F4 progeny of the interpopulation cross were phenotyped. The phenotype distributions for Zn and Ni accumulation of the parental populations were non-overlapping, with MP having higher foliar metal concentrations than LC. Ni tolerance was also higher in MP, but the parental distributions were overlapping. The F3 and F4 progeny exhibited a clear segregation for the Ni and Zn accumulation trait as well as for Ni tolerance. Variance and covariance analysis of the F3 progeny demonstrated significant heritability values (h2) for Ni and Zn foliar accumulation (0.70 and 0.59, respectively) and Ni tolerance (0.47), as well as a significant positive genetic correlation between the foliar accumulation of Ni and Zn (rA2 = 0.82). Ni tolerance and Ni accumulation were uncorrelated. Regressing the F4 family means on the F3 parent values yielded similar estimates for the heritabilities of Ni and Zn accumulation in the leaves (0.66 and 0.55, respectively)

  • Intraspecific variation of nickel and zinc accumulation and tolerance in the hyperaccumulator Thlaspi caerulescens
    Plant and Soil, 2008
    Co-Authors: Kerstin H. Richau, Henk Schat
    Abstract:

    Plants from two contrasting populations of the hyperaccumulator Thlaspi caerulescens, one from the serpentine area of Monte Prinzera (MP) in northern Italy and a Belgian calamine population, La Calamine (LC), were crossed to study the genetic correlation of Ni and Zn accumulation as well as Ni accumulation and Ni tolerance. Parental populations and

  • variation in root to shoot translocation of cadmium and zinc among different accessions of the hyperaccumulators Thlaspi caerulescens and Thlaspi praecox
    New Phytologist, 2008
    Co-Authors: Henk Schat, S P Mcgrath, Jian Feng, Daisei Ueno, J P Xing, Rongfeng Jiang, Fang-jie Zhao
    Abstract:

    • Efficient root-to-shoot translocation is a key trait of the zinc/cadmium hyperaccumulators Thlaspi caerulescens and Thlaspi praecox, but the extent of variation among different accessions and the underlying mechanisms remain unclear. • Root-to-shoot translocation of Cd and Zn and apoplastic bypass flow were determined in 10 accessions of T. caerulescens and one of T. praecox, using radiolabels

Fang-jie Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Physiological evidence for a high‐affinity cadmium transporter highly expressed in a Thlaspi caerulescens ecotype
    New Phytologist, 2020
    Co-Authors: Enzo Lombi, Fang-jie Zhao, S.d. Young, S P Mcgrath, Gian Attilio Sacchi
    Abstract:

    • Uptake kinetics and translocation characteristics of cadmium and zinc are presented for two contrasting ecotypes of the Cd/Zn hyperaccumulator Thlaspi caerulescens, Ganges (southern France) and Prayon (Belgium). • Experiments using radioactive isotopes were designed to investigate the physiology of Cd and Zn uptake, and a pressure-chamber system was employed to collect xylem sap. • In contrast to similar Zn uptake and translocation, measurements of concentration-dependent influx of Cd revealed marked differences between ecotypes. Ganges alone showed a clear saturable component in the low Cd concentration range; maximum influx Vmax for Cd was fivefold higher in Ganges; and there was a fivefold difference in the Cd concentration in xylem sap. Addition of Zn to the uptake solution at equimolar concentration to Cd did not decrease Cd uptake by Ganges, but caused a 35% decrease in Prayon. • There is strong physiological evidence for a high-affinity, highly expressed Cd transporter in the root cell plasma membranes of the Ganges ecotype of T. caerulescens. This raises evolutionary questions about specific transporters for non-essential metals. The results also show the considerable scope for selecting hyperaccumulator ecotypes to achieve higher phytoextraction efficiencies.

  • Identification and functional analysis of two ZIP metal transporters of the hyperaccumulator Thlaspi caerulescens
    Plant and Soil, 2009
    Co-Authors: Jian Wu, Artak Ghandilyan, Barbara Logoteta, Myriam Olortegui Guzman, Fang-jie Zhao, Xiaowu Wang, Henk Schat, Mark G M Aarts
    Abstract:

    The heavy metal hyperaccumulator Thlaspi caerulescens expresses several ZIP-like genes at higher levels than their orthologues in non-hyperaccumulator species, but it is not clear why. To elucidate the function of the T. caerulescens orthologues of the Arabidopsis thaliana ZIP5 and ZIP6 genes, full-length cDNAs of TcZNT5-LC and TcZNT6-LC were cloned, their expression was examined and genes were expressed in A. thaliana. Transcript level analysis revealed the constitutively high expression of these two genes in T. caerulescens compared to AtZIP5 and AtZIP6 genes and differential expression of both genes when comparing two accessions of T. caerulescens with different metal accumulation properties. Expression of TcZNT5-LC in A. thaliana did not modify Cd or Zn tolerance, but mildly affected the root and shoot Zn concentrations towards a hyperaccumulator shoot to root concentration ratio. A. thaliana zip5 knock-out mutants showed increased tolerance to Cd and decreased seed mineral concentrations. Expression of TcZNT6-LC enhanced the Cd sensitivity of A. thaliana, but no phenotype was observed for the zip6 mutant. In conclusion, the changes in expression of TcZNT5-LC and TcZNT6-LC upon changes in Zn or Cd exposure indicate both genes act in metal homeostasis, but their CaMV 35S-mediated expression in A. thaliana does not create T. caerulescens hyperaccumulator phenotypes.

  • variation in root to shoot translocation of cadmium and zinc among different accessions of the hyperaccumulators Thlaspi caerulescens and Thlaspi praecox
    New Phytologist, 2008
    Co-Authors: Henk Schat, S P Mcgrath, Jian Feng, Daisei Ueno, J P Xing, Rongfeng Jiang, Fang-jie Zhao
    Abstract:

    • Efficient root-to-shoot translocation is a key trait of the zinc/cadmium hyperaccumulators Thlaspi caerulescens and Thlaspi praecox, but the extent of variation among different accessions and the underlying mechanisms remain unclear. • Root-to-shoot translocation of Cd and Zn and apoplastic bypass flow were determined in 10 accessions of T. caerulescens and one of T. praecox, using radiolabels

  • does cadmium play a physiological role in the hyperaccumulator Thlaspi caerulescens
    Chemosphere, 2008
    Co-Authors: Junta Yanai, S P Mcgrath, Rongfeng Jiang, Fusuo Zhang, Fang-jie Zhao
    Abstract:

    Abstract The southern French (Ganges) ecotype of Thlaspi caerulescens J & C Presl is able to hyperaccumulate several thousand mg Cd kg −1 shoot dry weight without suffering from phytotoxicity. We investigated the effect of Cd on growth and the activity of carbonic anhydrase (CA), a typical Zn-requiring enzyme, of T. caerulescens in soil and hydroponic experiments. In one of the hydroponic experiments, T. caerulescens was compared to the non-accumulator Thlaspi ferganense N. Busch. In the soil experiment, additions of Cd at 5–500 mg kg −1 soil increased the growth of T. caerulescens significantly. In the hydroponic experiments, exposure to Cd at 1–50 μM for three weeks had no significant effect on the growth of T. caerulescens , but decreased the growth of T. ferganense markedly even at the lowest concentration of Cd (1 μM). Cadmium exposure significantly increased the CA activity in T. caerulescens , but decreased it in T. ferganense . The CA activity in T. caerulescens correlated positively with the Cd concentration in the shoots up to 6000 mg kg −1 , even though shoot Zn concentration was decreased by the Cd treatments. For comparison, Cd treatments had no consistent effect on the activity of superoxide dismutase in T. caerulescens . The results suggest that Cd may play a physiological role in the Cd-hyperaccumulating ecotype of T. caerulescens by enhancing the activities of some enzymes such as CA. Further research is needed to establish whether a Cd-requiring CA exists in T. caerulescens .

  • synthesis of low molecular weight thiols in response to cd exposure in Thlaspi caerulescens
    Plant Cell and Environment, 2006
    Co-Authors: Javier Hernandezallica, Fang-jie Zhao, Carlos Garbisu, J M Becerril, Oihana Barrutia, Jose Ignacio Garciaplazaola, S P Mcgrath
    Abstract:

    In this study, we investigated the accumulation of phytochelatins (PCs) and other low molecular weight (LMW) thiols in response to Cd exposure in two contrasting ecotypes differing in Cd accumulation. Using a root elongation test, we found that the highly accumulating ecotype Ganges was more tolerant to Cd than the low Cd-accumulation ecotype Prayon. l-buthionine-(S,R)-sulphoximine (BSO), a potent inhibitor of the γ-glutamylcysteine synthetase (γ-ECS) (an enzyme involved in the PC biosynthetic pathway), increased the Cd sensitivity of Prayon, but had no effect on Ganges. Although PC accumulation increased in response to Cd exposure, no significant differences were observed between the two ecotypes. Cd exposure induced a dose-dependent accumulation of both Cys and a still unidentified LMW thiol in roots of both ecotypes. Root accumulation of Cys and this thiol was higher in Ganges than in Prayon; the ecotypic differences were more pronounced when the plants were treated with BSO. These findings suggest that PCs do not contribute to the Cd hypertolerance displayed by the Ganges ecotype of Thlaspi caerulescens, whereas Cys and other LMW thiols might be involved.

Steven N Whiting - One of the best experts on this subject based on the ideXlab platform.

  • a comparison of the Thlaspi caerulescens and Thlaspi arvense shoot transcriptomes
    New Phytologist, 2006
    Co-Authors: A J M Baker, Victoria Mills, Steven N Whiting, Philip J. White, John P Hammond, Helen C Bowen, Kevin A Pyke, Martin R. Broadley
    Abstract:

    Summary • Whole-genome transcriptome profiling is revealing how biological systems are regulated at the transcriptional level. This study reports the development of a robust method to profile and compare the transcriptomes of two nonmodel plant species, Thlaspi caerulescens, a zinc (Zn) hyperaccumulator, and Thlaspi arvense, a nonhyperaccumulator, using Affymetrix Arabidopsis thaliana ATH1-121501 GeneChip® arrays (Affymetrix, Santa Clara, CA, USA). • Transcript abundance was quantified in the shoots of agar- and compost-grown plants of both species. Analyses were optimized using a genomic DNA (gDNA)-based probe-selection strategy based on the hybridization efficiency of Thlaspi gDNA with corresponding A. thaliana probes. In silico alignments of GeneChip® probes with Thlaspi gene sequences, and quantitative real-time PCR, confirmed the validity of this approach. • Approximately 5000 genes were differentially expressed in the shoots of T. caerulescens compared with T. arvense, including genes involved in Zn transport and compartmentalization. • Future functional analyses of genes identified as differentially expressed in the shoots of these closely related species will improve our understanding of the molecular mechanisms of Zn hyperaccumulation.

  • Salt (NaCl) tolerance in the Ni hyperaccumulator Alyssum murale and the Zn hyperaccumulator Thlaspi caerulescens
    Plant and Soil, 2005
    Co-Authors: Elena Comino, Steven N Whiting, Peter M Neumann, Alan J. M. Baker
    Abstract:

    Many metal hyperaccumulating plants have to tolerate abiotic stresses in their native soils such as high metal concentrations, low nutrient status and drought. This paper tests the ability of the Ni-hyperaccumulator Alyssum murale and two races of the Zn-hyperaccumulator Thlaspi caerulescens (Prayon and Close House) to tolerate salinity. The plants were exposed to salt (NaCl) solutions ranging between 0 mM and 100 mM in conjunction with either high or low concentrations of Ni or Zn. Alyssum murale was most resistant to salt in terms of seedling emergence and survival of emerged seedlings. The two races of T. caerulescensand T. arvense were salt sensitive. High Ni or Zn concentrations did not have a clear effect on the salt tolerance of any of the plants tested. The implications of the findings are discussed for the development of metal phytoremediation/phytomining technologies on saline soils or where brackish water (e.g., mining wastewater) could be used to irrigate phytoremediation ‘crops’.

  • nickel and zinc hyperaccumulation by alyssum murale and Thlaspi caerulescens brassicaceae do not enhance survival and whole plant growth under drought stress
    Plant Cell and Environment, 2003
    Co-Authors: Steven N Whiting, Peter M Neumann, A J M Baker
    Abstract:

    Nickel and Zn hyperaccumulation by Alyssum murale and Thlaspi caerulescens bear substantial energetic costs and should confer benefits to the plant. This research determined whether metal hyperaccumulation can increase osmotic adjustment and resistance to water stress (drought). Alyssum murale and Thlaspi caerulescens treated with low or high concentrations of Ni or Zn were exposed to moderate (−0·4 MPa) and severe (−1·0 MPa) water stresses using aqueous polyethylene glycol. In the absence of metals both water deficits inhibited shoot growth. Nickel and Zn hyperaccumulation did not ameliorate growth inhibition by either level of water stress. The water stress did not induce major changes in shoot metal concentrations of these constitutive hyperaccumulators. Moreover, metal hyperaccumulation had minimal effects on the osmolality of leaf-sap extracts, relative water content of the shoots, or rate of evapotranspiration. It is concluded that Ni or Zn hyperaccumulation does not augment whole-plant capacity for drought resistance in A. murale and T. caerulescens.

  • Applying a solute transfer model to phytoextraction: Zinc acquisition by Thlaspi caerulescens
    Plant and Soil, 2003
    Co-Authors: Steven N Whiting, Martin R. Broadley, Philip J. White
    Abstract:

    Phytoextraction is the removal of metals from contaminated soils into harvested plant tissues. The rate of phytoextraction is governed by both soil and plant characteristics. Most effort has focused on identifying appropriate plants for phytoextraction, but the benefits from this effort will be marginal unless the metals are in phytoavailable forms in the rhizosphere. The concentration of a metal in the rhizosphere can be estimated using solute transfer models that incorporate: the metal concentration in the bulk soil solution, the buffer power of the soil, diffusion coefficient for the metal, water movement, root size and morphology, and the rate of entry of metal into the roots. Here a solute transfer model is developed to predict the concentration of Zn in the rhizosphere solution ([Zn]ext) of Thlaspi caerulescens, a hyperaccumulator species that could be exploited for Zn phytoextraction. The model predicts that Zn accumulation by T. caerulescens is sub-optimal when the Zn concentration in the bulk soil solution is

  • assessment of zn mobilization in the rhizosphere of Thlaspi caerulescens by bioassay with non accumulator plants and soil extraction
    Plant and Soil, 2001
    Co-Authors: Steven N Whiting, Jonathan R Leake, Stephen P Mcgrath, A J M Baker
    Abstract:

    This study used co-cultivated plants as a bioassay to test the hypothesis that the roots of the zinc-hyperaccumulating plant Thlaspi caerulescensmobilize Zn from less-available pools in the soil. Thlaspi caerulescens was grown in uncompartmentalised pots, or pots that were divided by solid or mesh barriers to limit the extent of root intermingling (rhizosphere interaction) with co-cultivated Thlaspi arvense or Festuca rubra. Thlaspi caerulescens did not increase the concentration of Zn in either indicator species, suggesting that T. caerulescens does not strongly mobilize Zn in its rhizosphere. The increase in the shoot mass of T. arvense when its roots were permitted to intermingle with those of T. caerulescens was explained by greater intensity of competition of T. arvense compared to T. caerulescens.