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Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.

ABSTRACT: Engineering enhanced transport of zinc to the aerial parts of plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression of the AhHMA4 gene encoding a metal pump of the P(1B)-ATPase family is necessary for both Zn hyperaccumulation and the full extent of Zn and Cd hypertolerance that are characteristic of this species. In this study, an AhHMA4 cDNA was introduced into N. tabacum var. Xanthi for expression under the control of its endogenous A. halleri promoter known to confer high and cell-type specific expression levels in both A. halleri and the non-hyperaccumulator A. thaliana. The transgene was expressed at similar levels in both roots and shoots upon long-term exposure to low Zn, control, and increased Zn concentrations. A down-regulation of AhHMA4 transcript levels was detected with 10 muM Zn resupply to tobacco plants cultivated in low Zn concentrations. In general, a transcriptional regulation of AhHMA4 in tobacco contrasted with the constitutively high expression previously observed in A. halleri. Differences in root/shoot partitioning of Zn and Cd between transgenic lines and the wild type were strongly dependent on metal concentrations in the hydroponic medium. Under low Zn conditions, an increased Zn accumulation in the upper leaves in the AhHMA4-expressing lines was detected. Moreover, transgenic plants exposed to cadmium accumulated less metal than the wild type. Both modifications of zinc and cadmium accumulation are noteworthy outcomes from the biofortification perspective and healthy food production. Expression of AhHMA4 may be useful in crops grown on soils poor in Zn.

SUBMITTER: Barabasz A

PROVIDER: S-EPMC2892146 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.

Barabasz Anna A Krämer Ute U Hanikenne Marc M Rudzka Justyna J Antosiewicz Danuta Maria DM

Journal of experimental botany 20100519 11

Engineering enhanced transport of zinc to the aerial parts of plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression of the AhHMA4 gene encoding a metal pump of the P(1B)-ATPase family is necessary for both Zn hyperaccumulation and the full extent of Zn and Cd hypertolerance that are characteristic of this species. In this study, an AhHMA4 cDNA was introduced into N. tabacum var. Xanthi for expression under the control of its endogenous A. halleri promo ...[more]

PMID: 20484319

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Project description:Soil contamination with trace metal(loid) elements (TME) is a global concern. This has focused interest on TME-tolerant plants, some of which can hyperaccumulate extraordinary amounts of TME into above-ground tissues, for potential treatment of these soils. However, intra-species variability in TME hyperaccumulation is not yet sufficiently understood to fully harness this potential. Particularly, little is known about the rhizosphere microbial communities associated with hyperaccumulating plants and whether or not they facilitate TME uptake. The aim of this study is to characterize the diversity and structure of Arabidopsis halleri rhizosphere-influenced and background (i.e., non-Arabidopsis) soil microbial communities in four plant populations with contrasting Zn and Cd hyperaccumulation traits, two each from contaminated and uncontaminated sites. Microbial community properties were assessed along with geographic location, climate, abiotic soil properties, and plant parameters to explain variation in Zn and Cd hyperaccumulation. Site type (TME-contaminated vs. uncontaminated) and location explained 44% of bacterial/archaeal and 28% of fungal community variability. A linear discriminant effect size (LEfSe) analysis identified a greater number of taxa defining rhizosphere microbial communities than associated background soils. Further, in TME-contaminated soils, the number of rhizosphere-defining taxa was 6-fold greater than in the background soils. In contrast, the corresponding ratio for uncontaminated sites, was 3 and 1.6 for bacteria/archaea and fungi, respectively. The variables analyzed explained 71% and 76% of the variance in Zn and Cd hyperaccumulation, respectively; however, each hyperaccumulation pattern was associated with different variables. A. halleri rhizosphere fungal richness and diversity associated most strongly with Zn hyperaccumulation, whereas soil Cd and Zn bioavailability had the strongest associations with Cd hyperaccumulation. Our results indicate strong associations between A. halleri TME hyperaccumulation and rhizosphere microbial community properties, a finding that needs to be further explored to optimize phytoremediation technology that is based on hyperaccumulation.

Project description:This application is from a NERC-funded consortium (Mark MacNair, Nick Smirnoff, Exeter) and (Brian Ford-Lloyd, John Newbury, Birmingham). Metal tolerance is one of the classic examples of micro-evolution. Despite extensive research the physiological bases of the adaptation in plants are largely unknown. Arabidopsis halleri is a zinc tolerant, zinc accumulating species whereas Arabidopsis petraea is non-accumulating and non-tolerant. The objective of our programme is to identify: a) those key genes that act to determine Zn tolerance and accumulation in Arabidopsis (and which account for the difference in performance of A. halleri and A. petraea grown in the presence of elevated Zn), and b) those _downstream_ genes that are expressed as part of the tolerance or accumulation response. Phase 1: Total of 24 chips: Material ready by May 2003. The results will: a) tell us how effectively material derived from other Arabidopsis species hybridises to the chips, and b) identify genes that are differentially expressed in the two species in the presence and absence of Zn stress (thus providing initial lists of genes that may be responsible for Zn tolerance or accumulation- (but see phase 2). A. halleri exposed to low and high Zn; root and leaf mRNAs extracted: 3 replicates of each: = 12 slides. A. petraea exposed to low and high Zn; root and leaf mRNAs extracted: 3 replicates of each: = 12 slides. Phase 2: Total of 48 chips: Material ready by September 2003. The results will tell us which genes, identified as having appropriate expression patterns, co-segregate with the Zn tolerance or accumulation phenotype and will provide firmer candidate genes for intensive study. Bulks will be produced from F3 progeny (from the halleri x petraea cross) following phentoypic analyses for Zn tolerance and accumulation. A bulk of F3 progeny all exhibiting high Zn tolerance: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides. A bulk of F3 progeny all exhibiting low Zn tolerance: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides. A bulk of F3 progeny all exhibiting high Zn accumulation: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides. A bulk of F3 progeny all exhibiting low Zn accumulation: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides. Experimenter name = H. John Newbury Experimenter phone = 0121 414 5581 Experimenter fax = 0121 414 5925 Experimenter institute = University of Birmingham Experimenter address = School of Biosciences Experimenter address = University of Birmingham Experimenter address = Edgbaston Experimenter address = Birmingham Experimenter zip/postal_code = B15 2TT Experimenter country = UK Keywords: stimulus_or_stress_design; organism_part_comparison_design; strain_or_line_design

Project description:This application is from a NERC-funded consortium (Mark MacNair, Nick Smirnoff, Exeter) and (Brian Ford-Lloyd, John Newbury, Birmingham). Metal tolerance is one of the classic examples of micro-evolution. Despite extensive research the physiological bases of the adaptation in plants are largely unknown. Arabidopsis halleri is a zinc tolerant, zinc accumulating species whereas Arabidopsis petraea is non-accumulating and non-tolerant. The objective of our programme is to identify a) those key genes that act to determine Zn tolerance and accumulation in Arabidopsis (and which account for the difference in performance of A. halleri and A. petraea grown in the presence of elevated Zn) and b) those _downstream_ genes that are expressed as part of the tolerance or accumulation response. Phase 1: Total of 24 chips: Material ready by May 2003 The results will a) tell us how effectively material derived from other Arabidopsis species hybridises to the chips, and b) identify genes that are differentially expressed in the two species in the presence and absence of Zn stress (thus providing initial lists of genes that may be responsible for Zn tolerance or accumulation- but see phase 2)· A. halleri exposed to low and high Zn; root and leaf mRNAs extracted: 3 replicates of each: = 12 slides· A. petraea exposed to low and high Zn; root and leaf mRNAs extracted: 3 replicates of each: = 12 slides Phase 2: Total of 48 chips: Material ready by September 2003 The results will tell us which genes, identified as having appropriate expression patterns, co-segregate with the Zn tolerance or accumulation phenotype and will provide firmer candidate genes for intensive study. Bulks will be produced from F3 progeny (from the halleri x petraea cross) following phentoypic analyses for Zn tolerance and accumulation.· A bulk of F3 progeny all exhibiting high Zn tolerance: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides· A bulk of F3 progeny all exhibiting low Zn tolerance: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides· A bulk of F3 progeny all exhibiting high Zn accumulation: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides· A bulk of F3 progeny all exhibiting low Zn accumulation: exposed to low and high Zn; leaf and root mRNAs: 3 replicates: = 12 slides Experimenter name = H. John Newbury Experimenter phone = 0121 414 5581 Experimenter fax = 0121 414 5925 Experimenter department = Newbury lab Experimenter institute = University of Birmingham Experimenter address = School of Biosciences Experimenter address = University of Birmingham Experimenter address = Edgbaston Experimenter address = Birmingham Experimenter zip/postal_code = B15 2TT Experimenter country = UK Keywords: stimulus_or_stress_design; organism_part_comparison_design; strain_or_line_design

Dataset Information

Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.

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Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.

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