An arsenic-accumulating, hypertolerant brassica, Isatis capadocica

Authors

  • Naser Karimi,

    1. Institute of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK
    2. Department of Biology, University of Isfahan, Isfahan, Iran
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  • Seyed Majid Ghaderian,

    1. Department of Biology, University of Isfahan, Isfahan, Iran
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  • Andrea Raab,

    1. Institute of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK
    2. School of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Aberdeen, AB24 3UE, UK
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  • Joerg Feldmann,

    1. School of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Aberdeen, AB24 3UE, UK
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  • Andrew A. Meharg

    1. Institute of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK
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Author for correspondence:
A. A. Meharg
Tel:+44 (0)1224 272264
Email: a.meharg@abdn.ac.uk

Summary

  • • Isatis capadocica, a brassica collected from Iranian arsenic-contaminated mine spoils and control populations, was examined to determine arsenate tolerance, metabolism and accumulation.
  • • I. cappadocica exhibited arsenate hypertolerance in both mine and nonmine populations, actively growing at concentrations of > 1 mm arsenate in hydroponic solution.
  • • I. cappadocica had an ability to accumulate high concentrations of arsenic in its shoots, in excess of 100 mg kg−1 DW, with a shoot : root transfer ratio of > 1. The ability to accumulate arsenic was exhibited in both hydroponics and contaminated soils.
  • • Tolerance in this species was not achieved through suppression of high-affinity phosphate/arsenate root transport, in contrast to other monocotyledons and dicotyledons. A high percentage (> 50%) of arsenic in the tissues was phytochelatin complexed; however, it is argued that this is a constitutive, rather than an adaptive, mechanism of tolerance.

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