Cadmium uptake, translocation and tolerance in the hyperaccumulator Arabidopsis halleri

Authors


Author for correspondence: Fangjie Zhao Tel: +44 1582763133 Fax: +44 1582760981 Email: Fangjie.zhao@bbsrc.ac.uk

Summary

  • • Arabidopsis halleri is a well-known zinc (Zn) hyperaccumulator, but its status as a cadmium (Cd) hyperaccumulator is less certain. Here, we investigated whether A. halleri can hyperaccumulate Cd and whether Cd is transported via the Zn pathway.
  • • Growth and Cd and Zn uptake were determined in hydroponic experiments with different Cd and Zn concentrations. Short-term uptake and root-to-shoot transport were measured with radioactive 109Cd and 65Zn labelling.
  • • A. halleri accumulated > 1000 mg Cd kg−1 in shoot dry weight at external Cd concentrations ≥ 5 µm, but the short-term uptake rate of 109Cd was much lower than that of 65Zn. Zinc inhibited short-term 109Cd uptake kinetics and root-to-shoot translocation, as well as long-term Cd accumulation in shoots. Uptake of 109Cd and 65Zn were up-regulated, respectively, by low iron (Fe) or Zn status. A. halleri was much less tolerant to Cd than to Zn.
  • • We conclude that A. halleri is able to hyperaccumulate Cd partly, at least, through the Zn pathway, but the mechanisms responsible for cellular Zn tolerance cannot detoxify Cd effectively.

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