Ni-induced oxidative stress in roots of the Ni hyperaccumulator, Alyssum bertolonii

Authors

  • Rengasamy Boominathan,

    1. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052, Australia
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  • Pauline M. Doran

    Corresponding author
    1. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052, Australia
      Author for correspondence:Pauline Doran Tel: +61 2 9385 2058 Fax: +61 2 9313 6710 Email: p.doran@unsw.edu.au
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Author for correspondence:Pauline Doran Tel: +61 2 9385 2058 Fax: +61 2 9313 6710 Email: p.doran@unsw.edu.au

Summary

  • • The aim of this study was to determine whether superior antioxidative defences contribute to Ni tolerance in roots of the hyperaccumulator species, Alyssum bertolonii . Antioxidative responses were compared in hairy roots of A. bertolonii and the nonhyperaccumulator, Nicotiana tabacum .
  • • Growth, Ni uptake, antioxidative enzyme activities, lipid peroxidation and concentrations of H 2O2 and surface -SH groups were measured in hairy root cultures exposed to 25 ppm (426 µm) Ni.
  • • Growth of A. bertolonii roots was not affected by Ni, whereas Ni prevented N. tabacum root growth. Endogenous activities of superoxide dismutase and catalase were 2.4 and > 500 times greater, respectively, in A. bertolonii roots than in N. tabacum . H 2O2 levels rose significantly with Ni treatment in both species, by factors of 3.6 and 8.6, respectively.
  • • Compared with N. tabacum , oxidative damage may be minimised in A. bertolonii roots by high endogenous activities of catalase and, to a lesser extent, superoxide dismutase. As accumulation of H 2O2 was not detrimental to A. bertolonii, enhanced mechanisms for tolerating active oxygen species may also be present.

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