Phytochelatin-based complexes bind various amounts of cadmium in maize seedlings depending on the time of exposure, the concentration of cadmium and the tissue

Authors


Author for correspondence: Wilfried E. Rauser Tel: +1 519 821 0303 Fax: +1 519 7671991 Email: wrauser@rogers.com

Summary

  • • The aims were to determine the quantities of tissue cadmium (Cd) bound in maize (Zea mays) roots through phytochelatin-based complexes with changes in time of exposure, the concentration of Cd, the part of the primary root system, and the status of the complexes in shoots.
  • • Six buffer extractions solubilized most tissue Cd and a rapid small-scale gel filtration resolved the buffer soluble Cd into high and low molecular weight Cd-binding complexes.
  • • Six buffer extractions, rather than one, effectively represented high and low molecular weight phytochelatin-based Cd-binding complexes. The low molecular weight complex predominated in root apices and after 1 d of 3 µm Cd; the high molecular weight complex predominated in mature root parts and after 2 d of exposure. More tissue Cd was bound by both complexes with increasing time of exposure and concentration of Cd. Buffer extracted less Cd from shoots than roots and phytochelatin-based complexes bound less shoot Cd (29% vs 88%).
  • • The phytochelatin-based complexes are in a dynamic state dependent on the treatment and they function to bind variable amounts of tissue Cd.

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