Induction of phytochelatins under cadmium stress in water lettuce (pistia stratiotes L.)

Abstract

Plants of Pistia stratiotes L. accumulated appreciable amounts of Cd from aqueous solution, maximum being in roots than leaves. Accumulation was concentration ‐ duration dependent, however, plant reached metal steady state concentration on 7 d at 10.0 μM Cd. The accumulation of Cd was accompanied by a decline in cellular levels of glutathione which was more evident in roots at different treatment durations. Both the concentrations of Cd (2.5 and 10.0 μM.) enhanced cysteine content, accumulation of acid‐soluble thiols and induced synthesis of phytochelatins(PCs). On the other hand, lower concentration induced synthesis of low molecular weight proteins, while higher Cd concentration completely inhibited low molecular weight proteins and reduced concentrations of other high molecular weight proteins in the SDS‐Gel electrophoretic patterns. Buthionine sulfoximine, an inhibitor of glutathione synthesis, reduced glutathione and acid‐soluble thiols. However, protein synthetic inhibitor cycloheximide did not affect initial production of acid‐soluble thiols showing the participation of phytochelatins in tolerance mechanism of the plant to Cd.

Key words:

• Cadmium accumulation
• Phytochelatins
• Detoxification
• Pistia stratiotes

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