[Effects of Cu2+ stress on leaf physiological indice and ultrastructure of Potamogeton malaianus].

With solution culture, this paper studied the toxic effects of different concentrations of Cu2+ (0, 2, 4, 6, and 8 mg x L(-1)) on the chlorophyll content, soluble protein content, protective enzyme activities, active oxygen generation, and ultrastructural changes in Potamogeton malaianus leaf. The results showed that with increasing concentration of Cu2+, the chlorophyll, carotenoid and soluble protein contents and superoxide dismutase (SOD) and peroxidase (POD) activities decreased, catalase (CAT) activity increased first and decreased then, while O2-*, H2O2, MDA and soluble sugar content increased. SDS-PAGE revealed that Cu2+ induced the disappearance or the decrease of the expression amount of four polypeptides with apparent molecular weights of 60.9, 18.8, 15.7, 22.3 and 30.0 kDa. Transmission electron microscopy observation indicated that the higher Cu2+, concentration, the more serious damages the leaf organelles, especially chloroplast, mitochondria and nucleus, suffered. It was concluded that the death of P. malaianus plant under Cu2+ stress was resulted from the destruction of physiological function and structural foundation, and the disorder of physiological metabolism. The lethal concentration of Cu2+ could be 2-4 mg x L(-1).