Responses of antioxidative enzymes to accumulation of copper in a copper hyperaccumulator of Commoelina communis

Discovery of a copper hyperaccumulator is very important for phytoremediation of copper-contaminated soil. In the present study a link was established between the copper accumulation in hyperaccumulator and that in nonaccumulator species of Commelina communis and its responses of antioxidative enzymes, including superoxide dismutase, guaiacol peroxidase, and ascorbate peroxidase. It was verified that copper exerted little physiological damage to copper hyperaccumulator species of Commelina communis at copper accumulation of >1000 mug/g in dry leaf tissue. However, in nonaccumulator species of Commelina communis superoxide dismutase, guaiacol peroxidase, and ascorbate peroxidase were activated, and malondialdehyde content was increased, which were symptoms of physiological damage by copper intoxication. Therefore, antioxidative enzymes can be used as an indicator of copper toxicity before the visible symptoms can be observed.