Effects of Cadmium Stress on Antioxidant Enzymes Activities and Soluble Protein Content in Cyphomandra betacea Seedlings

Abstract

To find out the toxic mechanism of Cyphomandra betacea seedlings to cadmium (Cd) stress and provide reference for its reduction of Cd content, the annual C. betacea seedlings were treated with Cd of different concentration gradients (0-25 mg/kg) by pot experiment, the soluble protein content and the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), were determined. The results showed that with the increase of Cd concentration in soil, the soluble protein content and the activity of SOD, POD and CAT in the leaves of C. betacea seedlings first increased and then decreased. The antioxidant enzyme activities reached their maximum when the soil Cd concentration was 10 mg/kg, and the soluble protein content reached its maximum when the soil Cd concentration was 1 mg/kg. The antioxidant enzymes might have a cooperative action with detoxification mechanism when the C. betacea seedlings were under Cd stress. Moreover, the C. betacea seedlings could reduce the Cd toxicity by increasing the soluble protein content when the Cd concentration in soil was within 1 mg/kg; when the concentration became higher, they might reduce the Cd toxicity by binding protein to Cd to form complex.