Studies on antioxidative enzymes induced by cadmium in pea plants (Pisum sativum)

Pea plants (Pisum sativum cv. Swati) exposed to different concentration of cadmium (50, 100, 200 mu M Cd) under controlled glass house conditions were quantified for different physiological parameters and antioxidative enzymes. In pea plants, Cd produced a significant inhibition of growth and induced chlorosis, marginal yellowing and necrosis in young leaves, the effect being most pronounced at 200 mu M Cd supply. An alteration in the activated oxygen metabolism of pea plants were also detected as evidenced by an increase in concentration of H2O2 and TBARS along with decrease in the chlorophyll and carotenoid concentration in leaves. Cadmium toxicity induced an increase in non- protein thiol, ascorbate, proline and cysteine concentration. A significant increment in the activity of SOD, APX and OR, and a decrease in CAT was observed as a result of Cd treatment. The enhanced activity of SOD and inhibition of CAT and POD produces a high build up of H2O2 which appears to be the main cause of oxidative stress due to Cd toxicity in pea plants.