Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots

Effect of two Ni concentrations (10 and 200 mu M) on growth, Ni accumulation, chlorophyll and proline contents, relative water content (RWC) as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione S-transferase (GST) were studied in shoots of wheat plants. Treatments caused a considerable accumulation of Ni in the shoots. However, exposure of plants to 10 mu M Ni did not lead to significant alterations in shoot growth except for a slight increase in fresh mass. The other parameters studied were not affected by treatment of plants with 10 mu M Ni. In contrast, 200 mu M Ni caused inhibition of shoot growth, a decline in RWC and chlorophyll content, accumulation of proline and occurrence of visible symptoms of Ni toxicity. The activities of SOD and CAT decreased in response to 200 mu M Ni. Conversely, several-fold enhancements of POD and GST activities were observed following the 3(rd) day of 200 mu M Ni treatment.