Antioxidant enzymes as bio-markers for copper tolerance in safflower (Carthamus tinctorius L.)

Activities of antioxidants enzymes were investigated in order to evaluate protective mechanism of plants against oxidative stress induced by high concentration of copper. Safflower (Carthamus tinctorius L.) plants were exposed to 100 mu M copper (Cu) for two weeks under controlled environmental conditions using hydroponic culture. Cu induced changes in chlorophyll and carotenoids pigments. More Cu accumulated in the roots as compared with the leaves. Level of lipid peroxidation and antioxidative enzyme activities (peroxidase, catalase and superoxide dismutase) also correlated with the Cu content of the plant tissues. However, restricted transfer of the metal to the foliage and enhanced activity of peroxidase, catalase and superoxide dismutase may be of great significance for scavenging oxidative stress caused by excessive copper in safflower plants. Thus, these antioxidant enzymes served as good predictors for the evaluation of heavy metal tolerance.