Abstract
Changes in growth, photosynthetic activity and antioxidative scavenging systems were investigated in leaves and roots of Zea mays L. seedlings treated with Cd2+ in order to investigate whether Cd2+ disturbs common plant defense pathways. Higher concentration of Cd2+ (100 mu M) significantly reduced growth and leaf area of the seedlings. The contents of total chlorophyll (a + b) and carotenoids decreased, with a higher magnitude at high concentration of Cd2+. Furthermore, an alteration in activated oxygen species and increased lipid peroxidation was also detected. A significant decrease, especially with high concentrations of Cd2+, in the non-enzymatic antioxidant glutathione and GSH/GSSG ratio and enhanced accumulation of H2O2 were also observed. The activities of antioxidant enzymes i.e. superoxide dismutase, catalase, ascorbic peroxidase and guaiacol peroxidase rapidly enhanced in response to moderate concentration (20 mu M), indicating the capacity of Zea mays L. plant to scavenge O-center dot 2(-) and H2O2. A progressive increase of cell death in roots and accumulation of soluble phenolics were also concomitant with increase in Cd2+ concentration. The plant physiological stress indicators phenolics and carotenoids and the indicator of unbalanced metabolism of free radicals (concentration of MDA and H2O2) both were enhanced with respect to Cd2+ application.