Cadmium-induced antioxidant status and sister-chromatid exchanges in Vicia faba L.

The effects of cadmium (Cd) on antioxidant responses and sister chromatid exchanges (SCE) were studied in Vicia faba L. The activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR), and the levels of ascorbate (ASC), glutathione (GSH), hydrogen peroxide, and malondialdehyde (MDA, indicator of lipid peroxidation) were measured. Genotoxicity was evaluated by measuring the changes in the mitotic index (MI) and sister chromatid exchanges (SCE). Increased activities of SOD and CAT were observed in plants treated with 50 and 100 μM Cd. It was found that APX activity increased remarkably with 50 μM Cd, but no significant changes were found in GR activity in any of the treatment groups. These changes in antioxidant enzyme activities were negatively correlated with lipid peroxidation. However, a positive correlation between the increase of H2O2 levels and Cd concentration occurred with all levels of Cd. A significant increase in the malondialdehyde (MDA) level was only observed at the highest (200 μM) Cd concentration. This finding suggests that membrane damage did not occur in moderate Cd frequency. SCE increased significantly in high Cd concentration (200 μM), while MI decreased. The results suggest that exposure of high Cd concentrations is cytotoxic as well as genotoxic for Vicia faba L. and also suggest that the 2 phenomena are related.