Selenium Treatment Alleviated Oxidative Alteration Generated by Cadmium in Sunflower Roots

The present study investigated the role of selenium (Se) in regulating cadmium (Cd)-induced oxidative stress in sunflower (Helianthus annuus) roots. Short-term exposure of plants to 20 µM Cd intensively increased hydrogen peroxides (H2O2), protein carbonyl (PCO) content and lipid peroxidation as indicated by malondialdehyde (MDA) accumulation. In contrast, Se (5, 10 and 20 μM) pretreatment alleviated the oxidative damages as evidenced by the lowered H2O2, protein carbonyl (PCO) and MDA content. Concomitantly, Se treatment enhanced the activities of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione peroxidase (GPX, EC 1.11.1.9), but lowered that of superoxide dismutase (SOD, EC 1.15.1.1) in the root exposed Cd. Taken together, our results strongly suggest that exogenous Se may improve the tolerance of the plant to the Cd-induced oxidative stress.