Arsenate-induced toxicity: effects on antioxidative enzymes and DNA damage in Vicia faba

A glasshouse hydroponic experiment was conducted to investigate the toxicity of arsenate to broad bean (Vicia faba) plants when grown with external arsenate concentrations at 10 micromol/L. The treated plants showed no obvious symptoms of phytotoxicity, but shoot/root growth was inhibited. Lipid peroxidation in leaves and roots increased with the addition of arsenate, indicating oxidative stress. We investigated the responses to arsenate exposure in the activities of several representative antioxidant enzymes, including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), in plant tissues, and the DNA damage in plant leaves and root tips induced by arsenate in this plant was detected for the first time. Arsenate addition increased POD activity in the leaves significantly but decreased its activity in the roots in the 10 micromol/L treatment. Arsenate addition caused an induction of SOD and CAT activities in both leaves and roots, but not in roots at the arsenate concentration of 10 micromol/L. The DNA damage in V. faba was detected using Comet assay; in both leaves and roots, DNA damage increased with increasing arsenate concentrations, indicating genotoxicity of arsenate. These results indicate that arsenate toxicity causes oxidative stress in V. faba, which might be one of the mechanisms through which arsenic induces DNA damage.