Glutathione-mediated alleviation of chromium toxicity in rice plants.

A hydroponic experiment was conducted to determine the possible effect of exogenous glutathione (GSH) in alleviating chromium (Cr) stress through examining plant growth, chlorophyll contents, antioxidant enzyme activity, and lipid peroxidation in rice seedlings exposed to Cr toxicity. The results showed that plant growth and chlorophyll content were dramatically reduced when rice plants were exposed to 100 μM Cr. Addition of GSH in the culture solution obviously alleviated the reduction of plant growth and chlorophyll content. The activities of some antioxidant enzymes, including superoxide dismutase, catalase (CAT) and glutathione reductase in leaves, and CAT and glutathione peroxidase in roots showed obvious increase under Cr stress. Addition of GSH reduced malondialdehyde accumulation and increased the activities of these antioxidant enzymes in both leaves and roots, suggesting that GSH may enhance antioxidant capacity in Cr-stressed plants. Furthermore, exogenous GSH caused significant decrease of Cr uptake and root-to-shoot transport in the Cr-stressed rice plants. It can be assumed that GSH is involved in Cr compartmentalization in root cells.