Salt and genotype impact on antioxidative enzymes and lipid peroxidation in two rice cultivars during de-etiolation

Crop yield is severely affected by soil salinity, as salt levels that are harmful to plant growth occur in large terrestrial areas of the world. The present investigation describes the studies of enzymatic activities, in-gel assays, gene expression of some of the major antioxidative enzymes, tocopherol accumulation, lipid peroxidation, ascorbate and dehydroascorbate contents in a salt-sensitive rice genotype PB1, and a relatively salt-tolerant cultivar CSR10 in response to 200 mM NaCl. Salt solution was added to the roots of hydroponically grown 5-day-old etiolated rice seedlings, 12 h prior to transfer to cool white fluorescent + incandescent light (100 mu mol photons m(-2) s(-1)). Total tocopherol and ascorbate contents declined in salt-stressed rice seedlings. Among antioxidative enzymes, an increase in the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), glutathione reductase (EC 1.6.4.2), and their gene expression was observed in both cultivars in response to salt stress. The salt-tolerant cultivar CSR10 resisted stress due to its early preparedness to combat oxidative stress via upregulation of gene expression and enzymatic activities of antioxidative enzymes and a higher redox status of the antioxidant ascorbate even in a non-stressed environment.