Differential responses of antioxidant system and expression profile of some genes of two rice genotypes in response to salinity stress

Sketching an appropriate genotyping strategy needs a comprehensive understanding of plant endurance under stress. This study was performed to investigate the physiological and molecular responses of two rice genotypes (Hashemi parental and Hashemi advanced mutant line) with different sensitivity to salinity stress. Twenty five-day-old seedlings were treated with 0 (as control), 5 and 10 dS/m of NaCl and their characteristics corresponding to antioxidant enzymes were evaluated three times including 6 h, 48 h and 1 w after salinity treatment. The results showed that salinity stress significantly enhanced the cell oxidation levels [as thiobarbituric acid reactive substances (TBARS) content and lipoxygenase (LOX) activity] as well as antioxidant enzymes activities [superoxide dismutase (SOD), catalase (CAT), peroxidase (POX) and glutathione reductase (GR)] and ascorbate content. Moreover, the relative expression of SOD, CAT, ascorbate peroxidase (APX) and Oryza sativa dehydration responsive element binding (OsDREB2) genes significantly increased in response to salinity stress. Hashemi advanced mutant line (as tolerant genotype) showed the highest antioxidant enzymes activities and relative genes expression compared with Hashemi parental (as sensitive genotype). It can be concluded that overexpression of SOD, CAT, APX and OsDREB2 genes could be applied to enhance tolerance to salt stress.