Biochemical characteristics and expression of some oxidative pathway genes in rice (Oryza sativa L.) under salt stress condition

In this research, the expression of glutathione peroxidase (OsGpx) and proxy redoxin (OsPrx), H2O2 and Guaiacol dependent peroxidase (POD) content was measured in Iranian local (Hassani and Anbarboo) and improved (Nemat and Khazar) rice varieties with two well-known international salt tolerant (FL 478) and sensitive (IR29) varieties as checks in response to 100 mM salt stress. The results showed that the activity of peroxidase (POD) was different at different times in the studied cultivars, so that the enzyme activity in resistant cultivars was higher than susceptible ones under salt stress. Gene expression of glutathione peroxidase (OsGpx) showed the highest expression of this gene in the roots of tolerant varieties 6 hours after the stress treatment and then 12, 24, 48 and 72 hours after the stress the expression of this gene significantly decreased. In susceptible cultivars, gene expression increased gradually. The study of peroxy-redoxin (OsPrx) gene expression showed that in the first hours after the stress, tolerant varieties did not show any change in this gene expression, but in the final hours of stress (72 hours) gene expression was significantly increased. There was no consistent pattern for this gene in susceptible cultivars. The results showed there was a direct relationship between the reduction of H2O2 and increased activity of antioxidant genes and enzymes.