The effect of iron stress on the relative expression level of SOD, MDHR and GPX1 genes in tolerant and sensitive genotypes of Rice

Increasing of reactive oxygen species (ROS) under iron toxicity is considered as one of the major constraints to rice production. In this study the alterations of SOD, GPX1 and MDHR expression level in two genotypes of rice, Pokkali (as tolerant) and IR64 (as sensitive) were monitored under different concentrations of iron levels [(0) (nonstress)], 100, 250, 400 and 500 mg/lit-1Fe-EDTA). The treatments were done when the plants were at 4-leaf stage and lasted for two weeks. Results showed that the expression levels of genes in Pokkali were higher than IR64. The expression level of SOD in IR64, increased at iron concentration increased, while it decreased at higher Fe-level. The expression level of GPX1 was increased in IR64, but decreased in Pokkali. The expression level of MDHR in IR64 was decreased at early stage of Fe-treatment, but then increased. Inversely, in Pokkali MDHR expression reduced constantly under Fe stress. Overall, the relative over expression of genes in Pokkali and presence of different expression levels of them between different concentrations of Fe in tolerant and sensitive genotypes indicate that the gene could remarkably effect on the tolerant level of pokkali by reducing ROS production under Fe-toxicity.