Assessment of antioxidant responses of a mutant rice root under salinity stress in the seedling stage

In this study, in order to investigate the response to salinity stress, seedlings of two rice kinds, Hashemi and its advanced mutant line, have exposed to 100 mM NaCl as a salinity stress in an experiment, conducted in 2017 at Gorgan University of Agricultural Sciences and Natural Resources, Iran. For the biochemical investigation, root sampling is performed during three and six days after the salinity stress treatment. The experiment is conducted as a split plot with randomized complete block design with three replications in hydroponic culture. Under salinity stress, the sodium ion content in both genotypes’ roots has increased significantly, while this trend is much lower in the root of mutant genotype than wild type. The induced oxidative stress of salinity stress is measured by the amount of hydrogen peroxide, indicating that the wild type is under higher oxidative stress which is confirmed by the higher amount of malondialdehyde. Evaluation of antioxidant enzymes’ activity include superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. It reveals a significant rise in the root of the mutant genotype. Overall, this study shows that mutation in the rice genotype leads to salt tolerance, compared to the wild type, through promoting the activity of oxidative enzymes and the synthesis of some osmolytes in the root tissue.