Evaluation of salinity response through the antioxidant defense system and osmolyte accumulation in a mutant rice

In order to assess the responses of Hashemi rice genotype and its advanced mutant line under salinity stress of 100 mM Sodium chloride (NaCl) for three and six days the shoot samples were taken for biochemical analysis. This experiment was performed in split plot based on randomized complete block design with three replications. The main factor was factorial combination of saline treatment and sampling period, sub factor included genotypes. The result showed that the chlorophyll content decreased (16.3) under salt stress for the wild type, but higher amount (21.2) in the mutant was recorded. The mutant rice showed higher amount of K+ and lower of Na+ concentrations in shoots under salt stress condition. The results revealed, although the amount of H2O2 of both genotypes was significantly increased by exposure to NaCl, the effect was superior in the wild genotype (44.85). The antioxidant enzymes activity include catalase and peroxidase activity were grow up significantly in advanced mutant line. Also, the level of flavonoids and phenol content under salinity stress were enhanced dramatically in mutant line. In order to evaluate ion homeostasis under salinity stress condition the measurement of osmolytes such as proline, glycine betaine and trehalose indicated the mutant rice by rising the production (4.4, 0.81 and 87.55 respectively) of these metabolites in shoot showed the better tolerance to salinity stress. In conclusion, the observation indicated that mutation had a positive impact on ROS scavenging system and ion homeostasis mechanism and ultimately have led to salt tolerance in the mutant genotype.