Physiological and molecular comparison of oxidative stress responses in Oryza sativa and Aeluropus littoralis under salt stress condition

Abstract

Abstract The present study aimed to investigate the effects of different concentrations of NaCl on membrane stability, potassium (K+) to sodium (Na+) ratio, and the expression of stress-responsive genes in aerial and underground organs of O. sativa cv. IR64 and Aeluropus littoralis to shed more light on the salt stress adaptive mechanisms in the grass species towards the improvement of salt tolerance in rice. The expression of stress-responsive genes signified the importance of tissue-specific isoforms to circumvent the harmful effects of salinity. Among the antioxidant enzymes, catalase (CAT) showed a complete differential expression pattern in two species and its expression was induced in both organs of halophyte but was suppressed in IR64, suggesting it may function as a determining factor in salt adaptability differences in these two species. The cytoplasmic APX (cAPX) seems to be more effective than its peroxisomal counterpart (pAPX), confirming the specialized functions of subcellular isoforms in association with conferring salt tolerance in each species. In general, A. littoralis displayed a more coordinated function among different antioxidant genes, leading to a more elaborated adaptive mechanism to salinity stress in this halophyte, as evidenced by a higher K+/Na+ ratio and lower membrane permeability. The finding of this study provide relevant information regarding the molecular mechanisms underlying salt adaptability in grasses and highlight the importance of some of the antioxidant enzymes in reducing the detrimental effects of high salt concentrations, which would be highly beneficial for utilization in crop improvement programs and incorporation of salt hardiness into elite rice cultivars.