Abstract:
Salt stress is one of the major abiotic stresses that seriously limit plant growth and development and can lead to a significant reduction in crop yield, especially rice. Salt stress affects plants via ionic toxicity and osmotic stress. Osmotic stress results in a reduction of water absorption ability. Ionic toxicity causes Na+ toxicity, which disrupts photosynthesis, protein synthesis, and enzyme activity. The previous study of KDML105 rice transcriptome profile and qRT-PCR revealed that rice malate synthase (OsMS) encoding malate synthase, which is one of the key enzymes in glyoxylate cycle was up-regulated under salt stress, so OsMS may involve in salt tolerance mechanisms. In this study, OsMS was transferred into Atms mutant Arabidopsis and wild type to constructed revertant Arabidopsis and OsMS-overexpressing Arabidopsis, respectively, in order to characterize the function of OsMS in response to salt stress. The results showed that Atms mutant Arabidopsis exhibited the lower germination rate than wild type and two lines of revertant (OX/ms4-2 and OX/ms5-2) were able to revert the phenotype under high salt treatment. For fresh weight, 5-day old Atms mutant Arabidopsis treated with salt stress for 3 days and recovered for 5 days had the higher reduction of fresh weight than wild type, revertants (OX/ms4-2, OX/ms5-2, and OX/ms13-3), and OsMS-overexpressing lines (OX/WT13). Leaf greenness, chlorophyll, and total carotenoid were found to be higher in Atms mutant Arabidopsis than wild type, which consistent with those during dark-induced senescence. Under dark-induced condition, revertant lines exhibited chlorophyll and carotenoid contents closer to those of wild type and OX/WT13. Moreover, expression levels of SAG12 involving in senescence in the Atms mutant were lower than wild type, OX/WT13 and all revertant lines. Taken together, OsMS may play important roles in leaf senescence induction in response to salt stress condition.
