Loss of Function Mutation of IOS1 in Arabidopsis Is More Sensitive to Salt Stress

Plants are subjected to a variety of environmental stressors, including salinity, drought and pathogens, and have consequently developed a sophisticated sensing system. In Arabidopsis, malectin-like LRR-RLK impaired oomycete susceptibility 1 (IOS1, AT1G51800) plays an important role in both abiotic and biotic stresses by attenuating abscisic acid responses and regulating pattern-triggered immunity. This research aimed to investigate the role of IOS1 in regulating cellular responses to salinity. We compared the growth, antioxidant defence system, the expression of abiotic stress response marker genes and phosphorylation of MPKs between wild-type (Col-0) and ios1 mutant (SALK-137388) seedlings grown under salt stress. Our results demonstrated that the ios1 loss-of-function seedlings conferred more hypersensitivity to salinity. Salt stress-induced greater H2O2 accumulation in ios1 mutants than in Col-0 seedlings. Furthermore, salt stress-induced higher levels of ATL31, ZAT6, CRK13, CTP1, RD29A, RD29B, COR15A and RD22 in Col-0 than in ios1 plants after salt treatment. Moreover, ios1 mutants exhibited significantly weaker phosphorylation of MPK6 and accelerated dephosphorylation of activated MPK6 than Col-0 during NaCl treatment. These findings suggest that IOS1 is important and positively regulates salt stress in Arabidopsis.