Abstract
Nitric oxide (NO) production via NO synthase (NOS) plays a vital role in plant tolerance to salt stress. However, the factor(s) regulating NOS-like activity in plant salt stress tolerance remains elusive. Here, we show that Arabidopsis SORTING NEXIN 1 (SNX1), which can restore H2O2-induced NO accumulation in yeast Δsnx4 mutant, functions in plant salt stress tolerance. Salt stress induced NO accumulation through promoted NOS-like activity in the wild type, but this induction was repressed in salt-stressed snx1-2 mutant with the mutation of SNX1 because NOS-like activity was inhibited in the mutant. Consistently, snx1-2 displayed reduced tolerance to high salinity with decreased survival rate compared with the wild type, and exogenous treatment with NO donor significantly rescued the hypersensitivity of the mutant to salt stress. In addition, the snx1-2 mutant with reduced NOS-like activity repressed the expression of stress-responsive genes, decreased proline accumulation and anti-oxidant ability compared with wild-type plants when subjected to salt stress. Taken together with our finding that salt induces the expression of SNX1, our results reveal that SNX1 plays a crucial role in plant salt stress tolerance by regulating NOS-like activity and thus NO accumulation.
Highlights
High salinity severely affects plant growth and cause substantial crop losses, posing a serious threat to global food security (Munns and Tester, 2008; Liu W. et al, 2015)
To assess whether SORTING NEXIN 1 (SNX1) plays a role in the regulation of Nitric oxide (NO) accumulation as yeast Sorting Nexin 4 (SNX4), we transformed pYES260-AtSNX1 plasmid into snx4, where the expression of AtSNX1 is driven by galactose-induced yeast GAL1 promoter
When subjected to H2O2 treatment, the reduced NO accumulation in snx4 is rescued by AtSNX1 expression in pGAL1-AtSNX1 snx4 in the presence of galactose (Figures 1D,E), demonstrating that Arabidopsis SNX1 and yeast SNX4 play a conserved role in H2O2-induced NO accumulation
Summary
High salinity severely affects plant growth and cause substantial crop losses, posing a serious threat to global food security (Munns and Tester, 2008; Liu W. et al, 2015). ABA, a well-known stress phytohormone induced by high salt stress, SNX1 Acts in Stress Tolerance upregulates a large number of salt stress-responsive genes with various protective functions in tolerance (Fujita et al, 2009; Yoshida et al, 2010). Other phytohormones such as indole-3acetic acid (IAA), gibberellic acid (GA) and ethylene are involved in plant salt stress response by coordinating plant growth, development and stress tolerance (Achard et al, 2006; Liu W. et al, 2015; Ryu and Cho, 2015; Shi et al, 2017)
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