Proteomic analysis reveals the protective role of exogenous hydrogen sulfide against salt stress in rice seedlings

Hydrogen sulfide (H2S) is an important gaseous signal molecule which participates in various abiotic stress responses. However, the underlying mechanism of H2S associated salt tolerance remains elusive. In this study, sodium hydrosulfide (NaHS, donor of H2S) was used to investigate the protective role of H2S against salt stress at the biochemical and proteomic levels. Antioxidant activity and differentially expressed proteins (DEPs) of rice seedlings treated by NaCl or/and exogenous H2S were investigated by the methods of biochemical approaches and comparative proteomic analysis. The protein-protein interaction (PPI) analysis was used for understanding the interaction networks of stress responsive proteins. In addition, relative mRNA levels of eight selected identified DEPs were analyzed by quantitative real-time PCR. The result showed that H2S alleviated oxidative damage caused by salt stress in rice seedling. The activities of some antioxidant enzymes and glutathione metabolism were mediated by H2S under salt stress. Proteomics analyses demonstrated that NaHS regulated antioxidant related proteins abundances and affected related enzyme activities under salt stress. Proteins related to light reaction system (PsbQ domain protein, plastocyanin oxidoreductase iron-sulfur protein), Calvin cycle (phosphoglycerate kinase, sedoheptulose-1,7-bisphosphatase precursor, ribulose-1,5-bisphosphate carboxylase/ oxygenase) and chlorophyll biosynthesis (glutamate-1-semialdehyde 2,1-aminomutase, coproporphyrinogen III oxidase) are important for NaHS against salt stress. ATP synthesis related proteins, malate dehydrogenase and 2, 3-bisphosphoglycerate-independent phosphoglycerate mutase were up-regulated by NaHS under salt stress. Protein metabolism related proteins and cell structure related proteins were recovered or up-regulated by NaHS under salt stress. The PPI analysis further unraveled a complicated regulation network among above biological processes to enhance the tolerance of rice seedling to salt stress under H2S treatment. Overall, our results demonstrated that H2S takes protective roles in salt tolerance by mitigating oxidative stress, recovering photosynthetic capacity, improving primary and energy metabolism, strengthening protein metabolism and consolidating cell structure in rice seedlings.