H2S induces NO in the regulation of AsA-GSH cycle in wheat seedlings by water stress

In current study, we investigated the relationship between hydrogen sulfide (H2S) and nitric oxide (NO) in the regulation of ascorbate-glutathione (AsA-GSH) cycle in wheat seedlings by water stress. Findings showed that water stress significantly stimulated the production of H2S and NO, the transcript levels and activities of enzymes in AsA-GSH cycle, as well as malondialdehyde (MDA) production and electrolyte leakage, but significantly decreased AsA/DHA and GSH/GSSG. Meanwhile, water stress significantly decreased plant height and dry biomass. Except MDA and electrolyte leakage, above changes induced by water stress were reversed by H2S synthesis inhibitor aminooxyacetic acid (AOA) and NO synthesis inhibitor N-G-nitro-L-arginine methyl ester (L-NAME). However, AOA and L-NAME significantly enhanced MDA production and electrolyte leakage, which further decreased plant height and dry biomass of wheat seedlings under water stress. Application of exogenous H2S donor sodium hydrosulfide (NaHS) to AOA-treated plants and application of exogenous NO donor sodium nitroprusside (SNP) to L-NAME-treated plants reversed above effects of AOA and L-NAME, respectively. Application of L-NAME plus water stress significantly decreased NO production induced by water stress. However, application of L-NAME plus water stress had no obvious influence on H2S production induced by water stress, while application of AOA plus water stress significantly reduced the production of H2S and NO induced by water stress. Current findings suggested that H2S acted upstream of NO in the regulation of AsA-GSH cycle in wheat seedlings by water stress.