Jasmonic acid-induced hydrogen sulfide activates MEK1/2 in regulating the redox state of ascorbate in Arabidopsis thaliana leaves

In this paper, we investigated the relationship between hydrogen sulfide (H2S) and mitogen-activated protein kinase kinase (MEK1/2) in jasmonic acid (JA)-regulated the redox state of ascorbate in the leaves of Arabidopsis thaliana. The results showed that JA significantly enhanced the phosphorylation level of MEK1/2, the production of endogenous H2S and the ratio of reduced ascorbate (AsA) to dehydroascorbate (DHA) (AsA/DHA) in wild type of A. thaliana (WT). However, there were no obvious effects of JA on above indicators in H2S synthetic mutant of A. thaliana (MT). H2S scavenger hypotaurine (HT) markedly reduced JA-induced the phosphorylation level of MEK1/2, AsA/DHA ratio and the production of endogenous H2S in WT. Application of H2S donor sodium hydrosulfide (NaHS) to JA-treated MT plants increased above indicators. Application of NaHS to (HT+JA)-treated MT plants did not reverse the effects of HT on above JA-induced indicators. MEK1/2 inhibitor PD98059 decreased JA-induced AsA/DHA ratio and the transcript levels and the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and L-galactono-1,4-lactone dehydrogenase (GalLDH) in WT. However, PD98059 had no effect on JA-induced the production of endogenous H2S in WT. Compared with Control-MT, there were no obvious effects of JA on the production of endogenous H2S, AsA/DHA ratio and the transcript levels and activities of above enzymes in MT. However, application of PD98059 reduced above JA-induced indicators except the production of endogenous H2S and DHA content in MT. Our results suggested that H2S activated MEK1/2 in JA-regulated AsA/DHA ratio in A. thaliana leaves through enzymes in ascorbate metabolism.