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.