Hydrogen sulfide mediated the melatonin induced stoma closure by regulating the K+ channel in Arabidopsis thaliana

The roles of the gasotransmitter hydrogen sulfide (H2S) and the phytohormone melatonin (MEL) in enhancing plant drought resistance are increasingly understood, but the specific regulatory mechanisms in response to drought remain unclear. This study investigated their relationship in the regulation of stomatal movement in response to drought stress. Under normal and drought stress conditions, exogenous MEL increased the H2S content, production rate and the transcription level of H2S production-related encoding genes LCD and DES1. The ability of MEL to increase drought stress tolerance was inhibited significantly in lcd, des1 and lcd/des1 mutants, which implied that MEL was partially dependent on H2S in this process. Exogenous MEL and H2S increased the transcriptional level of drought related transcription factors CBF2, CBF3, RD29A, DREB2A and DREB2B in response to drought stress and H2S and MEL affected the transcription level of K+ channel-related genes KCO1, GORK, AKT1, AKT2, KAT1, and KC1 to regulate stomatal movement. At the post-translational level, H2S increased the persulfidation levels of KCO1 and AKT1 and reduced their degradation rate. It was also found that endogenous H2S and MEL content had no effect on the mutants of kco1, kat1, akt1 and gork. It was concluded that H2S mediated the MEL induced stoma closure by regulating the K+ channel to enhance plant drought resistance in Arabidopsis.