H2S is involved in ABA-mediated stomatal movement through MPK4 to alleviate drought stress in Arabidopsis thaliana

Hydrogen sulfide (H2S) is a gaseous signaling molecule that participates in multiple physiological processes in both animals and plants. Mitogen-activated protein kinase (MAPK) is important signaling molecule that links the growth and developmental signals and environment stimuli to cellular responses. In the current study we explored the relationship between H2S and MAPK in drought stress resistance in Arabidopsis. The quantitative real-time (qRT)-PCR, root tip bending experiment and stomatal aperture assay were used in this paper. Drought stress activated both H2S biosynthesis and gene expression of MAPKs. The increase in MAPK expression was depressed in lcd/des1, a double mutant of H2S synthesis. Then we selected MPK4 as our target and used mpk4 mutants for further studies. H2S was able to alleviate the drought stress in wild-type (WT) Arabidopsis but not in mpk4 mutants. Meanwhile, H2S-induced stomatal movement was impaired in mpk4 mutants. We then examined the role of H2S and MPK4 in stomatal movements in response to abscisic acid (ABA) and hydrogen peroxide (H2O2). ABA- and H2O2- mediated stomatal movements were impaired in lcd/des1 and mpk4 mutants, and H2S-induced stomatal closure was impaired in slac1–3 mutants. Our results suggested that MPK4 is important downstream of H2S in the drought stress response and in stomatal movement, and that the H2S-MPK4 cascade is involved in ABA-mediated stomatal movement to regulate the drought stress.