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

Aim: Hydrogen sulfide (H S) 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 H S and MAPK in drought stress resistance in Arabidopsis. Methods: The quantitative real-time (qRT)-PCR, root tip bending experiment and stomatal aperture assay were used in this paper. Results: Drought stress activated both H S biosynthesis and gene expression of MAPKs. The increase in MAPK expression was depressed in lcd/des1, a double mutant of H S synthesis. Then we selected MPK4 as our target and used mpk4 mutants for further studies. H S was able to alleviate the drought stress in wild-type (WT) Arabidopsis but not in mpk4 mutants. Meanwhile, H S-induced stomatal movement was impaired in mpk4 mutants. We then examined the role of H S and MPK4 in stomatal movements in response to abscisic acid (ABA) and hydrogen peroxide (H O ). ABA- and H O - mediated stomatal movements were impaired in lcd/des1 and mpk4 mutants, and H S-induced stomatal closure was impaired in slac1–3 mutants. Conclusions: Our results suggested that MPK4 is important downstream of H S in the drought stress response and in stomatal movement, and that the H S-MPK4 cascade is involved in ABA-mediated stomatal movement to regulate the drought stress.