Calcium and Components of Lipid Signaling in Implementation of Hydrogen Sulfide Influence on the State of Stomata in Arabidopsis thaliana

A time and concentration dependence of the hydrogen sulfide donor sodium hydrosulfide (NaHS) influence on the state of stomata of Arabidopsis thaliana (Col-0) leaves, as well as the role of calcium and phospholipases in the implementation of its effects, was studied. Treatment of leaves with NaHS in the concentration range of 5–250 μM caused a decrease in the size of the stomatal aperture. The maximal effect of the stomatal closure was observed 90 min after the beginning of the treatment with H2S donor, and the stomatal aperture in NaHS variants was, on the contrary, much wider than in the control after 180 min of exposure. The effect of treatment with NaHS solutions on the stomata state was completely eliminated by hydroxylamine, the hydrogen sulfide scavenger, which indicates the specificity of NaHS effects as an H2S donor. The decrease in stomatal aperture and relative number of open stomata caused by the donor of hydrogen sulfide was almost completely leveled off by the pretreatment of leaves with the calcium channel blocker lanthanum chloride, the extracellular calcium chelator EGTA, the phospholipase C inhibitor neomycin, and the antagonist of the formation of cyclic adenosine-5'-diphosphate ribose—nicotinamide. In addition, the stomatal effect of theH2S donor was partially eliminated by the calmodulin antagonist chlorpromazine. The leveling of the hydrogen sulfide donor action on the state of stomatal apparatus of Arabidopsis leaves was also noted at the pretreatment of leaves with butanol-1, an inhibitor of phospholipase D-dependent formation of phosphatidic acid. A conclusion about the importance of calcium intake into the cytosol from various compartments, as well as lipid signaling mediators formed with the involvement of phospholipases C and D, in the implementation of hydrogen sulfide action on the state of stomata was made.