H2S is involved in drought-mediated stomatal closure through PLDα1 in Arabidopsis

Phospholipase D alpha 1 (PLD alpha 1) acting as one of the signal enzymes can respond to drought stress. It is well known that hydrogen sulfide (H2S) plays an important role in plant responding to biotic or abiotic stress. In this study, the functions and relationship between PLD alpha 1 and H2S in drought stress resistance in Arabidopsis were explored. Our results indicated that drought stress promotes PLD alpha 1 and H2S production by inducing the expression of PLD alpha 1 and LCD genes. PLD alpha 1 and LCD enhanced plant tolerance to drought by regulating membrane lipid peroxidation, proline accumulation, H2O2 content and stomatal closure. Under drought stress, the H2O2 content of PLD alpha 1-deficient mutant (pld alpha 1), L-cysteine desulfhydrase (LCD)-deficient mutant (lcd) was higher than that of ecotype (WT), the stomatal aperture of pld alpha 1 and lcd was larger than that of WT. The transcriptional and translational levels of LCD were lower in pld alpha 1 than that in WT. Exogenous application of the H2S donor NaHS or GYY reduced the stomatal aperture of WT, pld alpha 1, PLD alpha 1-CO, and PLD alpha 1-OE lines, while exogenous application of the H2S scavenger hypotaurine (HT) increased the stomatal aperture. qRT-PCR analysis of stomatal movement-related genes showed that the expression of CAX1, ABCG5, SCAB1, and SLAC1 genes in pld alpha 1 and lcd were down-regulated, while ACA1 and OST1 gene expression was significantly up-regulated. Thus, PLD alpha 1 and LCD are required for stomatal closure to improve drought stress tolerance.