Hydrogen sulfide interacting with abscisic acid in stomatal regulation responses to drought stress in Arabidopsis

Hydrogen sulfide (H2S) plays a crucial role in the regulation of stomatal closure in plant response to drought stress, and l-cysteine desulfhydrase (LCD) has been identified as being mainly responsible for the degradation of cysteine to generate H2S. In view of the similar roles to abscisic acid (ABA), in this study, the lcd, aba3 and abi1 mutants were studied to investigate the close inter-relationship between H2S and ABA. The lcd mutant showed enlarged stomatal aperture and more sensitivity to drought stress than wild-type plants. Expression of Ca2+ channel and outward-rectifying K+ channel coding genes decreased in the lcd mutant, and conversely, expression of inward-rectifying K+ increased. The stomatal aperture of aba3 and abi1 mutants decreased after treatment with NaHS (a H2S donor), but stomatal closure in responses to ABA was impaired in the lcd mutant. The expression of LCD and H2S production rate decreased in both the aba3 and abi1 mutants. Transcriptional expression of ABA receptor candidates was upregulated in the lcd mutant and decreased with NaHS treatment. The above results suggested that H2S may be an important link in stomatal regulation by ABA via ion channels; H2S affected the expression of ABA receptor candidates; and ABA also influenced H2S production. Thus, H2S interacted with ABA in the stomatal regulation responsible for drought stress in Arabidopsis.