Abstract
Hydrogen sulfide (H(2)S), a gasotransmitter molecule, plays critical roles in stomatal closure and cellular bioenergetics. Alternative splicing (AS) is a key regulatory mechanism during plant development and stress responses; however, the interplay between H(2)S signaling and AS in drought tolerance remains unexplored in Chinese cabbage. In this study, we found that the mitochondrial inner membrane enzyme succinate dehydrogenase (SDH) responds to H(2)S signaling during stomatal closure. Silencing of BrSDH1-1 impaired the effects of H(2)S on stomatal closure, SDH activity, and ATP production. RNA-Seq analysis revealed that H(2)S modulates the AS of BrSDH1-1, resulting in transcript variants with differential expression. Overexpression of BrSDH1-1A and BrSDH1-1C in Arabidopsis enhanced drought resistance, whereas BrSDH1-1B had no significant effect. H(2)S enhanced SDH activity and ATP production, promoted stomatal closure, and reduced excess reactive oxygen species (ROS) in OE-BrSDH1-1A and OE-BrSDH1-1C lines but not in OE-BrSDH1-1B. Furthermore, biotin-switch assays demonstrated that H(2)S induced persulfidation of BrSDH1-1A and BrSDH1-1C, with no effect on variant BrSDH1-1B. These findings reveal a novel regulatory mechanism by which H(2)S modulates BrSDH1-1 splicing to mediate stomatal closure and improve drought tolerance, offering valuable molecular insights for enhancing stress resilience in horticultural crops.