H2S modulates <i>BrSDH1-1</i> alternative splicing to induce stomatal closure in Chinese cabbage

Hydrogen sulfide (H₂S), 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 H₂S 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 H₂S signaling during stomatal closure. Silencing of <i>BrSDH1-1</i> impaired the effects of H₂S on stomatal closure, SDH activity, and ATP production. RNA-Seq analysis revealed that H₂S modulates the AS of <i>BrSDH1-1</i>, resulting in transcript variants with differential expression. Overexpression of <i>BrSDH1-1A</i> and <i>BrSDH1-1C</i> in <i>Arabidopsis</i> enhanced drought resistance, whereas <i>BrSDH1-1B</i> had no significant effect. H₂S enhanced SDH activity and ATP production, promoted stomatal closure, and reduced excess reactive oxygen species (ROS) in OE-<i>BrSDH1-1A</i> and OE-<i>BrSDH1-1</i>C lines but not in OE-<i>BrSDH1-1B</i>. Furthermore, biotin-switch assays demonstrated that H₂S induced persulfidation of BrSDH1-1A and BrSDH1-1C, with no effect on variant BrSDH1-1B. These findings reveal a novel regulatory mechanism by which H₂S modulates <i>BrSDH1-1</i> splicing to mediate stomatal closure and improve drought tolerance, offering valuable molecular insights for enhancing stress resilience in horticultural crops.