H₂S enhances drought resistance by orchestrating alternative splicing and persulfidation of ETFQO

Identifies ETFQO as a central target, showing H₂S induces its alternative splicing to generate functionally distinct isoforms that are differentially persulfidated, coordinating stomatal and respiratory responses for drought adaptation. Hydrogen sulfide (H₂S) is an important gasotransmitter known to enhance plant stress tolerance, but its specific role in reprogramming energy metabolism under drought remains poorly understood. Here, we demonstrate that electron transfer flavoprotein: ubiquinone oxidoreductase (ETFQO) functions as a significant target through which H₂S enhances drought tolerance via transcriptional and post-translational regulation. At the transcriptional level, both H₂S and drought stress induce the expression of ETFQO. Transcriptome sequencing further revealed that H₂S modulates alternative splicing (AS) of ETFQO under stress conditions, resulting in the accumulation of three distinct transcripts (ETFQO.1, ETFQO.2, and ETFQO.3). Physiological analyses in Arabidopsis overexpressing these isoforms revealed that OE-ETFQO.3 improved drought tolerance, whereas OE-ETFQO.1 and OE-ETFQO.2 did not confer enhanced tolerance; nevertheless, both OE-ETFQO.1 and OE-ETFQO.3 participated in H₂S-modulated stomatal closure and mitochondrial respiration and exhibited higher responsiveness to H₂S than OE-ETFQO.2. Mechanistically, this functional specificity stems from H₂S-induced persulfidation of ETFQO.1 and ETFQO.3, a modification absent in ETFQO.2. Thus, our findings reveal a coordinated transcriptional and post-translational mechanism by which H₂S regulates energy metabolism and stomatal responses via ETFQO. This model, integrating AS with persulfidation to optimize drought adaptation, advances our understanding of gasotransmitter function in stress responses and suggests new strategies for crop improvement.