Hydrogen Sulfide Primes bZIP68 via Persulfidation to Enhance Redox-Dependent Transcription and Adaptation to Osmotic Stress in Rice

Osmotic stress limits rice productivity, yet the crosstalk between hydrogen sulfide signaling and redox regulation remains incompletely understood. We previously showed that redox-dependent oligomerization of the basic (region) leucine zippers transcription factor bZIP68 at Cys245 confers osmotic tolerance. However, the role of an adjacent cysteine, Cys171, was undefined. Here, we demonstrate that osmotic stress induces persulfidation of bZIP68 specifically at Cys171. This modification facilitates Cys245-mediated oxidation-dependent oligomerization, thereby enhancing bZIP68 transcriptional activity toward COLD-REGULATED413-THYLAKOID MEMBRANE1 (COR413-TM1). Transgenic complementation and physiological assays confirmed that Cys171 persulfidation is essential for full bZIP68 function in osmotic adaptation. Transcriptomic analysis further revealed that Cys171 is required for bZIP68-driven transcriptional reprogramming under stress. Our findings establish a hierarchical redox cascade wherein persulfidation primes bZIP68 for oxidative activation, highlighting a regulatory crosstalk between distinct post-translational modifications. These mechanistic insights expand our understanding of H2S signaling and identify the bZIP68 cysteine network as a potential target for improving crop stress resilience.