Protein persulfidation in plants: a central regulator of multiple signaling pathways.

Protein persulfidation, a redox-based post-translational modification mediated by hydrogen sulfide (H2S) on cysteine thiols, plays a central regulatory role in plant growth, development, and stress adaptation. Elucidating its biological functions and molecular mechanisms depends on accurate detection, identification, and quantification. Over the past decade, various optimized methods for persulfidation detection have been developed, which can be categorized into modified biotin switch assays, mass spectrometry-based high-throughput analysis, antibody-dependent western blotting, electrophilic trapping strategies, fluorescent probing, and alkylating compound-based approaches. Critically, persulfidation acts as a versatile modulator that fine-tunes multiple phytohormone signaling pathways-including those of ethylene, abscisic acid, auxin, and melatonin-by targeting key enzymes, receptors, and transcription factors. This regulation governs essential processes, such as fruit ripening, stomatal movement, root development, and osmotic stress adaptation. Beyond hormonal regulation, persulfidation is essential for maintaining cellular ion homeostasis. It enhances salt and drought tolerance by activating the plasma membrane H+-ATPase and the SOS1 Na+/H+ antiporter to drive Na+ extrusion, while concurrently inhibiting K+ efflux channels to retain cellular K+, executing a coordinated 'activate efflux, inhibit leak' strategy. In summary, persulfidation emerges as a fundamental regulatory mechanism that integrates H2S signaling with phytohormone actions and ion transport to coordinate plant development and stress resilience. This synthesis provides a comprehensive framework for understanding its multifaceted roles and highlights its potential as a target for improving crop adaptation.