Global S-sulfenylation proteome analysis reveals a role of Fd-GOGAT in regulating GABA accumulation during Magnaporthe oryzae infection in rice.

Blast disease, caused by Magnaporthe oryzae, triggers complex redox signaling networks in rice involving reactive oxygen species (ROS) and reactive nitrogen species (RNS). These signaling molecules not only function as key regulators of plant immunity but also induce distinct cysteine-based post-translational modifications, namely S-sulfenylation and S-nitrosation, respectively, thereby modulating the activity, stability, and function of target proteins. While the role of S-nitrosation in rice immunity has been increasingly recognized, the contribution of S-sulfenylation remains largely unexplored. Here, we report the first global S-sulfenylation proteome analysis in rice using Dongjin (DJ, resistant) and Nipponbare (NIP, susceptible) cultivars, following M. oryzae infection. Using an iodoTMT-based approach, we identified 352 S-sulfenylated peptides corresponding to 263 non-redundant proteins, of which 29 showed significant differences in response to blast infection. Functional annotation indicated that S-sulfenylation predominantly targets proteins involved in photosynthesis, carbon metabolism, antioxidant defense, and stress signaling. Notably, differentially S-sulfenylated proteins in response to M. oryzae included a cytosolic Cu/Zn superoxide dismutase (SOD) and ferredoxin-dependent glutamate synthase (Fd-GOGAT), highlighting their potential roles as redox-regulated nodes. In vivo S-sulfenylation enhanced the enzymatic activities of both Cu/Zn SOD and Fd-GOGAT, while DTT treatment reversed these effects. Quantification of γ-aminobutyric acid (GABA) revealed increased levels in both cultivars following infection, which partially correlated with enhanced S-sulfenylation of Fd-GOGAT, suggesting a potential role for S-sulfenylation in modulating stress-induced GABA accumulation. Collectively, our findings establish S-sulfenylation as a critical component of redox signaling in rice and reveal its role in coordinating antioxidant defense, metabolic reprogramming, and immune responses during blast infection.