Proteomic evidence reveals that ROS regulation and methylglyoxal detoxification are central to Xa7-mediated resistance to bacterial leaf blight in rice seedlings

Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae , is a major constraint to rice production, especially when infection occurs at the seedling stage. The executor resistance gene Xa7 confers durable and broad‑spectrum resistance to BLB; however, the underlying protein‑level mechanisms governing Xa7‑mediated resistance during early development remain largely unclear. This study aims to perform comparative proteomic analysis between near‑isogenic lines of Xa7 locus in the background of KD18 variety. Rice seedlings were inoculated with Xoo , and total proteins were analyzed by two-dimensional gel electrophoresis followed by MALDI‑TOF/TOF mass spectrometry. Eight protein spots showing reproducible expression level changes (≥ 1.5-fold) between resistant and susceptible genotypes were identified, including six upregulated and two downregulated proteins in Xa7-NIL seedlings. Peroxiredoxin‑2C showed the strongest induction (+ 3.15-fold), together with increased levels of a glycine‑rich RNA‑binding protein (+ 1.87-fold) and lactoylglutathione lyase (+ 2.14-fold), indicating enhanced regulation of reactive oxygen species, post‑transcriptional processes, and methylglyoxal detoxification. In contrast, the cytochrome b6/f complex iron-sulfur subunit was markedly downregulated (-3.84-fold), suggesting reprogramming of photosynthetic electron transport during defense activation. These results provided direct proteomic evidence linking an executor resistance gene to specific defense‑associated protein responses during early rice development.