Comparative oxidation proteomics analyses suggest redox regulation of cytosolic translation in rice leaves upon Magnaporthe oryzae infection

Abstract

Pathogen attack can increase plant levels of reactive oxygen species (ROS), which act as signaling molecules to activate plant defense mechanisms. Elucidating these processes is crucial for understanding redox signaling pathways in plant defense responses. Using an iodo-tandem mass tag (TMT)-based quantitative proteomics approach, we mapped 3362 oxidized cysteine sites in 2275 proteins in rice leaves. Oxidized proteins were involved in gene expression, peptide biosynthetic processes, stress responses, ROS metabolic processes, and translation pathways. Magnaporthe oryzae infection led to increased oxidative modification levels of 512 cysteine sites in 438 proteins, including many transcriptional regulators and ribosomal proteins. Ribosome profiling (Ribo-seq) analysis revealed that the oxidative modification of ribosomal proteins promoted the translational efficiency of many mRNAs involved in defense response pathways, thereby affecting rice immunity. Our results suggest that increased oxidative modification of ribosomal proteins in rice leaves promotes cytosolic translation, thus revealing a novel function of post-translational modifications. Furthermore, the oxidation-sensitive proteins identified here provide a valuable resource for research on protein redox regulation and can guide future mechanistic studies.