Abstract: TOPLESS/TOPLESS-RELATED (TPL/TPR) proteins are transcriptional corepressors that play pivotal roles in plant development, hormonal signaling, and stress responses. Although TPL/TPR proteins have been identified in different organisms, their functions in disease resistance in rice (Oryza sativa L.) remain largely unexplored. Here, we conducted a comprehensive analysis of the three rice TPL/TPRs, designated OsTPR1, OsTPR2, and OsTPR3, for analyzing their evolutionary relationships, expression patterns, subcellular localization, and determining their functions in disease resistance. Phylogenetic analysis revealed that the three OsTPRs belong to distinct evolutionary clades. Expression pattern analysis demonstrated tissue-specific patterns and responsiveness to jasmonate (JA), with all three genes being induced upon infection with Xanthomonas oryzae pv. oryzae (Xoo). Consistent with their role as the transcriptional corepressors, all three OsTPRs localize to the nucleus. By performing disease resistance analysis, we found that after inoculation with Xoo, the lesion lengths of the Ostpr2 and Ostpr3 mutants were significantly shorter than those of the wild type. Protein interaction assays demonstrated that OsTPR2 interacts with JA ZIM-domain protein (OsJAZ12), whose expression is also induced by Xoo. Furthermore, haplotype analysis of OsTPRs revealed natural variation, leading to the identification of superior allelic variants that confer improved resistance to bacterial blight without a yield penalty. Collectively, our findings provide a systematic characterization of TPL/TPR in rice, highlighting their potential roles in resistance to bacterial leaf blight and identify valuable allelic resources for molecular breeding aimed at increasing both disease resistance and yield. 

Key words: TOPLESS and TOPLESS-related (TPL/TPR) protein, transcriptional corepressor, rice, disease resistance, breeding