Natural variation in SBRR1 shows high potential for sheath blight resistance breeding in rice

Sheath blight (ShB), caused by necrotrophic fungus Rhizoctonia solani, is one of the most serious rice diseases worldwide. To the best of our knowledge, no genes with high potential for rice ShB resistance breeding have been previously characterized. Here we identify a ShB resistance receptor-like kinase 1 (SBRR1) gene via a genome-wide association study. The SBRR1-R elite allele, containing a 256-bp insertion in its promoter, is preferentially present in indica varieties in geographical regions with highly favorable conditions for ShB development. Introduction of SBRR1-R into a commercial japonica rice variety significantly reduces yield loss under severe ShB disease pressure. Transcription factor bHLH57 specifically binds to the 256-bp sequence and accounts for highly induced expression and stronger resistance of SBRR1-R. Localization of SBRR1 on plasma membrane, aided by SBRR1-interaction-protein 1, and phosphorylation of SBRR1 are required for SBRR1 to rapidly upregulate downstream chitinase genes for resistance. These findings offer mechanistical insights into ShB resistance hidden in natural rice varieties.