Stay Green mutant regulates cytokinin content to enhance resistance to rice sheath blight caused by necrotrophic pathogen Rhizoctonia solani

Sheath blight (ShB), caused by Rhizoctonia solani, is a highly destructive disease in many crops worldwide and no major resistance genes are available. Here, we identified a sbr1 (sheath blight resistance 1) rice mutant, which shows enhanced ShB resistance and maintains wildtype agronomic traits including yield, but carries an undesired stay-green phenotype. Using map-based cloning and transgenic validation, we found that an insertion disrupting the Stay-Green (OsSGR) gene is responsible for the sbr1 phenotype.