SummarySheath 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. Through map‐based cloning and transgenic validation, we found that an insertion disrupting the Stay‐Green (OsSGR) gene is responsible for sbr1 phenotypes. Mechanistically, the sbr1/Ossgr mutants reduce the expression of most OsCKX genes, which function in cytokinin (CK) degradation, to accumulate CK leading to ShB resistance. Importantly, knockout of OsCKX7, predominantly expressed in the leaf sheath and highly induced by R. solani, significantly enhances ShB resistance without stay‐green phenotype nor yield penalty, showing high application potential. Thus, our study reveals novel insights that OsSGR and cytokinin play key roles in rice‐R. solani interaction and generates a valuable ShB‐resistant germplasm.

中文翻译：

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Stay-Green （OsSGR） 中的自然突变通过提高细胞分裂素含量增强了对水稻纹枯病的抵抗力


摘要由立枯丝核菌引起的纹枯病 （ShB） 是一种高度破坏性的疾病，在世界许多作物中都有，没有主要的抗性基因可用。在这里，我们鉴定了一个 sbr1 （纹枯病抗性 1） 水稻突变体，它显示出增强的 ShB 抗性并保持包括产量在内的野生型农艺性状，但带有不希望的保持绿色表型。通过基于地图的克隆和转基因验证，我们发现破坏 Stay-Green （OsSGR） 基因的插入是 sbr1 表型的原因。从机制上讲，sbr1/Ossgr 突变体降低了大多数 OsCKX 基因的表达，这些基因在细胞分裂素 （CK） 降解中起作用，从而积累 CK，从而导致 ShB 耐药。重要的是，敲除主要在叶鞘中表达并由 R. solani 高度诱导的 OsCKX7 的敲除显着增强了 ShB 抗性，而没有保持绿色的表型或产量损失，显示出很高的应用潜力。因此，我们的研究揭示了 OsSGR 和细胞分裂素在水稻-R. solani 相互作用中起关键作用的新见解，并产生了有价值的 ShB 抗性种质。