作者
Guo‐Bang Li,J. M. Liu,Jia-Xue He,Gao-Meng Li,Yuanlong Zhao,Xianhui Liu,Xiao‐Hong Hu,X. H. Zhang,Junquan Wu,Shuai Shen,Xin‐Xian Liu,Yong Zhu,Feng He,Han Gao,He Wang,Jing‐Hao Zhao,Yan Li,Fu-Yuan Huang,Yanyan Huang,Zhi‐Xue Zhao,Jiwei Zhang,Shuangyun Zhou,Yunpeng Ji,Mei Pu,Min He,Xuewei Chen,Jing Wang,Weitao Li,Xianjun Wu,Yuese Ning,Wenxian Sun,Zhengjun Xu,Wenming Wang,Jing Fan
摘要
Abstract The flower-infecting fungus Ustilaginoidea virens causes rice false smut, which is a severe emerging disease threatening rice (Oryza sativa) production worldwide. False smut not only reduces yield, but more importantly produces toxins on grains, posing a great threat to food safety. U. virens invades spikelets via the gap between the 2 bracts (lemma and palea) enclosing the floret and specifically infects the stamen and pistil. Molecular mechanisms for the U. virens–rice interaction are largely unknown. Here, we demonstrate that rice flowers predominantly employ chitin-triggered immunity against U. virens in the lemma and palea, rather than in the stamen and pistil. We identify a crucial U. virens virulence factor, named UvGH18.1, which carries glycoside hydrolase activity. Mechanistically, UvGH18.1 functions by binding to and hydrolyzing immune elicitor chitin and interacting with the chitin receptor CHITIN ELICITOR BINDING PROTEIN (OsCEBiP) and co-receptor CHITIN ELICITOR RECEPTOR KINASE1 (OsCERK1) to impair their chitin-induced dimerization, suppressing host immunity exerted at the lemma and palea for gaining access to the stamen and pistil. Conversely, pretreatment on spikelets with chitin induces a defense response in the lemma and palea, promoting resistance against U. virens. Collectively, our data uncover a mechanism for a U. virens virulence factor and the critical location of the host–pathogen interaction in flowers and provide a potential strategy to control rice false smut disease.