Wheat receptor-kinase-like protein Stb6 controls gene-for-gene resistance to fungal pathogen Zymoseptoria tritici

Deployment of fast-evolving disease-resistance genes is one of the most successful strategies used by plants to fend off (抵御) pathogens. In gene-for-gene relationships, most cloned disease-resistance genes encode intracellular nucleotide-binding leucine-rich-repeat proteins (NLRs; 富含亮氨酸重复蛋白) recognizing pathogen-secreted isolate-specific avirulence (Avr) effectors delivered to the host cytoplasm (细胞质). This process often triggers a localized hypersensitive response (过敏反应), which halts (停止) further disease development. Here we report the map-based cloning (图位克隆) of the wheat Stb6 gene and demonstrate that it encodes a conserved wall-associated receptor kinase (WAK)-like protein (细胞壁关联类受体激酶蛋白), which detects the presence of a matching apoplastic effector (质外体效应物) and confers pathogen resistance without a hypersensitive response. This report demonstrates gene-for-gene disease resistance controlled by this class of proteins in plants. Moreover, Stb6 is, to our knowledge, the first cloned gene specifying resistance to Zymoseptoria tritici, an important foliar fungal pathogen (叶面的真菌病原体) affecting wheat and causing economically damaging septoria tritici blotch (STB) disease.

配置快速演化的疾病抗性基因是植物中抵御病原菌采用的最为成功的一种策略。在基因与基因间的的关系中，大多数克隆到的疾病抗性基因均编码一个细胞内的可结合核酸的富含亮氨酸重复蛋白，该蛋白会识别由病原菌分泌的、会被传递到寄主细胞质中的无毒效应物。该过程常常会诱发一个局部的过敏反应，进而停止疾病的继续传染。本文报道了通过图位克隆的方法克隆到了小麦中的Stb6基因，并阐释了该基因编码一个保守的细胞壁关联类受体激酶蛋白，该蛋白会检测与其匹配的质外体效应物的出现，并可以不依赖过敏反应而赋予植物以病原菌抗性。本文揭示了植物中由该类蛋白所介导的基因对基因的疾病抗性。此外，据作者所致，Stb6是第一个克隆到了小麦叶枯病菌Zymoseptoria tritici的抗性基因，该病原菌是一类比较重要的小麦叶面真菌病原体，会影响小麦并导致有重大经济危害的小麦叶枯疾病。

doi: 10.1038/s41588-018-0051-x

Published online: 12 February, 2018

Stress and sexual reproduction affect the dynamics of the wheat pathogen effector AvrStb6 and strobilurin resistance

Host resistance and fungicide (杀菌剂) treatments are cornerstones (基础) of plant-disease control. Here, we show that these treatments allow sex and modulate parenthood (亲子关系) in the fungal wheat pathogen Zymoseptoria tritici. We demonstrate that the Z. tritici–wheat interaction complies with (符合) the gene-for-gene model by identifying the effector AvrStb6, which is recognized by the wheat resistance protein Stb6. Recognition triggers host resistance, thus implying removal of avirulent strains from pathogen populations. However, Z. tritici crosses on wheat show that sex occurs even with an avirulent parent, and avirulence alleles (无毒等位基因) are thereby retained in subsequent populations. Crossing fungicide-sensitive and fungicide-resistant isolates under fungicide pressure results in a rapid increase in resistance-allele frequency. Isolates under selection always act as male donors (雄性供体), and thus disease control modulates parenthood. Modeling these observations for agricultural and natural environments reveals extended durability (持久性) of host resistance and rapid emergence (出现) of fungicide resistance. Therefore, fungal sex has major implications for disease control.

寄主的抗性和杀菌剂的处理是植物疾病控制的基石。本文报道了这些处理会引起小麦真菌类病原菌Zymoseptoria tritici的有性生殖。本文通过鉴定由小麦抗性蛋白Stb6识别的病原菌效应物AvrStb6揭示了Z. tritici与小麦的互作符合基因对基因的模型。识别会诱导寄主的抗性，因此会移除病原菌群体中的无毒菌株。然而，Z. tritici在小麦的杂交显示即使在无毒亲本不存在的情况下也会发生交配，因此无毒等位基因会在后续的群体中保留下来。将杀菌剂敏感型和杀菌剂抗性的菌株在杀菌剂的条件下进行杂交会导致抗性等位基因频率的快速增加。在选择下的分离菌总是作为雄性供体，因此疾病控制了病原菌的有性生殖。通过对这些农艺和自然条件下的观察现象的建模揭示了寄主抗性的持久性和杀菌剂抗性的快速出现。因此，真菌病害的有性生殖对于植物疾病的防治有重要的启示作用。

doi: 10.1038/s41588-018-0052-9