Summary The barley Mla locus contains functionally diversified genes that encode intracellular nucleotide‐binding leucine‐rich repeat receptors (NLRs) and confer strain‐specific immunity to biotrophic and hemibiotrophic fungal pathogens. In this study, we isolated a barley gene Scs6, which is an allelic variant of Mla genes but confers susceptibility to the isolate ND90Pr (BsND90Pr) of the necrotrophic fungus Bipolaris sorokiniana. We generated Scs6 transgenic barley lines and showed that Scs6 is sufficient to confer susceptibility to BsND90Pr in barley genotypes naturally lacking the receptor. The Scs6‐encoded NLR (SCS6) is activated by a nonribosomal peptide (NRP) effector produced by BsND90Pr to induce cell death in barley and Nicotiana benthamiana. Domain swaps between MLAs and SCS6 reveal that the SCS6 leucine‐rich repeat domain is a specificity determinant for receptor activation by the NRP effector. Scs6 is maintained in both wild and domesticated barley populations. Our phylogenetic analysis suggests that Scs6 is a Hordeum‐specific innovation. We infer that SCS6 is a bona fide immune receptor that is likely directly activated by the nonribosomal peptide effector of BsND90Pr for disease susceptibility in barley. Our study provides a stepping stone for the future development of synthetic NLR receptors in crops that are less vulnerable to modification by necrotrophic pathogens.

中文翻译：

---

大麦 MLA 免疫受体被真菌非核糖体肽效应器激活，以提高疾病易感性


摘要： 大麦 Mla 基因座包含功能多样化的基因，这些基因编码细胞内核苷酸结合富含亮氨酸的重复受体 （NLR），并赋予对生物营养和半生物营养真菌病原体的菌株特异性免疫力。在这项研究中，我们分离了一个大麦基因 Scs6，它是 Mla 基因的等位基因变体，但赋予了对坏死真菌 Bipolaris sorokiniana 的分离株 ND90Pr （BsND90Pr） 的敏感性。我们生成了 Scs6 转基因大麦品系，并表明 Scs6 足以在天然缺乏受体的大麦基因型中赋予对 BsND90Pr 的易感性。Scs6 编码的 NLR （SCS6） 被 BsND90Pr 产生的非核糖体肽 （NRP） 效应子激活，以诱导大麦和本氏烟草的细胞死亡。MLA 和 SCS6 之间的结构域交换表明，SCS6 富含亮氨酸的重复结构域是 NRP 效应子激活受体的特异性决定因素。Scs6 在野生和驯化大麦种群中均得到维持。我们的系统发育分析表明，Scs6 是一种 Hordeum 特异性创新。我们推断 SCS6 是一种真正的免疫受体，可能被 BsND90Pr 的非核糖体肽效应子直接激活，以影响大麦中的疾病易感性。我们的研究为合成 NLR 受体在不太容易受到坏死病原体修饰的作物中的未来发展提供了垫脚石。