Population genomics and GWAS for virulence in the fungal plant pathogen Zymoseptoria tritici

Fungal pathogens can rapidly evolve virulence towards resistant crops in agricultural ecosystems. Gains in virulence are often mediated by the mutation or deletion of a gene encoding a protein recognized by the plant immune system. However, the loci and the mechanisms of genome evolution enabling rapid virulence evolution are poorly understood. We performed genome-wide association mapping on a global collection of 106 strains of Zymoseptoria tritici, the most damaging pathogen of wheat in Europe, to identify polymorphisms linked to virulence on two wheat varieties. We found distinct genomic loci associated with reproductive success of the pathogen. The main locus associated with virulence encoded a highly expressed, small secreted protein. Population genomic analyses showed that the gain in virulence was explained by a segregating gene deletion polymorphism.

在农业生态系统中，真菌病原体会快速进化出针对抗性作物的致病力。致病力的增强通常由编码植物免疫系统识别蛋白的基因发生突变或缺失所介导。然而，支持致病力快速进化的基因组位点及基因组进化机制，目前仍知之甚少。我们针对全球收集的106株小麦叶斑病菌（Zymoseptoria tritici）——该菌是欧洲危害最严重的小麦病原菌——开展全基因组关联分析，以鉴定与两个小麦品种上致病力相关的多态性位点。我们发现了多个与该病原菌繁殖能力相关的独特基因组位点，其中与致病力关联最为紧密的主效位点编码了一种高表达的小型分泌蛋白。群体基因组分析表明，致病力的增强可通过群体中分离的基因缺失多态性得以解释。