Downy mildew in hop (Humulus lupulus L.) is caused by Pseudoperonospora humuli and generates significant losses in quality and yield. To identify the biochemical processes that confer natural downy mildew resistance (DMR), a metabolome‐ and genome‐wide association study was performed. Inoculation of a high density genotyped F1 hop population (n = 192) with the obligate biotrophic oomycete P. humuli led to variation in both the levels of thousands of specialized metabolites and DMR. We observed that metabolites of almost all major phytochemical classes were induced 48 hr after inoculation. But only a small number of metabolites were found to be correlated with DMR and these were enriched with phenylpropanoids. These metabolites were also correlated with DMR when measured from the non‐infected control set. A genome‐wide association study revealed co‐localization of the major DMR loci and the phenylpropanoid pathway markers indicating that the major contribution to resistance is mediated by these metabolites in a heritable manner. The application of three putative prophylactic phenylpropanoids led to a reduced degree of leaf infection in susceptible genotypes, confirming their protective activity either directly or as precursors of active compounds.

中文翻译：

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霜霉病抗性是通过预防性生产啤酒花中的苯丙烷类基因而介导的

在跳（霜霉病啤酒花L.）是由引起的Pseudoperonospora蚜并生成质量和产量显著损失。为了确定赋予天然霜霉病抗性（DMR）的生化过程，进行了代谢组和全基因组关联研究。用专性生物营养性卵菌P. humuli接种高密度基因型F1啤酒花种群（n = 192）导致数千种专门代谢物和DMR的水平发生变化。我们观察到，接种后48小时几乎诱导了所有主要植物化学类别的代谢产物。但是，仅发现少量代谢物与DMR相关，并且这些代谢物富含苯丙烷。当从未感染的对照组中测量时，这些代谢物也与DMR相关。全基因组关联研究揭示了主要DMR基因座和苯丙烷途径标记的共定位，表明对耐药的主要贡献是由这些代谢物以遗传方式介导的。三种假定的预防性苯基丙烷的应用导致易感基因型的叶片感染程度降低，