Powdery mildew (PM) is a serious fungal disease of legumes. To gain novel insights into PM pathogenesis and host resistance/susceptibility, we used dual RNA-Seq to simultaneously capture host and pathogen transcriptomes at 1 d post-inoculation of resistant and susceptible Medicago truncatula genotypes with the PM Erysiphe pisi (Ep). Differential expression analysis indicates that R-gene mediated resistance against Ep involves extensive transcriptional reprogramming. Functional enrichment of differentially expressed host genes and in silico analysis of co-regulated promoters suggests that amplification of PTI, activation of the JA/ET signaling network, and regulation of growth-defense balance correlate with resistance. In contrast, processes that favor biotrophy, including suppression of defense signaling and programmed cell death, and weaker cell wall defenses are important susceptibility factors. Lastly, Ep effector candidates and genes with known/putative virulence functions were identified, representing a valuable resource that can be leveraged to improve our understanding of legume-PM interactions.

白粉病（PM）是一种严重的豆类真菌病。为了获得对PM发病机理和宿主抗性/敏感性的新颖见解，我们使用双RNA-Seq在PM和Erysiphe pisi（Ep）耐药和易感苜蓿苜蓿基因型接种后1 d同时捕获宿主和病原体转录组。差异表达分析表明R基因介导的抗Ep涉及广泛的转录重编程。差异表达的宿主基因的功能富集和共调控启动子的计算机分析表明，PTI的扩增，JA / ET信号网络的激活以及生长防御平衡的调控与抗性相关。相反，有利于生物营养的过程，包括抑制防御信号传导和程序性细胞死亡，以及较弱的细胞壁防御能力，都是重要的易感性因素。最后，鉴定了具有已知/推定毒力功能的Ep效应子候选物和基因，代表了一种宝贵的资源，可以利用它来提高我们对豆类-PM相互作用的理解。