Massonnet Mélanie, Riaz Summaira, Pap Dániel, Figueroa-Balderas Rosa, Walker M Andrew, Cantu Dario
Department of Viticulture and Enology, University of California Davis, Davis, CA, United States.
Front Plant Sci. 2022 Dec 19;13:1096862. doi: 10.3389/fpls.2022.1096862. eCollection 2022.
Multiple grape powdery mildew (PM) genetic resistance () loci have been found in wild grape species. Little is known about the defense responses associated with each locus. In this study, we compare the defense mechanisms associated with PM resistance in interspecific crosses segregating for a single locus from (, , , ) () ( and ), and the interspecific hybrid Villard blanc (). By combining optical microscopy, visual scoring, and biomass estimation, we show that the eight loci confer resistance by limiting infection at different stages. We assessed the defense mechanisms triggered in response to PM at 1 and 5 days post-inoculation (dpi) RNA sequencing. To account for the genetic differences between species, we developed for each accession a diploid synthetic reference transcriptome by incorporating into the PN40024 reference homozygous and heterozygous sequence variants and assembled transcripts. Most of the loci exhibited a higher number of differentially expressed genes (DEGs) associated with PM resistance at 1 dpi compared to 5 dpi, suggesting that PM resistance is mostly associated with an early transcriptional reprogramming. Comparison of the PM resistance-associated DEGs showed a limited overlap between pairs of loci, and nearly half of the DEGs were specific to a single locus. The largest overlap of PM resistance-associated DEGs was found between , , and genotypes at 1 dpi, and between and accessions at 5 dpi. The , , and were also found to have the highest number of locus-specific DEGs in response to PM. Both shared and locus-specific DEGs included genes from different defense-related categories, indicating that the presence of triggered distinct transcriptional responses in the eight loci.
在野生葡萄品种中已发现多个葡萄白粉病（PM）遗传抗性（）位点。对于每个位点相关的防御反应，人们了解甚少。在本研究中，我们比较了在种间杂交中与PM抗性相关的防御机制，这些杂交种针对来自（，，，）（）（和）的单个位点以及种间杂交种维拉 blanc（）进行分离。通过结合光学显微镜、视觉评分和生物量估计，我们表明这八个位点通过在不同阶段限制感染来赋予抗性。我们在接种后1天和5天（dpi）通过RNA测序评估了对PM触发的防御机制。为了考虑物种间的遗传差异，我们通过将纯合和杂合序列变体以及组装的转录本纳入PN40024参考，为每个材料开发了一个二倍体合成参考转录组。与5 dpi相比，大多数位点在1 dpi时表现出与PM抗性相关的差异表达基因（DEG）数量更多，这表明PM抗性主要与早期转录重编程相关。与PM抗性相关的DEG的比较表明，位点对之间存在有限的重叠，并且近一半的DEG是单个位点特有的。在1 dpi时，在，和基因型之间以及在5 dpi时在和材料之间发现了与PM抗性相关的DEG的最大重叠。还发现，和对PM响应时具有最高数量的位点特异性DEG。共享的和位点特异性DEG都包括来自不同防御相关类别的基因，这表明的存在在八个位点触发了不同的转录反应。
