The gray mold fungus is a necrotrophic pathogen that causes diseases in hundreds of plant species, including high-value crops. Its polyxenous nature and pathogenic success are due to its ability to perceive host signals in its favor. In this study, we found that laticifer cells of are a source of susceptibility factors required by to cause disease. Consequently, poor-in-latex () mutants, which lack laticifer cells, show full resistance to this pathogen, whereas -- mutants, which produce more laticifer cells, are hypersusceptible. These S factors are triterpenoid saponins, which are widely distributed natural products of vast structural diversity. The downregulation of laticifer-specific genes, which encode the first committed step enzymes for triterpene and, therefore, saponin biosynthesis, conferred disease resistance to . Likewise, the mutant, compromised in triterpenoid saponin biosynthesis, showed enhanced resistance. Interestingly, the application of different purified triterpenoid saponins pharmacologically complemented the disease-resistant phenotype of and mutants and enhanced disease susceptibility in different plant species. We found that triterpenoid saponins function as plant cues that signal transcriptional reprogramming in , leading to a change in its growth habit and infection strategy, culminating in the abundant formation of infection cushions, the multicellular appressoria apparatus dedicated to plant penetration and biomass destruction in . Taken together, these results provide an explanation for how plant triterpenoid saponins function as disease susceptibility factors to promote pathogenicity.

中文翻译：

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植物三萜皂苷作为易感因子促进灰霉菌致病性的作用


灰霉菌是一种坏死性病原体，会导致数百种植物物种患病，包括高价值作物。它的多氧体性质和致病成功是由于它能够感知对自己有利的宿主信号。在这项研究中，我们发现乳胶细胞是引起疾病所需的易感因素的来源。因此，缺乏乳胶细胞的 Poor-in-latex （） 突变体对这种病原体表现出完全抗性，而产生更多乳胶细胞的突变体则高度敏感。这些 S 因子是三萜皂苷，它们是分布广泛、结构多样性巨大的天然产物。乳胶科特异性基因的下调，编码三萜的第一个承诺步骤酶，因此，皂苷的生物合成，赋予了对 的疾病抗性。同样，在三萜类皂苷生物合成中受损的突变体显示出增强的耐药性。有趣的是，不同纯化的三萜皂苷的应用在药理学上补充了突变体的抗病表型，并增强了不同植物物种的疾病易感性。我们发现三萜皂苷作为植物线索，在 中发出转录重编程信号，导致其生长习性和感染策略发生变化，最终形成丰富的感染垫，感染垫是专门用于植物渗透和生物量破坏的多细胞附着装置。综上所述，这些结果为植物三萜皂苷如何作为疾病易感因子促进致病性提供了解释。