Novel Disease Susceptibility Factors for Fungal Necrotrophic Pathogens in Arabidopsis

Host cells use an intricate signaling system to respond to invasions by pathogenic microorganisms. Although several signaling components of disease resistance against necrotrophic fungal pathogens have been identified, our understanding for how molecular components and host processes contribute to plant disease susceptibility is rather sparse. Here, we identified four transcription factors (TFs) from Arabidopsis that limit pathogen spread. Arabidopsis mutants defective in any of these TFs displayed increased disease susceptibility to Botrytis cinerea and Plectosphaerella cucumerina, and a general activation of non-immune host processes that contribute to plant disease susceptibility. Transcriptome analyses revealed that the mutants share a common transcriptional signature of 77 up-regulated genes. We characterized several of the up-regulated genes that encode peptides with a secretion signal, which we named PROVIR (for provirulence) factors. Forward and reverse genetic analyses revealed that many of the PROVIRs are important for disease susceptibility of the host to fungal necrotrophs. The TFs and PROVIRs identified in our work thus represent novel genetic determinants for plant disease susceptibility to necrotrophic fungal pathogens.宿主细胞依托一套精密复杂的信号系统，响应病原微生物的侵染。尽管学界已鉴定出若干参与抗死体营养型真菌病原菌（necrotrophic fungal pathogens）的信号通路组分，但对于分子组分与宿主过程如何促成植物病害感病性的认知仍相当匮乏。本研究从拟南芥（Arabidopsis）中鉴定出4种可限制病原菌扩散的转录因子（transcription factors, TFs）。缺失任意一种上述转录因子的拟南芥突变体，对灰葡萄孢（Botrytis cinerea）和黄瓜旋孢腔菌（Plectosphaerella cucumerina）的感病性均显著提升，同时整体激活了一类可促成植物病害感病性的非免疫宿主过程。转录组（transcriptome）分析显示，这些突变体共有一套由77个上调基因构成的特征性转录谱。我们对其中若干编码携带分泌信号肽的上调基因展开了功能表征，并将其编码的蛋白命名为PROVIR（致病辅助因子，provirulence factors）。正向与反向遗传学分析表明，多数PROVIR因子对于宿主针对死体营养型真菌的病害感病性至关重要。因此，本研究鉴定出的转录因子与PROVIR因子，为植物对死体营养型真菌病原菌的病害感病性调控提供了全新的遗传决定因子。