Haile Zeraye Mehari, Malacarne Giulia, Pilati Stefania, Sonego Paolo, Moretto Marco, Masuero Domenico, Vrhovsek Urska, Engelen Kristof, Baraldi Elena, Moser Claudio
Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all'Adige, Italy.
Laboratory of Biotechnology and Plant Pathology, DISTAL, University of Bologna, Bologna, Italy.
Front Plant Sci. 2020 Jan 30;10:1704. doi: 10.3389/fpls.2019.01704. eCollection 2019.
is an important necrotroph in vineyards. Primary infections are mostly initiated by airborne conidia from overwintered sources around bloom, then the fungus remains quiescent from bloom till maturity and egresses at ripeness. We previously described in detail the process of flower infection and quiescence initiation. Here, we complete the characterization studying the cross-talk between the plant and the fungus during pathogen quiescence and egression by an integrated transcriptomic and metabolic analysis of the host and the pathogen. Flowers from fruiting cuttings of the cv. Pinot Noir were inoculated with a GFP-labeled strain of at full cap-off stage, and molecular analyses were carried out at 4 weeks post inoculation (wpi, fungal quiescent state) and at 12 wpi (fungal pre-egression and egression states). The expressed fungal transcriptome highlighted that the fungus remodels its cell wall to evade plant chitinases besides undergoing basal metabolic activities. Berries responded by differentially regulating genes encoding for different PR proteins and genes involved in monolignol, flavonoid, and stilbenoid biosynthesis pathways. At 12 wpi, the transcriptome of in the pre-egressed samples showed that virulence-related genes were expressed, suggesting infection process was initiated. The egressed expressed almost all virulence and growth related genes that enabled the pathogen to colonize the berries. In response to egression, ripe berries reprogrammed different defense responses, though futile. Examples are activation of membrane localized kinases, stilbene synthases, and other PR proteins related to SA and JA-mediated responses. Our results indicated that hard-green berries defense program was capable to hamper growth. However, ripening associated fruit cell wall self-disassembly together with high humidity created the opportunity for the fungus to egress and cause bunch rot.
是葡萄园中的一种重要坏死营养型病原菌。初次感染大多由花期前后越冬菌源产生的气传分生孢子引发，随后该真菌在花期至成熟阶段处于静止状态，并在成熟时逸出。我们之前详细描述了花朵感染和静止起始的过程。在此，我们通过对寄主和病原菌进行综合转录组学和代谢分析，完成了对病原菌静止和逸出过程中植物与真菌之间相互作用的表征研究。在赤霞珠葡萄品种的结果插条上，于完全脱帽期用绿色荧光蛋白标记的菌株进行接种，并在接种后4周（wpi，真菌静止状态）和12周（真菌预逸出和逸出状态）进行分子分析。表达的真菌转录组表明，除了进行基础代谢活动外，真菌还重塑其细胞壁以逃避植物几丁质酶。浆果通过差异调节编码不同病程相关蛋白的基因以及参与单木质醇、类黄酮和芪类生物合成途径的基因做出反应。在12周时，预逸出样本中的转录组显示与毒力相关的基因被表达，表明感染过程已启动。逸出的病原菌表达了几乎所有与毒力和生长相关的基因，使病原菌能够在浆果上定殖。作为对逸出的反应，成熟浆果重新编程了不同的防御反应，尽管徒劳无功。例如激活膜定位激酶、芪合酶以及与水杨酸和茉莉酸介导反应相关的其他病程相关蛋白。我们的结果表明，硬绿浆果的防御程序能够阻碍病原菌的生长。然而，成熟相关的果实细胞壁自分解以及高湿度为真菌逸出并导致穗腐病创造了机会。
