Fungal development of Verticillium resting structures and plant infection

土传植物病原性大丽黄萎病真菌形成黑化微菌核，可以在土壤中休息并存活十多年。这种休眠真菌生存结构的发展通常与特定次生代谢物的生物合成有关。微菌核的萌发是由适当宿主植物的根部分泌物触发的，这导致真菌菌丝向植物根部定向生长。大丽花弧菌定殖于根皮层并侵入维管系统。分生孢子在木质部开始，利用汁液流将真菌分布在植物内。真菌在宿主体内定殖会导致疾病症状，例如褪绿、坏死、生长迟缓或枯萎。植物致病性大丽葡萄球菌感染多达 400 种植物，包括重要的农业作物，并在全世界范围内造成越来越严重的经济损失。该研究项目旨在表征黄萎病菌 Vta-Som1-Velvet 与未折叠蛋白反应 Hac1 转录因子之间复杂的相互作用。这些调节因子协调顺序且相互关联的遗传网络，以促进大丽弧菌通过根部进入植物木质部系统的发育和感染。我们在第一个资助期确定的这些网络控制微菌核的形成，作为土壤中的休息和生存结构。它们发芽，真菌在植物上定殖，最后在季节结束时再次开始微菌核形成。对控制机制的详细分子了解将非常有帮助，这些控制机制可减少真菌定植于宿主植物或土壤中期间大丽花弧菌微菌核的形成。 VTA-SOM1-VELVET 网络对外部生物（例如根际微生物组、植物）和非生物环境以及内部信号通路做出反应。 VTA-SOM1-VELVET 网络控制和调整基因表达，以在生长、防御、发育或分泌中做出适当的真菌反应。我们将分析 (i) 不同的大丽花 VTA-SOM1-VELVET 基因网络如何协调和连接，以及哪些基因直接受特定转录因子控制。我们将 (ii) 确定翻译后修饰，包括磷酸化和泛素化/去泛素化，并检查 VTA-SOM1-VELVET 遗传网络转录因子的蛋白质稳定性控制机制及其对真菌发育和毒力的影响。我们将结合遗传、细胞生物学、蛋白质组学、代谢组学以及致病性实验，包括缺失菌株的生成和研究、GFP 下拉、ChIPSeq、根和植物感染。我们的目标是详细了解生长季节结束时微菌核形成、土壤中发芽微菌核衍生的菌丝、真菌根部附着和植物宿主定植以及疾病症状诱导所需的分子控制步骤。

Soil-borne plant-pathogenic Verticillium dahliae fungi form melanised microsclerotia, which can rest and survive for more than a decade in the soil. Development of such dormant fungal survival structures is often linked to the biosynthesis of specific secondary metabolites. Germination of microsclerotia is triggered by root exudates of appropriate host plants, which results in directed fungal hyphal growth towards plant roots. V. dahliae colonises the root cortex and invades the vascular system. Conidiation is started in the xylem to use the sap stream for distribution of the fungus within the plant. Fungal colonisation within the host can result in disease symptoms, such as chlorosis, necrosis, stunted growth or wilting. Plant-pathogenic V. dahliae infects up to 400 plants including agriculturally important crops and causes increasing economical damage worldwide. This research project aims to characterise the complex interplay between Verticillium Vta-Som1-Velvet and unfolded protein response Hac1 transcription factors. These regulators orchestrate sequential and interconnected genetic networks for development and infection of V. dahliae through the roots into the plant xylem system. These networks, which we have identified in the first funding period, control the formation of microsclerotia as resting and survival structures in the soil. They germinate, the fungus colonises the plant and finally microsclerotia formation is initiated again at the end of the season. A detailed molecular understanding of control mechanisms, which reduce V. dahliae microsclerotia formation during fungal colonisation of host plants or in soil would be very helpful. VTA-SOM1-VELVET networks respond to the external biotic (e.g. microbiomes in rhizosphere, plant) and abiotic environment as well as to internal signalling pathways. The VTA-SOM1-VELVET networks control and adapt gene expression for the appropriate fungal reply in growth, defense, development or secretion. We will analyse (i) how the different V. dahliae VTA-SOM1-VELVET gene networks are coordinated and connected and which genes are directly controlled by specific transcription factors. We will (ii) determine posttranslational modifications including phosphorylation and ubiquitination/deubiquitination and examine protein stability control mechanisms of transcription factors of the VTA-SOM1-VELVET genetic networks and their impact on fungal development and virulence. We will use a combination of genetic, cell biological, proteomic, metabolomic as well as pathogenicity experiments including for example the generation and investigation of deletion strains, GFP-pulldown, ChIPSeq, root and plant infection. Our goal is the detailed understanding of molecular control steps required for microsclerotia formation at the end of the growing season, for the hyphae derived from germinating microsclerotia in the soil, to fungal root attachment and colonisation of the plant host and disease symptom induction.