Fungal development of Verticillium resting structures and plant infection

土壤传播的植物病原大丽轮枝菌形成黑色的微菌核，可以在土壤中休息和存活十多年。这种休眠真菌生存结构的形成往往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的寄主植物的根分泌物引发的，这导致真菌菌丝向植物根方向生长。大丽叶病毒侵染根皮层，侵入维管系统。分生孢子在木质部开始，利用汁液流在植物内分布真菌。真菌在寄主内的定植可导致疾病症状，如黄化、坏死、生长迟缓或枯萎。植物致病的大丽弧菌侵染多达400种植物，包括重要的农业作物，并在世界范围内造成日益严重的经济损失。本研究旨在研究黄萎菌VTA-SOM1-天鹅绒与未折叠蛋白反应Hac1转录因子之间的复杂相互作用。这些调节子为大丽叶病毒的发育和通过根进入植物木质部系统的感染编排顺序和相互关联的遗传网络。我们在第一个资助期确定的这些网络，控制着土壤中作为休息和生存结构的微菌核的形成。它们萌发，真菌在植物上定居，最后在季节结束时再次启动微菌核的形成。对控制机制的详细分子理解将是非常有帮助的，因为控制机制在寄主植物或土壤中的真菌定殖期间减少了大丽弧菌微菌核的形成。VTA-SOM1-天鹅绒网络响应外部生物(如根际、植物中的微生物群)和非生物环境以及内部信号通路。VTA-SOM1-天鹅绒网络控制和适应基因的表达，以适应真菌在生长、防御、发育或分泌过程中的适当反应。我们将分析(I)不同的大丽弧菌VTA-SOM1-鹿茸基因网络是如何协调和连接的，以及哪些基因直接由特定的转录因子控制。我们将(Ii)确定翻译后修饰，包括磷酸化和泛素化/去泛素化，并研究VTA-SOM1-天鹅绒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。我们将使用遗传学、细胞生物学、蛋白质组学、代谢组学以及致病性实验的组合，包括例如缺失菌株的产生和调查、GFP-Pull-down、ChIPSeq、根和植物感染。我们的目标是详细了解在生长季节结束时微菌核形成所需的分子控制步骤，从土壤中萌发的微菌核衍生的菌丝到植物寄主的真菌根附着和定植以及疾病症状的诱导。

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.