SEPBLAST: Determining the molecular basis of septin-dependent plant infection by the blast fungus Magnaporthe oryzae

该研究项目的主要目的是了解被称为septin的形态发生蛋白如何调节致病真菌在植物内引起疾病的能力。植物病原真菌已经进化出专门的感染结构来进入它们的宿主。毁灭性的稻瘟病菌利用一种被称为附着胞的加压感染细胞来感染水稻植株，破坏植物坚硬的外层。一旦进入植物组织，真菌就会发展出第二种感染结构，称为上压胞，它利用这种结构从一个水稻细胞转移到另一个水稻细胞。最近的证据表明，异聚septin复合物对加压蛋白和转压蛋白的功能都是必需的。这个雄心勃勃的研究项目将确定这些感染结构中septin招募、组织和功能的分子基础。我建议评估隔层蛋白聚集的膜曲率依赖性，然后确定调节隔层蛋白募集的上游成分。在附着胞和上压胞发育的时间序列中，将使用蛋白质组学分析和接近标记方法为两种细胞类型定义一个全面的septin相互作用组。通过这种方式，新的septin相互作用将被识别和功能表征。与此同时，磷酸化蛋白质组学分析将用于研究septin组装所需的特定磷酸化事件，并确定相应的信号通路。结合使用前向基因筛选、靶向基因编辑、蛋白质组学分析和活细胞成像，该项目将测试septin复合物作为真菌侵入性细胞内主要组织中心的假设，这是真菌感染细胞集中部署极性和毒力决定因素以实现侵入性生长所必需的。

The major aim of this research project is to understand how morphogenetic proteins called septins condition the ability of a pathogenic fungus to cause disease within a plant. Plant pathogenic fungi have evolved specialised infection structures to enter their hosts. The devastating blast fungus Magnaporthe oryzae infects rice plants using a pressurised infection cell called an appressorium to breach the tough outer layer of plants. Once inside plant tissue, the fungus then develops a second type of infection structure, called a transpressorium, which it uses to move from one rice cell to the next. Recent evidence has shown that heteromeric septin complexes are necessary for the function of both appressoria and transpressoria. This ambitious research project will define the molecular basis of septin recruitment, organisation and function within these infection structures. I propose to evaluate the membrane curvature dependency of septin aggregation and then identify upstream components that regulate septin recruitment. A comprehensive septin interactome will be defined for both cell types using proteomic analysis and proximity labelling methods, during a time series of appressorium and transpressorium development. In this way, novel septin interactors will be identified and functionally characterised. In parallel, phosphoproteomic analysis will be used to investigate the specific phosphorylation events necessary for septin assembly and to identify the corresponding signalling pathways. Using a combination of forward genetic screens, targeted gene editing, proteomic analysis and live cell imaging, the project will test the hypothesis that septin complexes act as major organising centres within fungal invasive cells, required for the focused deployment of polarity and virulence determinants to enable invasive growth by fungal infection cells.