Molecular and cellular basis of infection-related dimorphism in Zymoseptoria tritici

侵染作物的真菌是全球粮食安全的主要威胁。事实上，小麦、水稻和玉米每年因真菌病原体造成的损失，相当于美国国土安全部每年的支出--约600亿美元。通过使用抗真菌化学物质，真菌得到了控制。然而，真菌作为快速生长的微生物，会对杀菌剂产生抗药性，因此我们需要不断开发新的杀菌剂。这就需要深入了解真菌病原菌的入侵策略。在本项目中，我们重点研究了欧洲头号小麦病原菌--小麦黑斑病病原菌ZymosepVictoria tritici。这种真菌生活在田野里的碎屑上，在那里它生长成一个类似酵母的小结构。然而，雨水飞溅会将这种孢子带到叶表面。在这里，真菌经历了生长的变化，形成了一串细长的细胞，即菌丝，菌丝在顶端扩张，侵入植物的叶片。已发表的数据和我们的初步结果清楚地表明，这种“二态开关”是该真菌感染植物所必需的。因此，了解酵母菌向菌丝转化的过程对于开发新的抗真菌化学药物是重要的。尽管它对小麦侵染很重要，但我们对小麦纹枯病菌的二态转换要求的了解是零散的。这个项目旨在了解真菌入侵宿主的潜在过程，并确定真菌内部控制二态转换的途径和要求。我们将通过基因筛选、确定蛋白质之间的相互作用、植物中的活细胞成像以及观察真菌细胞本身从酵母向菌丝的转变来开展这项工作。此外，我们还与一家提供新型抗真菌产品的公司合作，研究了杀菌剂抑制小麦赤霉菌侵染的途径。必须重申的是，这种二态转换发生在真菌感染过程的非常早期，此时真菌最容易接受杀菌剂治疗。因此，禁用这一过程可能会导致新一代“预防性”杀菌剂的产生，这种杀菌剂能够在STB损害其寄主植物小麦之前对其起作用。

Crop-infecting fungi are a major threat to the global food security. In fact, losses of wheat, rice, and maize to fungal pathogens, per year, is the same as the annual spend by US Department of Homeland Security - some 60 billion US dollars. Fungi are kept under control by treatment with anti-fungal chemicals. However, as fast growing microbes, fungi adapt to become resistant to fungicide treatments, and so we need to develop new fungicides all the time. This requires an in-depth knowledge of the invasion strategies of fungal pathogens.In this project, we focus on the number-one wheat pathogen in Europe, Zymoseptoria tritici, the causative agent of Septoria tritici blotch in wheat. The fungus lives on debris in the field, where it grows as a small "yeast-like" structure. However, rain-splash can transport this spore onto the leaf surface. Here, the fungus undergoes a change in growth and forms an elongated string of cells, the hypha, which expands at the tip and invades the plant leaf. Published data and our preliminary results clearly demonstrate that this "dimorphic switch" is an essential of infection of the plant by the fungus. Thus, understanding the process of the yeast-to-hypha transition is important to develop novel antifungal chemistries. Despite its importance for wheat infection, our knowledge of the requirements for dimorphic switching in Z. tritici is fragmentary. This project aims to understand the processes underlying host invasion by the fungus and to identify pathways and requirement within the fungus that control the dimorphic switching. We will undertake this work by genetic screening, identifying protein-protein interactions, live cell imaging in the plant and observing the fungal cell itself during its transition from a yeast to a hypha. Moreover, we collaborate with a company that provides a novel antifungal product and investigate the way by which fungicide inhibits infection of wheat by Z. tritici. It is important to reiterate that the dimorphic switch occurs very early in the fungal infection process, at a time when the fungi are most accessible to fungicide treatment. Disabling the process could therefore result in a new generation of "preventive" fungicides that are able to act on STB before the fungus has damaged its host plant , wheat.