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

侵染作物的真菌是对全球粮食安全的主要威胁。事实上，每年因真菌病原体造成的小麦、水稻和玉米损失相当于美国国土安全部的年度支出——约600亿美元。用抗真菌的化学药剂来控制真菌。然而，真菌作为快速生长的微生物，对杀菌剂产生了抗药性，因此我们需要不断开发新的杀菌剂。这需要对真菌病原体的入侵策略有深入的了解。在本项目中，我们重点研究了欧洲排名第一的小麦病原菌——小麦黑斑病的病原体——小麦酵母菌。这种真菌生活在田地里的碎片上，在那里它以一种小的“酵母状”结构生长。然而，雨水可以将孢子转移到叶片表面。在这里，真菌在生长过程中发生了变化，形成了一串细长的细胞，即菌丝，菌丝在顶端膨胀并侵入植物的叶子。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”是真菌感染植物的必要条件。因此，了解酵母向菌丝转变的过程对于开发新的抗真菌化学物质非常重要。尽管它对小麦侵染具有重要意义，但我们对小麦小麦偃麦草二态转换所需条件的认识是不完整的。本项目旨在了解真菌入侵宿主的过程，并确定真菌内部控制二态转换的途径和需求。我们将通过基因筛选，鉴定蛋白质-蛋白质相互作用，植物中的活细胞成像以及观察真菌细胞从酵母到菌丝的转变过程来开展这项工作。此外，我们还与一家提供新型抗真菌产品的公司合作，研究杀菌剂抑制小麦小麦小麦黑穗病的途径。重要的是要重申，二态转换发生在真菌感染过程的早期，在真菌最容易得到杀菌剂治疗的时候。因此，使这一过程失效可能会产生新一代的“预防性”杀菌剂，这些杀菌剂能够在STB破坏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.