Determining the mechanism of septin-mediated plant infection by the rice blast fungus Magnaporthe oryzae

这个项目的目的是了解水稻是如何患上一种非常严重的疾病——稻瘟病的。稻瘟病每年摧毁全球30%的水稻收成，并在撒哈拉以南非洲、东南亚和南美洲造成严重流行病。因此，它是对全球粮食安全的持续威胁。稻瘟病是由一种叫做Magnaporthe oryzae的真菌引起的，这个项目旨在确定这种真菌是如何感染水稻的。稻瘟病菌产生一种称为附着胞的特殊感染结构，它产生巨大的压力（高达8MPa，或汽车轮胎压力的40倍），并在叶片表面施加物理力以刺穿植物角质层。通过这种方式，真菌可以侵入叶片组织并引起疾病。我们的目标是研究附着胞内的压力如何在感染细胞的基部转化为物理力量。我们发现一组叫做septin的蛋白质，对附着胞刺穿水稻角质层至关重要。它们的作用是重新塑造细胞内部的细胞骨架，使其在叶片表面施加力，形成进入叶片的穿透栓。该项目将研究附着胞底部的septins是如何聚集的，细胞的这一区域是如何专门向植物细胞中分泌蛋白质的，附着胞是如何形成穿透性钉的，以及真菌是如何迅速侵入叶子的。我们将描述septin组装是如何被调节的，特别是，真菌如何能够监测附着胞内的膨胀压力，并确定渗透peg发育的最佳点（或触发点）。我们还将确定这一过程是如何与真菌的细胞分裂周期协调调节的，从而使植物感染过程得到有效控制。综合考虑，本研究项目的目标将为当今世界上最重要的作物病害之一的植物侵染生物学提供新的见解。这些信息将用于为迫切需要的新的疾病控制战略提供信息。除了稻瘟病的全球意义之外，从该项目中获得的知识也将对英国农业有价值，因为影响我们主要谷物作物大麦和小麦的许多最严重的疾病都有类似的感染机制。因此，从这项工作中产生的疾病控制策略可能对最重要的谷物疾病具有广谱性，除了稻瘟病之外，还包括锈病和白粉病。

The aim of this project is to understand how rice plants succumb to a very serious disease called rice blast. Each year, rice blast disease destroys up to 30% of the global rice harvest and causes serious epidemics in Sub-Saharan Africa, South-East Asia and South America. It is therefore a continuing threat to global food security. Rice blast is caused by a fungus called Magnaporthe oryzae and this project aims to determine how the fungus infects rice plants. The rice blast fungus produces a specialised infection structure called an appressorium, which generates enormous pressure (up to 8MPa, or 40 times the pressure of a car tyre) and to apply physical force at the leaf surface to puncture the plant cuticle. In this way the fungus can invade leaf tissue and cause disease. We aim to investigate how pressure inside the appressorium is translated into physical force at the base of the infection cell. We have discovered that a group of protein called septins, are essential for the appressorium to puncture the rice cuticle. Their role is to re-model the cell's internal cytoskeleton so it applies force at the leaf surface and forms a penetration peg that enter the leaf. This project will investigate how septins assemble at the base of the appressorium and how this region of the cell becomes specialised to secrete proteins into plant cells, how the appressorium develops a penetration peg, and how the fungus then rapidly invades the leaf. We will characterise how septin assembly is regulated and, in particular, how the fungus is able to monitor the turgor pressure within the appressorium and determine the optimal point (or trigger) for penetration peg development. We will also determine how this process is regulated in concert with the cell division cycle of the fungus, allowing the plant infection process to be controlled effectively.When considered together, the objectives of this research project will provide new insight into the biology of plant infection by one of the most important crop diseases in the world today. This information will be used to inform new disease control strategies that are urgently required. In addition to the global significance of rice blast, knowledge gained from the project will also be of value to UK agriculture because many of the most serious diseases that affect our major cereal crops, barley and wheat, share a similar infection mechanism. Disease control strategies emerging from this work are therefore likely to be of broad spectrum for the most important cereal diseases, such as rusts and powdery mildews in addition to rice blast.