基于感病基因发掘和操纵提高小麦白粉病抗性的研究

Susceptibility genes have been explored in different plant species in the last decade, and silencing or mutation of these susceptibility genes can lead to the resistance improvement of plants to various diseases. Some of susceptibility genes confer broad-spectrum and durable resistance, and have been widely used in the crop production. Wheat powdery mildew disease is one of the most serious diseases in China and worldwide. Currently, researchers usually focus on the resistance gene cloning and resistance mechanism elucidation to improve the resistance level of wheat to powdery mildew， and there is no reports about susceptibility gene isolation and manipulation for powdery mildew resistance improvement. In our previous study, two near-isogenetic lines of resistant/susceptible wheat have been developed, and the digital gene expression profiles of these materials inoculated with Blumeria graminis f. sp. tritici (Bgt)for different hours have been created using next generation sequencing technology. Based on the analysis of the differentially expressed genes, 14 susceptibility candidate genes (SCG) have been explored which was upregulated by Bgt in the susceptible wheat varieties specifically. In this study, improving the resistance of wheat to powdery mildew by SCGs manipulation will be carried out, including characterization of expression patterns of the SCGs in different susceptible wheat varieties, functional analysis of the SCGs in the wheat- Bgt interaction system, creating resistant wheat plants by manipulating of the SCGs, studying of the functional conservation of SCGs in different species and mechanism elucidation of the susceptibility mediated by the SCGs. This research will supply new genes and new strategy for improvement of wheat resistance to powdery mildew.

很多物种中已经发掘出了感病基因/抗病负调控因子，这些基因的突变或者沉默可使植物获得对不同病害的抗性，其中一部分基因可介导广谱和持久抗性，已在生产上发挥巨大作用。小麦白粉病是我国乃至世界上小麦最重要病害之一，对白粉病抗性研究目前主要集中在抗病基因发掘和抗性机制解析，未见通过对感白粉病基因发掘和操纵以获得白粉病抗性的报道。本研究前期创制了两对小麦抗/感白粉病的近等基因系，并获得其受白粉菌诱导后不同时间段的基因表达谱，筛选出14个仅在感病小麦中上调表达的感白粉病候选基因。本项目拟开展基于感病基因调控获得小麦白粉病抗性的研究：1、感白粉病候选基因在感病小麦中受白粉菌诱导表达的普遍性研究；2、感白粉病候选基因在小麦-小麦白粉菌互作体系中的功能研究；3、基于感白粉病基因的调控获得抗病小麦植株的研究；4、感白粉病基因的功能保守性和感病分子机制研究。本项目研究将为小麦抗白粉病育种提供新基因和新策略。

在植物和病原菌协同进化过程中，病原菌致病性的发挥不仅需要病原菌自身致病效应因子effector的参与，还需要激活或利用植物的某些基因去达到成功侵染的目的。自2002年拟南芥的PMR6基因被鉴定为可协助白粉菌侵染和生长的植物基因后，Eckardt首先提出 “感病基因”这个概念，包括抗病负调控因子和感病因子。感病基因应该是显性基因，当它们突变或者沉默后可以引起广谱和持久抗性，已在拟南芥、水稻、大麦、番茄、辣椒和小麦等多个物种中发掘出了抗病负调控因子和感病基因，有些基因已经在生产上获得广泛应用。目前绝大部分研究者致力于抗病基因的发掘及其介导的抗性机制的研究，关于植物“感病基因”发掘和“感病基因”作用机制的研究报道相对较少。小麦中对感病基因的发掘主要在寄主-腐生菌的互作过程中有所报道；而调控感病基因以获得白粉病抗性的研究，则主要集中在大麦和拟南芥中，小麦中尚未见相关报道。. 本项目组长期致力于小麦抗白粉病基因的克隆和功能研究。前期主要围绕小麦抗白粉病基因Pm21的精细定位、克隆和功能验证开展了系统研究工作，获得了两组抗/感小麦近等基因系，利用第二代测序技术获得了两组近等基因系的受白粉菌诱导前后的数字基因表达谱，经过严格的筛选从中获得了14个感白粉病候选基因。本研究对已筛选获得的感白粉病候选基因进行系统研究，明晰其在小麦白粉菌侵染、繁殖过程中的作用，并通过对其操纵以期获得小麦白粉病抗性；另外，利用获得的抗病转基因株系研究调控感病基因获得抗病性的分子机理。通过本项目的研究，将为小麦感白粉病基因发掘和研究提供思路和方法，同时为小麦白粉病抗性遗传育种提供新基因资源和新策略。