中国胶锈菌系统分类及其生活史发育类型的分子解析

The rust genus Gymnosporangium is widely spread in the northern hemisphere which mainly causes the disease of Cupressaceae and Rosaceae, and leads to the heavy economic and ecological losses. The taxonomic studies of Gymnosporangium is only based on morphology and the host species which leads to the confused identification and the lifecycle of most species is still unknown. This project aims to get a better understanding of the taxonomy, phylogenetic relationship and the lifecycle of Gymnosporangium. To achieve this goal, light and scanning electron microscopy will be used to determine the taxonomic characteristics of the rust fungi, with the comparative analysis of the phylogenetic studies, we can find out the important morphological characteristics of the classification of Gymnosporangium and get a closer insight of the status of this genus. Also, inoculation experiment will be used to identify the lifecycle and host specification of this rust. Through the molecular studies, more acute diagnostic and molecular monitoring system due to crack DNA code of each species of Gymnosporangium is aimed to be established. With the accomplishment of this project, disease protection and management in further control will be assured, which will help us understand the disease thoroughly, and the disease can be controlled successfully based on our research results.

胶锈菌属真菌引起的柏树和蔷薇科植物锈病作为经济植物的重要病害，严重威胁着我国经济林产业和绿化事业的发展，并已造成了巨大的经济和生态损失。本研究将利用形态学、分子系统学与人工接种试验相结合的方法，从形态特征、生活史和系统进化关系的水平上研究我国胶锈菌的分类学和系统发育学，分析形态学种与分子系统发育类型之间的相关性，从分子水平上揭示胶锈菌的生活史与寄主植物种类的相关性，从而明确我国胶锈菌种类、生活史类型和寄主范围，并建立胶锈菌属新的分类体系；同时确立重要胶锈菌的快速检测分子标记和DNA barcoding。项目的完成将建立胶锈菌属新的分类体系，明确其生活史类型，为开展胶锈菌与寄主互作的病理学机制，探索病害控制的新途径，也为树木锈病的防治提供理论和科学依据。

本研究采集和借阅了我国胶锈标本747份，采用以光学显微镜和扫描电镜观察为主的形态学研究手段和内转录间隔区2（ITS2）、核糖体大亚基（LSU）和翻译延长因子（TEF-1α）等基因片段的系统发育学研究手段相结合的方式，明确了中国27个胶锈菌（包括6个新种）的种类、寄主及地理分布；通过接种试验和系统发育分析确认了我国6种胶锈菌的生活史；完善了胶锈属种间形态学分类依据；明确了我国胶锈菌属种间的系统发育关系并构建了可用于我国胶锈菌分子鉴定的系统发育树。在摸清属内系统发育关系的基础上，对冬孢子阶段寄生于圆柏上的两种胶锈菌进行了比较转录组学研究，探究了胶锈菌基因表达及其所参与的代谢通路与生活史阶段和寄主的相关性，着重对冬孢子阶段胶锈菌分泌的效应蛋白进行了预测，并基于种间直系同源基因的替换率估计山田胶锈菌和亚洲胶锈菌的分化时间大约为520万年前。在山田胶锈菌全长转录组构建的基础上，筛选和开发多态性微卫星分子标记22条，并对采集自北京和陕西的96份山田胶锈菌样本进行遗传多样性和遗传结构分析，结果表明遗传结构与地理隔离没有明显相关性，推测带菌苗木全国范围内的运输可能是群体间基因交流频繁的主要原因。中国胶锈菌属研究的完善为其所引起的锈菌病害的防治提供了有效的理论指导。