玉米南方锈病传播与流行成灾的分子机制

Corn southern rust, caused by Puccinia polysora Underw，has become a worldwide devastating disease. The disease favors the low latitudinal and humid conditions. Recent epidemics in China covered 22 provinces. The risk of the pandemics of the disease is also a big threat. Since the urediniospores of the pathogen can disperse at as high as over 15000 feet, the long-distance dispersal over large corn-producing areas in China could be the causing reason of severe disease epidemics and disaster of corn yield losses. Designing of long-term disease management strategies needs full understanding of mechanisms of pathogen life cycle and dispersal pathways. Using traditional epidemiological research approaches combined with molecular epidemiological methods, we will propose several steps in this study to focus on molecular epidemiology of this disease. The study will start with intensive samplings and periodical disease surveys to include large corn-producing areas of China. In order to study the pathogen dispersal mechanism, two sampling strategies will be performed. One will involve samplings at various regions at different growth stages in single seasons, and another one will obtain the samples in the epidemically important regions but during various periods of a season. The Simple Sequence Repeat (SSR) markers will be developed in this study, and at least 30-50 SSR primer pairs will be tested and then used to process samples. The multiple displacement amplification (MDA) method will be applied to obtain samples’ DNA without the inefficient single-spore isolate reproduction approach. Thus, largenumber of samples covering and representing large regions of corn-producing areas of China will be obtained. The innovative parts of this study will be on using both direct and indirect population genetic methodologies to infer the major migration and dispersal pathways of the pathogen populations possibly existed inChina. These approaches will include modern population genetic analyses, such as Coalescence and Bayesian methods and other algorithms and statistical methods. The pathways of long-distance migration and dispersal of this pathogen over various corn-producing regions of China will be intensively studied. The mechanisms of such pathways to cause corn southern rust epidemics will be determined by focusingon pathogen population genetics. The achievements will be valuable to design national-wide disease management strategies.

由多堆柄锈菌（Puccinia polysora Underw）引起的玉米南方锈病是世界玉米生产上的毁灭性病害，近年该病在我国从次要病害上升为主要病害，并已波及到22个省份，呈大爆发流行态势，由于病菌随气流高空远距离传播，给防治带来很大困难。为制订科学合理的防病减灾措施，研究明确菌源传播路径和流行规律已成当前急需解决的关键科学问题。本项目拟在调查分析病害源头的基础上，通过各玉米产区单个生长季不同地点、不同时期病情调查及人工采样和自制的孢子捕捉器采样，利用设计、筛选SSR引物及采用多重置换扩增（MDA）新技术获得大样本量的方法进行样本处理，分析病菌多样性，再结合直接和间接的多种分子生物学和群体遗传学方法，以及简并法和贝叶斯等统计学方法，研究明确玉米南方锈病病原菌在我国不同生态区间的传播关系及其远距离传播规律、传播路径和流行成灾机制，为整体制定防病减灾措施提供科学依据。

玉米南方锈病是世界玉米生产上的毁灭性病害，近年该病在我国从次要病害上升为主要病害，并已波及到22个省份，呈大爆发流行态势，由于病菌随气流高空远距离传播，给防治带来很大困难。为制订科学合理的防病减灾措施，研究明确菌源传播路径和流行规律已成当前急需解决的关键科学问题。本项目在调查分析病害源头的基础上，通过各玉米产区单个生长季不同地点、不同时期病情调查及人工采样和自制的孢子捕捉器采样，利用设计、筛选SSR引物及采用多重置换扩增（MDA）新技术获得了大样本量的方法进行样本处理，分析了病菌多样性，结合直接和间接的多种分子生物学和群体遗传学方法，以及统计学方法，研究明确了玉米南方锈病病原菌在我国不同生态区间的传播关系及其远距离传播规律、传播路径和流行成灾机制，为玉米南方锈病的可持续治理提供了科学依据。