Data from: Understanding the recent colonization history of a plant pathogenic fungus using population genetic tools and Approximate Bayesian Computation

Understanding the processes by which new diseases are introduced in previously healthy areas is of major interest in elaborating prevention and management policies as well as in understanding the dynamics of pathogen diversity at large spatial scale. In this study, we aimed to decipher the dispersal processes that have led to the emergence of the plant pathogenic fungus Microcyclus ulei, which is responsible for the South American Leaf Blight (SALB) that has affected rubber trees across Latin America since the beginning of the twentieth century. As only imprecise historical information is available, the study of population evolutionary history based on population genetics appeared most appropriate. The distribution of genetic diversity in a continental sampling of four countries (Brazil, Ecuador, Guatemala and French Guiana) was studied using a set of 16 microsatellite markers developed specifically for this purpose. A very strong genetic structure was found (Fst = 0.70), demonstrating that there has been no regular gene flow between Latin American M. ulei populations. Strong bottlenecks probably occurred at the foundation of each population. The most likely scenario of colonization identified by the Approximate Bayesian Computation (ABC) method implemented in DIYABC suggested two independent sources from the Amazonian endemic area. The Brazilian, Ecuadorian and Guatemalan populations might stem from serial introductions through human-mediated movement of infected plant material from an unsampled source population, whereas the French Guiana population seems to have arisen from an independent colonization event through spore dispersal.

阐明新病害传入此前无该病害区域的过程，对于制定防控与管理策略、解析大空间尺度下病原物多样性动态均具有重要意义。本研究旨在解析引发植物病原真菌南美叶枯病菌（Microcyclus ulei）种群扩散的具体过程——该病原菌导致的南美叶枯病（South American Leaf Blight, SALB）自20世纪初起，已对拉丁美洲全境的橡胶树造成严重危害。由于可获取的历史信息较为模糊，基于种群遗传学的种群演化历史研究成为最为合适的研究手段。本研究对巴西、厄瓜多尔、危地马拉及法属圭亚那四个国家的大陆种群开展采样，通过专为该研究开发的16个微卫星标记（microsatellite markers）分析其遗传多样性分布特征。研究结果显示种群遗传结构极强（Fst = 0.70），表明拉丁美洲地区的南美叶枯病菌种群之间不存在规律性的基因流。各种群在建立初期大概率经历了严重的种群瓶颈事件。借助DIYABC软件实现的近似贝叶斯计算（Approximate Bayesian Computation, ABC）方法筛选得到的最可能定殖场景表明，该病原菌存在两个独立的亚马逊流域特有起源种群。巴西、厄瓜多尔与危地马拉种群可能源自未被采样的源种群通过人类媒介携带染病植物材料进行的系列引种传播，而法属圭亚那种群则似乎源自一次独立的孢子扩散定殖事件。