Wang Jianan, Fernández-Pavía Sylvia P, Larsen Meredith M, Garay-Serrano Edith, Gregorio-Cipriano Rosario, Rodríguez-Alvarado Gerardo, Grünwald Niklaus J, Goss Erica M
Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32611, USA.
Laboratorio de Patología Vegetal, Universidad Michoacana de San Nicolás de Hidalgo, IIAF, Tarímbaro, Michoacán, 58880, México.
Mol Ecol. 2017 Feb;26(4):1091-1107. doi: 10.1111/mec.14000. Epub 2017 Feb 4.
Globally destructive crop pathogens often emerge by migrating out of their native ranges. These pathogens are often diverse at their centre of origin and may exhibit adaptive variation in the invaded range via multiple introductions from different source populations. However, source populations are generally unidentified or poorly studied compared to invasive populations. Phytophthora infestans, the causal agent of late blight, is one of the most costly pathogens of potato and tomato worldwide. Mexico is the centre of origin and diversity of P. infestans and migration events out of Mexico have enormously impacted disease dynamics in North America and Europe. The debate over the origin of the pathogen, and population studies of P. infestans in Mexico, has focused on the Toluca Valley, whereas neighbouring regions have been little studied. We examined the population structure of P. infestans across central Mexico, including samples from Michoacán, Tlaxcala and Toluca. We found high levels of diversity consistent with sexual reproduction in Michoacán and Tlaxcala and population subdivision that was strongly associated with geographic region. We determined that population structure in central Mexico has contributed to diversity in introduced populations based on relatedness of U.S. clonal lineages to Mexican isolates from different regions. Our results suggest that P. infestans exists as a metapopulation in central Mexico, and this population structure could be contributing to the repeated re-emergence of P. infestans in the United States and elsewhere.
全球范围内具有破坏性的作物病原体常常通过迁出其原生范围而出现。这些病原体在其起源中心通常具有多样性，并且通过来自不同源种群的多次引入，可能在入侵范围内表现出适应性变异。然而，与入侵种群相比，源种群通常未被识别或研究不足。致病疫霉是马铃薯晚疫病的病原体，是全球范围内马铃薯和番茄最具破坏力的病原体之一。墨西哥是致病疫霉的起源和多样性中心，从墨西哥迁出的迁移事件对北美和欧洲的病害动态产生了巨大影响。关于该病原体起源的争论以及对墨西哥致病疫霉的种群研究，主要集中在托卢卡山谷，而邻近地区则很少被研究。我们研究了墨西哥中部致病疫霉的种群结构，包括来自米却肯州、特拉斯卡拉州和托卢卡的样本。我们发现米却肯州和特拉斯卡拉州存在与有性生殖一致的高度多样性，以及与地理区域密切相关的种群细分。基于美国克隆谱系与来自不同地区的墨西哥分离株的亲缘关系，我们确定墨西哥中部的种群结构促成了引入种群的多样性。我们的结果表明，致病疫霉在墨西哥中部以复合种群的形式存在，这种种群结构可能导致致病疫霉在美国和其他地区反复再次出现。
