Trujillo César A, Ochoa Juan C, Mideros María Fernanda, Restrepo Silvia, López Camilo, Bernal Adriana
Laboratorio de Micología y Fitopatología Uniandes (LAMFU), Universidad de Los Andes, Bogotá, Colombia,
Microb Ecol. 2014 Jul;68(1):155-67. doi: 10.1007/s00248-014-0411-8. Epub 2014 Apr 24.
Cassava bacterial blight, caused by Xanthomonas axonopodis pv. manihotis (Xam), is the most important bacterial disease affecting this crop. A continuous surveillance of the pathogen population dynamics is required to develop an efficient disease management program. During the 1990s, Xam populations showed high levels of genetic variation and relevant migratory processes that were important determinants of the distribution of the pathogen diversity in Colombia. Aiming to characterize the current population structure of the pathogen and the evolutionary forces that shape these populations, sampling collections were carried out from September 2008 until November 2010 in the Colombian Caribbean Region. One hundred and sixty bacterial isolates were characterized using amplified fragment length polymorphism (AFLP) markers. Additionally, a subset of effector genes were sequenced in some isolates to determine their usefulness in Xam population studies and to provide additional information to that obtained with AFLPs. Virulence patterns of ten isolates were determined in nine cassava accessions. Our results show a complex architecture of population and confirm migratory process previously reported in the Caribbean Region. Chinú, one of the locations sampled, presented remarkable features in population dynamics such as longer genetic distances, higher diversity indices, and a genetically differentiated population when it was compared with other locations. Virulence tests showed that MCOL2215, one of the most cultivated cassava varieties in the Caribbean coast, was susceptible to the majority of Xam isolates tested. This study shows the current condition of populations of Xam in the Caribbean Region of Colombia, and it contributes to improve the existing bacterial blight control practices.
木薯细菌性枯萎病由野油菜黄单胞菌木薯致病变种（Xam）引起，是影响该作物的最重要细菌性病害。为制定有效的病害管理计划，需要持续监测病原菌种群动态。在20世纪90年代，Xam种群表现出高水平的遗传变异和相关的迁移过程，这些是哥伦比亚病原菌多样性分布的重要决定因素。为了表征病原菌当前的种群结构以及塑造这些种群的进化力量，于2008年9月至2010年11月在哥伦比亚加勒比地区进行了采样收集。使用扩增片段长度多态性（AFLP）标记对160个细菌分离株进行了表征。此外，对一些分离株中的效应子基因子集进行了测序，以确定它们在Xam种群研究中的用途，并提供与AFLP获得的信息之外的额外信息。在9个木薯种质中测定了10个分离株的毒力模式。我们的结果显示了种群的复杂结构，并证实了先前在加勒比地区报道的迁移过程。采样地点之一的奇努在种群动态方面呈现出显著特征，如与其他地点相比遗传距离更长、多样性指数更高以及种群遗传分化。毒力测试表明，加勒比海岸种植最广泛的木薯品种之一MCOL2215对测试的大多数Xam分离株敏感。本研究展示了哥伦比亚加勒比地区Xam种群的当前状况，并有助于改进现有的细菌性枯萎病防治措施。
