Aldrich-Wolfe Laura, Travers Steven, Nelson Berlin D
Biology Department, Concordia College, Moorhead, Minnesota, United States of America.
Department of Biological Sciences, North Dakota State University, Fargo, North Dakota, United States of America.
PLoS One. 2015 Sep 29;10(9):e0139188. doi: 10.1371/journal.pone.0139188. eCollection 2015.
Sclerotinia sclerotiorum is an important pathogen of numerous crops in the North Central region of the United States. The objective of this study was to examine the genetic diversity of 145 isolates of the pathogen from multiple hosts in the region. Mycelial compatibility groups (MCG) and microsatellite haplotypes were determined and analyzed for standard estimates of population genetic diversity and the importance of host and distance for genetic variation was examined. MCG tests indicated there were 49 different MCGs in the population and 52 unique microsatellite haplotypes were identified. There was an association between MCG and haplotype such that isolates belonging to the same MCG either shared identical haplotypes or differed at no more than 2 of the 12 polymorphic loci. For the majority of isolates, there was a one-to-one correspondence between MCG and haplotype. Eleven MCGs shared haplotypes. A single haplotype was found to be prevalent throughout the region. The majority of genetic variation in the isolate collection was found within rather than among host crops, suggesting little genetic divergence of S. sclerotiorum among hosts. There was only weak evidence of isolation by distance. Pairwise population comparisons among isolates from canola, dry bean, soybean and sunflower suggested that gene flow between host-populations is more common for some crops than others. Analysis of linkage disequilibrium in the isolates from the four major crops indicated primarily clonal reproduction, but also evidence of genetic recombination for isolates from canola and sunflower. Accordingly, genetic diversity was highest for populations from canola and sunflower. Distribution of microsatellite haplotypes across the study region strongly suggest that specific haplotypes of S. sclerotiorum are often found on multiple crops, movement of individual haplotypes among crops is common and host identity is not a barrier to gene flow for S. sclerotiorum in the north central United States.
核盘菌是美国中北部众多作物的一种重要病原体。本研究的目的是检测该地区来自多种寄主的145个病原体分离株的遗传多样性。确定并分析了菌丝体亲和群（MCG）和微卫星单倍型，以进行群体遗传多样性的标准估计，并研究寄主和距离对遗传变异的重要性。MCG测试表明，群体中有49个不同的MCG，鉴定出52种独特的微卫星单倍型。MCG和单倍型之间存在关联，即属于同一MCG的分离株要么共享相同的单倍型，要么在12个多态位点中不超过2个位点存在差异。对于大多数分离株，MCG和单倍型之间存在一一对应关系。11个MCG共享单倍型。发现一种单倍型在整个地区都很普遍。在分离株集合中，大多数遗传变异存在于寄主作物内部而非寄主作物之间，这表明核盘菌在寄主之间的遗传分化很小。仅有微弱的距离隔离证据。对油菜、干豆、大豆和向日葵分离株的成对群体比较表明，寄主群体之间的基因流动在某些作物中比其他作物更常见。对四种主要作物分离株的连锁不平衡分析表明，主要是克隆繁殖，但也有油菜和向日葵分离株发生遗传重组的证据。因此，油菜和向日葵群体的遗传多样性最高。微卫星单倍型在研究区域的分布强烈表明，核盘菌的特定单倍型经常在多种作物上发现，单个单倍型在作物间的移动很常见，并且寄主身份不是美国中北部核盘菌基因流动的障碍。
