Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit-Crop Protection, Burg. Van Gansberghelaan 96 bus 2, 9820 Merelbeke, Belgium.
Mol Ecol. 2010 Jan;19(1):92-107. doi: 10.1111/j.1365-294X.2009.04443.x. Epub 2009 Nov 30.
Co-existence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, which begs the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a 7-year survey. Our main objectives were genetic characterization of this population to test for sexual reproduction, determination of population structure, evolution and spread, and evaluation of the effectiveness and impact of control measures. Novel, polymorphic simple sequence repeat (SSR) markers were developed after screening 149 candidate loci. Eighty isolates of P. ramorum, broadly representing the Belgian population, were analyzed using four previously described and three newly identified polymorphic microsatellite loci as well as amplified fragment length polymorphisms. SSR analysis was most informative and was used to screen the entire Belgian population. Thirty multilocus genotypes were identified, but 68% of the isolates belonged to the main genotype EU1MG1. Although accumulated mutation events were detected, the overall level of genetic diversity within the Belgian isolates of P. ramorum appears to be limited, indicating a relatively recent clonal expansion. Based on our SSR analysis there is no evidence of sexual recombination in the Belgian population of P. ramorum. Metalaxyl use decreased the genetic diversity of P. ramorum until 2005, when the majority of the isolates had become resistant. Most genotypes were site-specific and despite systematic removal of symptomatic and neighbouring plants, some genotypes were detected over a period of several years at a single site, sometimes discontinuously, indicating (latent) survival of the pathogen at those sites.
在比利时的 EU1 谱系中观察到了交配型 A1 和 A2 的共存，这不禁让人怀疑是否存在有性繁殖。在一项为期 7 年的调查中，收集了 411 个比利时根肿菌分离株。我们的主要目标是对该种群进行遗传特征分析，以检验是否存在有性繁殖，确定种群结构、进化和传播，以及评估控制措施的有效性和影响。在筛选了 149 个候选基因座后，开发了新的、多态性的简单重复序列 (SSR) 标记。使用先前描述的 4 个和新鉴定的 3 个多态微卫星标记以及扩增片段长度多态性，对 80 个广泛代表比利时种群的根肿菌分离株进行了分析。SSR 分析最具信息量，并用于筛选整个比利时种群。鉴定出 30 个多位点基因型，但 68%的分离株属于主要基因型 EU1MG1。尽管检测到了累积的突变事件，但比利时根肿菌分离株的遗传多样性水平似乎有限，表明最近发生了克隆扩张。根据我们的 SSR 分析，比利时根肿菌种群中没有有性重组的证据。甲霜灵的使用降低了根肿菌的遗传多样性，直到 2005 年，大多数分离株都产生了抗性。大多数基因型是特定于地点的，尽管有系统地清除了有症状和相邻的植物，但在单个地点的一段时间内，有时是不连续地，检测到了一些基因型，表明病原体在这些地点存在（潜伏）存活。
