Department of Plant, Soil, and Insect Sciences, University of Massachusetts, Amherst, MA 01003-9320, USA.
Mycologia. 2012 Jan-Feb;104(1):53-61. doi: 10.3852/11-113. Epub 2011 Sep 13.
The population structure of Armillaria gallica, an important pathogen of Quercus spp., was investigated from mixed oak forests in central Massachusetts, encompassing a sampling area over 500 km(2). From 16 plots at four sites a total of 153 isolates (34-40 isolates per site) was analyzed with amplified fragment length polymorphisms (AFLPs). Analyses of 204 polymorphic loci detected 38 AFLP genotypes from a sample area of 4.51 hectares (ha). Genets ranged in distribution from five to 33 genets per hectare (GPH), with a mean of eight GPH and the average A. gallica genet occupying 0.13 ha. Allele frequencies produced an unbiased expected heterozygosity (H(E)) value of 0.112 (SE = 0.006) and a Nei's expected heterozygosity (H(J)) value of 0.190 (SE = 0.009), indicating low genetic diversity within the population. Analysis of molecular variation (Φ(PT) = 0.301; P < 0.001) indicates high genetic differentiation, with 70% of the molecular variation explained at the site-level within A. gallica subpopulations. However, results of the Mantel test, used to assess the isolation-by-distance hypothesis, were inconclusive in determining whether the subpopulations were truly isolated by distance. A neighbor-joining tree constructed from a genetic distance matrix grouped genotypes from the same site (subpopulation) together, but from three of four sites genotypes were randomly clustered at the plot level. The results suggest that basidiospore dispersal is an important means of new genet formation at linear distances up to 2000 m.
对马先蒿属（一种重要的栎属病原菌）的种群结构进行了研究，该研究的样本取自马萨诸塞州中部的混合栎树林，采样面积超过 500 平方公里。在四个地点的 16 个样地中共分析了 153 个分离株（每个样地 34-40 个分离株），使用扩增片段长度多态性（AFLP）进行分析。对 204 个多态性位点的分析检测到了来自 4.51 公顷（ha）采样区的 38 个 AFLP 基因型。在每个样地的 5 到 33 个基因型（GPH）范围内分布着基因，平均有 8 个 GPH，平均每个马先蒿属基因占据 0.13 公顷。等位基因频率产生了无偏期望杂合度（H(E)）值为 0.112（SE=0.006）和 Nei 期望杂合度（H(J)）值为 0.190（SE=0.009），表明该种群内的遗传多样性较低。分子变异分析（Φ(PT)=0.301；P<0.001）表明遗传分化程度较高，70%的分子变异在马先蒿属亚种群的地点水平上得到了解释。然而，用于评估隔离距离假说的 Mantel 检验结果在确定亚种群是否真正被隔离距离所隔离方面没有定论。基于遗传距离矩阵构建的邻接树将来自同一地点（亚种群）的基因型聚在一起，但来自四个地点中的三个地点的基因型在样地水平上随机聚类。结果表明，担孢子的扩散是新基因形成的重要途径，在长达 2000 米的线性距离内可以形成新的基因。
