United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Department of Plant Pathology, University of California, One Shields Avenue, Davis 95616, USA.
Phytopathology. 2010 Jul;100(7):708-18. doi: 10.1094/PHYTO-100-7-0708.
ABSTRACT Armillaria mellea infects hundreds of plant species in natural and managed ecosystems throughout the Northern hemisphere. Previously reported nuclear genetic divergence between eastern and western U.S. isolates is consistent with the disjunct range of A. mellea in North America, which is restricted mainly to both coasts of the United States. We investigated patterns of population structure and genetic diversity of the eastern (northern and southern Appalachians, Ozarks, and western Great Lakes) and western (Berkeley, Los Angeles, St. Helena, and San Jose, CA) regions of the United States. In total, 156 diploid isolates were genotyped using 12 microsatellite loci. Absence of genetic differentiation within either eastern subpopulations (theta(ST) = -0.002, P = 0.5 ) or western subpopulations (theta(ST) = 0.004, P = 0.3 ) suggests that spore dispersal within each region is sufficient to prevent geographic differentiation. In contrast to the western United States, our finding of more than one genetic cluster of isolates within the eastern United States (K = 3), revealed by Bayesian assignment of multilocus genotypes in STRUCTURE and confirmed by genetic multivariate analyses, suggests that eastern subpopulations are derived from multiple founder sources. The existence of amplifiable and nonamplifiable loci and contrasting patterns of genetic diversity between the two regions demonstrate that there are two geographically isolated, divergent genetic pools of A. mellea in the United States.
摘要 蜜环菌感染了北半球自然和人工生态系统中的数百种植物物种。先前报道的美国东部和西部分离株之间的核遗传差异与蜜环菌在北美的离散分布一致，主要局限于美国的东西两岸。我们调查了美国东部（北阿巴拉契亚山脉、奥扎克山脉和大湖西部）和西部（伯克利、洛杉矶、圣海伦娜和圣何塞，加利福尼亚州）地区的种群结构和遗传多样性模式。总共使用 12 个微卫星标记对 156 个二倍体分离株进行了基因型分析。在东部（theta(ST) = -0.002，P = 0.5）或西部（theta(ST) = 0.004，P = 0.3）的亚种群内均未发现遗传分化，这表明每个区域内的孢子扩散足以防止地理分化。与美国西部不同，我们发现美国东部有一个以上的遗传聚类（K = 3），这是通过 STRUCTURE 中的多位点基因型贝叶斯分配和遗传多元分析证实的，这表明东部亚种群是由多个起源源衍生而来的。可扩增和不可扩增位点的存在以及两个区域之间遗传多样性的对比模式表明，在美国存在两个地理隔离的、分化的蜜环菌遗传库。
