Department of Plant Pathology, North Carolina State University, Raleigh, NC, USA.
Phytopathology. 2011 Nov;101(11):1373-84. doi: 10.1094/PHYTO-11-10-0302.
The evolutionary history of Phytophthora cryptogea and P. drechsleri isolates previously collected from floriculture crops in North Carolina commercial greenhouses was explored with coalescent- and parsimony-based analyses. Initially, 68 isolates representing 13 location-host groups were sequenced at multiple loci. Sequences of all isolates within a group were identical. A subset of isolates were selected, cloned to resolve heterozygous sites, and analyzed with SNAP Workbench. The internal transcribed spacer (ITS) region of the ribosomal DNA and cytochrome oxidase II gene genealogies were congruent and indicated that P. cryptogea and P. drechsleri are sister species diverged from a common ancestor with no evidence of gene flow. In contrast, genealogies inferred from β-tubulin (β-tub) and translation elongation factor 1α (EF-1α) genes were in conflict with these loci. Coalescent analysis based on a nonrecombining partition in β-tub and EF-1α showed an initial (older) split between P. cryptogea and P. drechsleri, with a later (recent) event separating the remaining P. cryptogea haplotypes from P. drechsleri. A parsimony-based minimal ancestral recombination graph inferred recombination between P. cryptogea and P. drechsleri isolates in the ITS region and β-tub, suggesting genetic exchange between species. Also, putative recombination between A1 and A2 mating types of P. cryptogea suggests that sexual reproduction has occurred in the history of these P. cryptogea isolates.
先前从北卡罗来纳州商业温室的花卉作物中采集的腐霉菌和德雷克斯勒菌分离株的进化历史，通过基于合并和简约的分析进行了探索。最初，在多个基因座对代表 13 个地点-宿主群的 68 个分离株进行了测序。组内所有分离株的序列完全相同。选择了一组分离株，克隆以解决杂合位点，并在 SNAP Workbench 中进行分析。核糖体 DNA 的内部转录间隔区（ITS）区域和细胞色素氧化酶 II 基因系统发育是一致的，表明腐霉菌和德雷克斯勒菌是姐妹种，从共同祖先分化而来，没有证据表明有基因流动。相比之下，从β-微管蛋白（β-tub）和翻译延伸因子 1α（EF-1α）基因推断的系统发育与这些基因座不一致。基于β-tub 和 EF-1α 中非重组分区的合并分析显示，腐霉菌和德雷克斯勒菌之间存在初始（较早）的分裂，随后（最近）事件将剩余的腐霉菌单倍型与德雷克斯勒菌分离。基于简约的最小祖先重组图推断了 ITS 区域和β-tub 中腐霉菌和德雷克斯勒菌分离株之间的重组，表明种间存在遗传交换。此外，腐霉菌 A1 和 A2 交配型之间的假定重组表明，这些腐霉菌分离株的历史上发生了有性生殖。
