Liu M, Rodrigue N, Kolmer J
USDA-ARS Cereal Disease Laboratory, St Paul, MN, USA.
Department of Mathematics and Statistics, University of Calgary, Calgary, Alberta, Canada.
Heredity (Edinb). 2014 Apr;112(4):443-53. doi: 10.1038/hdy.2013.123. Epub 2013 Dec 4.
Co-evolution of fungal pathogens with their host species during the domestication of modern crop varieties has likely affected the current genetic divergence of pathogen populations. The objective of this study was to determine if the evolutionary history of the obligate rust pathogen on wheat, Puccinia triticina, is correlated with adaptation to hosts with different ploidy levels. Sequence data from 15 loci with different levels of polymorphism were generated. Phylogenetic analyses (parsimony, Bayesian, maximum likelihood) showed the clear initial divergence of P. triticina isolates collected from Aegilops speltoides (the likely B genome donor of modern wheat) in Israel from the other isolates that were collected from tetraploid (AB genomes) durum wheat and hexaploid (ABD genomes) common wheat. Coalescence-based genealogy samplers also indicated that P. triticina on A. speltoides, diverged initially, followed by P. triticina isolates from durum wheat in Ethiopia and then by isolates from common wheat. Isolates of P. triticina found worldwide on cultivated durum wheat were the most recently coalesced and formed a clade nested within the isolates from common wheat. By a relative time scale, the divergence of P. triticinia as delimited by host specificity appears very recent. Significant reciprocal gene flow between isolates from common wheat and isolates from durum wheat that are found worldwide was detected, in addition to gene flow from isolates on common wheat to isolates on durum wheat in Ethiopia.
在现代作物品种驯化过程中，真菌病原体与其宿主物种的共同进化可能影响了病原体种群当前的遗传分化。本研究的目的是确定小麦专性锈病病原体小麦条锈菌（Puccinia triticina）的进化历史是否与对不同倍性水平宿主的适应性相关。生成了来自15个具有不同多态性水平位点的序列数据。系统发育分析（简约法、贝叶斯法、最大似然法）表明，从以色列节节麦（现代小麦可能的B基因组供体）采集的小麦条锈菌分离株与从四倍体（AB基因组）硬粒小麦和六倍体（ABD基因组）普通小麦采集的其他分离株明显最初分化。基于溯祖的谱系采样器也表明，节节麦上的小麦条锈菌最初分化，随后是埃塞俄比亚硬粒小麦的小麦条锈菌分离株，然后是普通小麦的分离株。在世界范围内种植的硬粒小麦上发现的小麦条锈菌分离株是最近合并的，并形成了一个嵌套在普通小麦分离株中的分支。按照相对时间尺度，由宿主特异性界定的小麦条锈菌的分化似乎非常近。除了在埃塞俄比亚从普通小麦分离株到硬粒小麦分离株的基因流动外，还检测到了世界范围内普通小麦分离株和硬粒小麦分离株之间显著的双向基因流动。
