Stukenbrock Eva H, Banke Søren, Javan-Nikkhah Mohammad, McDonald Bruce A
Plant Pathology, Institute of Integrative Biology, Eidgenössische Techniche Hochschule, Zurich Land und Forst Wissenschaft, Zurich, Switzerland.
Mol Biol Evol. 2007 Feb;24(2):398-411. doi: 10.1093/molbev/msl169. Epub 2006 Nov 9.
The Fertile Crescent represents the center of origin and earliest known place of domestication for many cereal crops. During the transition from wild grasses to domesticated cereals, many host-specialized pathogen species are thought to have emerged. A sister population of the wheat-adapted pathogen Mycosphaerella graminicola was identified on wild grasses collected in northwest Iran. Isolates of this wild grass pathogen from 5 locations in Iran were compared with 123 M. graminicola isolates from the Middle East, Europe, and North America. DNA sequencing revealed a close phylogenetic relationship between the pathogen populations. To reconstruct the evolutionary history of M. graminicola, we sequenced 6 nuclear loci encompassing 464 polymorphic sites. Coalescence analyses indicated a relatively recent origin of M. graminicola, coinciding with the known domestication of wheat in the Fertile Crescent around 8,000-9,000 BC. The sympatric divergence of populations was accompanied by strong genetic differentiation. At the present time, no genetic exchange occurs between pathogen populations on wheat and wild grasses although we found evidence that gene flow may have occurred since genetic differentiation of the populations.
新月沃地是许多谷类作物的起源中心和最早已知的驯化地。在从野草向驯化谷物过渡的过程中，许多寄主专化的病原体物种被认为已经出现。在伊朗西北部采集的野草上鉴定出了适应小麦的病原体禾谷格孢菌的一个姊妹种群。将来自伊朗5个地点的这种野草病原体分离株与来自中东、欧洲和北美的123个禾谷格孢菌分离株进行了比较。DNA测序揭示了病原体种群之间密切的系统发育关系。为了重建禾谷格孢菌的进化历史，我们对包含464个多态性位点的6个核基因座进行了测序。溯祖分析表明禾谷格孢菌起源相对较近，与公元前8000 - 9000年左右新月沃地已知的小麦驯化时间一致。种群的同域分化伴随着强烈的遗传分化。目前，小麦和野草上的病原体种群之间没有发生基因交流，尽管我们发现有证据表明自种群遗传分化以来可能发生过基因流动。
