Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, Switzerland.
Fungal Genet Biol. 2011 Mar;48(3):327-34. doi: 10.1016/j.fgb.2010.10.003. Epub 2010 Oct 16.
The two fungal pathogens Blumeria graminis f. sp. tritici (B.g. tritici) and hordei (B.g. hordei) cause powdery mildew specifically in wheat or barley. They have the same life cycle, but their growth is restricted to the respective host. Here, we compared the sequences of two loci in both cereal mildews to determine their divergence time and their relationship with the evolution of their hosts. We sequenced a total of 273.3kb derived from B.g. tritici BAC sequences and compared them with the orthologous regions in the B.g. hordei genome. Protein-coding genes were colinear and well conserved. In contrast, the intergenic regions showed very low conservation mostly due to different integration patterns of transposable elements. To estimate the divergence time of B.g. tritici and B.g. hordei, we used conserved intergenic sequences including orthologous transposable elements. This revealed that B.g. tritici and B.g. hordei have diverged about 10 million years ago (MYA), two million years after wheat and barley (12 MYA). These data suggest that B.g. tritici and B.g. hordei have co-evolved with their hosts during most of their evolutionary history after host divergence, possibly after a short phase of host expansion when the same pathogen could still grow on the two diverged hosts.
两种真菌病原体禾布氏白粉菌（B.g. tritici）和禾本科布氏白粉菌（B.g. hordei）分别特异性地引起小麦和大麦上的白粉病。它们具有相同的生命周期，但它们的生长仅限于各自的宿主。在这里，我们比较了两种谷物白粉菌中两个基因座的序列，以确定它们的分歧时间及其与宿主进化的关系。我们总共对来自 B.g. tritici BAC 序列的 273.3kb 进行了测序，并将其与 B.g. hordei 基因组中的同源区进行了比较。蛋白质编码基因是共线性的且很好地保守。相比之下，基因间区显示出极低的保守性，主要是由于转座元件的不同整合模式。为了估计 B.g. tritici 和 B.g. hordei 的分歧时间，我们使用了包括同源转座元件在内的保守基因间序列。这表明 B.g. tritici 和 B.g. hordei 大约在 1000 万年前（MYA）发生分歧，即在小麦和大麦（12 MYA）分化后 200 万年。这些数据表明，B.g. tritici 和 B.g. hordei 在其宿主分化后的大部分进化历史中与宿主共同进化，可能在宿主扩张的短暂阶段后也是如此，当时同一病原体仍能在两个分化的宿主上生长。
