Angular Leaf Spot (ALS), caused by the fungus Pseudocercospora griseola, is an important disease of common bean (Phaseolus vulgaris). Previous studies demonstrated that P. griseola and Phaseolus vulgaris have co-evolved, resulting in the classification of the fungus into Middle American and Andean populations that reflect the evolutionary history of the host. However, an unusual group of P. griseola isolates found in Africa, termed Afro-Andean, was previously found to be pathogenic on Middle American cultivars. This study evaluated the diversity of P. griseola isolates from four countries and confirmed the existence of an Afro-Andean clade using molecular methods. A total of 171 P. griseola isolates from Puerto Rico, Honduras, Guatemala and Tanzania were evaluated. Sequence from four nuclear genes (β-tubulin, actin, the internal transcribed spacer (ITS) region of the ribosomal DNA, and the small subunit rRNA gene) were used to construct phylogenetic trees by Bayesian inference. Phylogenetic trees grouped all isolates from Puerto Rico (43), Honduras (25) and Guatemala (14) in the Middle American clade. Of the 89 Tanzanian isolates, 37 were Middle American and 40 Andean, and a third population with 12 isolates was identified as Afro-Andean. Models using isolation with migration estimated that the divergence between Middle American and Andean P. griseola populations occurred approx. 100,000 years ago, and that the Afro-Andean clade is a sister clade of the Andean population that diverged approx. 40,000 years ago. The results provide an understanding of the co-evolution of beans and the ALS pathogen, and help inform current and future bean breeding efforts.

由真菌Pseudocercospora griseola引起的角叶斑病（ALS）是一种常见的菜豆（菜豆）病。以前的研究表明，灰粉青霉和菜豆共进化，导致真菌分为中美洲和安第斯种群，反映了宿主的进化历史。但是，以前在非洲发现的一组不寻常的灰粉青霉分离株称为非洲安第斯山脉，对中美洲品种具有致病性。这项研究评估了来自四个国家的灰粉青霉分离株的多样性，并使用分子方法确认了非洲-安第斯进化枝的存在。共171对来自波多黎各，洪都拉斯，危地马拉和坦桑尼亚的灰绿假单胞菌分离物进行了评估。通过贝叶斯推断，使用来自四个核基因（β-微管蛋白，肌动蛋白，核糖体DNA的内部转录间隔区（ITS）区域和小亚基rRNA基因）的序列来构建系统树。系统发育树将来自中美洲进化枝的波多黎各（43），洪都拉斯（25）和危地马拉（14）的所有分离物分组。在89个坦桑尼亚分离株中，有37个是中美洲和40个安第斯，第三个有12个分离株的人口被确定为非洲安第斯。使用隔离与迁移的模型估计中美洲和安第斯山灰粉虱之间的差异发生人口约。100,000年前，非洲-安第斯进化枝是安第斯人口的姊妹进化枝，大约相距约20万。40,000年前。结果提供了对豆类和ALS病原体共同进化的理解，并有助于为当前和未来的豆类育种工作提供信息。