Phytopathology. 2002 Jun;92(6):580-9. doi: 10.1094/PHYTO.2002.92.6.580.
ABSTRACT Coevolution of the angular leaf spot pathogen, Phaeoisariopsis griseola, with its common bean host has been demonstrated, and P. griseola isolates have been divided into Andean and Mesoamerican groups that correspond to defined bean gene pools. Recent characterization of P. griseola isolates from Africa has identified a group of isolates classified as Andean using random amplified polymorphic DNA (RAPD), but which are able to infect some Mesoamerican differential varieties. These isolates, designated Afro-Andean, have been identified only in Africa. Random amplified microsatellites, RAPD, and restriction digestion of amplified ribosomal intergenic spacer region were used to elucidate the relationships among the Afro-Andean, Andean, and Mesoamerican groups of P. griseola. Cluster and multiple correspondence analysis of molecular data separated isolates into Andean and Meso-american groups, and the Afro-Andean isolates clustered with Andean isolates. Analysis of molecular variance ascribed 2.8% of the total genetic variation to differences between Afro-Andean and Andean isolates from Africa. Gene diversity analysis revealed no genetic differentiation (G(ST) = 0.004) between Afro-Andean and Andean isolates from Africa. However, significant levels of genetic differentiation (G(ST) = 0.39) were observed between Afro-Andean or Andean isolates from Africa and Andean isolates from Latin America, revealing significant geographical differentiation within the Andean lineage. Results from this study showed that Afro-Andean isolates do not constitute a new P. griseola group and do not represent long-term evolution of the pathogen genome, but rather are likely the consequents of point mutations in genes for virulence. This finding has significant implications in the deployment of resistant bean genotypes.
摘要 叶斑病病原菌，斑痣盘菌（Phaeoisariopsis griseola）与它的普通豆科宿主的共同进化已经得到证实，并且 P. griseola 分离株被分为安第斯和中美洲群体，这些群体与特定的豆科基因库相对应。最近对来自非洲的 P. griseola 分离株的特征描述表明，使用随机扩增多态性 DNA（RAPD）分类的一组分离株被归类为安第斯组，但它们能够感染一些中美洲的差异品种。这些被称为非裔安第斯组的分离株仅在非洲被识别。随机扩增多态性微卫星、RAPD 和扩增核糖体基因间间隔区的限制性消化用于阐明非裔安第斯组、安第斯组和中美洲组的 P. griseola 之间的关系。分子数据的聚类和多重对应分析将分离株分为安第斯组和中美洲组，非裔安第斯组的分离株与安第斯组的分离株聚类。分子方差分析将总遗传变异的 2.8%归因于非洲的非裔安第斯组和安第斯组分离株之间的差异。基因多样性分析显示，非洲的非裔安第斯组和安第斯组分离株之间没有遗传分化（G(ST) = 0.004）。然而，非洲的非裔安第斯组或安第斯组分离株与来自拉丁美洲的安第斯组分离株之间存在显著的遗传分化（G(ST) = 0.39），这表明在安第斯谱系内存在显著的地理分化。本研究结果表明，非裔安第斯组分离株不构成新的 P. griseola 组，也不代表病原体基因组的长期进化，而是可能是毒力基因的点突变的结果。这一发现对抗性豆科基因型的部署具有重要意义。
