Septoria tritici blotch (STB), caused by Zymoseptoria tritici (formerly: Mycosphaerella graminicola or Septoria tritici), is one of the most devastating diseases of wheat globally. Understanding genetic diversity of the pathogen has supreme importance in developing best management strategies. However, there is dearth of information on the genetic structure of Z. tritici populations in Ethiopia. Therefore, the present study was targeted to uncover the genetic diversity and population structure of Z. tritici populations from the major wheat-growing areas of Ethiopia. Totally, 182 Z. tritici isolates representing eight populations were analyzed with 14 microsatellite markers. All the microsatellite loci were polymorphic and highly informative, and hence useful genetic tools to depict the genetic diversity and population structure of the pathogen. A wide range of diversity indices including number of observed alleles, effective number of alleles, Shannon's diversity index, number of private alleles, Nei's gene diversity and percentage of polymorphic loci (PPL) were computed to determine genetic variation within populations. A high within-populations genetic diversity was confirmed with gene diversity index and PPL values ranging from 0.34 - 0.58 and 79 - 100% with overall mean of 0.45 and 94%, respectively. Analysis of molecular variance (AMOVA) revealed a moderate genetic differentiation where 92 % of the total genetic variation resides within populations, leaving only 8% among populations. Cluster (UPGMA), PCoA and STRUCTURE analyses did not group the populations into sharply genetically distinct clusters according to their geographical origins, likely due to high gene flow (Nm = 5.66) and reproductive biology of the pathogen. All individual samples shared alleles from two subgroups (K=2) evidencing high potential of genetic admixture. In conclusion, the microsatellite markers used in the present study were highly informative and thus, helped to dissect the genetic structures of Z. tritici populations in Ethiopia. Among the studied populations, those of East Shewa, Arsi, South West Shewa and Bale showed a high genetic diversity, and hence these areas can be considered as hot spots for investigations planned on the pathogen and host-pathogen interactions. Therefore, the present study not only enriches missing information in Ethiopia but also provides new insights into the epidemiology and genetic structure of Z. tritici in Africa where the agro-climatic conditions and the wheat cropping systems are different from other parts of the world. Such baseline information is useful for designing and implementing durable and effective management strategies.

中文翻译：

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微卫星标记揭示埃塞俄比亚 Zymoseptoria tritici 的遗传多样性和种群结构。

小麦斑点病 (STB) 由小麦酵母菌（原名：Mycosphaerella graminicola 或 Septoria tritici）引起，是全球最具破坏性的小麦病害之一。了解病原体的遗传多样性对于制定最佳管理策略至关重要。然而，缺乏关于埃塞俄比亚黑小麦种群遗传结构的信息。因此，本研究旨在揭示埃塞俄比亚主要小麦产区小麦小麦种群的遗传多样性和种群结构。总共用 14 个微卫星标记分析了代表 8 个种群的 182 株小麦。所有微卫星位点都是多态的，信息量很大，因此是描述病原体遗传多样性和种群结构的有用遗传工具。计算了广泛的多样性指数，包括观察到的等位基因数、等位基因有效数、香农多样性指数、私有等位基因数、内氏基因多样性和多态性位点 (PPL) 百分比，以确定种群内的遗传变异。基因多样性指数和 PPL 值范围为 0.34 - 0.58 和 79 - 100%，总体平均值分别为 0.45 和 94%，证实了高种群内遗传多样性。分子方差分析 (AMOVA) 揭示了适度的遗传分化，其中 92% 的总遗传变异存在于种群内，仅剩下 8% 的种群之间。聚类 (UPGMA)、PCoA 和 STRUCTURE 分析没有根据它们的地理起源将种群分为明显不同的遗传聚类，可能是由于高基因流 (Nm = 5.66) 和病原体的生殖生物学。所有个体样本共享来自两个亚组 (K=2) 的等位基因，证明遗传混合物的潜力很大。总之，本研究中使用的微卫星标记信息量很大，因此有助于剖析埃塞俄比亚黑小麦种群的遗传结构。在所研究的种群中，East Shewa、Arsi、South West Shewa 和Bale 的种群表现出较高的遗传多样性，因此这些地区可以被认为是计划进行病原体和宿主-病原体相互作用研究的热点。因此，本研究不仅丰富了埃塞俄比亚的缺失信息，而且为Z.的流行病学和遗传结构提供了新的见解。非洲小麦，那里的农业气候条件和小麦种植系统与世界其他地区不同。此类基线信息对于设计和实施持久有效的管理策略非常有用。