Late blight disease caused by an Oomycete Phytophthora infestans is a major constraint to potato production and is causing significant yield losses in Ethiopia. This study was conducted to characterize the genetic diversity of the pathogen population in the major potato growing regions Awi, East Hararghe, South Gondar, West Arsi, West Gojjam and West Shewa in Ethiopia. In total 138 P. infestans isolates were collected using FTA cards in 2017, genotyped using 12-plex SSR markers and characterized for the mitochondrial haplotype. The genotypic patterns were compared to those of reference isolates from the EU2_A1 and US-1 clonal lineages. The population structure analysis using discriminant analysis of principal components (DAPC) and STRUCTURE indicated that most of the Ethiopian isolates were similar to the EU2_A1, while a second cluster of isolates was formed that was clearly different from EU2_A1 as well as the US-1 reference isolates. This new genotype was characterized by private alleles in the SSR D13 locus. We named this new genotype as ET-1 lineage. All isolates had the same mitochondrial haplotype (Ia). EU2_A1 was dominant clonal lineage in all locations except West Arsi which was dominated with ET-1 lineage. The old US-1 lineage was not discovered among the Ethiopian samples which suggest that it has been displaced. The West Arsi, West Gojjam and West Shewa populations were found to contain the highest genetic diversity, with the greatest number of multi locus genotypes (MLGs) and a higher diversity index compared to the other locations. The findings of this study establish a baseline of the pathogen population diversity in Ethiopia. Continuous tracking of P. infestans population in both potato and tomato is recommended to monitor the changes and migration patterns.

由卵菌疫霉菌引起的晚疫病是马铃薯生产的主要限制因素，并在埃塞俄比亚造成了严重的产量损失。进行这项研究以表征埃塞俄比亚主要马铃薯种植区Awi，East Hararghe，South Gondar，West Arsi，West Gojjam和West Shewa病原体种群的遗传多样性。总共138个疫霉菌2017年使用FTA卡收集了分离株，使用12重SSR标记进行基因分型并表征线粒体单倍型。将基因型与来自EU2_A1和US-1克隆谱系的参考分离株进行了比较。使用主成分判别分析（DAPC）和结构进行的人口结构分析表明，大多数埃塞俄比亚分离株与EU2_A1类似，而形成的第二个分离株群明显不同于EU2_A1和US-1参考隔离株。该新基因型的特征是SSR D13基因座中的私人等位基因。我们将该新基因型命名为ET-1谱系。所有分离株均具有相同的线粒体单倍型（Ia）。EU2_A1是所有地区的优势克隆谱系，但以Ar-1谱系为主的West Arsi除外。在埃塞俄比亚的样本中未发现旧的US-1血统，这表明它已被取代。发现西阿西族，西戈杰姆族和西谢瓦族的遗传多样性最高，与其他地区相比，多基因座基因型（MLG）的数量最多，多样性指数更高。这项研究的结果为埃塞俄比亚的病原体种群多样性建立了基线。建议连续跟踪马铃薯和番茄中的致病疫霉菌种群，以监测其变化和迁移方式。