Phylogenetic and population genetic analyses of Phaeosphaeria nodorum and its close relatives indicate cryptic species and an origin in the Fertile Crescent

The origin of the fungal wheat pathogen Phaeosphaeria nodorum remains unclear despite earlier intensive global population genetic and phylogeographical studies. We sequenced 1,683 bp distributed across three loci in 355 globally distributed Phaeosphaeria isolates, including 74 collected in Iran near the center of origin of wheat. We identified nine phylogenetically distinct clades, including two previously unknown species tentatively named P1 and P2 collected in Iran. Coalescent analysis indicates that P1 and P2 are sister species of P. nodorum and the other Phaeosphaeria species identified in our analysis. Two species, P. nodorum and P. avenaria f. sp. tritici 1 (Pat1), comprised ∼85% of the sampled isolates, making them the dominant wheat-infecting pathogens within the species complex. We designed a PCR-RFLP assay to distinguish P. nodorum from Pat1. Approximately 4% of P. nodorum and Pat1 isolates showed evidence of hybridization. Measures of private allelic richness at SSR and seque...尽管此前已开展过大量全球范围的群体遗传与系统地理学研究，但小麦真菌病原菌颖枯壳球菌（Phaeosphaeria nodorum）的起源仍不明确。本研究对全球分布的355株颖枯壳球菌分离株（含74株采自小麦起源中心附近的伊朗地区）的3个基因座上的1683个碱基对（bp）片段进行了测序。研究共鉴定出9个系统发育上独立的进化支，其中包含2个此前未被发现的物种，暂命名为P1和P2，均采自伊朗地区。溯祖分析结果显示，P1与P2为颖枯壳球菌以及本研究中鉴定出的其他颖枯壳球菌属物种的姊妹种。在采样分离株中，颖枯壳球菌与燕麦颖枯壳球菌小麦专化型1（P. avenaria f. sp. tritici 1，简称Pat1）这两个物种占比约85%，为该物种复合体中主要的小麦侵染性病原菌。本研究设计了聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）检测方法，用于区分颖枯壳球菌与Pat1。约4%的颖枯壳球菌与Pat1分离株显示出杂交现象的分子证据。对简单重复序列（SSR）及序列...