Faculty of Land and Food Systems, The University of British Columbia (UBC), Vancouver, BC, Canada.
Agriculture and Agri-Food Canada (AAFC), Summerland Research and Development Center, Summerland, BC, Canada.
BMC Biol. 2023 Oct 25;21(1):233. doi: 10.1186/s12915-023-01717-9.
The population structure of crop pathogens such as Puccinia striiformis f. sp. tritici (Pst), the cause of wheat stripe rust, is of interest to researchers looking to understand these pathogens on a molecular level as well as those with an applied focus such as disease epidemiology. Cereal rusts can reproduce sexually or asexually, and the emergence of novel lineages has the potential to cause serious epidemics such as the one caused by the 'Warrior' lineage in Europe. In a global context, Pst lineages in Canada were not well-characterized and the origin of foreign incursions was not known. Additionally, while some Pst mating type genes have been identified in published genomes, there has been no rigorous assessment of mating type diversity and distribution across the species.
We used a whole-genome/transcriptome sequencing approach for the Canadian Pst population to identify lineages in their global context and evidence tracing foreign incursions. More importantly: for the first time ever, we identified nine alleles of the homeodomain mating type locus in the worldwide Pst population and show that previously identified lineages exhibit a single pair of these alleles. Consistently with the literature, we find only two pheromone receptor mating type alleles. We show that the recent population shift from the 'PstS1' lineage to the 'PstS1-related' lineage is also associated with the introduction of a novel mating type allele (Pst-b3-HD) to the Canadian population. We also show evidence for high levels of mating type diversity in samples associated with the Himalayan center of diversity for Pst, including a single Canadian race previously identified as 'PstPr' (probable recombinant) which we identify as a foreign incursion, most closely related to isolates sampled from China circa 2015.
These data describe a recent shift in the population of Canadian Pst field isolates and characterize homeodomain-locus mating type alleles in the global Pst population which can now be utilized in testing several research questions and hypotheses around sexuality and hybridization in rust fungi.
引起小麦条锈病的病原菌条锈菌（Puccinia striiformis f. sp. tritici，Pst）的种群结构引起了研究人员的关注，这些研究人员希望从分子水平上了解这些病原菌，也有一些研究人员关注应用，如疾病流行病学。禾谷类锈菌可以有性或无性繁殖，新谱系的出现有可能引发严重的流行，如欧洲的“战士”谱系引起的流行。在全球范围内，加拿大的 Pst 谱系尚未得到很好的描述，也不知道外来入侵的来源。此外，虽然已在已发表的基因组中鉴定出一些 Pst 交配型基因，但尚未对该物种的交配型多样性和分布进行严格评估。
我们使用全基因组/转录组测序方法对加拿大 Pst 种群进行研究，以在全球范围内识别其谱系，并追溯外来入侵的证据。更重要的是：我们首次在全球范围内 Pst 种群中鉴定出 9 个同源域交配型基因座的等位基因，并表明以前鉴定出的谱系仅表现出这对等位基因中的一对。与文献一致，我们仅发现两种信息素受体交配型等位基因。我们表明，最近从“PstS1”谱系向“PstS1 相关”谱系的种群转变也与一种新的交配型等位基因（Pst-b3-HD）引入加拿大种群有关。我们还提供了证据表明，与 Pst 的喜马拉雅多样性中心相关的样本中存在高水平的交配型多样性，包括以前被鉴定为“PstPr”（可能是重组）的单个加拿大品种，我们将其鉴定为外来入侵种，与 2015 年左右从中国采样的分离株最为密切相关。
这些数据描述了加拿大 Pst 田间分离株种群的最近变化，并描述了全球 Pst 种群中同源域基因座交配型等位基因，现在可以用于测试几个围绕锈菌有性生殖和杂交的研究问题和假设。
