Bai Qing, Wan Anmin, Wang Meinan, See Deven R, Chen Xianming
Department of Plant Pathology, Washington State University, Pullman, WA, United States.
Wheat Health, Genetics, and Quality Research Unit, United States Department of Agriculture, Agricultural Research Service, Pullman, WA, United States.
Front Microbiol. 2021 Jul 22;12:696835. doi: 10.3389/fmicb.2021.696835. eCollection 2021.
Stripe rust, caused by f. sp. (), is a serious disease on wheat in the United States, especially after 2000. In the present study, 2,247 isolates collected over all stripe rust epidemiological regions in the United States from 2010 to 2017 were genotyped at 14 simple sequence repeat (SSR) loci to investigate the population diversity, dynamics, and differentiation. A total of 1,454 multilocus genotypes (MLGs) were detected. In general, the populations in the west (regions 1-6) had more MLGs and higher diversities than the populations in the east (regions 7-12). The populations of 2010 and 2011 were more different from the other years. Genetic variation was higher among years than among regions, indicating the fast changes of the population. The divergence () was bigger between the west population and east population than among regions within either the west or east population. Gene flow was stronger among the regional populations in the east than in the west. Clustering analyses revealed 3 major molecular groups (MGs) and 10 sub-MGs by combining the genotypic data of 2010-2017 isolates with those of 1968-2009. MG1 contained both 1968-2009 isolates (23.1%) and 2010-2017 isolates (76.9%). MG2 had 99.4% of isolates from 1968-2009. MG3, which was the most recent and distinct group, had 99.1% of isolates from 2010-2017. Of the 10 sub-MGs, 5 (MG1-3, MG1-5, MG3-2, MG3-3, and MG3-4) were detected only from 2011 to 2017. The SSR genotypes had a moderate, but significant correlation ( = 0.325; < 0.0001) with the virulence phenotype data. The standard index values of association (rbarD = 0.11) based on either regional or yearly populations suggest clonal reproduction. This study indicated high diversity, fast dynamics, and various levels of differentiation of the population over the years and among epidemiological regions, and the results should be useful for managing wheat stripe rust.
条锈病由小麦条锈菌（Puccinia striiformis f. sp. tritici）引起，是美国小麦上的一种严重病害，尤其是2000年以后。在本研究中，对2010年至2017年在美国所有条锈病流行区域收集的2247个分离株在14个简单序列重复（SSR）位点进行基因分型，以研究群体多样性、动态变化和分化情况。共检测到1454个多位点基因型（MLG）。总体而言，西部（1 - 6区）的群体比东部（7 - 12区）的群体具有更多的MLG和更高的多样性。2010年和2011年的群体与其他年份的群体差异更大。年份间的遗传变异高于区域间的遗传变异，表明群体变化迅速。西部群体与东部群体之间的分化程度（Gst）大于西部或东部区域内各群体之间的分化程度。东部区域群体间的基因流比西部更强。聚类分析通过将2010 - 2017年分离株的基因型数据与1968 - 2009年的基因型数据相结合，揭示了3个主要分子组（MG）和10个亚分子组。MG1包含1968 - 2009年的分离株（23.1%）和2010 - 2017年的分离株（76.9%）。MG2有99.4%的分离株来自1968 - 2009年。MG3是最新且独特的组，有99.1%的分离株来自2010 - 2017年。在10个亚分子组中，有5个（MG1 - 3、MG1 - 5、MG3 - 2、MG3 - 3和MG3 - 4）仅在2011年至2017年被检测到。SSR基因型与毒力表型数据具有中等但显著相关性（r = 0.325；P <
0.0001）。基于区域或年度群体的关联标准指数值（rbarD =
0.11）表明存在克隆繁殖。本研究表明多年来以及在不同流行区域，小麦条锈菌群体具有高度多样性、快速动态变化和不同程度的分化，研究结果应有助于小麦条锈病的治理。
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