Wan Anmin, Chen Xianming, Yuen Jonathan
Department of Plant Pathology, Washington State University, Pullman 99164-6430.
United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit; and Department of Plant Pathology, Washington State University, Pullman.
Plant Dis. 2016 May;100(5):966-975. doi: 10.1094/PDIS-10-15-1122-RE. Epub 2016 Feb 25.
Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases on wheat in the United States. In 2011, severe wheat stripe rust caused extensive application of fungicides in the western United States, and the disease was more widespread and caused more yield loss in the eastern United States in 2012. In this study, we characterized virulences and identified races of P. striiformis f. sp. tritici by testing the stripe rust samples collected throughout the United States in 2011 and 2012 on a set of 18 Yr single-gene differentials. In 2011, 35 races were identified from 349 viable samples collected from 19 states of the United States and Ontario province of Canada, with PSTv-11 (35.5%), PSTv-37 (12.6%), PSTv-14 (11.8%), PSTv-4 (5.4%), and PSTv-34 (3.4%) as the top five predominant races. In 2012, 23 races were identified from 341 viable samples collected from 24 states of the United States and Ontario of Canada, with PSTv-37 (47.5%), PSTv-11 (11.7%), PSTv-14 (10.0%), PSTv-52 (9.4%), and PSTv-48 (4.4%) as the top five predominant races. Nationally, PSTv-37, PSTv-52, and PSTv-34 were most widely distributed, while PSTv-11, PSTv-14, PSTv-4, and PSTv-48 were mostly detected in the western United States. High frequencies (>80%) were detected for virulences to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr44, and YrExp2; moderate frequencies (20 to 80%) for virulences to Yr1, Yr43, YrTr1, and YrTye; low frequencies (<10%) for virulences to Yr10, Yr24, Yr32, and YrSP; and virulences to Yr5 and Yr15 were not detected, indicating that these two genes are still effective against the P. striiformis f. sp. tritici population in the United States. Both positive and negative associations were identified between some of the virulences. In total, 55 races identified from 2010 to 2012 in the United States were clustered into two major virulence groups, and dynamics of predominant races and virulence frequencies for the 3 years were presented and discussed. This information is useful for making decisions when screening wheat germplasm for developing stripe-rust-resistant wheat cultivars and managing the disease by growing cultivars with adequate and durable resistance. The severe epidemics and the occurrence of the large number of races in the 3 years indicate that efforts should be made to use diverse resistance genes, especially to combine effective all-stage resistance genes with genes for high-temperature adult-plant resistance.
条锈病由条形柄锈菌小麦专化型（Puccinia striiformis f. sp. tritici）引起，是美国小麦上最重要的病害之一。2011年，严重的小麦条锈病导致美国西部大量施用杀菌剂，2012年该病在美国东部更为普遍且造成了更大的产量损失。在本研究中，我们通过用一套18个Yr单基因鉴别寄主对2011年和2012年在美国各地采集的条锈病样本进行测试，来鉴定条形柄锈菌小麦专化型的毒性并确定其生理小种。2011年，从美国19个州和加拿大安大略省采集的349个可育样本中鉴定出35个生理小种，其中PSTv - 11（35.5%）、PSTv - 37（12.6%）、PSTv - 14（11.8%）、PSTv - 4（5.4%）和PSTv - 34（3.4%）为前五大优势生理小种。2012年，从美国24个州和加拿大安大略省采集的341个可育样本中鉴定出23个生理小种，其中PSTv - 37（47.5%）、PSTv - 11（11.7%）、PSTv - 14（10.0%）、PSTv - 52（9.4%）和PSTv - 48（4.4%）为前五大优势生理小种。在全国范围内，PSTv - 37、PSTv - 52和PSTv - 34分布最广，而PSTv - 11、PSTv - 14、PSTv - 4和PSTv - 48大多在美国西部被检测到。对Yr6、Yr7、Yr8、Yr9、Yr17、Yr27、Yr44和YrExp2的毒性检测频率较高（>80%）；对Yr1、Yr43、YrTr1和YrTye的毒性检测频率中等（20%至80%）；对Yr10、Yr24、Yr32和YrSP的毒性检测频率较低（<10%）；未检测到对Yr5和Yr15的毒性，这表明这两个基因对美国的条形柄锈菌小麦专化型群体仍然有效。在一些毒性之间发现了正相关和负相关。从2010年到2年在美国鉴定出的55个生理小种总共被聚类为两个主要毒性组，并展示和讨论了这3年优势生理小种和毒性频率的动态变化。这些信息对于在筛选小麦种质以培育抗条锈病小麦品种以及通过种植具有充分且持久抗性的品种来管理该病时做出决策很有用。这3年的严重流行情况和大量生理小种的出现表明，应努力使用多样化的抗性基因，特别是将有效的全生育期抗性基因与高温成株期抗性基因相结合。
