Abstract：
Triticum mosaic virus (TriMV, genus Poacevirus, family Potyviridae) was first reported in 2006 (Seifers et al. 2008) to infect wheat, and since then, it has been established as a constraint for US wheat production (Byamukama et al. 2013). In the field, TriMV often exists as a coinfection with wheat streak mosaic virus (WSMV), and these two viruses interact synergistically to produce severe symptoms and greater yield loss (Byamukama et al. 2012; Tatineni et al. 2022). Both TriMV and WSMV are transmitted by wheat curl mites (Aceria tosichella Keifer) (McMechan et al. 2014). Wheat is the primary host reported for TriMV in the field, but Seifers et al. (2010) established oat, rye, barley, and several other cereals and grasses as hosts under controlled conditions. However, there are no documented cases of TriMV infecting oats in the field. Between 10-25 June, 2023, a total of 273 field oat plants showing foliar yellowing, yellow flecking, and streaking symptoms were collected from four different fields in Nebraska (Big Springs: 41.1029° N, 102.1451° W; Mead: 41.2292° N, 96.4938° W; Odell: 40.0459° N, 96.7984° W; Stumf: 40.5048° N, 101.4223° W). Total RNA was extracted using the MagMax Plant RNA Isolation kit (Thermo Fisher Scientific) and the KingFisher Flex Magnetic Particle Processor (Thermo Fisher Scientific) (Mondal et al. 2023). Sample RNA was assayed with a single-step multiplex reverse transcription polymerase chain reaction (RT-PCR) to determine presence of WSMV and TriMV. Out of 273 symptomatic oat plants, 254 (93.04%) tested positive for at least one virus. Out of total positive samples, 238 were positive for WSMV (93.70 %), 12 plants tested positive for both TriMV and WSMV (4.70%), and 4 plants were infected with TriMV alone (1.60%). As a secondary confirmation, amplified fragments from the TriMV single infection were gel purified using a gel extraction kit (QIAquick) and sequenced (Eurofins Genomics). The nucleotide sequences were analysed using the BlastN program, compiled, and edited in the BioEdit software (Hall 1999). Sequences were deposited in the NCBI GenBank database (accession number PP475806). Nucleotide BLAST searches of the target coat protein (CP) gene showed > 98% identity to the corresponding sequences in TriMV accession MK318274. For further validation, virus inoculum was prepared by grinding field-collected plant material from plants with only TriMV present in 20 mM sodium phosphate buffer, pH 7.0, and then mechanically inoculating two-week-old oats (cv. Shaw n=8) and wheat (cv. Sattler, n=8) plants. Three weeks post-inoculation, all the eight wheat plants exhibited mild yellowing and streaking symptoms, while oat plants did not show obvious foliar symptoms. All wheat and oat plants were further tested positive with DAC-ELISA (antibodies produced against TriMV CP at the USDA-ARS facility in Lincoln, NE) and with RT-PCR. The specific attribution of these symptoms to TriMV in oats is not possible as none produced prominent symptoms. Asymptomatic oat infection from symptomatic field-collected oat samples could be due to oat cultivar differences. Although the prevalence of TriMV in wheat has been established across the Great Plains of the United States, to our knowledge, this is the first report of TriMV infection in US oat fields. Our finding warrant further investigation into the incidence and impact of the virus in oat crop and its potential for serving as a asymptomatic virus reservoir.
摘要：
小麦花叶病毒（TriMV，痘病毒属,Potyviridae家族）于2006年首次报道（Seifers等人。2008)感染小麦，从那以后,它已被确立为美国小麦生产的制约因素(Byamukama等人。2013).在田野里,TriMV通常与小麦条纹花叶病毒（WSMV）共感染，这两种病毒协同相互作用，产生严重的症状和更大的产量损失(Byamukama等人。2012；Tatineni等人。2022年）。TriMV和WSMV均由小麦卷曲螨（AceriatosichellaKeifer）传播（McMechan等人。2014).据报道，小麦是田间TriMV的主要宿主，但是Seifers等人.(2010)成熟燕麦，黑麦,大麦,以及其他几种谷物和草在受控条件下作为宿主。然而,该领域没有记录的TriMV感染燕麦的病例。6月10日至25日，2023年，共有273种燕麦植物显示叶面变黄，黄色斑点，和条纹症状是从内布拉斯加州的四个不同领域收集的(大斯普林斯：41.1029°N，102.1451°W;米德:41.2292°N,96.4938°W;Odell:40.0459°N,96.7984°W;Stumf:40.5048°N,101.4223°W)。使用MagMax植物RNA分离试剂盒（ThermoFisherScientific）和KingFisherFisherFisherScientific）（Mondal等人。2023年）。用单步多重逆转录聚合酶链反应(RT-PCR)测定样品RNA以确定WSMV和TriMV的存在。在273种有症状的燕麦植物中，254（93.04%）对至少一种病毒检测呈阳性。在总阳性样本中，238例WSMV阳性（93.70%），12株植物的TriMV和WSMV均呈阳性（4.70％），4株植物单独感染TriMV(1.60%)。作为次要确认，使用凝胶提取试剂盒（QIAquick）对TriMV单次感染的扩增片段进行凝胶纯化并测序（EurofinsGenomics）。使用BlastN程序分析核苷酸序列，编译,并在BioEdit软件（Hall1999）中编辑。将序列保存在NCBIGenBank数据库中(登录号PP475806)。靶外壳蛋白(CP)基因的核苷酸BLAST搜索显示与TriMV登录号MK318274中的相应序列>98%同一性。为了进一步验证，通过研磨来自植物的田间收集的植物材料来制备病毒接种物，其中只有TriMV存在于20mM磷酸钠缓冲液中，pH7.0，然后机械接种两周大的燕麦（简历。肖n=8)和小麦(cv。萨特勒,n=8)植物。接种后三周,所有八株小麦都表现出轻微的变黄和条纹症状，而燕麦植物没有表现出明显的叶面症状。用DAC-ELISA进一步测试了所有小麦和燕麦植物的阳性（在林肯的USDA-ARS工厂生产的针对TriMVCP的抗体，NE）和RT-PCR。不可能将这些症状归因于燕麦中的TriMV，因为没有一个症状会产生突出的症状。来自现场收集的有症状的燕麦样品的无症状燕麦感染可能是由于燕麦品种差异所致。尽管在美国大平原地区已经确定了小麦中TriMV的流行，根据我们的知识，这是美国燕麦田TriMV感染的第一份报告。我们的发现值得进一步调查该病毒在燕麦作物中的发病率和影响及其作为无症状病毒库的潜力。
