Abstract：
During the spring of 2021, cabbage (Brassica oleracea var. capitata) planted in the research farm at the University of Georgia, Tifton, exhibited leaf distortion, yellow and purple discoloration at the leaf margin of older leaves, and severe stunting. Symptoms were present on nearly 30% of the plants in the field. To identify the potential agents associated, leaf tissues from two symptomatic plants were sent for high throughput sequencing (HTS) of small RNA (sRNA; DNB sequencing, SE read 1x75bp) to Beijing Genomics Institute, China. From each sample, ~ 18 million raw reads were generated. The reads with poor quality and adapter sequences were removed using CLC Genomics Workbench 21.2 (Qiagen, Germantown, MD). Of the total reads, 2,093 and 3,889 reads aligned to the genome of turnip yellows virus (TuYV) in samples one and two, respectively. Reads of turnip mosaic virus (TuMV) were also detected (data not shown). Partial sequences of TuYV assembled from samples one and two showed 89.5% and 89.9% match and 86% and 93% coverage, respectively, with the genome of the type isolate of TuYV (NC_003743) from the United Kingdom. To confirm the presence of TuYV in the samples collected from the same location, specific primers were designed targeting the P0 region (FP- 5\'ACAAAAGAAACCAG- GAGGGAATCC3\'; RP-5\'GCCTTTTCATACAAACATTTCGGTG3\') and coat protein (CP) region (FP-5\'GTTAATGAATACGGTCGTGGGTAG3\'; RP-5\'ATTCTGAAAGAACCAGCT- ATCGATG3\') of the virus. Eight of 20 (40%) symptomatic samples were determined to be infected with TuYV based on the amplification of expected size products of the P0 (786 nt) and the CP gene (581 nt) in reverse transcription-PCR (RT-PCR). All samples were also tested for the presence of TuMV by RT-PCR as in Sanchez et al. (2003), but none tested positive despite being identified in HTS. Symptoms on samples from which eithervirus could not be detected indicates the involvement of other factors and would require further studies. The partial P0 and CP gene amplicons of TuYV from two samples each were Sanger sequenced bi-directionally at Genewiz (South Plainfield, NJ) and confirmed as TuYV using BLASTn. The partial CP gene sequences from two samples shared 98.7% nucleotide sequence identity with each other and 88.0% (OK349421) and 87.1% (OK349422) identity with the type isolate. The partial P0 gene sequences (OK349423 and OK349424) shared 99.6% nucleotide sequence identity with each other and 92.2% identity with the type isolate. TuYV, formerly known as beet western yellows virus (BWYV) (Mayo, 2002), genus Palerovirus, family Solemoviridae (Walker et al., 2021), is transmitted persistently by aphids (Stevens et al., 2008), and is distributed throughout temperate regions of the world (Kawakubo et al., 2021). TuYV has a wide host range, including brassica, vegetables and weeds (Stevens et al., 2008). However, losses have been reported primarily on canola (B. napus) in Australia (Jones, 2007) and Europe (Stevens et al., 2008). On cabbage, TuYV infections have been reported from China (Zhang et al., 2016), Serbia (Milošević et al., 2020) and the Philippines (Buxton-Kirk et al, 2020). TuYV (BWYV) has been found infecting shepherd\'s purse (Capsella bursa-pastoris) in California (Falk and Duffus, 1984), but there are no reports of the virus from any cultivated crops in the USA. To our knowledge, this is the first report of TuYV in cabbage in the USA. More studies are needed to understand its occurrence and impact on cabbage crops in Georgia as well as other regions in the USA.
摘要：
在2021年春季，卷心菜（甘蓝变种。capitata）种植在乔治亚大学的研究农场，Tifton,表现出叶片变形，老叶叶缘的黄色和紫色变色，和严重的发育迟缓。在田间近30%的植物上存在症状。为了识别相关的潜在代理，将来自两个有症状植物的叶片组织进行小RNA的高通量测序（HTS）（sRNA；DNB测序，SE读数1x75bp)到北京基因组研究所，中国。从每个样本中，产生约1800万个原始读数。使用CLCGenomicsWorkbench21.2（Qiagen，日耳曼敦,MD）。在总阅读量中，2,093和3,889个读数与样品1和2中萝卜黄化病毒（TuYV）的基因组对齐，分别。还检测到萝卜花叶病毒(TuMV)的读数(数据未显示)。从样品1和2组装的TuYV的部分序列显示89.5%和89.9%的匹配以及86%和93%的覆盖率，分别,与来自英国的TuYV型分离物(NC_003743)的基因组。为了确认从同一地点收集的样本中是否存在TuYV，设计针对P0区(FP-5\'ACAAAAGAAAACCAG-GAGGGAATCC3\';RP-5\'GCCTTTTCATCAATTCATCGGTG3\')和外壳蛋白(CP)区(FP-5基于逆转录-PCR(RT-PCR)中P0(786nt)和CP基因(581nt)的预期大小产物的扩增,确定20个(40%)有症状样品中的8个被TuYV感染。如Sanchez等人所述,还通过RT-PCR测试所有样品中TuMV的存在。(2003),但尽管在HTS中被发现，但没有人检测为阳性。无法检测到其他病毒的样本症状表明涉及其他因素，需要进一步研究。来自两个样品的TuYV的部分P0和CP基因扩增子分别在Genewiz（SouthPlainfield，NJ），并使用BLASTn确认为TuYV。来自两个样品的部分CP基因序列彼此具有98.7%的核苷酸序列同一性,并且与类型分离物具有88.0%(OK349421)和87.1%(OK349422)的同一性。部分P0基因序列(OK349423和OK349424)彼此具有99.6%的核苷酸序列同一性,并且与类型分离物具有92.2%的同一性。TuYV,以前被称为甜菜西部黄化病毒(BWYV)(梅奥，2002),古病毒属,纯病毒科(Walker等人。,2021),由蚜虫持续传播(Stevens等人，,2008),并分布在世界各地的温带地区(Kawakubo等人。,2021)。TuYV具有广泛的主机范围，包括芸苔属,蔬菜和杂草(Stevens等人。,2008).然而,据报道，损失主要是在油菜上(B.napus)在澳大利亚(琼斯，2007)和欧洲(史蒂文斯等人。,2008).关于卷心菜，中国已经报道了TuYV感染(Zhang等人。,2016),塞尔维亚(米洛舍维奇等人。,2020)和菲律宾(Buxton-Kirk等人，2020）。TuYV（BWYV）被发现感染加利福尼亚州（Falk和Duffus，1984),但是在美国没有任何种植作物的病毒报道。据我们所知,这是TuYV在美国卷心菜中的第一份报告。需要更多的研究来了解其对佐治亚州以及美国其他地区的白菜作物的发生和影响。
