Eastwell K C, Glass J R, Seymour L M, Druffel K J
Washington State University, Prosser.
Washington State University, Puyallup.
Plant Dis. 2008 Dec;92(12):1710. doi: 10.1094/PDIS-92-12-1710C.
A commercial field of celery (Apium graveolens var. dulce) cvs. Conquistador and Sabroso was planted with sets between 1 June and 10 July 2004 in Pierce County in western Washington (WA). In late August, many plants were stunted and showed chlorotic line patterns. One symptomatic plant and five nonsymptomatic plants were transferred to a greenhouse and grown at 22°C with supplemental lighting to extend day length to 16 h; foliage was trimmed back. The symptomatic plant and three nonsymptomatic plants developed a distinctive chlorotic line pattern when new foliage emerged in February. Two plants remained nonsymptomatic. Young foliage was tested by ELISA with the general potyvirus monoclonal antibody (Agdia, Inc., Elkhart, IN). All symptomatic plants yielded a positive result and the two nonsymptomatic plants were negative. Celery mosaic virus (CeMV) was previously reported to be widespread in WA (3), but primers specific for CeMV did not yield amplicons in reverse transcription (RT)-PCR from RNA isolated from symptomatic leaf tissue (RNeasy Plant Mini Kit: QIAGEN, Valencia, CA). General potyvirus primers (1) were used to amplify ≈1,700 nucleotides from the 3' terminus of the virus genome adjacent to the poly-A tail. Six amplicons from each of three independent reactions were cloned into pCR2.1 (Invitrogen, Carlsbad, CA) and sequenced (GenBank Accession No. FJ010827). Comparison with the nucleotide sequence database revealed 98 and 97% identity to Australian isolates of Apium virus Y (ApVY) (family Potyviridae) from parsley (GenBank Accession No. AF207594) and poison hemlock (Conium maculatum) (GenBank Accession No. AY049716) (4) and 91% identity to North American isolates of ApVY from celery and Ammi majus reported from California (GenBank Accession No. EU515126) and Florida (GenBank Accession No. EU255632), respectively. To our knowledge, this is the first report of a natural infection of celery by ApVY in WA. No other potyvirus sequences were identified in RT-PCR products from symptomatic celery. In 2008, in an effort to locate local samples of CeMV, poison hemlock plants were randomly collected in Benton, Walla Walla, and Whitman counties of eastern WA. No symptoms were observed and no CeMV was detected by RT-PCR in any of these plants. No ApVY was detected in 10 of 10 poison hemlock collected from Walla Walla County, but based on sequence analysis of RT-PCR amplicons, two of two plants collected from Benton and Whitman counties were infected with ApVY. In contrast to the WA isolates from celery, sequences from these poison hemlock plants (GenBank Accession No. FJ010828) were 98% identical to previously reported North American isolates of ApVY (GenBank Accession Nos. EU515126 and EU255632) and only 91% identical to Australian isolates (GenBank Accession Nos. AF207594 and AY049716). To our knowledge, this is the first report of ApVY in WA and the first report of a natural infection of poison hemlock in the United States. The celery and poison hemlock isolates reported in this study were from different geographic regions of the state and were only 91% identical. As is the case for other potyviruses (2), weeds such as poison hemlock may serve as a reservoir of ApVY in eastern WA where many plants of the family Apiaceae are grown commercially. References: (1) J. Chen et al. Arch. Virol. 146:757, 2001. (2) W. E. Howell and G. I. Mink. Plant Dis. Rep. 61:217, 1977. (3) W. E. Howell and G. I. Mink. Plant Dis. 65:277, 1981. (4) J. Moran et al. Arch. Virol. 147:1855, 2002.
2004年6月1日至7月10日期间，在华盛顿州西部的皮尔斯县，一片种植了“征服者”和“萨布罗索”芹菜品种的商业田地用芹菜苗定植。8月下旬，许多植株生长受阻，呈现出褪绿线条状斑纹。将1株有症状植株和5株无症状植株转移至温室，在22°C条件下培养，并补充光照使日照时长延长至16小时；对叶片进行了修剪。2月新叶长出时，有症状植株和3株无症状植株出现了独特的褪绿线条状斑纹。另外2株植株仍无症状。用通用马铃薯Y病毒单克隆抗体（Agdia公司，印第安纳州埃尔克哈特）通过酶联免疫吸附测定法（ELISA）对幼叶进行检测。所有有症状植株检测结果呈阳性，2株无症状植株检测结果为阴性。芹菜花叶病毒（CeMV）此前报道在华盛顿州广泛存在（3），但针对CeMV的引物未能从有症状叶片组织分离的RNA（RNeasy植物微型试剂盒：QIAGEN公司，加利福尼亚州瓦伦西亚）通过逆转录（RT）-PCR扩增出扩增子。使用通用马铃薯Y病毒引物（1）从病毒基因组3'末端紧邻多聚腺苷尾处扩增出约1700个核苷酸。将三个独立反应中每个反应的六个扩增子克隆到pCR2.1（Invitrogen公司, 加利福尼亚州卡尔斯巴德）中并进行测序（GenBank登录号FJ010827）。与核苷酸序列数据库比对发现，与来自欧芹（GenBank登录号AF207594）和毒芹（Conium maculatum）（GenBank登录号AY049716）的澳大利亚芹菜Y病毒（ApVY）（马铃薯Y病毒科）分离株有98%和97%的同一性，与分别来自加利福尼亚州（GenBank登录号EU515126）和佛罗里达州（GenBank登录号EU255632）报道的北美芹菜和大阿米芹的ApVY分离株有91%的同一性。据我们所知，这是华盛顿州芹菜被ApVY自然感染的首次报道。在有症状芹菜的RT-PCR产物中未鉴定出其他马铃薯Y病毒序列。2008年，为了找到CeMV的本地样本，在华盛顿州东部的本顿县、沃拉沃拉县和惠特曼县随机采集了毒芹植株。未观察到症状，通过RT-PCR在这些植株中均未检测到CeMV。从沃拉沃拉县采集的10株毒芹中未检测到ApVY，但根据RT-PCR扩增子的序列分析，从本顿县和惠特曼县采集的2株植株中有2株感染了ApVY。与来自华盛顿州芹菜的分离株不同，这些毒芹植株的序列（GenBank登录号FJ010828）与先前报道的北美ApVY分离株（GenBank登录号EU515126和EU255632）有98%的同一性，与澳大利亚分离株（GenBank登录号AF207594和AY049716）只有91%的同一性。据我们所知，这是华盛顿州ApVY的首次报道以及美国毒芹自然感染的首次报道。本研究报道的芹菜和毒芹分离株来自该州不同地理区域，同一性仅为91%。与其他马铃薯Y病毒情况一样（2），毒芹等杂草可能是华盛顿州东部ApVY的储存宿主，该地区有许多伞形科植物商业化种植。参考文献：（1）J. Chen等人，《病毒学档案》146:757，2001年。（2）W. E. Howell和G. I. Mink，《植物病害报告》61:217，1977年。（3）W. E. Howell和G. I. Mink，《植物病害》65:277，1981年。（4）J. Moran等人，《病毒学档案》147:1855，2002年。
