Nischwitz C, Gitaitis R D, Mullis S W, Csinos A S, Langston D B, Sparks A N
University of Georgia, Department of Plant Pathology, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31794.
University of Georgia, Department of Entomology, Cooperative Extension Service, Tifton 31793-1209.
Plant Dis. 2007 Nov;91(11):1518. doi: 10.1094/PDIS-91-11-1518C.
Iris yellow spot virus (IYSV) is a member of the genus Tospovirus in the family Bunyaviridae. Its known host range is very limited, and the currently known hosts include onion, leek, lisianthus, and alstroemeria (2). The virus is vectored by onion thrips (Thrips tabaci). Onion (Allium cepa) is grown as a winter crop in Georgia from September to April and is the only known host commercially grown in the region. However, the virus has been found across the onion-growing region in the state every year since its first occurrence during 2003 (3). Consequently, the virus must oversummer in other host(s) or its insect vector. Accordingly, samples of weeds were collected in the vicinity of onion fields and cull piles in the Vidalia region and tested for the presence of IYSV by a double-antibody sandwich (DAS)-ELISA (Agdia, Inc., Elkhart, IN). One of three nonsymptomatic spiny sowthistle samples tested positive by ELISA for IYSV. Total RNA was extracted from the leaf using the RNeasy Plant Mini Kit (Qiagen, Valencia, CA) following the manufacturer's protocol. Two microliters were used for reverse transcription (RT)-PCR with the forward primer (5'-TCAGAAATCGAGAAACTT-3') and reverse primer (5'-TAATTATATCTATCTTTCTTGG-3') for the IYSV nucleocapsid gene (1). A band of the expected size (approximately 800 bp) was obtained and sequenced. The sequence from the sowthistle (GenBank Accession No. EU078327) matched IYSV sequences from Georgia and Peru in a BLAST search in GenBank (closest matches with Accession Nos. DQ838584, DQ838592, DQ838593, and DQ658242). This is to our knowledge, the first confirmed report of IYSV infecting spiny sowthistle. The distribution of IYSV in sowthistle and its role as an oversummering host for IYSV is currently an on-going study. References: (1) L. du Toit et al. Plant Dis. 88:222, 2004. (2) D. H. Gent et al. Plant Dis. 90:1468, 2006. (3) S. W. Mullis et al. Plant Dis. 88:1285, 2004.
鸢尾黄斑病毒（IYSV）是布尼亚病毒科番茄斑萎病毒属的成员。其已知宿主范围非常有限，目前已知的宿主包括洋葱、韭菜、洋桔梗和六出花（2）。该病毒由葱蓟马（西花蓟马）传播。洋葱（Allium cepa）在佐治亚州作为冬季作物于9月至次年4月种植，是该地区唯一已知的商业种植宿主。然而，自2003年首次出现以来，每年在该州的洋葱种植区都能发现这种病毒（3）。因此，该病毒必须在其他宿主或其昆虫媒介中度过夏季。据此，在维达利亚地区的洋葱田和剔除堆附近采集了杂草样本，并通过双抗体夹心（DAS）-ELISA（Agdia公司，印第安纳州埃尔克哈特）检测是否存在IYSV。三个无症状刺儿菜样本中有一个通过ELISA检测出IYSV呈阳性。按照制造商的方案，使用RNeasy植物微量提取试剂盒（Qiagen公司，加利福尼亚州瓦伦西亚）从叶片中提取总RNA。取两微升用于对IYSV核衣壳基因进行逆转录（RT）-PCR，正向引物为（5'-TCAGAAATCGAGAAACTT-3'），反向引物为（5'-TAATTATATCTATCTTTCTTGG-3'）（1）。获得了预期大小（约800 bp）的条带并进行了测序。在GenBank中进行BLAST搜索时，刺儿菜的序列（GenBank登录号EU078327）与来自佐治亚州和秘鲁的IYSV序列匹配（与登录号DQ838584、DQ838592、DQ838593和DQ658242的最接近匹配）。据我们所知，这是IYSV感染刺儿菜的首次确诊报告。IYSV在刺儿菜中的分布及其作为IYSV越夏宿主的作用目前正在研究中。参考文献：（1）L. du Toit等人，《植物病害》88:222，2004年。（2）D. H. Gent等人，《植物病害》90:1468，2006年。（3）S. W. Mullis等人，《植物病害》88:1285，2004年。
