Verhoeven J Th J, Jansen C C C, Roenhorst J W, Steyer S, Michelante D
Plant Protection Service, Unit Virology, P.O. Box 9102, 6700 HC Wageningen, the Netherlands.
CRA-W, Department of Biological Control and Plant Genetic Resources, Rue de Liroux 4, 5030 Gembloux, Belgium.
Plant Dis. 2007 Aug;91(8):1055. doi: 10.1094/PDIS-91-8-1055A.
During August of 2006, a sample of a tomato plant (Solanum lycopersicum, formerly Lycopersicum esculentum) from a greenhouse in Belgium was received for diagnosis. The plant showed severe growth reduction and the young leaves were chlorotic and distorted. In the greenhouse, the disease had been spreading slowly along the row. These observations suggested the presence of a viroid infection, and reverse transcriptase (RT)-PCR with two sets of universal pospiviroid primers (Pospi1-RE/FW and Vid-FW/RE; 3) yielded amplicons of the expected size (approximately 196 and 360 bp). Sequence analysis of the larger PCR product revealed that the genome was 358 nt and 100% identical to two isolates of Potato spindle tuber viroid (PSTVd) previously submitted to the NCBI GenBank (Accession Nos. AJ583449 from the United Kingdom and AY962324 from Australia). A pathogen associated with the symptomatic tomato plants was therefore identified as PSTVd. Tracing the origin of the infection revealed the following information: during November of 2005, 8-day-old tomato seedlings raised from seed by a Dutch nursery were transferred to a small part of the greenhouse of the Belgian grower; 7 to 8 weeks later, the plants were transplanted to their final destination; during May of 2006, the grower first observed growth reduction in a single plant; several weeks later, similar symptoms were observed in two more plants in the same row close to the first symptomatic plant; and by September, there were approximately 20 symptomatic tomato plants, all located in two adjacent rows. The viroid outbreak was fully eradicated by destroying all tomato plants in the affected rows as well as in two adjacent rows at both sides. The absence of further infections was confirmed by testing approximately 1,200 tomato plants in pooled samples for PSTVd by RT-PCR (2) and real-time RT-PCR (1). The origin and the method of introduction and spread of the viroid remain unclear. References: (1) N. Boonham et al. J. Virol. Methods 116:139, 2004. (2) R. A. Mumford et al. Plant Pathol. 53:242, 2004. (3) J. Th. J. Verhoeven et al. Eur. J. Plant Pathol. 110:823, 2004.
2006年8月，收到一份来自比利时某温室的番茄植株（番茄，原名为番茄属）样本用于诊断。该植株生长严重受阻，幼叶黄化且扭曲。在温室中，病害已沿行缓慢蔓延。这些观察结果表明存在类病毒感染，使用两组通用马铃薯纺锤块茎类病毒引物（Pospi1-RE/FW和Vid-FW/RE；3）进行逆转录酶（RT）-PCR扩增出预期大小的条带（约196和360 bp）。对较大PCR产物的序列分析表明，该基因组为358 nt，与之前提交至NCBI GenBank的两个马铃薯纺锤块茎类病毒（PSTVd）分离株100%相同（登录号分别为来自英国的AJ583449和来自澳大利亚的AY962324）。因此，与出现症状的番茄植株相关的病原体被鉴定为PSTVd。追溯感染源发现以下信息：2005年11月，一家荷兰苗圃用种子培育的8日龄番茄幼苗被转移至比利时种植者温室的一小部分；7至8周后，这些植株被移栽至最终种植地；2006年5月，种植者首次观察到一株植株生长受阻；几周后，在靠近第一株有症状植株的同一行中又有两株出现类似症状；到9月时，约有20株有症状的番茄植株，均位于相邻的两行。通过销毁受影响行以及两侧相邻两行的所有番茄植株，类病毒疫情被彻底根除。通过RT-PCR（2）和实时RT-PCR（1）对约1200株番茄植株的混合样本进行PSTVd检测，证实未出现进一步感染。类病毒的起源、引入和传播方式仍不清楚。参考文献：（1）N. Boonham等人，《病毒学方法杂志》116:139，2004年。（2）R. A. Mumford等人，《植物病理学》53:242，2004年。（3）J. Th. J. Verhoeven等人，《欧洲植物病理学杂志》110:823，2004年。
