Chiang B-T, Nakhla M K, Maxwell D P, Schoenfelder M, Green S K
Asian Vegetable Research and Development Center (AVRDC), Shunhua Tainan, Taiwan, ROC.
Department of Plant Pathology, University of Wisconsin, Madison 53706.
Plant Dis. 1997 Jan;81(1):111. doi: 10.1094/PDIS.1997.81.1.111B.
Leaf samples of tomato exhibiting yellow mottle, severe leaf curl, stunting, and upright stems were collected from Makutupora, Tanzania, in October 1994 by L. L. Black (AVRDC). Leaf tissue squashes on nylon membranes did not hybridize with DNA-A probes from tomato yellow leaf curl geminiviruses (TYLCVs) from Thailand (Thai) or Egypt (EG), an isolate of TYLCV-Isr (Israel). Polymerase chain reaction (PCR) with primer pair PAC1v1978/PAV1c715 (2), which specifically amplifies part of the rep (AC1) open reading frame (ORF), the intergenic region, and the cp (AV1) ORF of whitefly-transmitted geminiviruses, yielded a 1.5-kb fragment from a DNA extract of symptomatic tomato leaves. No virus-specific fragments were amplified from symptomless tomato leaves. The nucleotide sequence (GenBank accession no. U73478) of the PCR fragment (recombinant plasmid pAF1) was compared with the sequences of seven distinct subgroup III geminiviruses that infect tomato (1)-TYLCV-Isr, TYLCV-Sar (Sardinia), TYLCV-Thai, tomato leaf curl virus (TLCV)-;Aus (Australia), IndTLCV (India), TLCV-Ind (Bangalore I), and TLCV-Tai (Taiwan)-as well as three other subgroup III geminiviruses from the Old World: Indian cassava mosaic virus, African cassava mosaic virus, and mung bean yellow mosaic virus. Nucleotide sequence identities for the pairwise comparisons of the rep ORF (692 nucleotides) and the intergenic region (169 nucleotides) of this Tanzanian geminivirus with those of the 10 Old World geminiviruses showed low nucleotide identities, which were <79% for the rep ORF and <67% for the intergenic region. Since isolates of the same geminivirus usually have nucleotide sequence identities >90% (1), this Tanzanian geminivirus is considered to be different from all previously characterized Old World geminiviruses and is given the name TLCV-Tan. Further, tissue squash blots of samples previously collected from other areas in Tanzania gave strong positive reactions with the TYLCV-EG probe, so yet another geminivirus closely related to TYLCV-Isr may be present. References: (1) M. Padidam et al. J. Gen. Virol. 76:249, 1995. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
1994年10月，L. L. 布莱克（国际热带农业中心）从坦桑尼亚的马库图波拉采集了表现出黄色斑驳、严重叶片卷曲、发育迟缓以及茎直立的番茄叶片样本。尼龙膜上的叶片组织压片未与来自泰国（泰国）、埃及（埃及）的番茄黄化曲叶双生病毒（TYLCV）的DNA - A探针以及TYLCV - Isr（以色列）的分离株发生杂交。使用引物对PAC1v1978/PAV1c715（2）进行聚合酶链反应（PCR），该引物对可特异性扩增粉虱传播双生病毒的rep（AC1）开放阅读框（ORF）的部分、基因间隔区以及cp（AV1）ORF，从有症状的番茄叶片DNA提取物中获得了一个1.5 kb的片段。从无症状的番茄叶片中未扩增出病毒特异性片段。将PCR片段（重组质粒pAF1）的核苷酸序列（GenBank登录号U73478）与七种感染番茄的不同亚组III双生病毒（1）的序列进行了比较——TYLCV - Isr、TYLCV - Sar（撒丁岛）、TYLCV - Thai、番茄曲叶病毒（TLCV）- ;Aus（澳大利亚）、IndTLCV（印度）、TLCV - Ind（班加罗尔I）和TLCV - Tai（台湾）——以及另外三种来自旧世界的亚组III双生病毒：印度木薯花叶病毒、非洲木薯花叶病毒和绿豆黄花叶病毒。该坦桑尼亚双生病毒的rep ORF（692个核苷酸）和基因间隔区（169个核苷酸）与这10种旧世界双生病毒的两两比较的核苷酸序列同一性显示出低核苷酸同一性，rep ORF小于79%，基因间隔区小于67%。由于同一双生病毒的分离株通常具有大于90%的核苷酸序列同一性（1），所以这种坦桑尼亚双生病毒被认为与所有先前鉴定的旧世界双生病毒不同，并被命名为TLCV - Tan。此外，先前从坦桑尼亚其他地区采集的样本的组织压片印迹与TYLCV - EG探针产生了强烈的阳性反应，因此可能存在另一种与TYLCV - Isr密切相关的双生病毒。参考文献：（1）M. Padidam等人，《病毒学杂志》76:249，1995年。（2）M. R. Rojas等人，《植物病害》77:340，1993年。
