De La Torre-Almaráz R, Monsalvo-Reyes A C, Rivera-Bustamante R F, Méndez-Lozano J
UBIPRO, FESI, UNAM, P.O. Box 54090, Tlalnepantla, Edo. de México.
CINVESTAV-Irapuato, Irapuato, Gto., Mexico.
Plant Dis. 2003 Feb;87(2):202. doi: 10.1094/PDIS.2003.87.2.202B.
Okra is an annual vegetable species native to Africa. In Mexico, the states of Tamaulipas, Guerrero, and Morelos contain the most important okra-producing areas. Viral-like diseases have recently affected the fruit production. In the field, the most common symptoms encountered include yellow streak, distortion of fruits, and foliar yellow mottle. Total DNA extracts from symptomatic okra plants were used as a template for polymerase chain reaction (PCR)-based detection using begomovirus-specific primers. RepMot and CPMot primers (1) were used for the amplification of DNA fragments that included the Rep and coat protein (CP) genes of begomoviruses. PCR results suggested the presence of a begomovirus in symptomatic plants. Southern and dot blot hybridization analysis were performed using a DNA fragment containing the CP gene of Pepper huasteco virus as a probe. Hybridization conducted under low stringency conditions confirmed the presence of a geminivirus. Additionally, transmission by grafting and biolistic (total DNA extracts from symptomatic plants) inoculations induced consistently severe streak fruits and yellow mottle symptoms in okra plants. Cloning of the PCR products (approximately 632-bp fragment) was performed in the PCRTopo vector (Invitrogen, San Diego, CA). Cloned viral inserts were sequenced (Genbank Accession No. AF349113). Nucleotide sequence comparisons were performed using the Clustal Method (MegAlign, DNAStar software, Madison, WI) with the GenBank database. Analysis of the PCR products confirmed the begomovirus nature of the sequence. The first 64 amino acids of the CP had 89% identity with Squash leaf curl virus while the intergenic region had 85% identity with Sida golden mosaic virus. To our knowledge, this is the first report of a begomovirus infecting okra in Mexico. Reference: 1) J. T. Ascencio et al. Plant Dis. 86:692, 2002.
秋葵是一种原产于非洲的一年生蔬菜品种。在墨西哥，塔毛利帕斯州、格雷罗州和莫雷洛斯州是最重要的秋葵产区。类病毒疾病最近影响了果实产量。在田间，最常见的症状包括黄色条纹、果实变形和叶片黄化斑驳。以有症状的秋葵植株的总DNA提取物为模板，使用双生病毒特异性引物进行基于聚合酶链反应（PCR）的检测。RepMot和CPMot引物（1）用于扩增包含双生病毒Rep和外壳蛋白（CP）基因的DNA片段。PCR结果表明有症状的植株中存在双生病毒。使用含有辣椒瓦斯特科病毒CP基因的DNA片段作为探针进行Southern杂交和斑点杂交分析。在低严谨条件下进行的杂交证实了双生病毒的存在。此外，通过嫁接和生物弹道接种（有症状植株的总DNA提取物）在秋葵植株中一致诱导出严重的条纹果实和黄化斑驳症状。在PCRTopo载体（Invitrogen，加利福尼亚州圣地亚哥）中对PCR产物（约632 bp片段）进行克隆。对克隆的病毒插入片段进行测序（Genbank登录号AF349113）。使用Clustal方法（MegAlign，DNAStar软件，威斯康星州麦迪逊）与GenBank数据库进行核苷酸序列比较。对PCR产物的分析证实了该序列的双生病毒性质。CP的前64个氨基酸与南瓜曲叶病毒有89%的同一性，而基因间隔区与黄细心金色花叶病毒有85%的同一性。据我们所知，这是墨西哥首次报道双生病毒感染秋葵。参考文献：1）J. T. Ascencio等人，《植物病害》86:692，2002年。
