Diaz M, Maxwell D P, Karkashian J P, Ramírez P
Universidad de Costa Rica, San Jose, Costa Rica.
University of Wisconsin, Madison 53706.
Plant Dis. 2002 Feb;86(2):188. doi: 10.1094/PDIS.2002.86.2.188B.
Bean golden yellow mosaic virus (BGYMV, GenBank Accession No. M91604) is reported to be the main bean-infecting (Phaseolus vulgaris) begomovirus in Central America (1,2). Another begomovirus, Bean calico mosaic virus (BCaMV, GenBank Accession No. AF110189), is known to infect P. vulgaris in central Mexico. Bean samples with the viral symptom of foliar chlorosis were collected in different regions of Costa Rica from 1994 to 2001. Total nucleic acids were extracted and tested using polymerase chain reaction (PCR) with degenerate primer pair PBL1v2039/PCRc2 for DNA-B, which can give a different fragment size for some begomoviruses (4). PCR fragments were obtained from 119 bean samples. Fifty samples from the central valley produced 600-bp PCR fragments, which is typical for BGYMV (4), and one sample produced two fragments (500 and 600 bp). One sample from western Costa Rica had a 550-bp fragment, and 69 samples from the western and northern regions produced 500-bp fragments. One of the latter samples (No. 01-1152) was selected for PCR with degenerate primer pairs PAL1v1978/PAR1c715 for DNA-A and PBL1v2039/PBR1v800 for DNA-B (4). The amplified PCR fragments were 1.35 and 1.4 kb for DNA-A and DNA-B, respectively. These are expected sizes for a Western Hemisphere begomovirus. The DNA-A fragment was cloned and sequenced (GenBank Accession No. AF439402). Sequence comparisons indicated that this uncharacterized begomovirus (No. 01-1152) had 98, 97, and 93% nucleotide identities with the rep gene, common region, and coat protein gene promoter of Calopogonium golden mosaic virus (CalGMV, GenBank Accession Nos. AF439748 and AF439749, respectively) (3). CalGMV had been isolated from a weed, Calopogonium sp., collected in 1991 near Quepos in the west and Tilaran in the north of Costa Rica (3). Phylogenetic analysis of the viral sequence of the begomovirus associated with No. 01-1152 placed it in the Squash leaf curl virus clade (1). BCaMV is also in this phylogenetic clade, but sequence comparisons between CalGMV and BCaMV had <90% nucleotide identity, and so are distinct species. CalGMV is the begomovirus associated with No. 01-1152, and this is an example of the movement of a weed-infecting begomovirus into an agricultural crop. Since this Calopogonium sp. is widespread in Central America, it is important to determine if CalGMV is present in beans in other regions. The data also indicate that BGYMV and CalGMV infect beans in two geographically distinct regions of Costa Rica. References: (1) J. C. Faria et al. Phytopathology 84:321, 1994. (2) W. McLaughlin et al. Plant Dis. 78:1220, 1994. (3) M. R. Rojas et al. Annu. Rep. Bean Improv. Coop. 35:150, 1992. (4) M. R. Rojas et al. Plant Dis. 77:340, 1993.
菜豆金黄花叶病毒（BGYMV，GenBank登录号：M91604）据报道是中美洲主要感染菜豆（Phaseolus vulgaris）的双生病毒（1,2）。另一种双生病毒，菜豆花斑花叶病毒（BCaMV，GenBank登录号：AF110189），已知在墨西哥中部感染菜豆。1994年至2001年期间，在哥斯达黎加的不同地区采集了具有叶片黄化病毒症状的菜豆样本。提取总核酸并使用针对DNA-B的简并引物对PBL1v2039/PCRc2进行聚合酶链反应（PCR）检测，该引物对对于某些双生病毒可产生不同大小的片段（4）。从119个菜豆样本中获得了PCR片段。来自中央山谷的50个样本产生了600 bp的PCR片段，这是BGYMV的典型片段（4），还有一个样本产生了两个片段（500和600 bp）。来自哥斯达黎加西部的一个样本有一个550 bp的片段，来自西部和北部地区的69个样本产生了500 bp的片段。从后者的样本之一（编号01 - 1152）中选择用于针对DNA-A的简并引物对PAL1v1978/PAR1c715和针对DNA-B的PBL1v2039/PBR1v800进行PCR（4）。扩增的PCR片段对于DNA-A和DNA-B分别为1.35和1.4 kb。这些是西半球双生病毒的预期大小。DNA-A片段被克隆并测序（GenBank登录号：AF439402）。序列比较表明，这种未鉴定的双生病毒（编号01 - 1152）与Calopogonium golden mosaic virus（CalGMV，GenBank登录号分别为AF439748和AF439749）的rep基因、共同区域和外壳蛋白基因启动子具有98%、97%和93%的核苷酸同一性（3）。CalGMV于1991年从一种杂草Calopogonium sp.中分离出来，该杂草采集于哥斯达黎加西部的克波斯附近和北部的蒂拉兰（3）。对与编号01 - 1152相关的双生病毒的病毒序列进行系统发育分析，将其置于南瓜曲叶病毒进化枝中（1）。BCaMV也在这个系统发育进化枝中，但CalGMV和BCaMV之间的序列比较核苷酸同一性小于90%，因此是不同的物种。CalGMV是与编号01 - 1152相关的双生病毒，这是一种感染杂草的双生病毒转移到农作物中的一个例子。由于这种Calopogonium sp.在中美洲广泛分布，确定CalGMV是否存在于其他地区的菜豆中很重要。数据还表明BGYMV和CalGMV在哥斯达黎加的两个地理上不同的地区感染菜豆。参考文献：（1）J. C. Faria等人，《植物病理学》84:321，1994年。（2）W. McLaughlin等人，《植物病害》78:1220，1994年。（3）M. R. Rojas等人，《菜豆改良合作年报》35:150，1992年。（4）M. R. Rojas等人，《植物病害》77:340，1993年。
