Fernandes-Acioli N A N, Pereira-Carvalho R C, Fontenele R S, Lacorte C, Ribeiro S G, Fonseca M E N, Boiteux L S
Universidade de Brasília (UnB), Departamento de Fitopatologia, 70910-900, Brasília-DF, Brazil.
Embrapa Recursos Genéticos and Biotecnologia, CP 2372, 70770-900, Brasília-DF, Brazil.
Plant Dis. 2011 Sep;95(9):1196. doi: 10.1094/PDIS-05-10-0343.
Snap and common beans (Phaseolus vulgaris L.) are severely affected by Bean golden mosaic virus (BGMV) infection, so far the only begomovirus reported on these crops in Brazil (1). Samples of snap and common beans colonized by the whitefly Bemisia tabaci biotype B and displaying golden mosaic, chlorotic spots, and leaf distortion were collected in three production regions in Goiás State (Goianápolis, Luziânia, and Itaberaí) between 2003 and 2007. Total DNA extracted from leaf samples was used as template in PCR assays using universal primers targeting conserved regions of the DNA-A and DNA-B genomes (3). Begomovirus-specific amplicons were observed only with DNA template from symptomatic plants. Two single amplicons were observed for both genomic segments, indicating the presence of bipartite species in all samples. Sequence analysis of four isolates (named as GO-176, GO-260, GO-354, and GO-368) obtained from common bean samples indicated identity levels of approximately 95% with the DNA-A segment of BGMV (GenBank Accession No. FJ665283). However, the complete DNA-A sequence (GenBank Accession No. HM357459.1) of the GO-060 isolate (from a symptomatic snap bean plant collected in Goianápolis) displayed 76% identity with BGMV (GenBank Accession No. FJ665283) and 95% identity with the DNA-A of a Sida micrantha mosaic virus (SimMV) isolate (GenBank Accession No. EU908733.1) reported to be infecting okra (Abelmoschus esculentus L.) and 94.8% with a SimMV isolate reported to be infecting soybean (GenBank Accession No. FJ686693) in Brazil (2). Koch's postulates were fulfilled for the isolate GO-060 by inoculating a set of soybean and bean accessions via a biolistic approach. The ratio of positive PCR amplicons per total of inoculated plants were 15 of 16 for snap bean cv. Trepador, 9 of 10 for snap bean cv. Fartura, 18 of 24 for common bean cv. Olate Pinto, and 19 of 25 for common bean cv. Carioca. The isolate was also able to infect eight of nine soybean 'Doko' plants. Sequence analysis using symptomatic leaf samples (15 days after inoculation) confirmed SimMV as the causal agent. To our knowledge, this is the first report of a SimMV isolate infecting P. vulgaris. This virus is apparently fast expanding its host range from Malvaceae to Solanaceae species and leguminous hosts after the introduction of B. tabaci biotype B (2). More extensive surveys are necessary to access the current epidemiological importance of SimMV in both snap and common beans in Brazil. References: (1) J.C. Faria and D. P. Maxwell. Phytopathology 89:262, 1999. (2) F. R. Fernandes et al. Arch. Virol. 154:1567, 2009. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993.
菜豆和普通菜豆（Phaseolus vulgaris L.）受到菜豆金色花叶病毒（BGMV）感染的严重影响，这是目前在巴西这些作物上报道的唯一一种双生病毒（1）。2003年至2007年间，在戈亚斯州的三个产区（戈亚纳波利斯、卢齐尼亚和伊塔贝赖）采集了被烟粉虱Bemisia tabaci生物型B侵染且表现出金色花叶、褪绿斑点和叶片扭曲的菜豆和普通菜豆样本。从叶片样本中提取的总DNA用作PCR检测的模板，使用针对DNA - A和DNA - B基因组保守区域的通用引物（3）。仅在有症状植株的DNA模板上观察到双生病毒特异性扩增子。两个基因组片段均观察到单一扩增子，表明所有样本中均存在双分体病毒种。对从普通菜豆样本中获得的四个分离株（命名为GO - 176、GO - 260、GO - 354和GO - 368）进行的序列分析表明，它们与BGMV的DNA - A片段（GenBank登录号FJ665283）的同一性水平约为95%。然而，GO - 060分离株（来自在戈亚纳波利斯采集的有症状菜豆植株）的完整DNA - A序列（GenBank登录号HM357459.1）与BGMV（GenBank登录号FJ665283）的同一性为76%，与报道感染秋葵（Abelmoschus esculentus L.）的微小 sida花叶病毒（SimMV）分离株（GenBank登录号EU908733.1）的DNA - A同一性为95%，与报道在巴西感染大豆（GenBank登录号FJ686693）的SimMV分离株的同一性为94.8%（2）。通过生物弹道法接种一组大豆和菜豆品种，对分离株GO - 060满足了柯赫氏法则。接种的菜豆品种Trepador中，每接种植株总数的阳性PCR扩增子比例为16株中有15株，Fartura品种为10株中有9株，普通菜豆品种Olate Pinto为24株中有18株，Carioca品种为25株中有19株。该分离株还能够感染9株大豆‘Doko’植株中的8株。使用接种后15天的有症状叶片样本进行的序列分析证实SimMV是致病因子。据我们所知，这是SimMV分离株感染菜豆的首次报道。在烟粉虱生物型B引入后，这种病毒显然正在迅速将其寄主范围从锦葵科扩展到茄科物种和豆科寄主（2）。有必要进行更广泛的调查，以了解SimMV在巴西菜豆和普通菜豆中当前的流行病学重要性。参考文献：（1）J.C. Faria和D.P. Maxwell。植物病理学89:262，1999。（2）F.R. Fernandes等人。病毒学档案154:1567，2009。（3）M.R. Rojas等人。植物病害77:340，1993。
