First Report of Common Beans as a Non-Symptomatic Host of Tomato severe rugose virus in Brazil

Abstract

HomePlant DiseaseVol. 101, No. 1First Report of Common Beans as a Non-Symptomatic Host of Tomato severe rugose virus in Brazil PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Common Beans as a Non-Symptomatic Host of Tomato severe rugose virus in BrazilM. A. Macedo, S. S. Barreto, T. M. Costa, M. R. Maliano, M. R. Rojas, R. L. Gilbertson, and A. K. Inoue-NagataM. A. MacedoSearch for more papers by this author, S. S. BarretoSearch for more papers by this author, T. M. CostaSearch for more papers by this author, M. R. MalianoSearch for more papers by this author, M. R. RojasSearch for more papers by this author, R. L. GilbertsonSearch for more papers by this author, and A. K. Inoue-NagataSearch for more papers by this authorAffiliationsAuthors and Affiliations M. A. Macedo S. S. Barreto T. M. Costa , Plant Pathology Department, University of Brasilia, Brasília, DF, 70910-000, Brazil M. R. Maliano M. R. Rojas R. L. Gilbertson , Plant Pathology Department, University of California, Davis, CA 95616 A. K. Inoue-Nagata , Embrapa Vegetables, Brasília, DF, 70351-970, Brazil. Published Online:27 Oct 2016https://doi.org/10.1094/PDIS-03-16-0330-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In Brazil, diseases caused by begomoviruses may lead to severe losses in common bean (Phaseolus vulgaris L.) and tomato (Solanum lycopersicum L.). In beans, the most important disease is golden mosaic caused by Bean golden mosaic virus (BGMV), although other begomovirus species, such as Sida micrantha mosaic virus and Macroptilium yellow spot virus, and various RNA viruses, can cause disease symptoms (Inoue-Nagata et al. 2016). Tomato severe rugose virus (ToSRV) is currently the predominant begomovirus found in tomatoes in Brazil (Inoue-Nagata et al. 2016). To determine if ToSRV also infects common bean, 479 samples of cv. Carioca (with or without symptoms) were randomly collected from fields nearby tomato fields in five municipalities in central Brazil (Minas Gerais, São Paulo, and Goiás) in 2013 to 2015. DNA was extracted from these samples and used in a PCR test with the degenerate begomovirus primer pair PAR1c496/PAL1v1978 (Rojas et al. 1993). Two hundred and four samples were positive for begomovirus infection (i.e., the expected ∼1.1-kb DNA fragment was amplified). These extracts were then used in another PCR with a ToSRV-specific primer pair (ToSRV1f-ToSRV2r; Fernandes et al. 2010), and 14 samples were positive (i.e., the expected 820-bp DNA fragment was amplified). Rolling circle amplification (RCA) and RFLP analysis with Msp I enzyme were performed with the 14 ToSRV-positive samples, and the patterns of the DNA fragments were identical to each other and to the pattern of a known ToSRV isolate. Direct sequencing of the RCA products of the 14 ToSRV-positive bean samples with PAR1c496, which generated sequence of the 5′ end of the capsid protein gene and the intergenic region, revealed 96 to 98% nucleotide identity with the homologous sequence of ToSRV (accession FJ824808). For one of these samples, the full-length DNA-A component was cloned and sequenced (KX458238), and the sequence shares 98% nucleotide sequence identity to that of a ToSRV isolate from tomato (FJ824808). To confirm the susceptibility of common beans to ToSRV, bean plants (cv. Topcrop) were agroinoculated with the infectious DNA-A and DNA-B clones of an isolate of ToSRV (begomovirus collection, sample 1164) from tomato (Macedo et al. 2015). Controls were bean plants (cv. Topcrop) agroinoculated with the infectious DNA-A and DNA-B clones of BGMV-BR-CAM (Gilbertson et al. 1993), tomato plants (cv. Glamour) agroinoculated with ToSRV, and bean and tomato plants agroinoculated with an empty pCAMBIA vector. Twenty-one days after agroinoculation with ToSRV, common bean plants did not show obvious symptoms, but all plants were infected based on detection of ToSRV by PCR with the specific primer pair (18/18, results of three independent experiments). Common bean and tomato plants agroinoculated with BGMV and ToSRV, respectively, developed typical symptoms, whereas plants agroinoculated with empty pCAMBIA did not show symptoms. Taken together, these results demonstrate that ToSRV induces a symptomless infection in common bean, and suggest that infected beans could serve as source of ToSRV inoculum.