First Report of Broad bean wilt virus 2 in Dioscorea opposita Thunb. in Korea

Abstract

HomePlant DiseaseVol. 100, No. 2First Report of Broad bean wilt virus 2 in Dioscorea opposita Thunb. in Korea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Broad bean wilt virus 2 in Dioscorea opposita Thunb. in KoreaS.-J. Kwon, I.-S. Cho, J.-Y. Yoon, S.-K. Choi, and G.-S. ChoiS.-J. KwonSearch for more papers by this author, I.-S. ChoSearch for more papers by this author, J.-Y. YoonSearch for more papers by this author, S.-K. ChoiSearch for more papers by this author, and G.-S. ChoiSearch for more papers by this authorAffiliationsAuthors and Affiliations S.-J. Kwon I.-S. Cho J.-Y. Yoon S.-K. Choi G.-S. Choi , Horticultural and Herbal Crop Environment Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 565-862, Republic of Korea. Published Online:4 Dec 2015https://doi.org/10.1094/PDIS-07-15-0752-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Broad bean wilt virus 2 (BBWV2), a member of the genus Fabavirus, infects a wide range of plants, most of which are important agricultural and horticultural crops. In May 2015, to examine BBWV2 incidence in Chinese yam fields in Korea, two open fields were randomly selected in Andong City where Chinese yam has been cultivated intensively. Chinese yam plants showing virus-like symptoms, such as mosaic, stunting, mottle, yellowing, and leaf distortion, were easily found at a relatively high incidence of 10 to 15% in the surveyed fields. A total of 40 leaf samples were collected and evaluated for the presence of BBWV2 using a commercial double-antibody sandwich (DAS)-ELISA kit that detect both Broad bean wilt virus 1 (BBWV1) and BBWV2 (Agdia, Elkhardt, IN, USA). Interestingly, all the collected samples were positive by DAS-ELISA. To confirm the result from the DAS-ELISA assay and to specify whether the samples were infected with either BBWV1 or BBWV2, reverse transcription-polymerase chain reaction (RT-PCR) was performed using two sets of the primers that amplify specifically BBWV1 (5′-TGACACATATGTGGCCATGG-3′ and 5′-CAGATTCTCAAGTTGGTGACAGG-3′) and BBWV2 (5′-CAGAGTTCAGTAGTTCCTGCTTATG-3′ and 5′-GGCATTTCAACCCTGCATAATAC-3′) as described previously (Panno et al. 2014). The RT-PCR result showed that all the samples were infected with BBWV2 and no amplification was detected when using the BBWV1-specific primer set. One of the samples infected with BBWV2 was selected to determine complete genome sequence of BBWV2 isolated from Chinese yam in Korea. Total RNA extracted from the sample infected with BBWV2 was subjected to RT reactions using the Superscript III reverse transcription (Invitrogen, Carlsbad, CA, USA) and either the primer BBWVR1-3E-Rv (5′-CCCTCACTACTGAAATTTACTT-3′, designed to hybridize to the 3′ terminus of BBWV2 RNA1), or the primer BBWVR2-3E-Rv (5′-AAAATACTACTAAAGCTTATACATATA-3′, designed to hybridize to the 3′ terminus of BBWV2 RNA2). Full-length cDNAs of BBWV RNA1 and RNA2 were amplified by PCR using Phusion high-fidelity DNA polymerase (NEB, Beverly, MA, USA) with the primer BBWV-5E-Fw (5′-GTTTTAATATTTTATTAAAACAAACAGCT-3′, designed to hybridize to the 5′ terminus of BBWV2 RNA1 and RNA2) and either the primer BBWVR1-3E-Rv or BBWVR2-3E-Rv, respectively. Sequencing of the BBWV genome and the 5′ and 3′ rapid amplification of cDNA ends (RACE) of BBWV RNAs were performed as described previously (Kwon et al. 2014). The assembled full-length sequences of RNA1 and RNA2 of BBWV2 isolated from Chinese yam were 5954 and 3598 nucleotides in length, respectively. The sequences were deposited in GenBank under the Accession Nos. KT246495 and KT246496, respectively. Nucleotide blast searches showed that RNA1 and RNA2 of the BBWV2 isolate from Chinese yam have maximum nucleotide identities of 95% to RNA1 (Accession No. KJ789136) and 95% to RNA2 (KJ789137) of the isolate SG1 of BBWV2, which was isolated from D. opposite in China. To the best of our knowledge, this is the first report of BBWV2 in Chinese yam in Korea. As a high incidence of BBWV2 in Chinese yam was found in this study, the effect of BBWV2 infection on yields of Chinese yam production needs to be evaluated by further studies. Our results also suggest that development of management practices for BBWV2 and production system for virus-free seedling is required to increase Chinese yam yield in Korea.