Comparison of coat protein genes of Cymbidium mosaic virus and Odontoglossum ringspot virus from Phalaenopsis and Cymbidium in Korea.

摘要

Of more than 50 orchid viruses, the Potexvirus Cymbidum mosaic virus (CymMV) and the Tobamovirus Odontoglossum ringspot virus (ORSV) are the 2 most prevalent and economically important viruses that have attained a worldwide distribution. To detect possible molecular heterogeneity, the coat protein (CP) gene sequences of CymMV and ORSV infecting different genera of orchids from geographically distinct isolates were determined. The variabilities in the coat protein gene (CP) sequences of CymMV and ORSV that infect Phalaenopsis and Cymbidium orchids were investigated. Infected leaf samples of Phalaenopsis and Cymbidium were screened by RT-PCR with specific primers to both viruses. RT-PCR products of the viruses were cloned and their nucleotide sequences were determined. All determined CymMV CP genes have the same size of amino acid sequences (216 a.a), except for one clone derived from Cymbidium in Korea (197 a.a). The sequence data were compared to available published coat protein gene sequences of CymMV and ORSV, including those from Korea, Singapore, Japan and Thailand. Multiple alignments of CP genes of the viruses revealed that over 66.4 and 91.8% amino acid sequence identities with CymMV and ORSV, respectively, were observed. Such high sequence conservation suggested that both CymMV and ORSV CP genes were suitable candidates to provide resistance in orchids cultivated in different geographical locations. CP mediated resistance has been a widely used pathogen derived resistance strategy and its success in producing a broad ranging virus resistant orchid would depend on the sequence similarity between the transgenes and the virus infecting the plant..