COAT PROTEIN GENE AND 3'-NONCODING REGION OF A NEW KOREAN ISOLATE OF CYMBIDIUM MOSAIC-VIRUS

A new Korean isolate of cymbidium mosaic virus (denoted as CymMV-K2), a member of potexviruses, was identified and isolated from a Korean cu ltivar of Cymbidium species When the nucleotide sequence of the 3'-ter minal region of the viral RNA was compared with those of the correspon ding regions of two Singaporean isolates (denoted as CymMV-S1 and CymM V-S2) and a Korean isolate (denoted as CymMV-K1), the nucleotide seque nce of the coat protein gene of CymMV-K2 was highly homologous to othe r cymbidium mozaic viruses (92.9%-96.7% homology). The coat protein of CymMV-K2 and CymMV-S2 consists of 223 amino acids, while the coat pro tein of CymMV-K1 and CymMV-S1 consists of 220 amino acids. This differ ence was caused by deletions of 5 nucleotides in the coat protein open reading frame (ORF) of CymMV-S1 and CymMV-K1, when compared with CymM V-K2 and CymMV-S2, These deletions result in changes of the deduced am ino acid sequence and the length of the coat protein. The 3'-noncoding region of the CymMV-K2, which contains sequences involved in the repl ication and polyadenylation of viral RNA, was compared with those of o ther cymbidium mosaic viruses. No canonical polyadenylation signal was found in the 3'-noncoding region of CymMV-K2, whereas in other CymMVs AAUAAA boxes are present at the end of RNA with their AAA portions as the first A residue of the poly(A) tail.