A virus isolate causing symptoms of yellow mosaic, fern
leaves, malformation and plant necrosis on Rudbeckia
bicolor was prevalent around Pyeongchang area in
Korea. The causal virus was identified as Cucumber
mosaic virus (CMV) using characteristics from biological,
serological and molecular analyses and named
as CMV-Rb. CMV-Rb caused mosaic on Nicotiana
benthamiana, N. tabacum, Capsicum annuum, and Lycopersicon
esculentum. However, typical local lesions did
not develop on inoculated Pisum sativum, Cucurbita
moschata, Datura stramonium and Tetragonia expansa
plants. Full-length genome sequences of CMV-Rb
RNAs 1, 2 and 3 were obtained using 12 primer pairs by
RT-PCR analysis. The genome of CMV-Rb RNA segments
1, 2, and 3 consists of 3363nt, 3049nt, and 2214nt
in length, respectively. In order to ascertain their taxonomic
identity, nucleotide and the deduced amino acid
sequence analyses RNAs 1, 2 and 3 of CMV-Rb isolates
were conducted with previously reported sequences of
CMV strains and/or isolates. CMV-Rb RNAs showed
about 90 to 99% sequence identity to those of subgroup
I strains suggesting that CMV-Rb is more closely related
to CMV isolates belong to subgroup I. To our knowledge,
this is the first report of CMV on Rudbeckia
bicolor in Korea.