Complete nucleotide sequences and genome characterization of double-stranded RNA 1 and RNA 2 in the Raphanus sativus-root cv. yipinghong

Four distinct double-stranded (ds) RNA bands were extracted from leaves of Raphanus sativus-root cv. Yipinghong with yellowing at the leaf edge in China. Purified viral particles of 28–30 nm in diameter contained dsRNA segments with the same number and mobility as these extracted directly from radish leaves. The two major dsRNA segments, namely RasR 1 and RasR 2, were 1866 and 1791 bp in length, respectively. Computer analysis predicted that they both contained a single open reading frame (ORF) on their plus-stranded RNA, putatively encoding a RNA dependent RNA polymerase and a capsid protein similar to that encoded by members of the family Partitiviridae. In addition, both RasR 1 and RasR 2 were highly conserved at the 5′ untranslated regions (UTR) and had an adenosine-uracil rich stretch at the 3′ UTR, with an identical terminal motif (5′-AAAAUAAAACC-3′). Taken together, these results suggest that the two major dsRNA segments constitute the genome of a partitivirus infecting radish.