Nucleotide Sequence Analysis of RNA-3 and RNA-4 of Beet Necrotic Yellow Vein Virus, Isolates F2 and G1

Abstract
The nucleotide sequences of complementary DNA (cDNA) clones corresponding to RNA-3 and RNA-4 of beet necrotic yellow vein virus isolates F2 and G1 were determined. The cDNA of RNA-3 of isolate F2 is 1775 residues in length and contains a coding region of 219 codons. In isolate G1 this coding region has undergone an internal deletion of 354 nucleotides in such a way as to conserve a shortened reading frame. Otherwise, the RNA-3 sequences of the 2 isolates were closely similar. RNA-4 of isolate F2 has an extrapolated length of 1431 residues and contains an open reading frame of 282 codons. This open reading frame has undergone an internal deletion of 324 nucleotides in 1 cDNA clone of RNA-4(G1) with conservation of a shortened reading frame. Sequence analysis of other RNA-4(G1) cDNA clones revealed, that the exact boundaries of the deletion are not always the same. RNA-3 and RNA-4 of each isolate are > 90% homologous for the 3''-terminal 200 nucleotides. Short homologous sequences are also present in RNA-3 and RNA-4 of isolate F2 flanking the regions deleted in each of these RNA in the G1 isolate. These homologous sequences probably play a role in the deletion process.