Department of Plant Biology, Genetic Centre, SLU, P.O. Box 7080, S-750 07 Uppsala, Sweden
Because there were no previous reports on the molecular characterization of Potato virus V (PVV, genus Potyvirus, family Potyviridae), the complete genomic sequence of PVV isolate Dv42 was determined. The length of the single-stranded messenger-polarity RNA genome was 9,851 nt (nucleotides), followed by a poly(A) tail. The genome contained a 5′-terminal nontranslated region (5′-NTR; 204 nt), a single open reading frame (nucleotides 205-9406; 3,067 amino acids), and a 3′-NTR that was unusually long (446 nt) compared with that of Potato virus Y (PVY; 331-nt 3′-NTR), Potato virus A (PVA; 207-nt 3′-NTR), and other potyviruses that naturally infect Solanaceae species. Phylogenetic analysis with the cylindrical inclusion protein-encoding and coat protein (CP)-encoding regions indicated that PVV Dv42 was most closely related to Pepper mottle virus and PVY, respectively. Seven PVV isolates (including Dv42) collected from cultivated potatoes in the Netherlands, the United Kingdom, and Norway from 1964 to 1997 were uniform in serological properties and symptomatology in indicator hosts that could distinguish strains of PVY and PVA. The nucleotide sequences of the 5′-NTR, P1, CP, and 3′-NTR regions of the PVV isolates were determined and were 94.6 to 99.5, 96.3 to 98.8, 96.4 to 98.7, and 96.3 to 99.6% identical, respectively. The amino acid similarities for the P1 and CP were 95.8 to 98.6 and 96.0 to 97.8%, respectively. Phylogenetic analysis of the CP sequences of PVV revealed no significant grouping, in contrast to PVY and PVA, which were grouped largely according to the previously recognized strains based on host responses. However, the relatively few differences in the P1 sequences of PVV were correlated with the different countries of origin. Hence, the PVV isolates infecting potatoes in Europe seem to vary little genetically and may belong to a single strain.