Rosner, A., Virology Department, ARO, Volcani Center, Bet Dagan 50250, Israel
Maslenin, L., Virology Department, ARO, Volcani Center, Bet Dagan 50250, Israel

Potato virus Y (PVY) isolates from potato were divided into two major groups - I and II - on the basis of nucleotide sequence variability at the 5′-UTR of the virus genome. In this paper, a consensus sequence for each group was compiled by examining PVY isolates of potato. The consensus sequences of the two groups differed from each other by as much as 31% of nucleotide sequence divergence. However, sequences of most individual members within each group (except for one, the 605 strain) were conserved and varied by less than 1% in group II and up to 6% in group I. These results confirm that the two virus groups are markedly distinct but that the 5′-UTR sequence of individual members within each group is highly conserved. These findings imply that the 5′-UTR can be reliably applied for major grouping of isolates but that its use for discrimination among individual isolates within each group is limited. Isolates of both group I and II included members of the O/N-NTN virus types. Classification of PVY isolates in potato is discussed. © 2007 EAPR.