Comparison of Genome Sequence of PVY Isolates with Biological Properties

The whole RNA genomes of six European Potato virus Y (PVY) isolates, representing isolates of the PVY O , PVY N and PVY NTN subgroups, were sequenced and the reactions of a range of tobacco and potato cultivars after the inoculation were determined. One isolate induced symptoms of veinal necrosis when inoculated to tobacco, but reacted with PVY O - specific antibodies. The genome sequence of this isolate showed that it had a recombinant genome comprising large sections of sequence that are characteristic of N and O sub-group isolates. Another isolate caused mosaic symptoms when inoculated to tobacco, and reacted with PVY N - specific antibodies. The nucleotide sequence of its genome was very closely related to the genome sequence published for two potato-infecting PVY isolates from North America. These three isolates are the members of interesting group NA (North American). They have highly similar genome sequences throughout their length, but biologically represent isolates from the PVY O , PVY N and PVY NTN subgroups. The occurrence of these biologically diverse isolates with their highly homologous genomes brings into question the exact nature of gene structure in relation to function.