Biological and molecular characterization of a recombinant isolate of Potato virus Y associated with a tomato necrotic disease occurring in Italy

The biological and molecular characterization of a Potato virus Y (PVY) isolate, denoted PVY(C)-to, associated with a necrotic phenotype of tomato plants grown in the province of Foggia (Apulia, southern Italy) is reported. The fully sequenced PVY(C)-to genome consists of 9,691 nucleotides and is 94,8% similar to that of PVY LYE84.2, an isolate of the PVY(C) strain group. Using programs in RDP package, a putative recombination breakpoint was identified at approximately nucleotide position 2056 to 2632, corresponding to the HC-Pro/P3 coding region. The event seems to represent an introgression of a PVY strain group sequence and, in particular, of PVY-OZ, which is a non recombinant isolate of the 0 lineage. From this analysis PVY(C)-to appeared to be a recombinant isolate. The virus has a very weak infectivity in pepper and possesses a CP coding region characterised by a PVY(C2) restrictotype. Our results seem to support the hypothesis that PVY(C)-to is a recombinant isolate of the PVY(C2) strain group.