Differentiation of Potato virus Y strains using improved sets of diagnostic PCR-primers

Potato virus Y (PVY) is one of the most important viruses of potato world-wide, several strain groups are recognized. In the past two decades, novel PVY variants have appeared causing necrotic symptoms on potato tubers. Implicated are two groups of recombinant strains: PVYNW and PVYNTN, and NA-PVYNTN. While the first two are recombinants between PVY-N- and O-strains the latter is a recombinant between an N-strain and an unknown PVY strain or other Potyvirus. Available biological and molecular data on PVY suggest that classification of PVY strains has to be revised. Some drawbacks have been found with recently published primers used in RT-PCR based differentiation of PVY strains as some defined isolates could not be identified correctly. Consequently we developed new primers using both recently available sequences and newly generated complete sequences of PVY strains. The reliability of these newly developed primers and procedures was successfully demonstrated on nearly 100 biologically and serologically characterised PVY isolates.