Strains of Potato virus Y in Dutch seed potato culture

Potato virus Y (PVY) is a growing problem in Dutch seed potato culture, with an increasing number of seed potato lots failing to meet quality standards. The reasons for this are unknown. In addition to the well-known PVYN and PVYO strains, several new strains of PVY have been reported, of which PVYNTN and PVYN-Wilga (both characterised as being between PVYN and PVYO) are the best known. In 2006, a survey for PVY strains was done on potato plant material grown in the control fields of the General Inspection Service NAK. This material is representative of Dutch seed potato stocks. In the survey, over 120 samples showing distinct PVY symptoms were collected. Each sample was tested by ELISA using polyclonal antibodies for PVY and monoclonal antibodies to distinguish PVYN from PVYO/PVYC. All ELISA-positive samples were further tested for the presence of PVYN, PVYO, PVYNTN and PVYN-Wilga by two molecular methods and in addition inoculated to a set of indicator plants. The results show that a significant shift in PVY strain populations in the Netherlands has occurred and that PVYNTN and PVYN-Wilga are more widespread than previously assumed