Comparison of three methods for the detection of Potato virus Y in seed potato certification

Potato virus Y (PVY) is becoming increasingly important in potato growing regions worldwide. The main reason for this is an increase in the incidence of infections with recombinant forms of PVY, such as PVY(N)Wi and PVYNTN. They are characterized by high virulence and low symptom expression, which is especially true of PVY(N)Wi. This makes it difficult to detect infected seed potato plants during certification. In Mecklenburg-Western Pomerania (North-East Germany) in 2008 an unusually high incidence of infection with PVY was recorded in fields where seed potatoes were being grown. In this study we examined, which strains of PVY caused these infections. Furthermore, we have developed a reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) assay for direct tuber testing, which we compared to direct tuber testing by ELISA and growing-on tests. As a result, we recommend for direct tuber testing by RT-qPCR or ELISA. These methods are less space- and time-consuming and therefore less costly alternatives to conventional ELISA testing of eye cuttings from seed potatoes. Additionally, the RT-qPCR method has a high efficacy, so that even freshly harvested non-dormant tubers can be tested, which makes testing very fast and economical. This is of special interest in cases when tubers shall be exported to the other hemisphere of the world.