Specific detection of the PVYN-W variant of Potato virus Y

PVYN-W is one of the variant populations of Potato virus Y (PVY). This variant is of concern in seed potato production and requires a specific diagnosis since it induces more or less symptomless infections and is not detectable easily in field inspections. Moreover, this variant is serologically indistinguishable from the common strain PVYO. This study describes a simple and specific molecular detection test for the PVYN-W variant using a PCR protocol based on the recombinant point within the HC-Pro/P3 region of PVYN variants (PVYNTN, PVYN-W). To avoid both detection of recombinant PVYNTN and PVYN-W isolates, a forward PVYN-like primer located in the HC-Pro region coupled to a reverse PVYO-like primer located in the NIa region was designed to amplify a specific PCR product of 4114 nt from PVYN-W isolates. This technique was assessed on 41 PVY reference and field isolates. Only isolates referenced as PVYN-W were amplified and gave the expected PCR product of 4114 nt, whereas no band was obtained from PVYN, PVYNTN or PVYO isolates. In conclusion, this PVYN-W diagnosis tool is rapid, easy-to-use and suitable for large-scale testing in laboratories of seed potato certification.