Identification and Molecular Characterization of Recombinant Potato Virus Y (PVY) in Potato from South Korea, PVYNTN Strain

Potato is an important source of food in South Korea, and viruses represent a significant threat to sustainable and profitable potato production. However, information about viruses affecting the potato crop in South Korea is limited. In 2017, potato plants of five cultivars exhibiting foliar mosaic, crinkling, and mottle were collected in two seed potato production areas, in Gangwon-do and Jeollabuk-do Provinces, and subjected to virus testing and characterization. Potato virus Y (PVY) was found associated with mosaic symptoms, and samples were characterized using reverse transcription polymerase chain reaction (RT-PCR) and whole genome sequencing. All analyzed PVY-positive samples were found to represent the same recombinant PVY strain: PVYNTN. Three PVY isolates were subjected to whole genome sequencing using overlapping RT-PCR fragments and Sanger methodology, and all three were confirmed to represent strain PVYNTNa after a recombination analysis of the complete genomes. In phylogenetic analysis, the three South Korean isolates were placed most closely to several PVYNTNa isolates reported from Japan and Vietnam, suggesting a common source of infection. This is the first report and complete molecular characterization of a PVYNTN strain present in the country, and because this strain induces tuber necrotic ringspot disease in susceptible cultivars of potato, appropriate management tools need to be implemented to mitigate potential tuber quality losses.