Potato virus Y (PVY) is one of the most damaging and contagious viruses in potato, tobacco and many other plants around the world, and causes systemic mosaic or necrotic symptoms in tobacco. Aphids transmit the virus from potatoes to other crops including tobacco. PVY isolates have been divided into several strains. Among them, PVYNTN, which causes tuber necrosis, is highly prevalent among potato crops and has persisted as a severe problem in recent years throughout the world, especially in Europe. In fact, PVY^NTN has also become a virus strain severely affecting tobacco crops. Particularly in European and Asian countries, tobacco varieties that inherited their resistance to PVY from VAM or Wiślica having va, have been damaged by newer, resistance-breaking (RB) variants. However, no reports describe PVY strains occurring in tobacco fields or their pathogenicity to resistant tobacco varieties in Japan.

Therefore, we collected PVY strains from tobacco plants growing in various areas of Japan in 2010 and classified them using multiplex PCR methods. Results have confirmed the existence of PVY^O, PVY^N, PVY^NTN strains in tobacco production areas in Japan. Inoculation tests were conducted for pathogenicity to the PVY resistant varieties. Although RB variants have become a problem in foreign countries, their existence has not been confirmed in Japan.