Studies on Potato virus Y Isolates Infecting Potato and Tobacco in Korea

A survey of Potato virus Y (PVY) was conducted in farmers' fields in 9 Korean provinces, Gyeonggi-do, Gangwon-do, Gyeongsangnam-do, Gyeongsangbuk-do, Jeollanam-do, Jeollabuk~io, Chungchcongnam-do, Chungcheongbuk-do and Jeju-do from 1998 to 2000. One hundred and fifty nine samples from potato and tobacco were collected and analyzed. Based on ELISA results, three samples PVY-tob, PVY-potlii and PVY-pot-chw representing PVYN and PVYo, respectively, were further subjected to biological, serological and molecular analysis. Host range studies showed that PVY-pot-chw is symptomatically distinguishable from PVY-tob and PVY-pot-j isolates, both of which were symptomatically indistinguishable. However, all the three isolates failed to infect 10 capsicum varieties systemically. Isolates PVY-tob and PVY-pot-j reacted strongly wlth monoclonal antibody (MAb), anti-PVYN while PVY-pot-chw failed to react wlth the MAb but reacted strongly wlth anti-PVYo'c. Interestingly, both PVY-tob and PVY-pot-j isolates did not react with anti-Pvyo,C indicating that isolate PVY-pot-chw is serologically distinguishable from both PVY-tob and PVY-potlii. In order to ascertain the taxonomic status of the three isolates, the 3' untranslated terminal regions (3'-UTR) were sequenced. Alignment of the sequences revealed 990/0 sequence identity between PVY-tob and PVY-pot-j, both of which had 780/0 nt sequences identical to PVY-pot-chw. Phylogenetic analysis of the aligned 3'-UTRs clustered PVY-tob and PVY-pot-j in the PVY~ subgroup, and PVY-pot~:hw in the PVYO subgroup.