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-do, Chungcheongnam-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-pot-jj 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-jj 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-jj reacted strongly with monoclonal antibody (MAb), anti-PVYN while PVY-pot-chw failed to react with the MAb but reacted strongly with anti-PVYO/C. Interestingly, both PVY-tob and PVY-pot-jj isolates did not react with anti-PVYO/C indicating that isolate PVY-pot-chw is serologically distinguishable from both PVY-tob and PVY-pot-jj. 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 99% sequence identity between PVY-tob and PVY-pot-jj, both of which had 78% nt sequences identical to PVY-pot-chw. Phylogenetic analysis of the aligned T-UTRs clustered PVY-tob and PVY-pot-jj in the PVYN subgroup, and PVY-pot-chw in the PVYO subgroup.