Rosner, A., Department of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Maslenin, L., Department of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel

A procedure for differentiating PVY(NTN) from PVY(N) is described and is based on the unique cleavage of their respective PCR products with strain specific restriction endonucleases. The PCR products corresponding to the 5' end of the N and NTN strains of PVY were cloned and sequenced, and a restriction map was constructed which included common enzymes that were used for the differentiation of PVY(NTN.) Unique, single cleavage of PCR products derived from the 5' end of the PVY(NTN) genome by Nco I, and that of the N-strain of PVY by Bgl II restriction endonuclease were demonstrated. The specific digestion patterns in polyacrylamide gel were used for the unequivocal differentiation between the N and NTN strains of the virus. Both single and mixed infections were detected in field samples of potatoes using this procedure.