Differentiating PVYNTN by unique single-restriction cleavage of PCR products

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