MOLECULAR CHARACTERIZATION OF POTATO-VIRUS Y-N ISOLATES BY PCR-RFLP -DIFFERENTIATION OF PVYN ISOLATES BY PCR-RFLP

Based on the sequence polymorphism in the 5' terminal part of the vira l genome, a range of PVYN isolates were characterized by polymerase ch ain reaction (PCR) followed by restriction fragment length polymorphis m (RFLP). Three pairs of primers selected in the 5' non-translated and P1 protein region were tested. Two of them yielded PCR products of ab out 1Kb from all isolates tested. Restriction analysis of the PCR prod ucts gave two distinct electrophoretic patterns, whichever of the thre e enzymes was used. In this way, the 18 isolates were separated into t wo easily identifiable subgroups. All tuber necrosing isolates (PVYNTN ) were clustered in the same subgroup.