In consecutive annual statewide surveys of the incidence of Barley yellow dwarf viruses (BYDVs) in Illinois wheat and oat fields, 27 BYDV-PAV-like isolates were identified. Using polymerase chain reaction (PCR), the coat protein regions of all 27 isolates were analyzed for restriction fragment length polymorphisms. The PCR products of two isolates, one from each year, had restriction fragment profiles after digestion with HaeIII that differed from the other isolates. The nucleotide sequences of the coat protein regions of a laboratory isolate, BYDV-PAV-IL (PAV-IL), two of the isolates with the common restriction profile, and the two isolates with polymorphic profiles were more than 98% identical. The relatively rare isolate identified during the first year was designated BYDV-PAV-DK1 (PAV-DK1) and further characterized biologically. PAV-DK1 and PAV-IL did not differ significantly in symptom expression, but did differ significantly in rates of transmission by two of the three biotypes of Rhopalosiphum padiexamined. Since PAV-DK1 does not occur in high levels in the state of Illinois, and its PCR products have a unique restriction enzyme profile, it has the potential to be used as a traceable isolate in field epidemiological experiments.
Keywords: PCR-RFLP; aphid transmission.