DETECTION OF THE POTATO-TUBER NECROTIC RINGSPOT STRAIN OF POTATO-VIRUS-Y (PVYNTN) BY REVERSE TRANSCRIPTION AND IMMUNOCAPTURE POLYMERASE CHAIN-REACTION

The potato tuber necrotic ringspot strain of potato virus Y (PVYNTN) w as distinguished from the other members of the OVYN strain group by RT -immunocapture polymerase chain reaction (RT-PCR). The obligonucleotid primers were placed in the 5'-non coding region and in the adjacent P 1-protein gene of the PVYNTN genome. Both primers define a target sequ ence of 835 bp. Twelve virus isolates obtained from samples with tuber symptoms, together with the Hungarian isolate as the standard, gave t he expected band in the gel, but the five virus isolates of the PVYO g roup, 11 isolates of the PVYN group and one isolate of the PVYC group did not. Moreover, PVYNTN was detected in two potato samples without s ymptoms and in tomato samples. This indicates that PVYNTN infections d o not lead necessarily to PTNRD symptoms and that tomatoes can act as a virus reservoir. Three California virus isolates which induced PTNRD symptoms did not lead to the expected 835 bp band in the gel, indicat ing that these isolates differ from those collected in Europe.