Screening by a 3-primer PCR of North American PVYN isolates for European-type members of the tuber necrosis-inducing PVYNTN subgroup

Oligonucleotide primers for a 3-primer polymerase chain reaction (PCR) were optimized by adjusting their Tm values to identify European-type members of the potato tuber necrotic ringspot disease (PTNRD) inducing PVYNTN sub-group of PVYN. Fiftyseven North American isolates of PVYN were screened using this assay and one, originating from garden potato tubers in Ontario, was found to be positive. This isolate was confirmed to induce the diagnostic PTNRD, using a panel of 20 potato cultivars. AC Chaleur, AC Novachip, Century Russet, Cherokee, and Frontier Russet reacted severely and developed PTNRD either at the time of harvest or during storage. About 800 tubers collected from New Brunswick and Prince Edward Island fields, from plants exhibiting mosaic and leafroll symptoms were also screened for various strains of PVY using PCR primers. Results indicate that primer pairs developed are specific for PVY spp., PVYN, and PVYNTN.