Comparison of PLRV and PVY detection in potato seed samples tested by Florida winter field inspection and RT-PCR

Two sister-samples of 400 tubers each were taken from seed potato lots of cultivars Atlantic, Hampton, and Russet Norkotah, all of which were grown in New York State during the summer of 1996. One sample of each cultivar was planted in Homestead, Florida in a winter test plot where plants were inspected for disease symptoms. Tubers in the other sample were directly tested for the presence of potato potyvirus Y (PVY) and potato leafroll luteovirus (PLRV) using reverse transcription polymerase chain reaction (RT-PCR) methods. Hampton tubers appeared to have similar PVY infection rates in dormant tubers according to summer inspection, Florida winter inspection and RT-PCR, whereas Florida testing appeared to reveal a higher PVY infection rate in Atlantic tubers compared to RT-PCR and summer inspection. In contrast, higher rates of PVY infection in Russet Norkotah were observed by RT-PCR compared to Florida tests. In addition, RT-PCR appeared to detect PLRV at higher rates in all three cultivars compared to Florida test results. All tubers positive for virus by RT-PCR were sprouted in a greenhouse and ELISA results from leaves corroborated the PCR results in 85% of the positive cases, and 100% of the negative cases that were sprouted.