DETECTION OF STYLET-BORNE AND CIRCULATIVE POTATO VIRUSES IN APHIDS BYDUPLEX REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION

A reverse transcription polymerase chain reaction (RT-PCR) assay was d esigned to amplify stylet-borne potato virus Y-o (PVYo) in aphids usin g primers located in the viral capsid gene. A 480 bp long product was detected in aphids exposed to PVYo-infected potato plants. Approximate ly 40% of Myzus persicae and 15% of Aphis nasturtii exposed briefly to PVYo-infected plants acquired the virus. This rate of acquisition by both species of aphids was typical of our earlier observation of the v irus transmission tests. No significant difference in virus detection was observed whether the aphids were tested immediately after exposure to virus sources or stored for up to 45 days in ethanol at room tempe rature. The addition of a second pair of primers located in the capsid gene of circulative potato leafroll virus (PLRV) allowed simultaneous amplification of two viruses (duplex RT-PCR) in single aphids. Acquis ition of PVYo by the aphids already viruliferous with PLRV was signifi cantly reduced, compared to aphids not carrying PLRV. Duplex RT-PCR fo r PVYo and PLRV could be applied to analyze aphids collected from the field to ascertain the relative presence of both viruses in a single t est.