DETECTION OF POTATO LEAFROLL AND STRAWBERRY MILD YELLOW-EDGE LUTEOVIRUSES BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION AMPLIFICATION

DNA primers were constructed based on the nucleotide sequence of the coat protein gene of potato leafroll luteovirus (PLRV) and utilized for cDNA synthesis and polymerase chain reaction (PCR) amplification of a 487-bp DNA fragment from nucleic acid extracts of PLRV-infected tissue, and an approximately 500-bp DNA fragment from the luteovirus associated with strawberry mild yellow-edge-infected tissue. The amplified DNA fragments were identified by hybridization analysis with a cDNA probe for the coat protein gene of PLRV and differentiated by restriction fragment length polymorphism analysis. Reverse transcription (RT)-PCR assays were developed for the detection of PLRV in nucleic acid extracts of infected potato leaves and tubers, and in viruliferous aphids. The luteovirus-specific DNA was absent from amplified extracts of uninfected potato or nonviruliferous aphids. The RT-PCR assay for PLRV is more sensitive than existing detection methods and detects PLRV in plant hosts or insect vectors without requiring large samples or molecular hybridization.