A single tube, quantitative real-time RT-PCR assay that detects four potato viruses simultaneously

A high throughput, real-time multiplex, single tube RT-PCR assay was developed for simultaneous detection of Potato leafroll virus (PLRV), Potato virus X (PVX) and Potato virus S (PVS) in potato leaves and tubers, and Tomato spotted wilt virus (TSWV) in potato tubers and tomato leaves. The test uses four different fluorescently labelled TaqMan probes. Limits of detection sensitivity were established using a range of virus transcript copy numbers (8 x 10(1) to 8 x 10(9) copies of PVX and PVS, 1 x 10(2) to 1 x 10(10) copies of PLRV and 1 x 10(3) to 1 x 10(10) copies of TSWV). For each individual assay, the inter-assay reproducibility was high, with a coefficient of variation of the combined assays of <2%. Total RNA was extracted rapidly and efficiently from bulked samples equivalent to 300 dormant tubers to detect single infections of PLRV, PVX, PVS and TSWV simultaneously in a single assay. The multiplexed assay was validated in blind studies with leaves and tubers. This high-throughput test is accurate and sensitive, and provides seed potato industries with a cost-effective diagnostic tool to detect viruses reliably in bulked samples of dormant potato tubers.