Single-step multiplex RT-PCR for simultaneous and colourimetric detection of six RNA viruses in olive trees

A single-step multiplex RT-PCR was developed for the simultaneous and colourimetric detection of six RNA viruses (Cucumber mosaic virus, Cherry leaf roll virus, strawberry latent ringspot virus. Arabis mosaic virus, Olive latent-1 virus and Olive latent-2 virus) which infect olive trees. Six compatible primer set for one-step RT-PCR amplification in a single closed-tube and 3' digoxigenin labelled probes were designed in optimal, specific and conserved regions. The method has been assessed with 195 Spanish field olive trees, suggesting that similar to 1.5% of the tested material was infected by Cucumber mosaic virus and 0.5'%, by Cherry leaf roll virus. This method saves time and reagent costs compared with monospecific RT-PCR which needs several reactions for the same number of tests. Using colourimetric detection, it is possible to analyse many samples, it increases sensitivity 10-fold, and whilst facilitating the interpretation of results, it avoids the use of gels and the toxic ethidium bromide. The method could be used routinely for sanitary and certification programmes. (C) 2001 Elsevier Science B.V. All rights reserved