Detection of olive tree viruses in Egypt by one-step RT-PCR

Olive (Olea Europaea L.) is a major and economically important crop for the new reclamation land in Egypt. The estimated acreage of cultivated olive trees in Egypt is above one hundred and thirty five thousand Feddens of which total production is five hundred thousand tons per year (Ministry of Agriculture statistics, 2007). Olive trees are affected by several viruses and virus-like diseases. To date, 15 viruses in eight genera have been isolated from olive trees. In a preliminary study for the assessment of the sanitary status of olive trees in five locations in Egypt, shoots from 300 trees of 9 cultivars were collected. Using virus-specific primers, a one-step RT-PCR assay was used to detect and identify each of the eight viruses most commonly found in olives. Namely, Cucumber mosaic virus (CMV), Olive latent ringspot virus (OLRSV), Olive latent virus-1 (OLV-1), Olive latent virus-2 (OLV-2), Olive leaf yellowingassociated virus (OLYaV), Strawberry latent ringspot virus (SLRSV), Cherry leaf roll virus (CLRV), and Arabis mosaic virus (ArMV). Among the eight viruses assayed, OLRSV (6.7 %), OLV-1 (5.7 %), CLRV (4.7 %), OLV-2 (2.7 %), SLRSV (2.3 %), OLYaV (1.3 %) and ArMV (0.7%) were detected. The most common virus detected was CMV which prevailed with a high incidence of 24.7 % in olive orchards. The use of one step RT-PCR was efficient and reliable to detect the eight olive viruses found in Egypt. Surprisingly, the infection rate found is lower than expected, if we take into consideration previous surveys conducted in the Mediterranean area. This technique is useful for detection of olive viruses for production of certified plant propagative material in certification programs.