Abstract
Periwinkle (Catharanthus roseus L.) is an ornamental plant widely grown in the Mecca region in the Kingdom of Saudi Arabia (KSA). Different symptoms similar to those induced by viruses (mosaic, vein clearing, mottling, yellowing, flower variegation) prompted surveys in eight different regions of KSA to assess the presence of periwinkle-infecting viruses, i.e. Tomato spotted wilt virus (TSWV), Cucumber mosaic virus (CMV), Lettuce mosaic virus (LMV), Catharanthus mosaic virus (CatMV) and Catharanthus yellow mosaic virus (CYMV). Two hundred and forty leaf samples were collected from naturally infected nurseries, gardens and landscape plantings, and tested by DAS-ELISA, RT-PCR and PCR assays. Results showed that all five viruses were present in the surveyed areas, with incidence of infection reaching 58%. TSWV was the most widespread, found in 44% of samples, followed by CYMV (35%), whereas CatMV (15%), CMV (11%) and LMV (6%) were present to lesser extents. The virus incidence ranged between 43% in Rabigh to 77% in Taif. This is the first report of CYMV and CatMV in KSA, and of TSWV, LMV and CMV in periwinkle in western Saudi Arabia. The high incidence of viruses and of multiple infections in periwinkle plants endangers this crop in KSA, so a sanitation programme for eliminating virus infections is desirable.