Serological and Molecular Characterization of Prevalent Olive-Associated Viruses in Saudi Arabia

A survey was carried out during 2023-2024, and 363 asymptomatic and symptomatic olive samples with deformed leaves, mosaic, and yellow spots were collected from different regions in Saudi Arabia. These samples were tested by ELISA against eight important olive viruses. To investigate the presence of these viruses in olive trees, PCR and RT-PCR techniques were employed using the virus-specific primers. The obtained results from serological tests indicated that 44.4% of the collected samples were found to be positive with at least one of the tested viruses. The most prevalent virus was OEGV (14.3%), followed by ArMV (11.9%), SLRSV (11.3%), CLRV (9.4%), TuYV (5%), TNV-D (4.4%), OMMV (3.6%), whereas OLV-1, OLV-2, CMV, TMV, OLV-3, OLYaV, and OLRSV were not positive in the tested samples. Single, as well as mixed infections, were observed in a number of samples with 9.4% and 34.7%, respectively. The nucleotide sequence analysis of PCR amplified fragments revealed 99.7-100% identity to OEGV, 95-99% to TuYV, 85-98% to OMMV, 83-93% to ArMV, 92-97% to CLRV, 84-98% to TNV-D, and 85-97% to SLRSV isolates, according to the pairwise nucleotide identity percentage calculated by SDT software. This is the first comprehensive survey to investigate the genetic diversity and phylogenetic relationship of seven olive viruses detected in olive trees in Saudi Arabia, which can provide the missing local epidemiological understanding.