Identification of a monopartite begomovirus associated with yellow vein mosaic of Mentha longifolia in Saudi Arabia.

Mentha is a very important crop grown and used extensively for many purposes in the Kingdom of Saudi Arabia. Begomoviruses are whitefly-transmitted viruses causing serious disease in many important plants exhibiting variable symptoms with significant economic loss globally. During farmers' field survey, yellow vein mosaic disease was observed in Mentha longifolia plants growing near tomato fields in Saudi Arabia. The causative agent was identified in 11 out of 19 samples using begomovirus-specific primers and the association of begomovirus with yellow vein mosaic disease in M. longifolia was confirmed. The full-length viral genome and betasatellite were amplified, cloned, and sequenced bidirectionally. The full DNA-A genome was found to have 2785 nucleotides with 1365 bp-associated betasatellite molecule. An attempt was made to amplify DNA-B, but none of the samples produced any positive amplicon of expected size which indicated the presence of monopartite begomovirus. The sequence identity matrix and phylogenetic analysis, based on full genome showed the highest identity (99.6%) with Tomato yellow leaf curl virus (TYLCV) and in phylogenetic analysis it formed a closed cluster with Tomato leaf curl virus infecting tomato and Corchorus crop in Saudi Arabia. The sequence analysis results of betasatellites showed the highest identity (98.9%) with Tomato yellow leaf curl betasatellites infecting tomato and phylogenetic analysis using betasatellites formed a close cluster with Tomato yellow leaf curl betasatellites infecting tomato and Corchorus crops, which has already been reported to cause yellow vein mosaic and leaf curl disease in many cultivated and weed crops growing in Saudi Arabia. The identified begomovirus associated with yellow vein mosaic disease in mentha could be a mutated strain of TYLCV and tentatively designated as TYLCV-Mentha isolate. Based on published data and latest information, this is the first report of identification of Tomato yellow leaf curl virus associated with yellow vein mosaic disease of M. longifolia from Saudi Arabia.