Identification and characterization of a novel begomovirus, Withania leaf curl virus associated with leaf curl disease of Withania somnifera

Begomovirus is the largest genus of the family Geminiviridae with wide host range and responsible for a considerable amount of economic damage to many important crops globally. Withania somnifera (Indian ginseng) is an important medicinal plant with high demand in pharmaceutical industries worldwide. During the routine survey in 2019, typical characteristic viral symptoms such as severe leaf curling, downward rolling of the leaves, vein clearing, and poor growth of Withania plants with 17-20% disease incidence were observed in Lucknow, India. Typical symptoms, abundant presence of whiteflies, PCR and RCA based detection indicated the amplification of similar to 2.7 kb and suspected the causal pathogen to be a begomovirus, associated with a betasatellite (similar to 1.3 kb). Transmission electron microscopy revealed the presence of twinned particles of similar to 18-20 nm in diameter. Full genome sequencing (2758 bp) of the virus and its analysis showed only 88% sequence identity with the begomovirus sequences present in the database. Hence, based on the nomenclature guidelines we concluded that the virus associated with the present disease of W. somnifera is a novel begomovirus and its name is proposed as Withania leaf curl virus.