Metagenomic analysis for detection and discovery of plant viruses in wild <i>Solanum</i> spp. in South Africa

Abstract Wild plant species play an important role in plant virus epidemiology, mainly by harbouring viruses pathogenic to cultivated plant species. The genus Solanum includes important crop species as well as some highly abundant and widely distributed wild plant species. The aim of the present study was to profile the viromes of 11 wild Solanum spp. found in five provinces of South Africa. Metatranscriptomic analysis of pooled RNA samples from each of the Solanum spp. detected viruses belonging to 13–19 families. Reverse transcription PCR confirmed the detection of potato virus Y (PVY), potato leaf roll virus (PLRV), tomato torrado virus (ToTV) and tomato chlorosis virus (ToCV) for the first time in some of the Solanum spp. studied. Phylogenetic analyses indicated that the PVY and PLRV strains from the wild Solanum spp. were divergent from those reported in cultivated crops, while there was limited divergence among ToTV and ToCV isolates. Viruses detected for the first time in South Africa included tobacco mild green mosaic virus, tomato matilda virus, a pepper enamovirus from Rwanda and a cytorhabdovirus from potato in Kenya. Potentially novel viruses were also detected in S . lichtensteinii , S . mauritianum and S . viarum . This study demonstrates the role of Solanum spp. in harbouring viruses pathogenic to solanaceous crops, and in the emergence of new virus strains. It may therefore inform strategies for virus disease management by control of wild solanums that harbour viruses pathogenic to important Solanum crops.