Speciation driven by recombination in the evolution of tomato curly stunt virus in Mozambique

Begomoviruses constitute a group of viruses of great economic importance in agriculture, mainly in tropical and subtropical regions, including southern Africa. Tomato curly stunt virus (ToCSV) is an important begomovirus described in South Africa and later reported in Mozambique impacting tomato cultivation. In Mozambique, the severe disease caused by ToCSV limits tomato cultivation and compromises the income of small and medium farms. Due to the scarcity of information about this pathogen, in this study we explored its genetic variability to elucidate the mechanisms that drive its evolution. In 2019, 27 ToCSV full-length sequences were obtained from tomato foliar samples with virus-like symptoms collected in the district of Chokue in Gaza province, Mozambique. Sequence analysis showed that isolates from Mozambique have a nucleotide identity of 90.9%–96.9% with the isolate from South Africa (AF261885) and are grouped into two distinct strains that we named ToCSV-Chok I and ToCSV-Chok II. The ToCSV-Chok II strain has a higher nucleotide diversity than ToCSV-Chok I in the Rep gene. Recombination is involved in the evolutionary history of ToCSV, with both intraspecific and interspecific recombination events detected in the Rep gene. Our results indicate a prevalence of ToCSV in tomato crops in the Chokue district of Mozambique (the major tomato-producing region of the country) and suggest that ToCSV is undergoing speciation due to the effect of recombination.