Recapitulation of virus-mediated DNA transfer in plants

The strict interactions established between viruses and their hosts makes them excellent candidates to mediate horizontal gene transfer. Historical events of exchange of nucleic acids between a host organism and a virus have become evident following genomic studies, but virus-mediated horizontal transfer is considered to occur rarely in nature, and be relevant only in evolutionary time. We previously observed the spontaneous formation of circular hybrid DNA molecules (minicircles) during the infection of Beta vulgaris plants by a single-stranded DNA virus belonging to the Geminiviridae family, the Beet curly top Iran virus (BCTIV). These DNA minicircles can replicate systemically in BCTIV-infected plants, are encapsidated in viral particles and can also be transcribed, being therefore optimal candidates to mediate transfer of DNA elements from one host to plants that can be infected by the same virus. Conclusively, we document in real time the initial steps of a possible path of virus-mediated horizontal transfer of chromosomal DNA between plant species. This work demonstrates that, in specific virus-host combinations, horizontal gene transfer could be much more frequent than previously thought.