Plant viruses of the Amalgaviridae family evolved via recombination between viruses with double-stranded and negative-strand RNA genomes

Plant viruses of the recently recognized family Amalgaviridae have monopartite double-stranded (ds) RNA genomes and encode two proteins: an RNA-dependent RNA polymerase (RdRp) and a putative capsid protein (CP). Whereas the RdRp of amalgaviruses has been found to be most closely related to the RdRps of dsRNA viruses of the family Partitiviridae, the provenance of their CP remained obscure. Here we show that the CP of amalgaviruses is homologous to the nucleocapsid proteins of negative-strand RNA viruses of the genera Phlebovirus (Bunyaviridae) and Tenuivirus. The chimeric genomes of amalgaviruses are a testament to the effectively limitless gene exchange between viruses that shaped the evolution of the virosphere. Reviewers: This article was reviewed by Lakshminarayan M. Iyer and Nick V. Grishin. For complete reviews, see the Reviewers’ Reports section. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13062-015-0047-8) contains supplementary material, which is available to authorized users.