An Umbra-related Virus Found in Vasconcellea X Heilbornii (Caricaceae)
Abstract The complete sequence of a new viral RNA from babaco (Vasconcellea x heilbornii) was determined. The genome consisted of 4,584 nucleotides organized in two non-overlapping open reading frames (ORFs 1 and 2), a 9-nt-long noncoding region (NCR) at the 5’ terminus and a 1,843 -nt-long NCR at the 3’ terminus. Sequence comparisons of ORF 2 revealed homology to the RNA-dependent-RNA-polymerase (RdRp) of several umbra- and umbra-related viruses. Phylogenetic analysis of the RdRp placed the new virus in a well-supported and cohesive clade that includes umbra-like viruses reported from papaya, citrus, opuntia, maize and sugarcane hosts. This clade shares a most recent ancestor with the umbraviruses but has different genomic features. The creation of a new genus, within the Tombusviridae, is proposed for the classification of these novel viruses.