The Virome of Babaco (Vasconcellea × heilbornii) Expands to Include New Members of the Rhabdoviridae and Bromoviridae.

Babaco (Vasconcellea × heilbornii) is a subtropical species in the Caricaceae family. The plant is native to Ecuador and represents an important crop for hundreds of families. The objective of this study was to characterize, at the genomic level, two new babaco viruses identified by high-throughput sequencing. The viruses, an ilarvirus and a nucleorhabdovirus, were found in a symptomatic babaco plant from a commercial nursery in the Azuay province of Ecuador. The tripartite genome of the new ilarvirus, provisionally named babaco ilarvirus 1 (BabIV-1), is related to subgroup 3 ilarviruses, including apple mosaic virus, apple necrotic mosaic virus, and prunus necrotic ringspot virus as the closest relatives. The genome of the nucleorhabdovirus, provisionally named babaco nucleorhabdovirus 1 (BabRV-1), showed the closest relation with joa yellow blotch-associated virus and potato yellow dwarf nucleorhabdovirus. Molecular-based detection methods found BabIV-1 and BabRV-1 in 21% and 36%, respectively, of plants surveyed in a commercial babaco nursery, highlighting the importance of enforcing virus testing and nursery certification programs for babaco.

Two new umbravirus-like associated RNAs (ulaRNAs) discovered in maize and johnsongrass from Ecuador.

Two new umbravirus-like associated RNAs (ulaRNAs) were found, respectively, in maize and Johnsongrass samples from Ecuador. The complete sequences consist of 3,053 and 3,025 nucleotides, respectively, and contain four open reading frames (ORFs). Their genome sequences were 58% identical to each other and 28 to 60% identical to the most closely related viruses. Phylogenetic analysis using full genome sequences and amino acid sequence of the RNA-dependent-RNA polymerase (RdRp) placed both sequences in a clade sharing the most recent common ancestor with ulaRNAs from sugarcane and maize, suggesting that they belong to a monophyletic grass-infecting lineage. Their terminal regions exhibit features common to umbraviruses and ulaRNAs.

Characterization of a new potyvirus infecting Thevetia ahouai in Ecuador.

A new potyvirus was found in Thevetia ahouai L. (Fam. Apocynaceae) plants exhibiting white spots on leaves and fruit discoloration in Ecuador. The complete genome sequences of two isolates of this virus, tentatively named "thevetia white spot virus" (ThWSV), were determined and found to be 9,912 (isolate 1) and 9,904 (isolate 2) nucleotides (nt) in length, each encoding a polyprotein of 363 kDa. Sequence comparisons between the two isolates showed 80 and 87% identity at the nt and amino acid (aa) level, respectively, whereas the overall sequence identity between ThWSV and its closest relative was 69% and 71% at the nt and aa level, respectively.