Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 21, 2004
Publication Date: February 1, 2005
Citation: French, R.C., Stenger, D.C. 2005. Reciprocal monophyly of the genera potyvirus and rymovirus is supported by genome sequences of agropyron mosaic virus and hordeum mosaic virus. Archives of Virology 150: 299-312. Interpretive Summary: The complete nucleotide sequences of Agropyron mosaic virus (AgMV) and Hordeum mosaic virus (HoMV) were determined. Sequence comparisons indicate that AgMV and HoMV are most closely related to each other and, along with Ryegrass mosaic virus, constitute the genus Rymovirus of the plant virus family Potyviridae. Three separate phylogenetic analyses indicated that the genus Rymovirus was distinct from the genus Potyvirus. These results indicate that mite-transmitted species of the genus Rymovirus form a single lineage that is sufficiently distinct from aphid-transmitted species of the genus Potyvirus to warrant retention of the genus Rymovirus as a taxonomic grouping within the family Potyviridae.
Technical Abstract: Assignment of mite-transmitted species to the genus Rymovirus (family Potyviridae) has changed several times, and the status of the genus has been questioned. To address this issue, complete nucleotide sequences of the rymoviruses Agropyron mosaic virus (AgMV) and Hordeum mosaic virus (HoMV) were determined. AgMV (9540 nucleotides) and HoMV (9463 nucleotides) each encode a single polyprotein with proteinase cleavage sites demarcating protein products characteristic of monopartite species of the family Potyviridae. Genetic distance measurements indicate that AgMV and HoMV are most closely related to each other (68.5% nucleotide; 71.6% amino acid sequence identity) and equidistant (~53% nucleotide; ~49% amino acid sequence identity) from a third rymovirus, Ryegrass mosaic virus (RGMV). Phylogenetic analyses by neighbor joining, maximum parsimony, and Bayesian inference each grouped the three Rymovirus species in an exclusive clade distinct from a clade containing 34 species of the genus Potyvirus. Because AgMV, HoMV, and RGMV share a reciprocal monophyletic relationship with species of the genus Potyvirus and are divergent in sequence and type of vector, the genus Rymovirus should be retained as a taxonomic unit within the family Potyviridae.