Genus: Roymovirus

Genus: Roymovirus

Distinguishing features

The amino acid motifs KITC and PTK are not present in HC-Pro. Roymoviruses have low nucleotide and amino acid identities with other potyvirids. The nucleotide and deduced amino acid sequences of the polyprotein share greatest identities with other viruses in the family Potyviridae, but they are not clearly closer to members of any particular genera in the family. Comparison of the deduced amino acid sequence of the large ORF revealed identities with other viruses of the family to be low, ranging from 13% (some bymoviruses) to 23% (some potyviruses).

Virion

Morphology

Particles are 720 to 750 nm in size.

Nucleic acid

Rose yellow mosaic virus has a genome of 9,508 nt.

Proteins

The large polyprotein is probably processed in the same manner as potyviruses. PIPO is present.

Genome organization and replication

Genome organization (Figure 1.Roymovirus) resembles that of members of the genus Potyvirus (Figure 2.Potyviridae).

Figure 1. Roymovirus Schematic diagram of the rose yellow mosaic virus (RYMV) genome. The polyprotein ORF is indicated by the large open box divided into putative mature proteins. The pretty interesting Potyviridae protein (PIPO) is represented by a small box. The untranslated regions (UTR) are represented by lines on each end of the large ORF. Activities of mature proteins are postulated by analogy with genus Potyvirus. Conventions are as for the potyvirus genome organization map (Figure 2.Potyviridae). Not to scale.

Biology

Isolates of the typical species, Rose yellow mosaic virus, were described in several rose cultivars in New York and Minnesota (Mollov et al., 2013).

The conserved amino acid motifs KITC and PTK are not present in the HC-Pro of rose yellow mosaic virus. Instead, a putative C-2x-C eriophyid mite transmission motif is located at amino acid residues 48–51 at the N-terminus of the protein. The CP acid motif DAG found in most aphid-transmitted potyvirids is also lacking. Together this information suggests that rose yellow mosaic virus may be transmitted by eriophyid mites, although this has not been proven experimentally.

Phylogenetic analysis of the coat protein and ORF places rose yellow mosaic virus basal to viruses belonging to the genera Tritimovirus, Poacevirus, and Ipomovirus (Figure 3.Potyviridae).

Species demarcation criteria

See discussion under family description.

Member species

Exemplar isolate of the species
SpeciesVirus nameIsolateAccession numberRefSeq numberAvailable sequenceVirus Abbrev.
Passiflora edulis symptomless virusPassiflora edulis symptomless virusPeSV-RehovotMH379332NC_055497Complete genomePeSV
Rose yellow mosaic virusrose yellow mosaic virusMinnesotaJF280796NC_019031Complete coding genomeRYMV

Virus names, the choice of exemplar isolates and virus abbreviations are not official ICTV designations.