Subfamily: Betarhabdovirinae

Genus: Alphagymnorhavirus

Distinguishing features

Plant rhabdoviruses usually infect angiosperms. Viruses classified in the genus Alphagymnorhavirus have unsegmented genomes and infect gymnosperms. They form a distinct monophyletic clade in well-supported Maximum Likelihood or Maximum Clade Credibility trees using full-length L sequences and are most closely related to the betagymnorhavirus and the bisegmented varicosaviruses (Bejerman et al., 2022).

Virion

Morphology

Not known.

Nucleic acid

The negative-sense, single-stranded RNA genome is unsegmented.

Proteins

The N and L proteins are encoded in the alphagymnorhavirus genome but the functions of proteins encoded in other genes are unknown.

Lipids

Not known.

Genome organisation and replication

The alphagymnorhavirus genome (11.1–12.2 kb) has the gene order 3′-N-P2-P3-P4-L-5′- (Figure 1 Alphagymnorhavirus). All but one member have this genome organization; the other member has an additional gene (P5) between P4 and L genes.

Figure 1 Alphagymnorhavirus. Schematic representation of the alphagymorhavirus genome shown in reverse (positive-sense) polarity. N and L represent ORFs that encode the known structural proteins. Other ORFs (2, 3, 4 and 5) encode proteins of unknown function (purple, green, orange and red). ORFs that appear to be homologous are shown in the same colour.

Biology

Viruses in the genus were identified from an in-silico analysis of plant gymnosperm transcriptome datasets.

Species demarcation criteria

Viruses assigned to different species within the genus Alphagymnorhavirus have several of the following characteristics: A) nucleotide sequence identity lower than 75% in the L ORF; and B) occupy different ecological niches as evidenced by differences in hosts.