Notes on Genus: Furovirus

rigid rods

Type member: Soil-borne wheat mosaic virus

Contents

Members of this Genus
General Description
Morphology
Electron Micrograph
Genome
Genus Genomic Organization
Genome Map
Type Member Genomic Organization
All Known Sequences
Curated Sequences

General Description

Furoviruses (fungally-transmitted rod-shaped viruses) had originally been classified with tobamoviruses but are distinct in having multipartite genomes and in fungus transmission. The vectors (or putative vectors) of all members are root-infecting parasites, classified in the Plasmodiophorales. One of these, Polymyxa graminis, also transmits Bymoviruses. Some viruses originally classified in the genus have now been moved to separate genera (Benyvirus, Pecluvirus, Pomovirus) on the basis of differences in numbers of genome segments and in genome organisation.

Morphology

Virions rod-shaped, not enveloped. Usually straight with a distinct central canal. Generally of two modal lengths, 250-300 nm and 92-160 nm, (but difficult to estimate because they are fragile) and about 20 nm in diameter. Symmetry helical. Surface capsomere arrangement obvious. Pitch of helix 2.6 nm.

Genome

Linear, single-stranded, positive sense RNA in two segments. The 3'-terminus has a tRNA-like structure.

Genus Genomic Organization

There are three ORFs on each RNA. Product(s) for replication are encoded on RNA1. The coat protein, followed by a readthrough domain are at the 5'-end of RNA2.

Type Member Genomic Organization

RNA1 (c. 7100 nucleotides) produces:
1 150 kDa       Replication protein containing methyltransferase and helicase motifs
2 209 kDa       Polymerase readthrough of P1, incorporating RNA polymerase motif
3 37 kDa      Movement (cell-to-cell transport) protein
RNA2 (c. 3600 nucleotides) produces:
4 19 kDa      Coat protein
5 84 kDa      Coat protein readthrough, probably involved in fungus transmission
6 19 kDa       Cysteine-rich protein