Notes on Genus: Furovirus
Type member: Soil-borne wheat mosaic virus
d-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
) on the basis of differences in numbers of genome segments and in genome organisation.
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.
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 |