Notes on Genus: Poacevirus
Type member: Triticum mosaic virus
This is one of the genera in the family Potyviridae
. Like the other genera, it is characterised by its flexuous filamentous particles, inclusion bodies in infected plant cells and by having a polyprotein genome strategy. It differs from most of the others in having mite transmission and from the genus Bymovirus
in having a monopartite genome. The viruses in this genus are phylogenetically very distant from those of other mite-transmitted members in the genera Rymovirus
. Their genomes also have a very much longer 5'-UTR (>700 nt). The genus name is derived from Poaceae
, the family name of the host plants.
Virions filamentous, not enveloped, usually flexuous, 680-750 nm long and 12-15 nm in diameter. Symmetry helical with a pitch of 3.4 nm
Virions composed of 5 % nucleic acid and 95 % protein.
Monopartite, linear, single stranded, positive sense RNA, 9700-10300 nucleotides long. The 3' terminus has a poly(A) tract and the 5' terminus has a genome-linked protein (VPg).
Genus Genomic Organization
Genome organisation appears to be uniform throughout this genus and is similar to other members of the family. The genome is translated into a single polyprotein, which is subsequently processed into ten products, with the coat protein at the C-terminus. An additional small ORF (PIPO) is generated by frameshifting within the third (P3) cistron.
Type Member Genomic Organization
The genome is translated into a single polyprotein of 353 kDa, from which an estimated ten functional products are produced by proteolytic processing:
|P1 protein|| ||putative protease|| ||45 kDa |
|HC-Pro || || putative helper component protease|| ||53 kDa|
|P3 protein|| ||unknown function|| || 33 kDa|
|6K1|| ||unknown function|| ||6 kDa |
|CI || || Cylindrical inclusion putative helicase|| ||73 kDa|
|6K2|| ||unknown function|| || 6 kDa|
|VPg|| ||Genome-linked protein|| || 23 kDa|
|NIa-Pro|| ||Nuclear Inclusion putative protease|| ||26 kDa|
|NIb|| ||Nuclear Inclusion putative polymerase|| ||56 kDa|
|CP|| ||coat protein || ||32 kDa|