Tombusviridae

Abstract

The Tombusviridae is a relatively large and diverse family of soil‐borne viruses that have single‐stranded, positive‐sense, RNA ( ribonucleic acid ) genomes and that share morphological, structural, molecular and genetic features. Their high titres, compact genomes and extremely stable virions lend to their attractiveness as research subjects. Indeed, the Tombusviridae are a particularly well‐characterized family of viruses in the areas of virus structure, gene expression strategies, virus movement, the support of satellite viruses and defective‐interfering RNAs as well as RNA recombination. Although the RNA‐dependent RNA polymerases share a great deal of sequence identity, the capsid proteins can be separated by the presence (or absence) of a C ‐terminal protruding domain which gives the virions a bumpy appearance in electron micrographs. Transmission of several members by fungal zoospores in a species‐specific manner has been reported. The virions of several members have been utilized for biotechnology purposes. Key Concepts: Virions are nonenveloped and extremely stable. Tombusviridae species replicate to high titres within their host cells. RNA genomes are small with a limited number of gene products that serve multiple functions. RNA–RNA interactions control gene expression in several genera. Viral‐encoded suppressors of RNA silencing act at several different stages in the response cascade. Several members transmitted through soil by specific fungal zoospores.

A trans-activator-like structure in RCNMV RNA1 evokes the origin of the trans-activator in RNA2

“…Dianthovirus is the only genus in the family Tombusvididae that possesses a segmented genome and, as such, its members face unique challenges [1]. There are currently three approved dianthoviruses, the type species Carnation ringspot virus (CRSV), Sweet clover necrotic mosaic virus (SCNMV), and Red clover necrotic mosaic virus (RCNMV) [2][3][4].…”

Subgenomic mRNA transcription in Tombusviridae

“…Depending on the genus, members of Tombusviridae transcribe either one or two sg mRNAs during host infections, 1 though there is at least one exception, Pelargonium flower break virus (genus carmovirus), where four sg messages have been detected. 7 a template for sg mRNA transcription (Fig.…”

“…1). 1 Collectively, this family of viruses infects a wide range of plant species and its members are related by similarities in particle structure and genome organization, as well as the likeness of their encoded polymerase proteins. These plant viruses possess messenger-sensed, or plus-strand, RNA genomes that are packaged into spherical particles with diameters of ~30 nm.…”

Investigation of Novel RNA Elements in the 3′UTR of Tobacco Necrosis Virus-D

“…TNV-D is a plus-sense RNA plant virus in the family Tombusviridae , and is the type-member of the genus Betanecrovirus, which also includes Beet black scorch virus (BBSV) [ 9 ]. The genome of TNV-D is 3.8 kb in length and contains five open reading frames (ORFs) ( Figure 1 A) [ 10 ].…”