Tobamovirus
Tobamovirus is a genus in the virus family Virgaviridae.[2] Many plants, including tobacco, potato, tomato, and squash, serve as natural hosts. There are currently 37 species in this genus including the type species Tobacco mosaic virus. Diseases associated with this genus include: necrotic lesions on leaves.[2][3][4] The name Tobamovirus comes from the host and symptoms of the first virus discovered (Tobacco mosaic virus).
| Tobamovirus | |
|---|---|
 | |
| Electron micrograph of TMV particles negative stained to enhance visibility at 160,000× magnification | |
Virus classification  | |
| (unranked): | Virus |
| Realm: | Riboviria |
| Phylum: | incertae sedis |
| Family: | Virgaviridae |
| Genus: | Tobamovirus |
| Type species | |
| Tobacco mosaic virus | |
| Species[1] | |
| |
There are four informal subgroups within this genus: these are the tobamoviruses that infect the brassicas, the cucurbits, and malvaceous and solanaceous plants. The main differences between these groups are genome sequences, and respective range of host plants.
Evolution
These viruses are thought to have codiverged with their hosts from a common ancestor.[5] There are at least 3 distinct clades of tobamoviruses, which to some extent follow their host ranges: that is, there is one infecting solanaceous species; a second infecting cucurbits and legumes and a third infecting the crucifers.[6]
Genome
| TMV-like coat protein | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | TMV_coat | ||||||||
| Pfam | PF00721 | ||||||||
| InterPro | IPR036417 | ||||||||
| CATH | 1ei7 | ||||||||
| SCOPe | 1ei7 / SUPFAM | ||||||||
| |||||||||
The RNA genome encodes at least four polypeptides:[2] these are the non-structural protein and the read-through product which are involved in virus replication (RNA-dependent RNA polymerase, RdRp); the movement protein (MP) which is necessary for the virus to move between cells and the coat protein (CP). The read-through portion of the RdRp may be expressed as a separate protein in TMV.[7] The virus is able to replicate without the movement or coat proteins, but the other two are essential. The non-structural protein has domains suggesting it is involved in RNA capping and the read-through product has a motif for an RNA polymerase. The movement proteins are made very early in the infection cycle and localized to the plasmodesmata, they are probably involved in host specificity as they are believed to interact with some host cell factors.
Structure
Tobamoviruses are non-enveloped, with helical rod geometries, and helical symmetry. The diameter is around 18 nm, with a length of 300-310 nm. Genomes are linear and non-segmented, around 6.3-6.5kb in length.[2][3]
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Tobamovirus | Rod-shaped | Helical | Non-enveloped | Linear | Non-Segmented |
Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. Translation takes place by suppression of termination. The virus exits the host cell by monopartite non-tubule guided viral movement. Plants serve as the natural host. Transmission routes are mechanical.[2][3]
| Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Tobamovirus | Plants | None | Unknown | Viral movement | Cytoplasm | Cytoplasm | Mechanical |
Routes of Infection
The infection is localized to begin with but if the virus remains unchallenged it will spread via the vascular system into a systemic infection. The exact mechanism the virus uses to move throughout the plant is unknown but the interaction of pectin methylesterase, a cellular enzyme important for cell wall metabolism and plant development, with the movement protein has been implicated.[8]
Classification
Species Details
- Bell pepper mosaic virus (BPeMV)
- Brugmansia mild mottle virus
- Cactus mild mottle virus (CMMoV)[9]
- Clitoria yellow mottle virus
- Cucumber fruit mottle mosaic virus
- Cucumber green mottle mosaic virus (CGMMV)
- Cucumber mottle virus
- Frangipani mosaic virus (FrMV)
- Hibiscus latent Fort Pierce virus (HLFPV)
- Hibiscus latent Singapore virus (HLSV)
- Kyuri green mottle mosaic virus
- Maracuja mosaic virus (MarMV)
- Obuda pepper virus (ObPV)
- Odontoglossum ringspot virus (ORSV)
- Paprika mild mottle virus
- Passion fruit mosaic virus
- Pepper mild mottle virus (PMMoV)
- Rattail cactus necrosis-associated virus (RCNaV)
- Rehmannia mosaic virus
- Ribgrass mosaic virus (HRV)
- Sammons's Opuntia virus (SOV)
- Streptocarpus flower break virus
- Sunn-hemp mosaic virus (SHMV)
- Tobacco latent virus
- Tobacco mild green mosaic virus
- Tomato mosaic virus (ToMV)
- Tobacco mosaic virus (T2MV) - Type Species
- Tomato mottle mosaic virus
- Tropical soda apple mosaic virus
- Turnip vein-clearing virus (TVCV)
- Ullucus mild mottle virus
- Wasabi mottle virus (WMoV)
- Yellow tailflower mild mottle virus
- Youcai mosaic virus (YoMV) aka oilseed rape mosaic virus (ORMV)
- Zucchini green mottle mosaic virus
Proposed members
- Beet necrotic yellow vein virus (BNYVV)
- Chara corallina virus (CCV)
- Nicotiana velutina mosaic virus (NVMV)
- Peanut clump virus (PCV)
- Potato mop-top virus (PMTV)
- Soil-borne wheat mosaic virus (SBWMV)
- Streptocarpus flower break virus (SFBV)
- cucumber green mottle mosaic virus (CGMMV)
- cucumber fruit mottle mosaic virus (CFMMV)
References
- "Virus Taxonomy: 2018b Release" (html). International Committee on Taxonomy of Viruses (ICTV). March 2019. Retrieved 18 March 2019.
- "ICTV Online Report Virgaviridae".
- "Viral Zone". ExPASy. Retrieved 15 June 2015.
- ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
- Stobbe AH, Melcher U, Palmer MW, Roossinck MJ, Shen G (February 2012). "Co-divergence and host-switching in the evolution of tobamoviruses". The Journal of General Virology. 93 (Pt 2): 408–18. doi:10.1099/vir.0.034280-0. PMID 22049092.
- Lartey RT, Voss TC, Melcher U (December 1996). "Tobamovirus evolution: gene overlaps, recombination, and taxonomic implications" (PDF). Molecular Biology and Evolution. 13 (10): 1327–38. doi:10.1093/oxfordjournals.molbev.a025579. PMID 8952077.
- Creager AN, Scholthof KB, Citovsky V, Scholthof HB (March 1999). "Tobacco mosaic virus. Pioneering research for a century". The Plant Cell. 11 (3): 301–8. doi:10.1105/tpc.11.3.301. PMID 10072391.
- Chen MH, Citovsky V (August 2003). "Systemic movement of a tobamovirus requires host cell pectin methylesterase". The Plant Journal. 35 (3): 386–92. doi:10.1046/j.1365-313X.2003.01818.x. PMID 12887589.
- Min BE, Chung BN, Kim MJ, Ha JH, Lee BY, Ryu KH (January 2006). "Cactus mild mottle virus is a new cactus-infecting tobamovirus". Archives of Virology. 151 (1): 13–21. doi:10.1007/s00705-005-0617-7. PMID 16132178.
- "Descriptions of Plant Viruses: Tobamovirus Group". The Association of Applied Biologists (AAB).
Further reading
- Hagiwara Y, Komoda K, Yamanaka T, Tamai A, Meshi T, Funada R, Tsuchiya T, Naito S, Ishikawa M (January 2003). "Subcellular localization of host and viral proteins associated with tobamovirus RNA replication". The EMBO Journal. 22 (2): 344–53. doi:10.1093/emboj/cdg033. PMC 140108. PMID 12514140.