The Pospiviroidae[1] are a incertae sedis family of ssRNA viroids with 5 genera and 39 species, including the first viroid to be discovered, PSTVd, which is part of genus Pospiviroid.[2] Their secondary structure is key to their biological activity. The classification of this family is based on differences in the conserved central region sequence.[3] Pospiviroidae replication occurs in an asymmetric fashion via host cell RNA polymerase, RNase, and RNA ligase. Its hosts are plants, specifically dicotyledons and some monocotyledons.
| Pospiviroidae | |
|---|---|
Virus classification 
| |
| (unranked): | Viroid |
| Family: | Pospiviroidae |
| Genera | |
Genome
editMembers of the family Pospiviroidae have circular ssRNA of 246–375 nt. They assume rod-like or quasi-rod-like conformations containing a central conserved region (CCR) and a terminal conserved hairpin (TCH) or a terminal conserved region (TCR). The genome of viroids does not encode any proteins.[4]
Replication
editThis section may be too technical for most readers to understand. (August 2023) |
Its replication is nuclear and mediated by DNA-dependent RNA polymerase II, which is redirected to use RNA templates through an asymmetric RNA–RNA rolling-circle mechanism. (+) polarity circRNA molecules (by convention the most abundant strand in vivo) are repeatedly transcribed into oligomeric complementary (−) RNAs. Such intermediates serve as templates for generating oligomeric (+) RNAs that are cleaved by a host enzyme of the RNase III class. The termini of the resulting linear monomers are ligated by the host DNA ligase 1 to generate the mature circular viroid RNA.[4]
Taxonomy
edit- Apple dimple fruit viroid
- Apple scar skin viroid
- Apscaviroid aclsvd
- Apscaviroid cvd-VII
- Apscaviroid dvd
- Apscaviroid glvd
- Apscaviroid lvd
- Apscaviroid plvd-I
- Apscaviroid pvd
- Apscaviroid pvd-2
- Australian grapevine viroid
- Citrus bent leaf viroid
- Citrus dwarfing viroid
- Citrus viroid V
- Citrus viroid VI
- Grapevine yellow speckle viroid 1
- Grapevine yellow speckle viroid 2
- Pear blister canker viroid
References
edit- ^ Di Serio, F; Owens, RA; Li, SF; Matoušek, J; Pallás, V; Randles, JW; Sano, T; Verhoeven, JTJ; Vidalakis, G; Flores, R; ICTV Report Consortium (17 December 2020). "ICTV Virus Taxonomy Profile: Pospiviroidae". The Journal of General Virology. 102 (2). doi:10.1099/jgv.0.001543. PMC 8116940. PMID 33331814.
- ^ "Virus Taxonomy: 2022 Release". International Committee on Taxonomy of Viruses (ICTV). March 2023. Retrieved 20 August 2023.
- ^ "ICTV Report Pospiviroidae".
- ^ a b Francesco Di Serio, Robert A. Owens, Shi-Fang Li, Matoušek J, Pallás V, John W. Randles, Sano T, Jacobus Th. J. Verhoeven, Vidalakis G, Flores R (2020). "ICTV Virus Taxonomy Profile: Pospiviroidae". J Gen Virol. 102 (2): 001543. doi:10.1099/jgv.0.001543. PMC 8116940. PMID 33331814.
External links
edit- ICTV Report: Pospiviroidae
- Web Archive – extensive information on pospivirioidae and viroids.
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