''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known

plant virus Plant viruses are viruses that affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathogenic to higher plants. ...

es, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus.

Structure

Potyvirid virions are nonenveloped, flexuous filamentous, rod-shaped particles. The diameter is around 12–15 nm, with a length of 200–300 nm.

Genome

Genomes are linear and usually nonsegmented, around 8–12kb in length, consisting of positive-sense RNA, which is surrounded by a protein coat made up of a single viral encoded protein called a

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or ma ...

. All induce the formation of virus

inclusion bodies Inclusion bodies are aggregates of specific types of protein found in neurons, a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells ...

called cylindrical inclusions (‘pinwheels’) in their hosts. These consist of a single protein (about 70

kDa The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at re ...

) made in their hosts from a single viral genome product. Member viruses encode large polypeptides that are cleaved into mature

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s. In 5'–3' order these proteins are * P1 (a

serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − for ...

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...

): 83 kDa * HC (a protease): 51 kDa * P3: 34 kDa * 6K1: 5 kDa * Cl (

helicase Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separatin ...

): 71 kDa * 6K2: 6 kDa * VPg (the 5' binding protein): 20 kDa * NIa-Pro (a protease): 27 kDa * NIb (

RNA dependent RNA polymerase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template. This is in contrast to t ...

): 57 kDa * Capsid protein: 34 kDa There may be some variation in the number of the proteins depending on the genera and species. For instance some genera lack P1, some virus of the genus ''

Ipomovirus ''Ipomovirus'' is a genus of positive-strand RNA viruses in the family ''Potyviridae''. Member viruses infect plants and are transmitted by whiteflies (''Bemisia tabaci''). The name of the genus is derived from ''Ipomoea'' – the generic name ...

'' lack HC and have a P1 tandem. Pretty interesting sweet potato potyviral ORF (PISPO), alkylation B (AlkB), and

inosine triphosphate pyrophosphatase Inosine triphosphate pyrophosphatase is an enzyme that in humans is encoded by the ''ITPA'' gene, by the ''rdgB'' gene in bacteria ''E.coli'' and the ''HAM1'' gene in yeast ''S. cerevisiae''; the protein is also encoded by some RNA viruses of the ...

(known as ITPase or HAM1) are protein domains identified in atypical members.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration. Replication follows the positive-stranded RNA virus replication model. Positive-stranded RNA virus transcription is the method of transcription. Translation takes place by −1 ribosomal frameshifting. The virus exits the host cell by tubule-guided viral movement. Plants serve as the natural host. The virus is transmitted via a vector (often an insect or mite). Transmission routes are vector and mechanical.

Transmission

''Potyvirus'' is the largest genus in the family, with 183 known species. These viruses are 720–850 nm in length and are transmitted by

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s. They can also be easily transmitted by mechanical means. These viruses shared a common ancestry 6,600 years agoNigam D, LaTourrette K, Souza PFN, Garcia-Ruiz H (2019) Genome-wide variation in Potyviruses. Front Plant Sci 10:1439 and are transmitted by over 200 species of aphids. The species in the genus ''Macluravirus'' are 650–675 nm in length and are also transmitted by aphids. The plant viruses in the genus ''Ipomovirus'' are transmitted by whiteflies and they are 750–950 nm long. ''Tritimovirus'' and the ''Rymovirus'' viruses are 680–750 nm long and are transmitted b
eriophydid mites
(The rymoviruses are closely related to the potyviruses and may eventually be merged with the potyviruses.Description of Plant Viruses
Family ''Potyviridae'' figure
/ref>) The ''Bymovirus'' genome consists of two particles instead of one (275 and 550 nm) and these viruses are transmitted by the chytrid fungus, '' Polymyxa graminis''.

Taxonomy

The following genera are recognized: * '' Arepavirus'' * '' Bevemovirus'' * ''

Brambyvirus ''Brambyvirus'' is a genus of viruses, in the family ''Potyviridae ''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The f ...

'' * ''

Bymovirus ''Bymovirus'' is a genus of viruses, in the family ''Potyviridae ''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The fam ...

'' * '' Celavirus'' * ''

'' * ''

Macluravirus ''Macluravirus'' is a genus of viruses, in the family ''Potyviridae ''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. Th ...

'' * ''

Poacevirus ''Poacevirus'' is a genus of viruses, in the family ''Potyviridae ''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The fa ...

'' * ''

Potyvirus ''Potyvirus'' is a genus of positive-strand RNA viruses in the family ''Potyviridae''. Plants serve as natural hosts. The genus is named after member virus ''potato virus Y''. Potyviruses account for about thirty percent of the currently known ...

'' * '' Roymovirus'' * '' Rymovirus'' * '' Tritimovirus'' The following species are unassigned to a genus: * '' Common reed chlorotic stripe virus'' * ''

Longan witches broom-associated virus ''Longan witches broom-associated virus'' (LWBD or LWBaV) is a species of positive-sense single-stranded RNA virus that has not been assigned to a genus within the family ''Potyviridae''. It is thought to be the cause of witch's broom in longan ...

'' * '' Spartina mottle virus''

References

External links

ICTV Online (10th) Report: ''Potyviridae''

{{Taxonbar, from=Q3043076 Viral plant pathogens and diseases Virus families Riboviria