Geminiviridae

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Geminiviridae
Purified Maize streak virus (MSV) particles stained with uranyl acetate. Size bar indicates 50 nm.
Virus classification Edit this classification
(unranked): Virus
Realm: Monodnaviria
Kingdom: Shotokuvirae
Phylum: Cressdnaviricota
Class: Repensiviricetes
Order: Geplafuvirales
Family: Geminiviridae
Genera

See text

Geminiviridae is a family of

ambisense). According to the Baltimore classification
they are considered class II viruses. It is the largest known family of single stranded DNA viruses.

Mastrevirus and curtovirus

Bemisia tabaci
.

These viruses are responsible for a significant amount of crop damage worldwide. Epidemics of geminivirus diseases have arisen due to a number of factors, including the recombination of different geminiviruses coinfecting a plant, which enables novel, possibly virulent viruses to be developed. Other contributing factors include the transport of infected plant material to new locations, expansion of agriculture into new growing areas, and the expansion and migration of vectors that can spread the virus from one plant to another.[5]

Virology

The genome of ssDNA can either be a single component between 2500–3100

icosahedra joined at the missing vertex. The capsids range in size from 18–20 nm in diameter with a length of about 30 nm. Begomoviruses with two component (i.e. bipartite) genomes have these components separated into two different particles both of which must usually be transmitted together to initiate a new infection within a suitable host cell
.

Genus Type Species Structure Symmetry Capsid Genomic arrangement Genomic segmentation
Becurtovirus Beet curly top Iran virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Begomovirus Bean golden yellow mosaic virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Segmented
Capulavirus[6] Euphorbia caput-medusae latent virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Curtovirus Beet curly top virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Eragrovirus Eragrostis curvula streak virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Grablovirus[7] Grapevine red blotch virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Mastrevirus Maize streak virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Topocuvirus Tomato pseudo-curly top virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite
Turncurtovirus Turnip curly top virus Twinned Icosahedral Incomplete T = 1 Non-enveloped Circular Monopartite

Taxonomy

The following genera are recognized:[3]

Several additional genera have been proposed: Baminivirus, Nimivirus and Niminivirus.[8]

Replication

Drawing of geminiviruses

Geminivirus genomes encode only a few proteins; thus, they are dependent on host cell factors for replication: these include factors such as

plasmodesmata.[10]

These viruses tend to be introduced into and initially infect differentiated plant cells, via the piercing mouthparts of the vector insect: however, these cells generally lack the host enzymes necessary for DNA replication, making it difficult for the virus to replicate. To overcome this block geminiviruses can induce plant cells to reenter the cell cycle from a quiescent state so that viral replication can occur.[11]

Virus Rep protein

The only protein encoded in the viral genome that is essential for geminiviral DNA replication is the geminiviral replication protein Rep.[12] Rep initiates rolling circle replication of the viral DNA and interacts with other host proteins that are components of the replication machinery.

Host RAD54 and DNA polymerases

Host protein

RAD54 modulates geminiviral DNA replication.[13] RAD54 protein acts in DNA recombination and repair and appears to be necessary for rolling circle replication of the viral DNA. Also, replication of the geminivirus DNA is mediated by the host plant DNA polymerases alpha and delta.[14]

Genus Host details Tissue tropism Entry details Release details Replication site Assembly site Transmission
Becurtovirus Spinach Phloem; sieve; phloem-limited Viral movement; mechanical inoculation Budding Nucleus Nucleus Viral movement; contact
Begomovirus Dicotyledonous plants Phloem; sieve; phloem-limited Viral movement; mechanical inoculation Budding Nucleus Nucleus Bemisia tabaci whiteflies
Capulavirus Dicotyledonous plants None Viral movement; mechanical inoculation Budding Nucleus Nucleus Aphid
Curtovirus Dicotyledonous plants Phloem-limited Viral movement; mechanical inoculation Budding Nucleus Nucleus Beet leefhopper
Eragrovirus Plants None Viral movement; mechanical inoculation Budding Nucleus Nucleus Treehopper; leafhopper
Grablovirus Vitis vinifera (grapevine) None Viral movement; mechanical inoculation Budding Nucleus Nucleus Treehopper
Mastrevirus Monocots[15] None Viral movement; mechanical inoculation Budding Nucleus Nucleus Leafhopper
Topocuvirus Dicotyledonous plants None Cell receptor endocytosis Budding Nucleus Nucleus Leafhopper
Turncurtovirus Turnip None Cell receptor endocytosis Budding Nucleus Nucleus Leafhopper

Evolution

These viruses may have evolved from a phytoplasma plasmid.[16] Geminiviruses are capable of horizontal gene transfer of genetic information to the plant host.[17]

References

  1. PMID 28284245
    .
  2. ^ a b "Geminiviridae". ICTV Online (10th) Report.
  3. ^ a b "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 13 May 2021.
  4. ^ "Viral Zone". ExPASy. Retrieved 15 June 2015.
  5. PMID 10066833
    .
  6. ^ "Genus: Capulavirus - Geminiviridae - ssDNA Viruses - International Committee on Taxonomy of Viruses (ICTV)". International Committee on Taxonomy of Viruses (ICTV). Retrieved 18 August 2017.[dead link]
  7. ^ "Genus: Grablovirus - Geminiviridae - ssDNA Viruses - International Committee on Taxonomy of Viruses (ICTV)". International Committee on Taxonomy of Viruses (ICTV). Archived from the original on 22 October 2020. Retrieved 18 August 2017.
  8. ^ Ng TF, Marine R, Wang C, Simmonds P, Kapusinszky B, Bodhidatta L, Oderinde BS, Wommack KE, Delwart E (2012) High variety of known and new RNA and DNA viruses of diverse origins in untreated sewage. J Virol
  9. PMC 1464598
    .
  10. PMID 10698921
    .
  11. ^ Hanley Bowdoin lab Archived 11 February 2007 at the Wayback Machine
  12. ^ Rizvi I, Choudhury NR, Tuteja N. Insights into the functional characteristics of geminivirus rolling-circle replication initiator protein and its interaction with host factors affecting viral DNA replication. Arch Virol. 2015 Feb;160(2):375-87. doi: 10.1007/s00705-014-2297-7. Epub 2014 Dec 2. PMID 25449306
  13. ^ Kaliappan K, Choudhury NR, Suyal G, Mukherjee SK. A novel role for RAD54: this host protein modulates geminiviral DNA replication. FASEB J. 2012 Mar;26(3):1142-60. doi: 10.1096/fj.11-188508. Epub 2011 Dec 14. PMID 22171001
  14. ^ Wu M, Wei H, Tan H, Pan S, Liu Q, Bejarano ER, Lozano-Durán R. Plant DNA polymerases α and δ mediate replication of geminiviruses. Nat Commun. 2021 May 13;12(1):2780. doi: 10.1038/s41467-021-23013-2. PMID 33986276; PMCID: PMC8119979
  15. ^ "Mastrevirus ~ ViralZone".
  16. PMID 19460138
    .
  17. PMID 30546019
    .

External links