Notes on Family: Geminiviridae
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| twinned icosahedra |
Contents
| Members of this Family General Description Morphology Genome Genera in the Family All Known Sequences Curated Sequences |
General Description
This family is characterised by its twinned (geminate) icosahedral particles and a circular, single-stranded DNA genome in one or two components. The only other known plant viruses with ssDNA genomes have many more, smaller, segments and are placed in the family Nanoviridae. Genera are distinguished by the number of genome segments, the type of vector and the host plants infected.Morphology
Virions twinned (geminate) icosahedral, non-enveloped, 38 nm long and 22 nm in diameter. 22 capsomeres per nucleocapsid.Genome
Mono-, or bi-partite, circular single-stranded DNA. Total genome 2500-3000 or 4800-5600 nucleotides. There are coding regions in both the virion (+) and complementary (-) sense strands. All members have a single coat protein of 28-34 kDa and a replication (Rep) protein of c. 41 kDa, that initiates rolling-circle replication. In all members, there is a potential stem-loop structure in the intergenic region that includes a conserved nonanucleotide sequence (TAATATTAC) where ssDNA synthesis is initiated.Genera in the Family
- Begomovirus (Gemini virus subgroup III): transmitted by whiteflies (Bemisia spp.) to dicotyledonous plants: usually two genome segments
- Curtovirus (Gemini virus subgroup II): one genome segment coding for 7 proteins; transmitted by leafhoppers or treehoppers to dicotyledonous plants
- Mastrevirus (Gemini virus subgroup I): one genome segment coding for (3 or) 4 proteins; transmitted by leafhoppers, usually to monocotyledonous plants
- Topocuvirus: one genome segment coding for 6 proteins; transmitted by treehoppers to dicotyledonous plants