begomoviruses การใช้

• No monopartite begomoviruses native to the New World have yet been identified.
• They may be able to reduce the severity of an infection by the begomoviruses.
• As begomoviruses are being characterised at the molecular level an increasing number of alphasatellites are being described.
• A division between those associated with the Begomoviruses and those with associated with Nanoviridae seems logical at present.
• There are two types of DNA satellite viruses the alphasatellites and the betasatellites both of which are dependent on begomoviruses.
• Like Begomoviruses, members of this genus may cause significant losses in agricultural, pastoral, horticultural and ornamental crops.
• Plants use gene silencing to suppress viral replication, though begomoviruses have evolved a counter-acting suppressor protein against this natural host defense.
• Alphasatellites associated with the begomoviruses require a begomovirus for movement in plants and insect transmission but are capable of self replication in host plants.
• The DNA B genome originated as a satellite that was captured by the monopartite progenitor of all extant bipartite begomoviruses and has subsequently evolved to become an essential genome component.
• The genome can either be a single component between 2500 3100 nucleotides, or, in the case of some begomoviruses, two similar-sized components each between 2600 and 2800 nucleotides.
• Both segments are generally required for successful symptomatic infection in a host cell but DNA B is dependent for its replication upon DNA A, which can in some begomoviruses apparently cause normal infections on its own.
• 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.
• Single stranded closed circular DNA . Many begomoviruses have a bipartite genome : this means that the genome is segmented into two segments ( referred to as DNA A and DNA B ) that are packaged into separate particles.
• Mastrevirus transmission is via various leafhopper species ( e . g . maize streak virus and other African streak viruses are transmitted by " Cicadulina mbila " ), curtoviruses and the only known topocuvirus species, " Tomato pseudo-curly top virus ", are transmitted by treehopper species ( e . g . " Tomato pseudo-curly top virus " is transmitted by the treehopper " Micrutalis malleifera " ), and begomoviruses are transmitted by the whitefly species, " Bemisia tabaci ".