Plant Virus

Viruses are very small (submicroscopic) infectious particles (virions) composed of a protein coat and a macromolecule core. They carry genetic information encoded in their macromolecule, which usually specifies two or more proteins. Translation of the genome (to produce proteins) or transcription and replication (to produce more nucleic acid) takes place within the host cell and uses variety of the host's biochemical "machinery". Viruses don't capture or store free energy and are not functionally active outside their host. They therefore parasites (and usually pathogens) but aren't usually considered genuine microorganisms. Most viruses are restricted to a selected kind of host. This is typically concerned with those viruses that infect plants but we also provide some taxonomic and genome information about viruses of fungi, protozoa, vertebrates and invertebrates where these are related to plant viruses. Chemical or biological control of the vector (the organism transmitting the disease, often an insect): this may be very effective where the vectors need to feed for a couple of time on a crop before the virus is transmitted but are of much less value where transmission occurs very rapidly and will have already got taken place before the vector succumbs to the pesticide.