Plant viruses are viruses that multiply by infecting plant cells and utilizing the plant cell's genetic replication machinery to manufacture new virus particles.

Plant viruses do not infect just a single species of plant. Rather, they will infect a group of closely related plant species. For example, the tobacco mosaic virus can infect plants of the genus Nicotiana. As the tobacco plant is one of the plants that can be infected, the virus has taken its name from that host. This name likely reflects the economic importance of the virus to the tobacco industry. Two other related viruses that were named for similar economic reasons are the potato-X and potato-Y viruses. The economic losses caused by these latter two viruses can be considerable. Some estimates have put the total worldwide damage as high as $60 billion a year.

The tobacco mosaic virus is also noteworthy as it...