Tobacco Mosaic Virus (TMV): Going Viral

Aliases: tobacco mosaic virus, TMV

 Plants get sick too. In fact, many illnesses afflict our photosynthetic brethren, from fungal pathogens to viruses. These diseases can decimate forests and destroy the crops we depend on. But they’re not all bad. The study of plant viruses has also led to critical advancements in infectious disease research, including the discovery of the first virus: tobacco mosaic virus (TMV), in 18982.

Fundamentally, TMV is a agricultural virus. Tobacco has been an astoundingly important crop in the United States since colonization, both culturally and economically. As of 2003, Americans consumed about 4 pounds of tobacco per capita, for those 18 and over (down from 11 pounds per capita for those 15 and over in 1962)1. With TMV epidemics threatening tobacco harvests, the value of the crop gave a potent incentive for scientific discovery about the pathogen.

The results have been impressive. Research on TMV has contributed to an array of scientific fields, including virology, plant pathology, and cellular biology. Its presence in the lab has become so commonplace that it is now considered a model system (a biological system or organism that is widely used throughout the scientific community, a kind of standard system)1.  TMV singlehandedly demonstrates that agricultural pathogens are important both on the farm and off.

tmv
They’re not just bad for your lungs.

Cause: Tobacco mosaic virus is a highly contagious virus that infects tobacco and over 200 other plant species1. Transmission can occur by several means, including contact with the leaf of an infected plant, contaminated farm tools, and contaminated seed coats. TMV is so infectious that it can even be transmitted by farmworkers whose hands that have been contaminated by infected tobacco in cigarettes. The virus enters a healthy plant through a damaged cell and can remain stable for 50 years2.

Consequence: The symptoms vary depending on the combination of host plant species, virus strain, and environmental conditions involved. They include everything from the mosaic (mottling of leaves with light and dark patches) for which it was named to necrosis. TMV can cause yield losses of 2-3% in tobacco and up to 20% in tomato1.

Cure: There is no cure for TMV. The most effective prevention is to plant TMV-resistant crop cultivars.

References

1. Scholthof, KBG. (2004). Tobacco Mosaic Virus: A model system for plant biology. Annual Review of Phytopathology, 42:13-34.

2. Scholthof, KBG. Tobacco Mosaic Virus. The Plant Health Instructor. 2005. Web. 28 November 2013. http://www.apsnet.org/edcenter/intropp/lessons/viruses/Pages/TobaccoMosaic.aspx.

Image credit: Public Domain, via Creative Commons and Wikimedia Commons