Author
|
Submitted to: International Conference on Tropical and Subtropical Plant Diseases
Publication Type: Proceedings Publication Acceptance Date: 11/1/2002 Publication Date: N/A Citation: N/A Interpretive Summary: The discovery of Tobacco mosaic virus (TMV) in the late 1800's is generally considered to herald the beginning of the science of virology. TMV is the type member of the Tobamovirus genus of RNA viruses, which also includes Tomato mosaic virus, Pepper mild mottle virus, Turnip vein-clearing virus and Cucumber green mottle mosaic virus. The early detection and ease of experimental manipulation of the tobamoviruses have made them some of the most intensively studied of all viruses. Although well characterized, tobamoviruses still cause significant economic losses worldwide, particularly in solanaceous and cucurbitaceous crops. This report provides a current status of tobamoviruses as model organisms and plant pathogens for growers, industry, Extension personnel, state and Federal research and regulatory scientists. Technical Abstract: Tobacco mosaic virus (TMV) was the first virus of any type discovered and has played an important role in many areas of science including the development of the field of virology. All tobamoviruses form rigid, rod-shaped particles approximately 300 nm in length. Tobamovirus genomes consist of one positive-sense, single-stranded RNA ranging from 6,300 to 6,600 nucleotides. Four proteins are encoded in the viral genome. Phylogenetic analysis of recognized and tentative tobamovirus species has revealed three sub-groups within the genus, which correspond well with groupings based on host range. These three tobamovirus sub-groups are those that infect (i) solanaceous plants, (ii) brassicas, or (iii) cucurbits or legumes. Coevolution of tobamoviruses with their hosts is the current theory for the correspondence of groupings based upon virus sequences with those based upon host range. Many tobamoviruses are distributed worldwide and can infect many field and greenhouse crops. The Solanaceae and Cucurbitaceae contain many of the most economically important hosts including pepper, tomato, tobacco, cucumber and squash. Tobamoviruses form very stable particles making them easy to spread and difficult to eliminate. Virus-free seeds should be used and care should be taken to not infect transplants during production to ensure that only uninfected transplants are set in the field. In spite of our ever-advancing knowledge of these pathogens, tobamoviruses are still capable of causing significant economic impact as evidenced by recent outbreaks of tobamoviruses in tomato and pepper in Florida, USA. |
