PPPodcast12 - PPPodcast: Week 12 Welcome to the PPPodcast...

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PPPodcast: Week 12 Welcome to the PPPodcast for Week 12. This week’s Major Concept is VIRUSES. Just what are viruses, and how do they differ from other plant pathogens? First of all, you’ll be glad to hear that when you learn about plant viruses there are no scientific names to memorize! Plant viruses are often named for the plant that they infect and a symptom or two that they induce. Tobacco mosaic virus , for example, infects tobacco plants and causes a mosaic pattern of dark and light green areas on the leaves. On the negative side, this virus also infects other plant species, sometimes causing different types of symptoms, which can be confusing. But on the positive side, there is a simple relationship between the pathogen name and the disease name for viral pathogens - just drop the word “virus”. Thus, the viral pathogen Tobacco mosaic virus causes the disease tobacco mosaic. Viruses are the smallest pathogens that we study in Plant Pathology 200. While fungi and nematodes are multicellular and bacteria are single celled organisms, viruses are sub cellular - smaller than a single cell. Individual virus particles, which are also called virions , cannot be seen with the naked eye and are not even visible with the aid of a light microscope. A powerful microscope that uses electrons to visualize minute objects is required in order to see virus particles. These particles are measured in nanometers , or billionths of a meter. Tobacco mosaic virus , a medium-sized plant virus, is 300 nanometers long - you’d have to line up 84,600 particles of Tobacco mosaic virus to create a line one inch long! Most plant viruses are composed of two major components: a nucleic acid genome and a protein
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This note was uploaded on 04/01/2012 for the course PLPA 200 taught by Professor Darcy during the Spring '08 term at University of Illinois, Urbana Champaign.

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PPPodcast12 - PPPodcast: Week 12 Welcome to the PPPodcast...

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