biology

Tobacco etch virus

Tobacco etch virus is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tobacco etch virus rather than just read about it. In short: Tobacco etch virus (TEV) is a plant virus in the genus Potyvirus and family Potyviridae. Like other members of the genus Potyvirus, TEV has a monopartite positive-sense, single-stranded RNA genome surrounded by a capsid made from a single viral encoded protein.

Key takeaways

Tobacco etch virus belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tobacco etch virus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tobacco etch virus from memory before moving on to harder problems.

Reference excerpt

Tobacco etch virus (TEV) is a plant virus in the genus Potyvirus and family Potyviridae. Like other members of the genus Potyvirus, TEV has a monopartite positive-sense, single-stranded RNA genome surrounded by a capsid made from a single viral encoded protein. The virus is a filamentous particle that measures about 730 nm in length. It is transmissible in a non-persistent manner by more than 10 species of aphids including Myzus persicae. It also is easily transmitted by mechanical means but is not known to be transmitted by seeds.

Host range This virus infects many species of Solanaceae. Agriculturally important crops that it infects include several species of Capsicum (i.e. C. annuum, C. frutescens), tomato (Lycopersicon esculentum), and tobacco (Nicotiana spp.). It also infects many perennial weed species that can act as virus reservoirs for susceptible agricultural crops. These weed species include Solanum nigrum (nightshade), S. aculeatissimum (soda apple), Chenopodium album (pigweed), Datura stramonium (jimson weed), Linaria canadensis (blue toadflax), and Physalis spp. (ground cherry). Thus, recommendations for the control of this virus include the control of weeds in and around susceptible solanaceous crops.

Signs and symptoms Symptoms seen on plants infected with this virus can vary depending on the plant. However typical symptoms include vein clearing, mottling, and necrotic lines or etching. Symptoms can occur on leaves and fruit and the plants can become stunted. Like other potyviruses, TEV makes viral inclusions that can be seen in the light microscope if properly stained. This particular potyvirus makes two kinds of inclusions that can be diagnostic in a known host. One of the inclusions is the cylindrical inclusions found in the cytoplasm of infected cells and the second inclusion is found in the nucleus. Neither inclusion type stains in the nucleic acid stain (AzureA). (Inclusions of tobacco etch virus in various hosts.)

Geographic distribution TEV appears to be a virus that evolved in the New World. It has been reported in Canada, the United States (including Hawaii), Mexico and Puerto Rico in North America and in Venezuela in South America.

Beyond plant disease Potyvirus RNA codes for at least seven different proteins. One of them is a protease. The TEV protease is a highly site-specific protease that biochemists have used to their advantage to create a protein purification system by incorporating TEV protease's recognition site into protein purification tags. A gene construct is created containing the protein of interest fused to a TEV protease recognition site, followed by an affinity tag, such as a polyhistidine-tag. Following affinity chromatography, the purified protein is then treated with TEV protease. TEV protease cleaves at its recognition site, removing the affinity tag. This allows for affinity purification of proteins that are not well-behaved when fused to protein tags.

References

External links Tobacco Etch Virus (Pepper Diseases) Archived 2010-08-27 at the Wayback Machine Tobacco Etch Virus (Tomato Diseases) Archived 2011-07-16 at the Wayback Machine Tobacco Etch Virus (DAS-ELISA) Archived 2016-04-17 at the Wayback Machine ICTVdB - The Universal Virus Database: Tobacco etch virus Family Groups - The Baltimore Method Archived 2000-01-15 at the Wayback Machine Descriptions of Plant Viruses (DPV)

Illustrations

Worked examples

Example 1 — a first encounter with Tobacco etch virus

Start with the simplest possible case. Write down what Tobacco etch virus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tobacco etch virus before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tobacco etch virus ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tobacco etch virus

In research: Tobacco etch virus appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tobacco etch virus in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tobacco etch virus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Potyviruses, Viral plant pathogens and diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Tobacco etch virus outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Tobacco etch virus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tobacco etch virus means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tobacco etch virus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tobacco etch virus in simple terms?

Why does Tobacco etch virus matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tobacco etch virus?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tobacco etch virus.