Cucumber mosaic virus facts for kids
Quick facts for kids Cucumber mosaic virus |
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| Cucumber mosaic virus symptoms | |
Virus classification  |
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| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Kitrinoviricota |
| Class: | Alsuviricetes |
| Order: | Martellivirales |
| Family: | Bromoviridae |
| Genus: | Cucumovirus |
| Species: |
Cucumber mosaic virus
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The Cucumber mosaic virus (CMV) is a tiny germ, called a virus, that makes plants sick. It belongs to the Bromoviridae family. This virus is found all over the world and can infect more types of plants than any other known plant virus. It can spread from one plant to another in a few ways: through plant sap (like when tools touch an infected plant and then a healthy one), by tiny insects called aphids, through seeds, and even by parasitic weeds like Cuscuta sp. (also known as dodder).
Contents
What Plants Get Sick and How They Look
This virus was first found in cucumbers (Cucumis sativus) in 1934. The cucumbers had a strange pattern on their leaves, which looked like a mosaic, giving the virus its name. Since then, scientists have found it in many other plants.
These include common vegetables like squash, melons, peppers, eggplants, tomatoes, beans, carrots, celery, lettuce, spinach, and beets. It also infects many ornamental plants (plants grown for their beauty), like Narcissus, and various weeds. CMV has been found on every continent, even Antarctica.
When a plant gets CMV, you might see several signs:
- Leaves can have a mosaic pattern or look mottled (Fig. 1), like a mix of light and dark green or yellow.
- Leaves might turn yellow.
- You might see ring-shaped spots.
- The plant's growth can be stunted, meaning it stays small.
- Leaves, flowers, and fruits can look twisted or misshapen.
- Sometimes, young leaves become very narrow, which is called the "shoestring" effect.
For example, cucumbers infected with CMV can become pale and bumpy. Their leaves might look wrinkled and odd. The plants often don't grow well and produce few flowers. The cucumber fruits themselves can be strangely shaped, look gray, and taste bitter. People sometimes call these "white pickles."
Tomato plants often stop growing tall and have oddly shaped leaves, sometimes called "fernleaf" because they look like fern fronds. Some types of CMV can cause farmers to lose most or all of their tomato crop.
In peppers, CMV causes severe damage to the leaves, showing mosaic patterns and dark, dead rings. The peppers themselves can be misshapen and have yellow rings or spots.
CMV has also been found in other plants like Allium crops (onions and garlic). It can cause garlic plants to be very deformed and onion leaves to have mild damage or severe dark streaks.
Inside infected plant cells, this virus forms special shapes called viral inclusion bodies. These shapes are like tiny hexagonal or rhomboid (diamond-like) structures (Fig. 2) made up of virus particles. They can help scientists diagnose the virus.
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Fig. 1 Symptoms in Commelina diffusa
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Fig. 2 Cucumber mosaic virus inclusion bodies
Why CMV is Important
CMV is a big problem because it spreads very easily. More than 80 different types of aphids can carry it from one plant to another. This means the virus can be found all over the world.
CMV can infect over 1,200 different plant species, including many important crops that farmers grow for food and beautiful ornamental plants. When plants get CMV, it can cause a lot of damage, leading to big financial losses for farmers. For example, it can cause a 10-20% loss in crop yield in fields.
How the Disease Spreads
CMV is mainly spread by aphids. These tiny insects pick up the virus when they feed on an infected plant and then pass it to healthy plants when they feed again. The virus can also be spread by people, for example, if they touch an infected plant and then a healthy one without cleaning their tools or hands. However, this is less common than with some other viruses, like Tobacco mosaic virus.
Aphids can pick up the virus in just a few seconds and pass it on within about a minute. After a couple of hours, it becomes much harder for them to spread it.
CMV can also survive the winter. It hides in perennial plants (plants that live for more than two years) and weeds. The virus stays in the roots during the cold months and then moves up to the leaves and stems in the spring, ready to be spread by aphids to new plants.
Once the virus gets inside a plant cell, it releases its genetic material. Then, it uses the plant's own machinery to make many copies of itself and build new virus particles. These new virus particles are then ready to move to other cells. The virus can move from cell to cell over short distances and also travel long distances throughout the plant using the plant's transport system, called the phloem.
Virus Details
What the Virus Looks Like
CMV particles are not covered by an outer envelope. They are round or rod-shaped and very tiny, about 26-35 nanometers across (a nanometer is one billionth of a meter!). The different parts of the virus's genetic material are packaged into separate particles, so you can find a variety of shapes.
Where it is Found
CMV is naturally found in areas with moderate climates, which is also where its main carriers, aphids, are common.
How to Detect It
Scientists can confirm if a plant has CMV using special tests. These include ELISA (a test that uses antibodies to find the virus), PCR (a test that finds the virus's genetic material), or by testing which plants the virus can infect.
How to Control It
Right now, there's no chemical that can cure a plant once it's infected with CMV. So, the best way to deal with it is to stop the infection from happening in the first place. This means:
- Removing weeds and sick plants from fields.
- Using clean tools when working with plants.
- Planting resistant varieties of crops (plants that are naturally stronger against the virus).
- Using "trap crops," which are plants grown specifically to attract pests like aphids away from the main crop.
