Plants, like humans and other living things, are susceptible to viral diseases. Similarly, many viruses have adapted to target specific plant species. Mosaic viruses are a broad term for a group of plant pathogens that disrupt the normal function of plant cells, causing leaves to have a mottled or Mosaic appearance. There are hundreds of strains of Mosaic disease that are not genetically related to each other. Many of these strains, whose names include the notorious tobacco Mosaic virus, cucumber Mosaic virus, rose Mosaic virus, cowpea Mosaic virus and pepper Mosaic virus, to name just a few, cause considerable economic loss to farmers.In the past few years, the world has had a crash course in virology. Unlike prokaryotes (like bacteria) or eukaryotes (like humans, plants, etc.), virus particles cannot reproduce on their own, which is why most scientists do not consider viruses to be living organisms. A virus is a genetic material contained in a protein shell. This genetic information can be single stranded RNA or double stranded DNA fragments. Mosaic viruses include both RNA and DNA variants, although RNA viruses are the most common type found to affect eukaryotes.Once a Mosaic virus infects a plant, there is no treatment. Proper handling and hygiene are essential to protect vulnerable plants and control infections.The following content also has some reference value for raised garden beds.

 How does Mosaic virus work?

A virus is like an intruder with a copy of the key. To enter a plant cell, a virus binds to a receptor on the cell wall and provides the receptor with a key to enter the cell. Cells are like small factories inside living things, carrying out tasks or producing specific substances. When a virus hijacks a cell with viral genetic information, it reprograms the cell and alters its function at the molecular level. The cell will then help the virus multiply, rather than carrying out its intended purpose. Most of the time, infected tissue dies and the virus can spread systematically throughout the plant.


Infected plants are a threat to other plants in their vicinity, and those infected early on should be removed immediately to prevent outbreaks. Plant viruses can be transmitted by leaf-to-leaf contact, grafting, propagation or insect damage, mechanical or weather-induced damage to plant tissue. Mosaic virus affects a wide range of plants and can survive on contaminated hands, plant debris, gardening or farming tools, and even clothing.


Mosaic virus symptoms

Healthy plants have dark green or lush green leaves, while infected plants typically have mottled light green or dark green or yellow spots on the leaves and twisted leaves. Because these leaves are not functioning at an optimal level, they can fall off and cause the plant to develop stunted. Infected plants may also have small, misshapen leaves and flowers. Flowers may also have brown stripes. If the plant bears fruit, the fruit may also ripen unevenly, appear discolored or exhibit other deformities. Total fruit production will be affected. The symptoms of Mosaic virus may vary depending on the strain and host plant species.

 A common strain of Mosaic disease

Tobacco Mosaic virus

Tobacco Mosaic virus is one of the most studied of all Mosaic viruses and was the first virus to be purified in the late 19th century. The virus transmits viral RNA within baculovirus particles (virions). Tobacco Mosaic virus can infect many edible and ornamental plants, such as its namesake plants, as well as different types of tomatoes, peppers, lettuce, cucumbers, morning glory, etc. These plants are also affected by other types of Mosaic viruses, so it is impossible to diagnose a specific type of virus without sending samples to a lab. Tobacco Mosaic virus is persistent and can linger in infected soil without a host and survive high temperatures. In the seed catalog, there are tomato plants with resistant varieties labeled "TMV".


Tomato Mosaic virus

This virus is another Mosaic virus that plagues tomato growers, but there are also resistant varieties. Researchers have been studying genetically modified plants, which introduce genetic material from another plant to help improve resistance. Seeds with disease resistance will be labeled "ToMV". Infected plants can spread disease when they come into contact with healthy plants. This strain affects many other plants besides tomatoes.


Cucumber Mosaic virus

Cucumber Mosaic virus (CMV) is a disease found around the world that affects more than 1,200 plant species. In addition to mottling on the leaves, infected plants may also develop ringed spots on the leaves and fruit. The virus is spread by seed (it can be spread by seeds) and pollen, and the most common is one of the aphid-borne viruses.

Control of Mosaic virus

Purchase virus-free seeds or seedlings from a certified dealer to start your garden. You can also save the seeds of your own healthy plants for use later in the season and soak the seeds in a disinfectant solution to disinfect them. Infected plants should not be composted because the virus can remain in the soil for years.


Disinfecting garden tools or farm equipment is important to control the spread of some viral diseases. Viruses can also be transmitted to new host plants through minor insect damage. For example, aphid vectors or thrips exacerbate disease transmission. Using floating row cover can be an effective way to create a physical barrier around susceptible plants. Finally, as with other viral diseases, antibiotics or antifungal treatments do not work.


Mosaic virus immune engineering

Using genetic engineering techniques, researchers are harnessing the unique properties of Mosaic viruses to help treat human diseases. Several studies around the world have investigated the feasibility of using Mosaic viruses as targeted nanodrug delivery systems to treat tumors. Both tobacco Mosaic virus and cucumber Mosaic virus were tested in these studies. The modified virus will retain its protein shell but will not contain viral RNA or DNA, and the capsules will contain the chemotherapy drug doxorubicin. The coat protein would also be enhanced with a layer of serum albumin formulation to help the virus become more biocompatible in the human body and direct it to target only tumor cells.

March 05, 2023

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