Mosaic Disease in Plants and Its Viral Causes

The mosaic plant disease is an umbrella term for a group of virulent diseases that infect various types of foliage. The eponymous mosaic virus causes the condition. The mosaic viruses come from a range of unrelated lineages, and no taxon unites the group. The virus affects many economically significant crops such as tobacco, tomato, cucumber, beet, alfalfa, and so forth. The virus causes a mottled appearance in plants.

Plant viruses may be hard to detect as the symptoms are diverse and akin to nutrient deficiency or herbicide injury. But some of the common mosaic symptoms are –

• The most typical sign of mosaic infection is yellow, white or green stripes, streaks or spots on the foliage.

• The plant leaves may become wrinkled, curled or puckered.

• There will also be visible yellowing of plant veins.

• The yield capacity declines, and the plants suffer from stunted growth.

• The fruits infected by the mosaic virus may appear mottled and have warty areas on the surface.

The mosaic symptoms may be masked or latent, mainly when the temperature is below 81 degrees Fahrenheit. Aphids and other insects, mites, fungi and nematodes spread the causal viruses. Like most viruses, the mosaic virus is also contagious, and pollen and seeds can transmit it via air. Often, soil, seed, starter pots and containers can also be infected by the virus, thereby passing it on to the plant. Cuttings or divisions from infected plants will also carry the virus to the new plant.

Tobacco Mosaic Disease

A viral infection of foliage, the tobacco mosaic disease, is a common viral disease that affects plants worldwide. The cause of the disease is the Tobacco Mosaic Virus, or TMV, which was the first plant virus to be ever identified. Irrespective of its name, the ‘tobacco’ mosaic virus can infect over 350 species of herbaceous and woody plants. The common hosts of the virus are tobacco, potatoes, tomatoes, cucumbers, and the like. The tobacco mosaic disease tremendously impacts vegetables wherein there is so much reduction of the yield and quality that commercial selling becomes impossible. The Tobacco Mosaic Virus survives in infected plants, their seeds, and the debris of infected plants. TMV can stay for long periods, and owing to its stability, the virus can survive on hands, clothing gardens, gardening tools, etc., and we can pick it from there. The tobacco mosaic disease is highly transmissible and is most typically spread by handling infected plants. Contagion via gardening tools is also pretty common.

The tobacco mosaic disease symptoms vary in type and severity, depending upon the plant species, plant age, variant of the infecting virus and likewise. But, some of the recurring signs that TVM infects a plant are

1. Blotchy and dark or light irregular patches on the leaves called leaf mosaic.

2. Curling, wrinkling and cupping of leaves

3. Stunted growth and dwarfism in the infected plant

4. The fruits of the infected plant are more diminutive and malformed with an off-putting taste.

Cucumber Mosaic Disease

Cucumber Mosaic Virus (CVM) virus causes disease among plants known as cucumber mosaic disease. CVM is one of the most common and destructive cucurbit viruses and prevalent throughout the temperate and tropical regions of the world. The virus can infect over 1200 plant species. The disease is highly infectious and can be transmitted from one plant to another plant, both mechanically by sap and by aphids. It can also be transmitted via seeds and parasitic weeds. If a plant is suffering from the cucumber mosaic disease, the typical yield losses range from 10 to 20 per cent, and even failures of up to 100 percent can occur.

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Tomato Mosaic Disease

The tomato mosaic disease is a highly contagious and severe condition infecting plants. The disease is brutal to identify as symptoms vary widely depending upon the plant's species and age, the strain of the infecting virus, environmental conditions, and so forth. Furthermore, it is challenging to distinguish the tomato mosaic disease from the closely related tobacco mosaic disease. You can identify the Tomato Mosaic Virus symptoms at all stages of growth, and the virus may infect any part of the plant.

Conclusion

Mosaic disease is an amalgamation of different virulent infections caused by mosaic viruses. Numerous strands of the mosaic virus lead to a range of mosaic diseases. The concept of plant mosaic disease may seem tedious, but with the proper preparation, the topic becomes relatively manageable. The optimal technique is to study the basics first, then move to particular types of mosaic infections such as the Tobacco Mosaic Virus, the Cucumber Mosaic Virus, etc. Moreover, complementing the preparation with past years’ question papers, concept pages, and educational videos goes a long way.