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Tomato Mosaic Virus and Cucumber Mosaic Virus


Tomato growers in Maharashtra attribute crop decline to the Cucumber Mosaic Virus (CMV), while growers in Karnataka and other South Indian states blame the Tomato Mosaic Virus (ToMV) for their crop losses.


GS-III: Agriculture

Dimensions of the Article:

  1. ToMV (Tomato mosaic virus)
  2. CMV (Cucumber mosaic virus)
  3. Similarities between ToMV and CMV

ToMV (Tomato mosaic virus):

  • ToMV is a member of the Virgaviridae family and is closely related to the Tobacco Mosaic Virus (TMV).
  • It primarily infects tomato plants but can also affect tobacco, peppers, and certain ornamental plants.
  • The virus was first identified in tomato plants in 1935.
  • ToMV spreads through various means, including infected seeds, saplings, agricultural tools, and human contact.
  • Certain insect vectors, such as thrips and whiteflies, can also transmit the virus.
  • Infected plants display green mottling and yellowing of leaves, often appearing as blisters or fern-like patterns.
  • Leaf curling in either an upward or downward direction and distortion may occur.
  • Younger plants may experience stunted growth, and fruit setting can be affected.
Prevention and Control:
  • Emphasize the implementation of biosafety standards in nurseries and ensure compulsory seed treatment.
  • Farmers should thoroughly inspect saplings before planting and discard any infected materials.

CMV (Cucumber mosaic virus):

  • CMV belongs to the Bromoviridae family and is one of the most widespread plant viruses.
  • It has a broad host range, affecting crops such as cucumber, melon, eggplant, tomato, carrot, lettuce, celery, cucurbits, and some ornamental plants.
  • The virus was first identified in cucumber plants in 1934.
  • CMV primarily spreads through aphids, which are sap-sucking insects capable of acquiring and transmitting the virus within minutes.
  • Transmission can also occur through infected seeds, mechanical inoculation, and grafting.
  • Infected plants exhibit leaf distortion, primarily at the top and bottom, while the middle portion remains relatively unaffected.
  • In cucumber plants, CMV causes a mosaic-like pattern of yellow and green spots on the leaves.
  • Fruit formation can be adversely affected, resulting in stunting and reduced production.
Prevention and Control:
  • The key focus should be on preventing aphids, the primary vector, by employing quick-acting insecticides or mineral oils.
  • Care should be taken to avoid aphid migration and the spread of the virus to other fields.

Similarities between ToMV and CMV:

Genome and Replication:
  • Both ToMV and CMV have a single-stranded RNA genome that is enclosed within a rod-shaped protein coat.
  • Both viruses enter plant cells through wounds or natural openings and replicate within the cytoplasm.
  • They can move systemically throughout the plant via the phloem, spreading to different parts of the plant.
Impact on Crop:
  • Both ToMV and CMV have the potential to cause significant crop losses, often approaching 100% if not adequately addressed in a timely manner.
  • The severity of the crop loss depends on the susceptibility of the specific crop and the extent of infection.

-Source: Indian Express

December 2023