Which organism is held responsible for causing root-knots in food and fibre crops especially tobacco?

Options

A. Caenorhabditis elegans
B. Meloidegyne incognita
C. Nicotiana tobaccum
D. Ascaris

Answer

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about the organism responsible for causing root-knots in food and fiber crops, particularly tobacco. The disease in question is known as "root knot."

2. **Determine the Causative Agent**: Root-knot disease is primarily caused by a specific type of organism. In this case, it is a pathogenic nematode.

3. **Classify the Nematode**: Pathogenic nematodes belong to different phyla. The nematode responsible for root-knot disease is classified under the phylum Meloidogyne.

4. **Understand the Mechanism of Infection**: The nematode introduces messenger RNA (mRNA) into the host plant. This mRNA is then translated into proteins that lead to the disease state in the plant.

5. **Prevention Methods**: To prevent root-knot disease, RNA interference (RNAi) can be utilized. This involves introducing both sense and antisense RNA strands into the host plant, which bind to the mRNA produced by the nematode, preventing protein synthesis and thus stopping the disease.

6. **Conclusion**: The organism responsible for causing root-knots in tobacco is a nematode from the genus Meloidogyne.

**Final Answer**: The organism responsible for causing root-knots in food and fiber crops, especially tobacco, is the nematode from the genus Meloidogyne.

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