Strategy used to prevent nematode infection of tobacco roots is

Options

A. Use of agrochemicals
B. Bt toxin gene
C. Gene mutation
D. RNA interference

Answer

### Step-by-Step Solution:

1. **Understanding Nematodes**:
- Nematodes are a group of organisms that can parasitize plants and animals, including humans. One of the most significant nematodes affecting tobacco is *Meloidogyne incognita*.

2. **Impact on Tobacco**:
- *Meloidogyne incognita* infects the roots of tobacco plants, leading to a significant reduction in yield. This necessitates the development of strategies to prevent such infections.

3. **Exploring Prevention Strategies**:
- The question asks for a strategy to prevent nematode infections specifically in tobacco roots. The options provided are:
- Use of agrochemicals
- DT toxin gene
- Gene mutation
- RNA interference

4. **Identifying the Effective Strategy**:
- Among the options, RNA interference (RNAi) is a novel strategy that has been successfully used to combat nematode infections in plants.

5. **Mechanism of RNA Interference**:
- RNA interference involves the use of a vector, such as *Agrobacterium*, to introduce nematode-specific genes into the tobacco plant.
- These genes lead to the production of both sense and anti-sense RNA in the plant cells, which are complementary to each other.

6. **Formation of Double-Stranded RNA**:
- The sense and anti-sense RNA combine to form double-stranded RNA (dsRNA), which triggers the RNA interference process.

7. **Silencing Nematode mRNA**:
- The dsRNA initiates the silencing of specific mRNA of the nematode, preventing the nematode from surviving in the transgenic tobacco host.

8. **Conclusion**:
- The effective strategy to prevent nematode infection of tobacco roots is RNA interference (RNAi), which allows the plant to resist nematode attacks.

### Final Answer:
The strategy used to prevent nematode infection of tobacco roots is RNA interference (RNAi).

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