A novel strategy was adopted to prevent the infection of nematode was based on which process?

Answer

### Step-by-Step Solution:

1. **Identify the Nematode and Its Impact**:
- The nematode in question is *Meloidogyne incognita*, which infects the roots of tobacco plants, leading to decreased yields.

2. **Understanding the Genetic Mechanism**:
- The process of gene expression involves DNA being transcribed into RNA, which is then translated into proteins. Proteins are crucial for various cellular functions, including those that can lead to infections.

3. **Modification of RNA**:
- A novel strategy was developed to prevent the infection by modifying the RNA. Instead of allowing the RNA to remain single-stranded, it was converted into double-stranded RNA (dsRNA).

4. **Effect of Double-Stranded RNA**:
- Ribosomes, which are responsible for protein synthesis, can only attach to single-stranded RNA. When RNA is double-stranded, ribosomes cannot bind to it, preventing the formation of proteins.

5. **Use of a Vector for Gene Transfer**:
- A vector, specifically *Agrobacterium tumefaciens*, was used to transfer the gene of interest into the tobacco plant. This gene encoded for the double-stranded RNA.

6. **RNA Silencing Mechanism**:
- Once the double-stranded RNA was produced inside the plant, it interacted with the target RNA. Special proteins called "dicers" cut the double-stranded RNA into smaller pieces.

7. **Silencing of Target RNA**:
- The cut pieces of double-stranded RNA bound to the single-stranded target RNA, preventing it from being translated into proteins. This process is known as RNA silencing.

8. **Conclusion**:
- The novel strategy to prevent nematode infection is based on RNA silencing, also referred to as RNA interference (RNAi). This technique effectively silences the RNA responsible for the infection, thereby preventing the nematode from causing harm to the tobacco plants.