Incorrect regarding RNAi in transgenic tobacco plant

Options

A. Nematode specific genes are introduced into host plant
B. The introduced DNA produces both sense and anti-sense RNA
C. ds RNA initiates RNAi, there by nematode specific m RNA is silenced
D. Host plant generated dsRNA triggers protection against nematode infection

Answer

### Step-by-Step Solution:

1. **Understanding RNAi**: RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. In the context of transgenic tobacco plants, RNAi is used to combat nematode infections.

2. **Analyzing the Options**:
- **Option 1**: "Nematodes specific genes are introduced into the host plant."
- This statement is correct. In RNAi, specific genes that target nematodes are indeed introduced into the tobacco plant, often using Agrobacterium vectors.

- **Option 2**: "The introduced DNA produces both sense and antisense RNA."
- This statement is also correct. The introduction of double-stranded RNA (dsRNA) into the plant leads to the production of both sense and antisense RNA, as the plant's cellular machinery processes the dsRNA.

- **Option 3**: "Double-stranded RNA initiates RNAi which silences nematode-specific mRNA."
- This statement is correct. The dsRNA introduced into the plant is complementary to the nematode mRNA, leading to its silencing through RNAi.

- **Option 4**: "Host plant generated double-stranded RNA triggers protection against nematode specific infection."
- This statement is incorrect. The dsRNA does not merely protect the plant; it actively leads to the degradation of the nematode's mRNA, thereby preventing the infection rather than just providing protection.

3. **Conclusion**: The incorrect statement regarding RNAi in transgenic tobacco plants is option 4.