How many of the following vectors are used for gene transfer in plants ?
Ri plasmid, Ti plasmid, PEG, CMV, Gene gun

Options

A. 1
B. 2
C. 3
D. 5

Answer

To determine how many of the listed vectors are used for gene transfer in plants, we will analyze each option one by one.

### Step 1: Analyze each vector

1. **Ri Plasmid**:
- The Ri plasmid is derived from *Agrobacterium rhizogenes*, which is known for its ability to transfer genes into plant cells. Therefore, it is a vector used for gene transfer in plants.

2. **Ti Plasmid**:
- The Ti plasmid comes from *Agrobacterium tumefaciens*, and it is one of the most commonly used vectors for transferring genes into plants. Thus, it is also a vector used for gene transfer in plants.

3. **PEG (Polyethylene Glycol)**:
- PEG is a chemical used to facilitate the uptake of DNA by plant cells, but it is not a vector itself. It is a method for gene transfer rather than a vector.

4. **CMV (Cucumber Mosaic Virus)**:
- CMV is a viral vector that can be used for gene transfer in plants. It is known for its ability to infect a wide range of plant species, making it a useful tool for plant genetic engineering.

5. **Gene Gun**:
- The gene gun is a physical method used to introduce DNA into plant cells by shooting microscopic gold or tungsten particles coated with DNA into the cells. However, it is not classified as a vector.

### Step 2: Count the vectors used for gene transfer in plants

From the analysis:
- Ri Plasmid: Yes (vector)
- Ti Plasmid: Yes (vector)
- PEG: No (not a vector)
- CMV: Yes (vector)
- Gene Gun: No (not a vector)

### Conclusion

The total number of vectors used for gene transfer in plants from the given options is **3**: Ri Plasmid, Ti Plasmid, and CMV.

### Final Answer: 3

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