Which of the following bacterial plasmids are commonly used as vectors for gene transfer in higher plants?

Options

A. Ti plasmid of Agrobacterium tumefaciens
B. Ri plasmid of Agrobacterium rhizogenes
C. Yeast integrative plasmid
D. Both (1) and (2)

Answer

To determine which bacterial plasmids are commonly used as vectors for gene transfer in higher plants, we can analyze the given options step by step:

### Step 1: Understand the Role of Plasmids in Gene Transfer
Plasmids are small, circular DNA molecules that can replicate independently of chromosomal DNA. They can be used as vectors to transfer genes into host organisms, including plants.

### Step 2: Identify the Relevant Bacterial Plasmids
The question provides several options:
1. **Ti plasmid of Agrobacterium tumefaciens**
2. **Yeast integrative plasmid**
3. **Rhizobium plasmid**
4. **Both 1 and 2**

### Step 3: Analyze Each Option
- **Ti plasmid of Agrobacterium tumefaciens**: This plasmid is well-known for its role in transferring genes into plant cells. It has a natural ability to integrate into the plant genome, making it a common vector for plant genetic engineering.

- **Yeast integrative plasmid**: While yeast plasmids can be used in yeast systems, they are not typically used for gene transfer in higher plants.

- **Rhizobium plasmid**: Rhizobium is involved in nitrogen fixation in legumes but is not primarily used as a vector for gene transfer in higher plants.

- **Both 1 and 2**: Since only the Ti plasmid is relevant for gene transfer in plants, this option is not correct.

### Step 4: Conclusion
Based on the analysis, the most appropriate answer is:
**A. Ti plasmid of Agrobacterium tumefaciens**

### Final Answer
The bacterial plasmid commonly used as a vector for gene transfer in higher plants is the **Ti plasmid of Agrobacterium tumefaciens**.

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