The tumour inducing capacity of Agrobacterium tumefaciens is located in large extrachromosomal plasmids called :

Options

A. Ti plasmid
B. Ri plasmid
C. Lambda phage
D. Plasmind pBR322

Answer

To answer the question regarding the tumor-inducing capacity of Agrobacterium tumefaciens, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Agrobacterium tumefaciens**:
- Agrobacterium tumefaciens is a bacterium known for its ability to induce tumors in plants. This characteristic is significant in biotechnology, particularly in plant genetic engineering.

2. **Role of Plasmids**:
- The tumor-inducing capacity of Agrobacterium tumefaciens is associated with specific plasmids. Plasmids are small, circular pieces of DNA that exist independently of chromosomal DNA and can replicate on their own.

3. **Identifying the Relevant Plasmids**:
- The two main types of plasmids associated with Agrobacterium are:
- **Ti plasmid (Tumor-inducing plasmid)**: This plasmid is responsible for the tumor-inducing ability of Agrobacterium tumefaciens.
- **Ri plasmid (Root-inducing plasmid)**: This plasmid is found in another species of Agrobacterium (Agrobacterium rhizogenes) and is not responsible for tumor induction in the same way as Ti plasmid.

4. **Eliminating Incorrect Options**:
- **Lambda phage**: This is a type of bacteriophage that infects E. coli and is not related to Agrobacterium.
- **PBR 322 plasmid**: This is a plasmid used in E. coli for cloning purposes and does not have any association with Agrobacterium tumefaciens.

5. **Conclusion**:
- Based on the above analysis, the tumor-inducing capacity of Agrobacterium tumefaciens is located in the Ti plasmid. Therefore, the correct answer is **Ti plasmid**.

### Final Answer:
The tumor-inducing capacity of Agrobacterium tumefaciens is located in large extrachromosomal plasmids called **Ti plasmids**.

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