Choose the incorrect statement with respect to Agrobacterium tumefaciens.

Options

A. It is a Gram-negative soil bacterium.
B. It produces crown gall disease in dicot plants.
C. The foreign DNA is inserted at the ori site of Ti plasmid.
D. Ti plasmid becomes incorporated into the plant chromosomal DNA.

Answer

To determine the incorrect statement regarding Agrobacterium tumefaciens, let's analyze the provided statements step by step.

### Step-by-Step Solution:

1. **Identify the Characteristics of Agrobacterium tumefaciens**:
- Agrobacterium tumefaciens is a soil-borne bacterium.
- It is rod-shaped and classified as gram-negative.

2. **Understanding the Disease Caused**:
- Agrobacterium tumefaciens is known to cause crown gall disease in dicot plants. This disease is characterized by the formation of tumors on roots, twigs, and branches due to uncontrolled cell growth.

3. **Examine the Role of Ti Plasmid**:
- The bacterium contains a tumor-inducing plasmid (Ti plasmid), which is crucial for its pathogenicity.
- The foreign DNA is not inserted at the ovary site of the Ti plasmid; instead, it is inserted into the transfer DNA (T-DNA) region of the Ti plasmid.

4. **Integration into Plant DNA**:
- The Ti plasmid, after transferring the T-DNA into the plant cell, becomes incorporated into the plant's chromosomal DNA. This process is essential for the transformation of the plant cells.

5. **Identify the Incorrect Statement**:
- The statement claiming that "the foreign DNA is inserted at the ovary site of Ti plasmid" is incorrect. The correct insertion site is the T-DNA region.

### Conclusion:
The incorrect statement with respect to Agrobacterium tumefaciens is: **"The foreign DNA is inserted at the ovary site of Ti plasmid."**

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