Which of the following is not applicable to Agrobacterium tumifaciens?

Options

A. Pathogen of several dicot plants.
B. Has the ability to transform normal plant cells.
C. Delivers gene of our interest.
D. Ti plasmid of it is always pathogenic to plants without any exception.

Answer

To solve the question "Which of the following is not applicable to Agrobacterium tumefaciens?", we will analyze each option provided and determine its relevance to Agrobacterium tumefaciens.

### Step-by-Step Solution:

1. **Understand Agrobacterium tumefaciens**:
- Agrobacterium tumefaciens is a bacterium known for its role in plant pathology and biotechnology. It is particularly known for causing crown gall disease in plants.

2. **Evaluate Option A**:
- "Pathogen of several dicot plants."
- Agrobacterium tumefaciens is indeed a pathogen that affects many dicotyledonous plants by causing tumors.
- **Conclusion**: This statement is applicable.

3. **Evaluate Option B**:
- "Has the ability to transform normal plant cells."
- Agrobacterium tumefaciens can transfer a portion of its DNA (T-DNA) into the plant genome, leading to the transformation of normal plant cells into cancerous cells.
- **Conclusion**: This statement is applicable.

4. **Evaluate Option C**:
- "Deliver gene of our interest."
- Agrobacterium tumefaciens is widely used in genetic engineering to deliver genes of interest into plant cells via its Ti plasmid, making it a crucial tool in recombinant DNA technology.
- **Conclusion**: This statement is applicable.

5. **Evaluate Option D**:
- "Ti plasmid of it is always pathogenic to plant without any exception."
- This statement is misleading because while the Ti plasmid can cause disease, not all plants are susceptible to it. Some plant species exhibit resistance to the effects of the Ti plasmid.
- **Conclusion**: This statement is **not applicable**.

6. **Final Answer**:
- Based on the evaluations, the option that is not applicable to Agrobacterium tumefaciens is **Option D**.

### Summary:
The correct answer to the question is **Option D**: "Ti plasmid of it is always pathogenic to plant without any exception."