T-DNA for gene transfer is present in:

Options

A. Bacillus thuringiensis
B. Meloidogyne incognita
C. Agroacterium tumefaciens
D. E.Coli

Answer

**Step-by-Step Solution:**

1. **Understanding T-DNA**: T-DNA stands for Transfer DNA, which is a segment of DNA that is transferred from the bacterium Agrobacterium tumefaciens to the plant cell. This DNA is responsible for the formation of tumors in plants and is crucial for gene transfer in biotechnology.

2. **Identifying the Source of T-DNA**: The primary source of T-DNA is Agrobacterium tumefaciens, a gram-negative bacterium that naturally infects plants. When a plant is wounded, this bacterium can transfer its T-DNA into the plant's genome, leading to tumor formation.

3. **Examining the Options**:
- **Bacillus thuringiensis**: This bacterium is known for producing toxins used in pest control (e.g., BT cotton) but does not contain T-DNA.
- **Melodigine incognita**: This is a nematode that infects plants but does not have T-DNA.
- **Agrobacterium tumefaciens**: This is the correct answer as it is the only organism among the options that contains T-DNA for gene transfer.
- **E. coli**: While E. coli is used as a vector in recombinant DNA technology, it does not have T-DNA.

4. **Conclusion**: Based on the information, the organism that contains T-DNA for gene transfer is **Agrobacterium tumefaciens**.

**Final Answer**: Agrobacterium tumefaciens

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