The introduction of t-DNA into plants involves

Options

A. Infection of the plant by Agrobacterium tumefaciens
B. Altering the pH of the soil, then heat shocking the plants
C. Exposing the plants to cold for a brief period
D. Allowing the plant roots to stand in water.

Answer

To answer the question regarding the introduction of T-DNA into plants, we can break down the process into several key steps:

### Step-by-Step Solution:

1. **Understanding T-DNA and Agrobacterium tumefaciens**:
- T-DNA (transfer DNA) is a segment of DNA that is transferred from the bacterium Agrobacterium tumefaciens into the plant's genome. Agrobacterium tumefaciens is a soil bacterium known for causing crown gall disease in plants.

2. **Infection Process**:
- The first step in the introduction of T-DNA is the infection of the plant by Agrobacterium tumefaciens. This bacterium attaches to the plant cells and transfers T-DNA into the plant's cells.

3. **Integration into Host Genome**:
- Once the T-DNA is transferred into the plant cell, it integrates into the plant's nuclear genome. This integration is crucial as it allows the plant to express the genes carried by the T-DNA.

4. **Transcription and Expression**:
- After integration, the T-DNA is transcribed along with the plant's own DNA, leading to the expression of the genes of interest that were introduced through the T-DNA.

5. **Application in Genetic Engineering**:
- This natural ability of Agrobacterium tumefaciens to transfer T-DNA is exploited in genetic engineering to introduce desired traits into plants, such as resistance to pests or improved nutritional content.

### Conclusion:
The introduction of T-DNA into plants primarily involves the infection of the plant by Agrobacterium tumefaciens, which facilitates the transfer and integration of T-DNA into the plant genome.

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