Which of the following bacteria are known as natural genetic engineers of plants, as gene transfer is happening in nature without human interference?

Options

A. a.Azotobacter
B. b.Agrobacterium tumefaciens
C. c.Escherichia coli
D. d.Rhizobium

Answer

To solve the question regarding which bacteria are known as natural genetic engineers of plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which bacteria are recognized as natural genetic engineers of plants due to their ability to transfer genes without human intervention.

2. **Analyze the Options**: The given options are:
- A) Azobacter
- B) Agrobacterium tumefaciens
- C) Escherichia coli
- D) Rhizobium

3. **Research Each Bacterium**:
- **Azobacter**: This is a nitrogen-fixing bacterium that is often used as a biofertilizer. It does not transfer genes to plants.
- **Agrobacterium tumefaciens**: This bacterium is known for its ability to transfer a part of its DNA (tDNA) into the plant cells, causing crown gall disease. This process occurs naturally and is a classic example of natural genetic engineering.
- **Escherichia coli**: Commonly found in the intestines of warm-blooded animals, it does not play a role in gene transfer to plants.
- **Rhizobium**: This bacterium is involved in nitrogen fixation in legumes but does not transfer genes to plants.

4. **Identify the Correct Answer**: Based on the analysis, **Agrobacterium tumefaciens** is the only bacterium among the options that is recognized as a natural genetic engineer of plants.

5. **Conclusion**: Therefore, the correct answer is **B) Agrobacterium tumefaciens**.