Question

The vector useful for delivering rDNA into dicot plant cell is

• A. Agrobacterium tumefaciens
• B. Retrovirus
• C. Bacillus thuringiensis
• D. Baculovirus

Answer 1

The correct option is A

Agrobacterium tumefaciens

The correct option is A.

Explanation of the correct option:

1. In recombinant DNA technology, a vector is used as a vehicle for transferring a particular DNA segment into the host cells.
2. Agrobacterium tumefaciens is used as a cloning vector in dicot plants.
3. It is a rod-shaped, gram-negative soil bacteria that causes crown gall disease in plants.
4. The crown gall disease occurs when the bacteria releases tumor-inducing plasmid into the plant cell.
5. The piece of Ti plasmid that transform normal cells of plants into cancerous cells is called as T-DNA.
6. The tumor-inducing plasmid is made noncancerous in the laboratory by removing cancerous genes and can act as a cloning vector for transferring desired genes into the host genome.
7. Agrobacterium tumefaciens is used as a cloning vector for producing transgenic plants.

Explanation of the incorrect options:

Option B:

1. The viruses belong to the family Retroviridae.
2. Retroviruses carry RNA as genetic material.
3. Retroviruses contain an enzyme called reverse transcriptase that is responsible for causing HIV in humans.
4. When a person gets infected by HIV then the viral enzyme converts the viral genome (RNA) into single-stranded DNA, which incorporates into the host genome and replicates by using host machinery and increases its number.

Option C:

1. Bacillus thuringienis is a bacteria that produces a toxin that kills insects and pests.
2. Bt acts as an important bacteria for controlling insect pests by directly introducing the bacterial genes into host plants
3. Bt cotton is an example of a genetically modified plant.
4. Bt cotton was developed to control the insecticidal attack on cotton plants.
5. The cotton plant is made resistant to insects such as pink bollworms by inserting cryIAc and cryIIAb genes in the genome of the cotton plant.
6. The bacterial genes of Bacillus thuringiensis, cryIAc and cryIIAb produce insecticidal toxins, when the insect ingests bt cotton plant, the insecticidal toxin binds to the surface of midgut epithelial cells, and creates pores in the cells which leads to swelling and lysis, eventually causes the death of the insect.

Option D:

Baculoviruses are a group of DNA viruses that infect a large range of insects such as flies from Diptera, wasps, bees, and ants from Hymenoptera order, and butterflies and moths from Lepidoptera.

Final Answer: the vector useful for delivering rDNA into a dicot plant cell is Agrobacterium tumefaciens.