Question:
Which of the following bacterium is considered to be a natural genetic engineer?
Which of the following bacterium is considered to be a natural genetic engineer?
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Agrobacterium is the most important topic in plant biotech exams.
Key words: Ti-plasmid, T-DNA, Vir genes, Opines, Acetosyringone (the signal from the wounded plant).
It primarily transforms dicots; monocots were historically harder but are now also transformed using specific protocols.
Key words: Ti-plasmid, T-DNA, Vir genes, Opines, Acetosyringone (the signal from the wounded plant).
It primarily transforms dicots; monocots were historically harder but are now also transformed using specific protocols.
Updated On: Aug 21, 2026
- Agrobacterium tumefaciens
- Agrobacterium radiobactor
- Pseudomonas putida
- Thermus aquaticus
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Question:
The term "natural genetic engineer" refers to an organism that has a natural mechanism to transfer its own genetic material into the genome of a different host species (specifically plants) and make it express there.
Detailed Explanation:
• Mechanism of Agrobacterium tumefaciens:
Agrobacterium tumefaciens is a soil-dwelling, Gram-negative bacterium that causes Crown Gall disease in dicotyledonous plants.
It contains a large plasmid called the Ti plasmid (Tumor inducing plasmid).
A specific segment of this plasmid, known as T-DNA (Transfer DNA), is naturally transferred into the plant cell nucleus and integrated into the plant's genome.
• Why "Natural Genetic Engineer"?
Once integrated, the T-DNA genes force the plant cell to produce opines (nutrients for the bacteria) and phytohormones (causing uncontrolled cell division/gall formation).
Scientists have "disarmed" this bacterium by removing the disease-causing genes and replacing them with desirable genes of interest.
Because it naturally performs the complex task of DNA delivery and integration, it is the most widely used tool for plant transformation.
• Analyzing other options:
Agrobacterium radiobactor: Used in biological control of crown gall but does not naturally engineer plant genomes in the same context as A. tumefaciens.
Pseudomonas putida: A "superbug" known for degrading hydrocarbons (bioremediation).
Thermus aquaticus: A thermophilic bacterium from which Taq DNA polymerase is isolated for PCR.
Step 3: Final Answer:
Agrobacterium tumefaciens is the classic "natural genetic engineer" due to its T-DNA transfer mechanism.
The term "natural genetic engineer" refers to an organism that has a natural mechanism to transfer its own genetic material into the genome of a different host species (specifically plants) and make it express there.
Detailed Explanation:
• Mechanism of Agrobacterium tumefaciens:
Agrobacterium tumefaciens is a soil-dwelling, Gram-negative bacterium that causes Crown Gall disease in dicotyledonous plants.
It contains a large plasmid called the Ti plasmid (Tumor inducing plasmid).
A specific segment of this plasmid, known as T-DNA (Transfer DNA), is naturally transferred into the plant cell nucleus and integrated into the plant's genome.
• Why "Natural Genetic Engineer"?
Once integrated, the T-DNA genes force the plant cell to produce opines (nutrients for the bacteria) and phytohormones (causing uncontrolled cell division/gall formation).
Scientists have "disarmed" this bacterium by removing the disease-causing genes and replacing them with desirable genes of interest.
Because it naturally performs the complex task of DNA delivery and integration, it is the most widely used tool for plant transformation.
• Analyzing other options:
Agrobacterium radiobactor: Used in biological control of crown gall but does not naturally engineer plant genomes in the same context as A. tumefaciens.
Pseudomonas putida: A "superbug" known for degrading hydrocarbons (bioremediation).
Thermus aquaticus: A thermophilic bacterium from which Taq DNA polymerase is isolated for PCR.
Step 3: Final Answer:
Agrobacterium tumefaciens is the classic "natural genetic engineer" due to its T-DNA transfer mechanism.
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