Plant Genetic Engineering—What Is Agrobacterium tumefaciens? In biotechnology, Agrobacterium tumefaciens is best described as:
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AA bacterium that can be used to introduce DNA into plants
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BA human disease that causes loss of sight
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CA fungus used to produce antibiotics at industrial scale
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DA human disease that causes significant weight loss
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EA viral vector specific for mammalian cells
Answer
Correct Answer: A bacterium that can be used to introduce DNA into plants
Explanation
Introduction / Context:Agrobacterium tumefaciens naturally transfers a segment of DNA (T-DNA) from its Ti plasmid into plant genomes, causing crown gall disease. This biological mechanism has been repurposed to deliver transgenes into many plant species.
Given Data / Assumptions:
- Ti (tumor-inducing) plasmid harbors T-DNA and virulence (vir) genes.
- Engineered disarmed vectors remove tumor genes and carry transgenes of interest.
- Plant tissue culture enables regeneration of whole plants from transformed cells.
Concept / Approach:The bacterium attaches to wounded plant tissue, activates vir genes, and transfers T-DNA into the plant nucleus, where it integrates into the genome. Molecular biologists exploit this system by replacing oncogenes with selectable markers and target genes, enabling stable plant transformation.
Step-by-Step Solution:
Use disarmed Agrobacterium carrying a binary vector with the gene of interest.Infect explants; allow T-DNA transfer and genomic integration.Select transformed cells and regenerate plants through tissue culture.Verification / Alternative check:Transgene presence is confirmed by PCR, Southern blotting, or reporter gene expression (e.g., GUS, GFP).
Why Other Options Are Wrong:
- It is not a human disease, nor a fungus, nor a mammalian viral vector.
Common Pitfalls:Confusing Agrobacterium-mediated transformation (dicots easily, many monocots now feasible) with biolistics; both are used but have different efficiencies and host ranges.
Final Answer:A bacterium that can be used to introduce DNA into plants