NEETZoologyBiotechnology - Principles and Processes
A biotechnologist wants to use Agrobacterium tumefaciens to deliver a desirable gene into a dicot plant. To ensure that the plant does not develop crown gall disease after the gene transfer, which specific modification must be made to the wild-type Ti plasmid?
Options
- AThe disease-causing genes must be removed to disarm the plasmid while keeping the transfer mechanism intact
- BThe entire T-DNA region must be deleted to prevent the integration of any bacterial DNA into the plant genome
- CThe origin of replication (ori) must be excised to stop the plasmid from multiplying inside the plant cells
- DAntibiotic resistance genes must be added to actively suppress the tumor-inducing property of the bacteria
Correct answer
A. The disease-causing genes must be removed to disarm the plasmid while keeping the transfer mechanism intact
Step-by-step solution
The correct modification is to disarm the Ti plasmid by removing its disease-causing (tumor-inducing) genes. In nature, the T-DNA of the Ti plasmid carries genes that transform normal plant cells into tumor cells. To use it as a safe cloning vector, these pathogenic genes are removed while the sequences required for DNA transfer are kept intact. The gene of interest is then inserted into this disarmed T-DNA. Deleting the entire T-DNA would prevent any gene transfer. Excising the origin of replication would stop the