Question

The Ti plasmid is chosen to be an effective plant cell vector for genetic modification because

• A. it can induce tumours in all organisms
• B. it is commonly available in many different plant pathogens
• C. a specific segment of this plasmid integrates itself into the host genome during infection
• D. it can induce tumors even after modification
  

Answer 1

The correct option is C a specific segment of this plasmid integrates itself into the host genome during infection

Agrobacterium tumefaciens is a bacterial plant pathogen which carries the Ti Plasmid or Tumour inducing plasmid (extrachromosomal DNA). The T-DNA segment of the Ti plasmid integrates itself into the plant cell’s genome to induce tumour formation in plants and not all organisms. This property of the plasmid makes it an effective vector for transferring foreign genes into plant cells.

The T-DNA segment of the Ti Plasmid can be genetically modified to carry foreign DNA. A restriction enzyme can be used to cut the T- DNA segment at a specific site and the DNA fragment carrying the gene of interest can be inserted into this segment using ligase enzyme. Once modified, the T-DNA becomes incapable of inducing tumours.

During Agrobacterium infection, the recombinant T-DNA segment enters the plant host cell and gets integrated into its genome. This finally helps in integration of the gene of interest into the plant genome and thus genetically modified the plant. Thus Ti plasmids are considered to be excellent plant cells vectors.