Question

Ti plasmid used in plant genetic engineering is a plasmid found naturally in

• A. Clostridium butyricum
• B. Rhizobium leguminosarum
• C. Agrobacterium tumefaciens
• D. Thermus aquaticus

Answer 1

The correct option is C Agrobacterium tumefaciens

Tumor inducing (Ti) plasmid is present in Agrobacterium tumefaciens which is a pathogen of several dicot plants. This bacteria naturally delivers its “T-DNA” piece of Ti plasmid to the host. This leads to transformation of normal plant cells into tumor cells which produce chemicals required by the bacterial pathogen. This Ti plasmid has now been modified and engineered into a cloning vector which is no more pathogenic to the plants but is still able to deliver genes of our interest into a variety of plants.

Clostridium butyricum is a bacterium that produces butyric acid which is being used on an industrial scale.
Rhizobium leguminosarum is a bacterium which lives in symbiotic association with leguminous plants in their root nodules and fixes nitrogen for them.
Thermus aquaticus is also a bacterium which is a source of Taq DNA polymerase, a thermostable enzyme used in polymerase chain reaction (PCR).