Question

Which of the following modifications are made to make a “tamed” Ti plasmid which can transfer cry genes to a plant’s genome ?

• A. Removal of kanamycin resistance gene and adding phytohormone genes
• B. Removal of phytohormone gene and adding kanamycin resistance gene
• C. Removal of both kanamycin resistance gene and phytohormone genes
• D. Adding both phytohormone and kanamycin resistance gene

Answer 1

The correct option is B Removal of phytohormone gene and adding kanamycin resistance gene

Wild Ti plasmid is bulky with 200 to 800 kilobases of DNA. It has phytohormone genes which induce tumor formation due to overproduction of auxins, cytokinins and opines. The Ti plasmid is modified in such a way that it does not induce tumor formation i.e. by removing these phytohormone genes. Kanamycin or tetracycline genes are then added in its place to help in screening of transformed cells.