Explain with the help of one example how genetically modified plants can:

(a) Reduce usage of chemical pesticides
(b) Enhance nutritional value of food crops

Reduce usage of chemical pesticides :

The genetically modified plants can be resistant to insects and pests, hence the disadvantage of using chemical pesticides and the resultant environmental pollution can be eliminated.

Example - Bt cotton.

• Bt cotton is a commercially available, insect pest resistant GM crop. It is resistant to lepidoptera, diptera and coleoptera.
• The toxin produced by Bacillus thuringiensis kills the insect pests in nature.
• The gene responsible for producing this toxin is called the cry gene, and the toxin produced is the delta endotoxin.
• It is a crystalline protein secreted as protoxin (inactive form).
• This toxin gets activated inside the alkaline environment of the insect gut causing perforations in the epithelial lining of the stomach ultimately leads to death.
• Therefore the gene responsible for the production of that toxin is isolated and incorporated into the plant.
• Now the toxin is produced by the plant and it becomes resistant to the insects.

Enhance nutritional value of food crops:

Transgenic plants are produced to enhance the nutritional value of food crops.

Example - golden rice

• A rice variety containing high quantities of pro vitamin A.
• Rice plants have been genetically modified to carry the ß-carotene gene from Narcissus pseudonarcissus (Daffodil) and inserted into the Oryza sativa (Rice) using the Agrobacterium as a vector.
• In this way, Rice plants are modified to have the nutritional value of Vitamin A as well.