Question

why are many plants genetically modified to carry the cry gene

Answer 1

Many plants are genetically modified to carry the cry genes, because cry genes from the soil bacteria Bacillus thuringiensis are used for developing insect resistant transgenic crops. Th cry genes form cry proteins, which form crystalline inclusions in bacterial spores. The cry proteins are responsible for imparting insecticidal property to B. thuringiensis.

These cry proteins are active against insects of the order Lepidoptera, Diptera, Colioptera and Hymenoptera, as well as against nematodes. Injestion of toxin crystals by the insect, paralyses the digestive tract of the insect forming a pore. The insect starves to death.

Therefore cry genes are used to produce genetically modified plants, in order to make it insect resistant.