Question

Identify the Bt toxin gene which controls the corn borer.

• A. cryIAc
• B. cryIIAb
• C. cryIAb
• D. cryIIAc

Hint:

cry Genes to Remember:
$\bullet$ Cotton bollworms $\rightarrow$ cryIAc and cryIIAb
$\bullet$ Corn borer $\rightarrow$ cryIAb

Answer 1

The Correct Option is C

Concept:
Bacillus thuringiensis produces specific crystalline endotoxins encoded by different cry genes, each targeting specific insect orders and agricultural pests.

Step 1: Specificity of Bt cry Genes in Crops:
The insecticidal crystal proteins produced by Bacillus thuringiensis are coded by genes called cry genes.
Different cry genes have distinct pest-specificity:
- {cryIAc and {cryIIAb genes: Code for delta-endotoxin proteins that effectively control the cotton bollworm (Helicoverpa armigera).
- {cryIAb gene: Specifically codes for an endotoxin that controls the corn borer (Ostrinia nubilalis).

Step 2: Conclusion:
The specific gene utilized in biotechnology to control the corn borer pest in maize crops is cryIAb.
Therefore, Option (C) is the correct answer.