Question

Cotton boll worm and corn borer are killed by which genes?

• A. CryIAc, CryIIAb and CryIAb
• B. CryIAb and CryIIAc
• C. CryIAb, CryIIAb and CryIAc
• D. None of above

Hint:

Remember the important Bt genes: \[ \boxed{ \begin{aligned} CryIAc &\rightarrow \text{Cotton bollworm}\\ CryIIAb &\rightarrow \text{Cotton bollworm}\\ CryIAb &\rightarrow \text{Corn borer} \end{aligned} } \] Bt crops are genetically modified plants containing Cry genes from Bacillus thuringiensis.

Answer 1

The Correct Option is A

Concept: Bacillus thuringiensis (Bt) produces crystal (Cry) proteins that are toxic to specific insect pests. Different Cry genes are effective against different insects. The important Bt genes are: \[ \boxed{ \begin{aligned} CryIAc &\rightarrow \text{Cotton bollworm}\\ CryIIAb &\rightarrow \text{Cotton bollworm}\\ CryIAb &\rightarrow \text{Corn borer} \end{aligned} } \] These genes are introduced into crop plants to provide insect resistance.

Step 1: Identify the Bt genes effective against cotton bollworm.
Cotton bollworm is controlled by \[ \boxed{CryIAc \text{ and } CryIIAb.} \] These genes produce insecticidal proteins that destroy the larval gut.

Step 2: Identify the Bt gene effective against corn borer.
Corn borer is effectively controlled by \[ \boxed{CryIAb.} \] This gene is widely used in Bt maize.

Step 3: Select the correct combination.
The combination containing all three genes is \[ CryIAc,\;CryIIAb,\;CryIAb. \] Hence, \[ \boxed{\textbf{Option (A)}} \] is the correct answer.