Question

In Bt Cotton, the Bt toxin present in plant tissue as pro-toxin is converted into active toxin due to.

• A. Alkaline pH of the insect gut
• B. Presence of conversion factors in insect gut
• C. Action of gut microorganisms
• D. Acidic pH of the insect gut

Answer 1

The correct option is A

Alkaline pH of the insect gut

The correct option is A.

Explanation for the correct option:

1. Crop plants have been genetically modified to express the B. thuringiensis insecticidal toxin gene, which kills insects that try to consume them.
2. During sporulation, B. thuringiensis produces intracellular crystalline structures that contain the Cry protein, also known as Cry endotoxin, which is an insecticidal protein.
3. The Cry protein accumulates in the bacterium as an inactive precursor until it is ingested by the insect.
4. Due to the alkaline pH of the insect's gut, this protoxin is cleaved by proteases, resulting in shorter variants of the protein that have hazardous activity by attaching to the inside of the insect's gut and disrupting the surface epithelium.

Final answer: Bt toxin gets activated by proteases at the alkaline pH of the gut.