Question

Toxin produced by Bt cotton plant gets activated in:

• A. Mouth of insect by acidic pH
• B. Midgut of insect by alkaline pH
• C. Leaves of plant by acidic pH
• D. Stem of plant by alkaline pH

Answer 1

The correct option is B Midgut of insect by alkaline pH

Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilizes the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect.