MP Board · Class 12 · Biology · Biotechnology and its ApplicationsHow does Bt toxin protect cotton plants from insect pests without harming the plant itself?

Bt toxin is produced by the bacterium Bacillus thuringiensis as inactive protoxins. When an insect pest ingests the plant containing this inactive toxin, the alkaline pH of the insect's gut solubilizes the crystals, converting the protoxin into its active form. The active toxin binds to the midgut epithelial cells, creating pores that cause cell swelling and lysis, eventually leading to the death of the insect. The plant remains unaffected because the toxin requires an alkaline gut environment to activate.