Bt cotton is a plant that has been genetically modified to kill insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).
However, the plant is not harmed because the toxin is present in the plant's inactive stage
Bt cotton contains a gene from the bacterium Bacillus thuringiensis.
Bt toxin:
the Bt toxin gene was cloned from bacteria and expressed in cotton plants to provide insect resistance without the use of insecticides.
As a result, the need for insecticides decreases, resulting in less soil pollution from these non-biodegradable chemicals.
Many plants have this gene, including Bt corn, Bt rice, Bt tomato, and Bt soybean.
Bt toxin works:
The Bt toxin gene produces protein crystals containing a toxic insecticidal protein.
This Bt toxin exists within the plant as inactive Pro-toxins and thus has no effect on the plant.
When an insect feeds on a plant, the toxin is consumed by the insect.
Once in the gut, the toxin is converted into an active form by the alkaline pH of the gut, which solubilizes the crystals.
The activated toxin binds to the surface of the midgut epithelial cells, causing pores to form.
This causes swelling and lysis, which eventually leads to the insect's death.
