The pest that destroys the cotton balls are cotton boll worms and cotton borer. Bt cotton is created by using some strains of a bacterium, Bacillus thuringiensis (Btis short form). (i) This bacterium produces protein that kill certain insects such as lepidopterans (tobacco budworm and armyworm), coleopterans (beetles) and dipterans (flies and mosquitoes). (ii) Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. (iii) Bt toxin protein exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form due to the alkaline pH of the gut which solubilise the crystals. (iv) The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis leading to death of insect. (v) Specific Bttoxin genes were isolatedfrom Bacillus thuringiensis and incorporated into several crop plants. (vi) Most Bttoxins are insect-group specific.Hence, the toxin is coded by a gene named cry. For example, the proteins encoded by the genes cry I Ac and cry lAb control the cotton boll worms and cry lAb controls corn borer.
How is the Btcotton plant created as a GM plant? How is it protected against bollworm infestation?
Answers
Ashu bhat
The pest that destroys the cotton balls are cotton boll worms and cotton borer. Bt cotton is created by using some strains of a bacterium, Bacillus thuringiensis (Btis short form).
(i) This bacterium produces protein that kill certain insects such as lepidopterans (tobacco budworm and armyworm), coleopterans (beetles) and dipterans (flies and mosquitoes).
(ii) Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.
(iii) Bt toxin protein exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form due to the alkaline pH of the gut which solubilise the crystals.
(iv) The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis leading to death of insect.
(v) Specific Bttoxin genes were isolatedfrom Bacillus thuringiensis and incorporated into several crop plants.
(vi) Most Bttoxins are insect-group specific.Hence, the toxin is coded by a gene named cry. For example, the proteins encoded by the genes cry I Ac and cry lAb control the cotton boll worms and cry lAb controls corn borer.