Question

A farmer grew 2 varieties of corn crops in fields A and B. He grew normal corn crops in field A and GM corn crops in field B. He observed corn borers attacked only in field A. To control it, spores of Bt were sprayed in field A.

1. Name the gene in the spores responsible for the control of this pest.
2. What effect will the spores of Bt have on the insect pest?
3. How has field B developed resistance against this pest?

Answer 1

1. Cry/Ab
2. The spores of Bt contain a crystalline toxin, which is inactive; for this crystalline toxin protein to become active, it needs alkaline pH, which is present in the insect gut. The gut lining is broken down/mid-gut epithelial cells become porous/swollen/cell lysis.
3. The Bt-toxin gene is cloned and inserted into the plant genome by recombinant DNA technology. These genetically modified (GM) plants express the Bt-toxin genes and become pest-resistant.