a) Why are certain cotton plants called Bt - cotton palnts?
b) Explain how Bt- cotton is resistant to pests.
A gene coding for Bt (Bacillus thuringiensis-bacterium) toxin is introduced in cotton plants, such plants are known as Bt cotton plants. Such plants produce a natural insecticide in their tissue. This Bt toxin protects the cotton plants from the attack of moth, butterfly, beetles etc.
a. certain plants are called bt- cotton plants as they are produced by technique called plant tissue culture. where a plant cell having recombinant dna as ex plant the whole plant is produced. recombinant dna is formed by putting cry gene into suitable vector and then transfering it to plant cell by various transfer techniques.
b. bt cotton is resistent to pests. as cry gene undergoes transcription and then translation to form delta - endotoxin which when ingested by any pest goes into it's midgut where delta- endotoxin's white crytalline covering gets dissolved due to alkaline medium and delta endotoxin attaches to mid gut epithelial cellls thereby causing pores leading to ionic imbalance which ultimately causes death of the organism.