Chapter 234 of 2363 min read
Applications in agriculture: Bt crops, RNAi
Why this is asked: Bt cotton's toxin is made as an inactive protoxin and only becomes active once it meets the alkaline pH of an insect's gut — which is also why it is considered harmless if eaten by humans, whose acidic gut never activates it. RNAi-based nematode resistance uses the same silencing logic in reverse: a nematode-specific gene introduced into tobacco as both sense and antisense RNA forms double-stranded RNA that triggers interference, silencing the nematode's own mRNA when it feeds on the transgenic plant.
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- •Silencing of specific mRNA is possible via RNAi because of:
- •Given below are two statements: Statement I: Bt toxins are insect-group specific and coded by a gene cryIAc. Statement II: Bt toxin exists as an inactive protoxin in B. thuringiensis. However, after ingestion by the insect the inactive protoxin gets converted into the active form due to the acidic pH of the insect gut. In the light of the above statements, choose the correct answer from the options given below:
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