Role of RNAi in pest resistant plants is to:

The correct answer is Option (2) → Prevent the translation of mRNA

RNA interference (RNAi) is a method of cellular defence in eukaryotes. A double-stranded RNA that is complementary to a particular mRNA binds to it. The mRNA can then no longer be translated into protein, so the gene is silenced. In pest resistant plants, genes are introduced that make RNA complementary to an mRNA of the pest. The pest then cannot make an important protein. This was done to protect tobacco roots from a nematode.

(1) Prevent the transcription of mRNA — Incorrect. Transcription makes the mRNA from DNA. RNAi acts later, on the mRNA that has already been made.

(2) Prevent the translation of mRNA — Correct. The complementary double-stranded RNA binds to the specific mRNA and prevents its translation, which is silencing.

(3) Silence the DNA synthesis — Incorrect. RNAi does not act on the replication of DNA.

(4) Silence the lipid synthesis — Incorrect. RNAi silences the mRNA of a gene. It is not aimed at the synthesis of lipids.

NCERT Extract:
Biotechnological Applications in Agriculture – …