In RNA interference (RNAi), what is the result of the formation of do…

The correct answer is Option (3) → Silencing of specific mRNA and prevention of nematode survival

RNA interference (RNAi) is a defence method found in all eukaryotes. A double-stranded RNA (dsRNA) that matches a particular mRNA binds to it and stops its translation, so that mRNA is silenced. This was used against the nematode Meloidogyne incognita, which infects tobacco roots. Nematode-specific genes were put into the tobacco plant using Agrobacterium so that the plant made both sense and anti-sense RNA. The two strands paired to form dsRNA and silenced the nematode's mRNA.

Option (1) Increased growth rate of the plant — Incorrect. RNAi silences a gene of the parasite. It does not change the growth rate of the plant.

Option (2) Enhanced photosynthesis in the plant — Incorrect. The method protects the plant from the nematode. It has no link with photosynthesis.

Option (3) Silencing of specific mRNA and prevention of nematode survival — Correct. The dsRNA silenced the specific mRNA of the nematode, so the parasite could not survive in the transgenic host.

Option (4) Production of additional plant hormones — Incorrect. No plant hormone is involved. RNAi works by blocking translation of a target mRNA.

NCERT Extract:
Biotechnological Applications in Agriculture – “… Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant (Figure 10.2). The introduction of DNA was such that it produced both sense and anti-sense RNA in the host cells. These two RNA’s being complementary to each other formed a double stranded (dsRNA) that initiated RNAi and thus, silenced the specific mRNA of the nematode. The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA.”