Lesson 6 of 12 · 10 min
RNA interference
NCERT §10.1
A tobacco field near Guntur has plants that stand tall while the next field's plants are stunted. The difference is underground: a tiny worm in the roots.
The lesson in notes
In short
Several nematodes parasitise a wide range of plants and animals, humans included. The nematode Meloidogyne incognita infects tobacco roots and greatly reduces the yield.
A new strategy against it uses RNA interference (RNAi), a cellular defence that operates in all eukaryotic organisms.
In RNAi a specific mRNA is silenced: a complementary double-stranded RNA (dsRNA) binds to it and prevents its translation.
In nature this complementary RNA may come from an infection by viruses with RNA genomes, or from transposons (mobile genetic elements) that replicate through an RNA intermediate.
Nematode-specific genes were carried into the tobacco plant by Agrobacterium vectors, inserted so that the plant's cells made both sense and anti-sense RNA.
The two RNAs, being complementary, paired into dsRNA that set off RNAi and silenced the specific mRNA of the nematode.
The parasite could not survive in the transgenic host expressing the interfering RNA, so the plant was protected.