Question

Explain how advent of biotechnology has helped in preventing infestation by nematodes and thereby increasing crop yield.

Answer 1

• Several nematodes parasitize a wide variety of plants and animals including human beings.
• A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield.
• A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).
• RNAi takes place in all eukaryotic organisms as a method of cellular defense.
• This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing).
• The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.
• Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant.
• 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. The transgenic plant therefore got itself protected from the parasite.