B.

nematodes

RNA interference (RNAi) takes place in all eukaryotic organisms as a method of cellular defence. This method involves silencing of a specific mRNA due to a complementary ds RNA molecule that binds to an prevents translation of the mRNA (silencing). The source of the complementary RNA could be from an infection by viruses having RNA genome of 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 t hat it produced both sense and anti -sense RNA in the host cells. These two RNA's being complementary to each other formed a dsRNA that initiated RNAi and thus, silenced the specific mRNA of the nematode. The result 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.