Nematode - Meloidogyne incognita.
A nematode Meloidogyne incognita infect the roots of tobacco plants and causes a great reduction is yield. 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 dsRNA molecule that builds to and prevents translation of the mRNA
2. Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. The introduction of DNA was such that it produces both sense and anti-sense RNA in the host cells. These two RNAs being complementary to each other formed a double-stranded RNA that initiated RNAi and thus silences the specific mRNA of the nematode. As a consequence the parasite could not survive in a transgenic host expressing specific interrfering RNA.