How did the process of RNA interference help to control the nematode from infecting the roots of tobacco plants?

RNA Interference (RNAi) is a gene-silencing process that is used for cellular defense in all eukaryotic organisms. RNAi has been used to control the nematode Meloidegyne incognitia that affects the roots of tobacco plants in the following way:

 Using Agrobacterium vectors, nematode specific genes were introduced in the host plant. The genes were introduced in such a way that it produced both sense and anti-sense RNA in the host cells. The two RNA’s being complementary to each other form a double-stranded RNA dsRNA that initiates RNA interference and silences mRNA that is it inhibits mRNA expression. The nematode is not able to survive in the host which expresses specific interfering RNA and thus the plant is protected from the nematode.