RNAi in nematode resistant plants
The question is little bit unclear: is in vitro or in vivo introduction in question?

In vivo:


  As the nematode feeds on the plant during its parasitic phase, it
  consequently assures the introduction of dsRNA and/or siRNA molecules
  into the nematode’s digestive system.


in vitro introduction etc  ->

The status of RNAi-based transgenic research in plant nematology