Insect White fly takes up plant gene with the help of which it can neutralize tomato plant toxin. This is a story of white fly becoming resistant to tomato plant leaves. @Ichha and @sakshiconsultant2002 explained the gene is transferred through Horizontal gene transfer with the help of Virus. White fly is a pest of tomato plant. This is a unique example how gene can be transferred from a plant to animal. With the help of the transferred gene it can neutralize the plant toxin and result in propagation of pest infection. Scientists are trying to look for interfering in the horizontal gene transfer process to prevent the white fly from taking up toxin resistant gene.
Here is the paper which shows gene transfer from plant to white fly resulting into white fly becoming resistant to tomato plant toxin.
The example helps us to understand the host-pathogen interaction and evolution of toxin resistance in pests.
Toxin resistance is one of the major problem in agriculture and the example shows how toxin resistance can evolve.