On the other hand,the techniques of geretic engineering are new, and quite different from conventional breeding. Conventionnal breeders always used plants or snimals that were related, or genetically similar. In so doing,they transferred tens of thousands of genes. By contrast, today's genetic engineers can transfer just a few genes at a time between species that are distantly related or not related at all. There are surprising examples: rat genes have been inserted into lettuce plants to make a plant that produces vitamin C and moth genes have been inserted into apple trees to add disease resitance.