Introduction - Overview of Genetic Engineering
Genetic engineering is one type of genetic modification. Traditional plant breeding also modifies the genetic composition of plants. Plant breeding, which involves crossing and selection of new superior genotype combinations, has been going on for hundreds of years. Every time someone crosses two plants in order to improve their traits, they are genetically modifying the plants.
Plant breeding is an important tool, but has limitations. First, breeding can only be done between two plants that can sexually mate with each other. This limits the new traits that can be added to those that already exist in that species. Second, when plants are mated, (crossed), many traits are transferred along with the trait of interest including traits with undesirable effects on yield potential.
Genetic engineering, on the other hand, is not bound by these limitations. It physically removes the DNA from one organism and transfers the gene(s) for one or a few traits into another. Since crossing is not necessary, the 'sexual' barrier between species is overcome. Therefore, traits from any living organism can be transferred into a plant. This method is more specific in that a single trait can be added to a plant.
Here's the animation Who Wants to be a Genetic Engineer.