Recombinant DNA Technology: Agriculture
Viruses and Pests
Besides pharmaceuticals and specialized bacteria, recombinant DNA technology has also had a major effect on agriculture, where it is now used to create crop plants and farm animals with desired traits. For quite a while it has been known that plants infected with a mild virus strain are more resistant to infection. With the help of this knowledge viral resistance was created by transferring viral proteins into the plant cells.
A second objective is to genetically engineer pest resistance into plants, which would reduce the need for chemical pesticides. Some bacterial toxins are lethal to certain pests, but harmless to wildlife, humans and other insects. By isolating the gene(s) for the toxin and transferring it to the plants (corn, tomato, potato and cotton), these plants are able to get rid of the pests themselves.
Transgenic Farm Animals
This set of techniques is also applied to a range of domesticated animals. An example is the administration of bovine growth hormone to cattle to increase milk production. The isolated gene for hormone production was isolated and transferred to bacteria, which then produced a large amount of this growth hormone.
Transgenic animals are also used in the development of pharmaceutical products. For example, a gene for the production of human clotting factor VIII was linked to the genes that are responsible for milk production in sheep, producing sheep whose milk contains the clotting factor, which is now used to treat people with hemophilia.
This genetic engineering of agricultural products is still a controversial area. A major source of concern is the potential effects of the release of these novel organisms into the wild. There are many examples of (non-engineered) invasive organisms replacing the indigenous ones through ecological disruption. While genetic engineering normally only transfers small sequences of DNA, these can have a serious impact on their survival in the wild.
Another area of concern is the potential hybridization between transgenic and native organisms and the transfer of their genetically altered traits. So, pest resistance could be transferred from one plant species to the next. However, the extent and effect of such transfer are still uncertain.
A third concern is health-safety issues associated with the presence of engineered products in natural foods. This has led to obligatory labeling of all foods that contain transgenic elements in the European Union. It is, however, not required in the United States.
Despite these concerns, it is clear that the use of genetically altered crops and animals provides potentially huge benefits, such as pest resistance, higher yield, increasing the food production per acre, decrease in land use for agriculture, and so on.