Genetic engineering can be used to modify the genetic compositions of plants, animals, and microorganisms.
The number of genes that have been isolated and are available for transfer is growing daily. Currently, the technology is used primarily to modify crops, although a number of other applications are in the wings.
Like other products, genetically engineered products undergo a period of research and development before they are ready for commercial release. Many products never emerge from the research and development pipeline. While this is true for almost any technology, genetic engineering is turning out to be more difficult and more expensive than early proponents expected. Although in the early 1980s biotechnology was touted as a miracle technology that was going to usher in a new era of agricultural abundance with minimal harm to the environment, the initial set of products has proved modest. Some of the most important commercial applications of biotechnology are discussed below.
Engineered Crops
The most widespread application of genetic engineering in agriculture by far is in engineered crops. Thousands of such products have been field tested and over a dozen have been approved for commercial use. The traits most commonly introduced into crops are herbicide tolerance, insect tolerance, and virus tolerance.
Herbicide Tolerance
Case Study: Soybeans
Herbicide tolerance allows crops to withstand otherwise lethal doses of herbicides, which are chemicals that kill plants. Some herbicides kill virtually all plants and cannot be used on crops. By offering crops tolerant to herbicides, chemical companies can expand the market for their products. Indeed, the major developers of herbicide-tolerant plants are companies that sell herbicides. The current set of commercially available herbicide-tolerant crops is tolerant to three herbicides based on three active ingredients: bromoxynil, glyphosate, and glufosinate.
Insect Tolerance
All of the commercially available insect-tolerant plants contain a version of the toxin Bacillus thuringiensis (Bt), which is found in nature in soil bacteria. Bt toxins are highly effective for many pest organisms, like beetles and moth larva, but not toxic to mammals and most other nontarget organisms. A major concern among farmers and environmentalists is that wide use of Bt crops will lead to the rapid development (over the course of perhaps as few as three to five years) of resistance to the toxin. If resistance develops, the Bt toxin will be useless as a pesticide. In this case, the environmental benefits of the product will be short lived.
Loss of Bt efficacy will affect those who currently use the engineered Bt crops, but also many other farmers who use Bt in its natural bacterial form, usually as a spray. These other farmers include those who grow food organically and those who use Bt as part of integrated pest management (IPM) plans. Natural Bt sprays are a valuable mode of pest control for these farmers. Organic farmers and others who rely on Bt question whether the companies who sell the Bt crops have the right to use up this resource guided only by commercial calculations. UCS considers Bt to be a public good that should be reserved for everyone.
Virus Tolerance
The third major application of biotechnology to crops is virus tolerance. These crops contain a gene taken from a virus. By a process that is not well understood, plants that produce certain viral proteins are able to fend off infections by the viruses from which the proteins were taken. Two virus-tolerant crops are currently approved for commercial use, papaya and squash. The squash, which is resistant to two viruses, is currently off the market. Although it is difficult to get information on why products are not on the market, it is possible that the squash did not perform well enough in the field to capture market share.
Other Engineered Products
Many other genetically engineered products have been envisioned, but only a few have so far come to market.
Several tomatoes engineered to delay ripening have been approved for commercial use. In some cases, delayed ripening just prolongs shelf life. But for the FlavrSavrTM, the objective was to increase the time on the vine without softening, producing a transportable, tasty winter tomato. After a highly publicized rollout, the FlavrSavrTM too is off the market. The problem appears to have been with transportability rather than taste.
On the livestock side, a drug has been produced for dairy cows—recombinant Bovine Growth Hormone (BGH) or Bovine Somatotropin (BST)—by engineering a bacterium to contain the gene for the hormone. The drug is administered to cows to increase milk production, despite the chronic oversupply of milk in the United States. A highly controversial product, BGH is currently used on about a third of the U.S. dairy herd.
An interesting product not related to agriculture is a rabies vaccine intended for use on wild raccoons. In this case, genetic engineering was used to construct a "hybrid" virus made up of a component of the rabies virus inserted into an unrelated "carrier" virus. The resulting virus confers immunity to rabies but poses no danger of causing the disease. Baits laced with the vaccine have been distributed in many parts of the eastern United States in attempts to combat rabies in wild raccoon populations. The vaccine has been approved by the U.S. Department of Agriculture, despite suspicions that it has been only marginally, if at all, effective. Early studies on efficacy failed to demonstrate that the product could control rabies in wild raccoon populations. Data from more recent studies are being withheld from the public as confidential business information.
Agricultural Biotechnology Research Projects
The following lists some of the organisms being engineered by agricultural researchers and indicates which products are commercially available and which are not. For up-to-date information about what is on the market, see our guide to Genetically Engineered Foods Allowed on the Market.
Genetically Engineered Livestock and Poultry
Animals Engineered for Leaner Meat
Status: No livestock engineered for leaner meat is currently near commercialization. Research done early in the 1980s to genetically engineer leaner pigs failed because of unacceptable side effects, including low fertility, arthritis, and impaired immune systems. Some low level of research activity may still be underway. Pigs have been engineered with roundworm genes to produce their own omega-3 fatty acids, but have not been commercialized.
Animals Engineered as Drug-Production Facilities
Status: Goats and sheep have been engineered to secrete bioactive molecules into their blood, urine, or milk. Companies are in the process of developing commercial enterprises based on these animals. So far, none of the drugs is on the market. It is likely that producers will want to slaughter the animals for food after they are no longer useful for drug production.
Animals Engineered as Sources of Transplant Organs
Status: Commercial entities are engineering pigs so that their organs will not be rejected by human transplant recipients. So far, the organs are not commercially available. It is likely that producers will want to use the carcasses of donor pigs as food.
Animals Engineered for Disease Resistance
Status: Chickens and turkeys have been engineered to resist avian diseases, but not commercialized.
Genetically Engineered Fish and Shellfish
Status: Fish and shellfish have been engineered to cause changes in hormones that accelerate growth in several laboratories, but so far not commercialized in the United States.
Genetically Engineered Plants Eaten Whole as Food
Status: Many plants have been commercialized, including tomatoes and squash and commodity crops like corn and soybeans. Most have been engineered for one of three traits: herbicide tolerance, insect resistance, or virus tolerance.
Genetically Engineered Fiber Plants
Status: Genetically engineered cotton has been approved for commercial use.
Engineered Insects Used in Agricultural Systems
Status: No engineered insects have been approved for commercial use. An engineered predatory mite has been field tested in Florida. Researchers have engineered honeybees and other beneficial insects to tolerate pesticides.
Engineered Microorganisms Used as Pesticides
Status: Several bacteria engineered to enhance their ability to kill or repel pests have been approved for commercial use. These products are used as pesticides in agricultural fields and gardens.
Food Processing Aids Made from Engineered Bacteria
Status: Bacteria have been genetically engineered to produce rennet, an enzyme important in making cheese. Genetically engineered rennet (chymosin) is approved for commercial use and widely used by U.S. cheese processors.
Animal Drugs Made by Engineered Bacteria
Status: Recombinant Bovine Growth Hormone (BGH) made from engineered bacteria is used commercially to stimulate milk production in cows. Currently this hormone is being used in about a third of the nations dairy herds.
According ucsusa