New Technology, Old Idea
GM plants have genes that have been artificially introduced into the plant’s genome. This technology gives plants a new characteristic, such as a new color or different flavor. To date, most genetically engineered foods have been bred for disease resistance. GM crops on the market include wheat, rice, corn, soybeans, potatoes, tomatoes, and cantaloupes.
Genetic engineering is a fairly new process, but plants have been modified through careful selection and cross-breeding for thousands of years. In fact, many experts argue that genetic engineering of crops is just a faster and more precise method of selective breeding.
The Green Revolution
In the 1960s, scientist Norman Borlaug and a team of researchers used cross-breeding techniques to develop a new strain of wheat. The new strain produced two to three times as much wheat as traditional varieties, and resisted many types of insects and diseases. Widely planted, these new varieties changed Mexico from an importer of wheat to an exporter within 20 years. Borlaug and his team began shipping the new strain of wheat to India and Pakistan. Both countries quickly doubled their wheat production. This scientific advance, led by Borlaug, became known as the Green Revolution and drastically improved crop yields worldwide. For his work, Borlaug received the Nobel Prize in 1970. Borlaug supported the genetic engineering of crops and viewed it as the next wave of the Green Revolution.
Benefits of GM Crops
GM crops have the potential to improve nutrition worldwide. For example, researchers have developed a GM variety of rice, called “golden rice,” that is high in vitamin A. Half of the world’s population relies on rice as the main part of their diet. Non-modified rice lacks vitamin A, however, and vitamin A deficiency in humans can cause blindness and sometimes death. Golden rice could prevent millions of deaths of young children in developing countries every year. Other promising uses of genetic engineering include growing fruits and vegetables that produce vaccines in their tissues. Carrying important vaccines in food might eventually make shipment, storage, and administration of medicine easier worldwide.
GM crops benefit farmers because they take less time, water, and land to grow. Some GM plants can grow in poor soils or withstand drought, cold temperature, and insect damage. These crops lessen the need for pesticide, herbicide, or fertilizer. Consumers benefit from GM produce that stays fresh longer.
Potential Hidden Costs of GM Crops
Opponents of genetically modified foods argue that it is impossible to predict exactly how the new crops—sometimes called “Frankenfoods”—will affect ecosystems. Two major concerns are herbicide-resistant weeds and pesticide-resistant pests, which create new ecological problems.
When herbicide-resistance genes are inserted into crop plants, the weeds are easily killed by herbicides while the crops remain unaffected. But pollen from plants can be carried by the wind for long distances, and seeds from GM crops could be accidentally dispersed outside their intended locations, causing the rise of “superweeds.” In the 1990s, several companies produced crops that were resistant to the herbicide Roundup. However, many weeds, such as pigweed, soon evolved resistance to Roundup. Pigweed can grow as much as three inches per day. It chokes out farm machinery and smothers crops. GM plants with the bacterial gene Bt produce an insecticidal toxin that is harmless to people. However, insects that evolve resistance will reproduce, increasing the population of pesticide-resistant pests.
Genetically modified crops are no longer considered new, but some questions about them remain. Many of the most important research questions concern the long-term effects of GM crops on human health and the environment. Specific questions include
- Will vitamin levels in genetically modified crops differ from those in their traditional relatives?
- Could GM crops, such as those engineered to produce medicines, have adverse effects on wildlife?
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Genetic engineers use various ways to insert new genes into host cells. For plant cells, which have thick cell walls, one of the best ways to put foreign DNA into the cell is to actually shoot it through the plant tissue using a gene gun.
- A researcher coats gold or tungsten particles with DNA and places them on the end of a microscopic plastic bullet.
- The plastic bullet is placed in the gene gun and directed toward the target plant tissue.
- A burst of helium propels the bullet to the end of the gun. The gold particles containing the DNA are released, while the bullet remains in the gun.
- Particles enter the cytoplasm of some of the cells in the target tissue. DNA is released from the gold particles and moves into the plant cell’s nucleus, where it ultimately combines with the cell’s DNA.
Dr. Tong-Jen Fu
Title: Research Engineer, Food and Drug Administration
Education: Ph.D., Chemical Engineering, Pennsylvania State University
Dr. Tong-Jen Fu is a research engineer with the U.S. Food and Drug Administration (FDA), where she evaluates the methods currently used by scientists to determine the allergic potential of GM foods. She and other researchers are trying to understand exactly what makes substances in food cause allergic reactions.
One of the concerns of GM food is its potential to increase allergies in humans. Many proteins can potentially be an allergen—that is, cause an allergic reaction in some people. Since genetic engineering introduces new proteins into crops, concerns have been raised that unexpected allergies may arise. GM foods could trigger allergies by including proteins already known to cause a reaction, or by introducing completely new allergy-causing proteins—such as those from bacteria—into the food supply.
Researchers use extensive safety tests to determine whether a genetically modified food is likely to cause an allergic reaction. If any of these tests has a positive reaction, the GM food is not likely to be commercially produced. These tests include checking the amino acid sequences of introduced proteins against those of known allergens and testing whether the introduced proteins are resistant to digestion.