• 89% of the corn grown in the United States in 2015 was produced from seed varieties developed through genetic modification technologies.¹
• As the use of genetically engineered crops has risen, the use of insecticides has decreased.²
• As the use of genetically engineered crops has risen, the use of herbicides has increased.²
• Many science organizations throughout the world, including the World Health Organization, find genetically modified crops to be safe for consumption.³
• Although significant science supports the safety of GM foods, many consumers are skeptical and perceive that non-GM foods are healthier.⁴

This lesson provides a brief introduction to genetic engineering in plants. After the introduction, students assess the risks and benefits of genetic engineering, learn why farmers would choose to grow a bioengineered (GMO) crop, and begin to recognize various perspectives about this controversial topic. To learn the scientific steps of creating a bioengineered seed variety see the lesson The Science of a GMO.

Plant Breeding Methods

Traditional plant breeding has been used since humans began domesticating plants for food production. Early crop domestication was accomplished by using basic plant selection techniques to identify and promote ideal food plants. This is known as selective breeding. Crossbreeding, inbreeding, and hybridization are specific plant breeding methods that fall under the umbrella of selective breeding. These methods have allowed farmers to isolate genes for specific characteristics and progressively create more plants well suited to provide an abundant supply of nutritious food (e.g., fruits, vegetables and grains). For example, tomatoes come in many varieties, including large slicing tomatoes and smaller roma, cherry, and grape tomatoes. Tomatoes also come in a variety of colors, including from bright red, orange, yellow, and even a dark burgundy color. In addition to color and size, these plants also vary in taste, shelf life, and the amount of time they take to grow from seed to fruit. All of these characteristics were brought about by selective breeding; identifying desirable traits and continually cross-pollinating plants with those traits to eventually create a variety with desirable characteristics. Often in traditional plant breeding processes plants will gain either a resistance or a propensity toward disease. All of these characteristics vary from variety to variety due to the plants changing genetics from generation to generation. While these traditional plant breeding methods have been successful, they can take a significant amount of time (years or decades) to achieve the desired result, and it can be difficult to isolate individual traits such as disease or pest tolerance, color, flavor, or any number of other traits. In addition, the desired gene or characteristic must already be available in the plant's gene pool.

Another method of plant breeding is called mutation breeding, or mutagenesis. This is the process of exposing seeds to chemicals or radiation in order to promote DNA mutations to maximize genetic diversity in an effort to create new traits in plants.⁵ In biology, a mutation is a permanent alteration in the DNA sequence. Some mutations cause little affect on an organism and others cause dramatic change. Mutations occur randomly, but are accelerated by exposure to UV rays, radiation, and some chemicals. Through the years, mutagenesis has helped create genetic variability and produce desired characteristics in crops such as wheat, barley, rice, cotton, sunflowers, and grapefruit.⁵ Mutagenesis can elicit results much faster than cross breeding or inbreeding. However, the changes are random and unpredictable.

Crossbreeding, inbreeding, hybridization, and mutagenesis are all traditional plant breeding techniques and do not use biotechnology. The resulting plants are not considered bioengeneered (GMO), although many people hold the common misconception that they are.

The Development of GM Crops

A genetically modified organism (GMO) is defined by the United Nations Food and Agriculture Organization as “any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology.”⁶ Common and synonymous terminology for genetically modified organisms include GMO (genetically modified organism), GM (genetically modified), GE (genetically engineered), and bioengineered. Watch the video clip, What is a GMO? for more illustration and comparisons of plant breeding techniques.

The first genetically engineered plant was created in 1983 when an antibiotic resistant gene was inserted into a tobacco plant.⁷ The first genetically modified food was the Flavr Savr tomato, created in 1994. This tomato had an extended shelf life, allowing it to be vine ripened and then shipped to grocery stores without rotting. However, production of the Flavr Savr tomato stopped three years later. Although the fruit had the desired extended shelf life without rotting, it still softened, making it little better than its traditional counterparts.⁸ Since that time, novel genes have been inserted into many crop plants. Genetically engineered crops have specific traits such as the following:

• Herbicide tolerance: This trait allows farmers to spray their crop with an herbicide which will kill the weeds, but not the crop. (Transgenic)
• Pest tolerance: These GM plants have a natural resistance to pests. For example, the European corn borer is a destructive pest that bores into corn stalks. When the bacterium Bacillus thuringiensis (Bt) is present in the corn, it produces a protein called Cry, which is toxic to the European corn borer. (Transgenic)
• Disease resistance: Just like people, plants are susceptible to diseases caused by fungi, bacteria, and viruses. Some GM crops are developed to be resistant to specific diseases. Examples include the papaya and some varieties of squash. (GE, Nontransgenic)
• Drought tolerance: Some crop varieties can be genetically engineered to be more hardy in drought conditions and use less water. (GE, Nontransgenic)
• Shelf life extended/Spoilage resistance: Crops must travel from the farm to the consumer without spoiling or being damaged. Some crops must even be harvested before they are ripe to increase their shelf life, tomatoes are an example. (GE, Nontransgenic)

Current Bioengeneered Crops approved by FDA

The Safety of Bioengineered Crops

While many view bioengineered crops as a promising innovation, there is still much controversy surrounding their use. This debate is taking place worldwide. There are many questions being raised in the minds of consumers. How do bioengineered crop varieties impact the environment? Is food from a bioengineered plant safe for consumption? How does the production of bioengineered crops impact communities and economics from various points of view?

It takes many years for a GM crop to be developed, tested, and finally approved for commercial release. Prior to their release, bioengineered crop varieties are monitored and regulated by three primary agencies in the United States:

• Food and Drug Administration: "FDA regulates the safety of food for humans and animals, including foods produced from genetically engineered (GE) plants. Foods from GE plants must meet the same food safety requirements as foods derived from traditionally bred plants."⁹
• United States Department of Agriculture: "The USDA, EPA, and FDA work to ensure that crops produced through genetic engineering for commercial use are properly tested and studied to make sure they pose no significant risk to consumers or the environment."⁹
• Environmental Protection Agency: The EPA focuses on reviewing the environmental impacts of a GE crop prior to field-testing and the commercial release of the seed. They ensure there are no unintended consequences to honeybees, other beneficial insects, earthworms, fish, or the environment in general.¹⁰ They also look for any possible impact on other crops.

After careful consideration by these three agencies, a bioengineered crop may be approved. After approval, seeds are made available for purchase and farmers can choose to grow the bioengineered variety or not. It's important to understand that not all farmers choose to grow bioengineered crop varieties even when they are available. Some choose to use conventional crop varieties and control pests, weeds, and disease using other methods. A small percentage of farmers choose to grow and market food that can be certified and labeled as organic. Organic label foods cannot be grown from genetically modified seeds and have specific regulations for how weeds and pests are managed. Although many studies have been conducted, none have proven that organic foods are nutritionally superior to conventionally grown foods.¹¹ However, many consumers still choose organic. The organic food industry has shown increased consumer demand over the last decade and some farmers have adopted this production method to meet the consumer demand.¹²

Although there are benefits to utilizing biotechnology, its important to recognize the risks as well. While great effort and extensive research is put into the development and approval process of GM crops, scientists are looking for negative impacts that could still be observed. One risk is of plants, particularly weeds, developing tolerance to the herbicides that are used to kill them. This is possible through the simple biological process of evolution as the weed can become more hardy with each generation and eventually become tolerant of the chemical.¹³ This process can happen with non-GM crops, but scientists are aware that it could happen faster with GM crops. Other risks that scientists test prior to release of a GM crop, and that they continue monitoring carefully, include how the crop affects non-target organisms (insects, fungi, soil biota), how the crop affects the biodiversity of the ecosystem, if the transgenes escape and affect other plants and/or organisms, and how the biodiversity of the ecosystem is potentially affected.

As a consumer, it can be difficult to wade through information about bioengineering. There are many groups who strongly advocate against bioengineering as well as others who advocate for it. It is important to seek credible scientific evidence, then make your choice as you purchase your food. To make a decision about the production and consumption of bioengineered food crops, the science and safety may be sound, but there may be other considerations to evaluate. In some situations bioengineering may be a solution, in others, it may solve one problem but create another.