Genetically Modified (GM) Crops: Techniques and Applications Fact Sheet No
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Genetically Modified (GM) Crops: Techniques and Applications Fact Sheet No. 0.710 Crop Series|Production by P. Byrne* Since GM crops were introduced in the modified genetically through domestication Quick Facts U.S. in the mid-1990s, they have become from wild species and many generations widely adopted by growers of several large- of selection by humans for desirable traits. • Genetic modification (GM) acreage field crops. This fact sheet explains The term is used here because it is the one technology allows the transfer the technology for developing GM crops and most widely used to indicate the use of of genes for specific traits describes GM crops currently on the market recombinant DNA technology. According between species using in the U.S. to USDA standards for organic agriculture, laboratory techniques. seeds or other substances derived through GM technology are not allowed in • GM crops were first What are GM crops? organic production. introduced in the U.S. in the The term genetically modified (GM), as mid-1990s. Most current it is commonly used, refers to the transfer GM crops grown in the U.S. Which GM crops are of genes between organisms using a series are engineered for insect of laboratory techniques for cloning genes, currently grown in the U.S.? resistance or herbicide splicing DNA segments together, and Although in the U.S. genetically tolerance. Corn, soybeans, inserting genes into cells. Collectively, these engineered versions of 19 plant species have and cotton are the three techniques are known as recombinant been approved, only eight GM crop species largest acreage GM crops. DNA technology. Other terms used for are grown commercially (Figure 1). Because GM plants or foods derived from them are several of them are major crops, the area • GM crops grown in Colorado genetically modified organism (GMO), planted to GM varieties is very large. Most include corn, alfalfa, sugar genetically engineered (GE), bioengineered, current GM crops have been engineered for beet, soybeans, and canola. and transgenic. ‘Genetically modified’ is an resistance to insects, tolerance to herbicides imprecise term and a potentially confusing one, (weed control products) or both. • Potential future applications in that virtually everything we eat has been of the technology include nutritional enhancements, stress tolerance, disease resistance, biofuel efficiency, and remediation of polluted sites. • GM crops are regulated at the federal level by the U.S. Department of Agriculture (USDA), the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA), each with authority to oversee specific aspects of the crops and their products. ©Colorado State University Figure 1. Currently grown GM crops in the U.S., traits for which they are modified, and percent of Extension. 8/14. total acreage of the crop that is planted to GM varieties. IR=insect resistant, HT=herbicide tolerant, www.ext.colostate.edu DT=drought tolerant, VR=virus resistant. * P. Byrne, Colorado State University, professor, soil and crop sciences. 8/2014 What traits have been • Biofuels: Plants with altered cell Are GM crops grown in modified in GM crops? wall composition for more efficient other countries? conversion to ethanol; Insect-resistant crops contain According to a recent report • Phytoremediation: Plants that extract genes from the soil bacterium Bacillus (James 2014), GM crops were grown in and concentrate contaminants like thuringiensis (Bt). The protein produced 26 other countries in 2013. The largest heavy metals from polluted sites. in the plant by the Bt gene is toxic to a global acreage crops were soybean, corn, targeted group of insects—for example cotton, and canola, in that order. The European corn borer or corn rootworm— How are GM crops U.S. has the greatest area of these crops, but not to mammals. The most common regulated in the U.S.? about 40% of the world total. Other large herbicide tolerant (HT) crops are known producers include Brazil, Argentina, India, Three U.S. government entities have as Roundup Ready®, meaning they are and Canada. authority to regulate GM crops: the tolerant to glyphosate (the active ingredient United States Department of Agriculture in Roundup® herbicide). Glyphosate (USDA), the Environmental Protection inactivates a key enzyme involved in amino Besides GM crops, are Agency (EPA), and the Food and Drug acid synthesis that is present in all green there other GM ingredients Administration (FDA). They do not, plants; therefore, it is an effective broad in our food supply? however, individually regulate all GM spectrum herbicide against nearly all crops. For example, USDA is involved in No GM food animals have yet been weeds. Roundup Ready® crops have been approving the field release of most GM approved in the U.S., although a GM engineered to produce a resistant form plants, but EPA is involved only in pest and salmon engineered for rapid growth is of the enzyme, so they remain healthy pesticide resistance traits, and FDA only under review. GM microorganisms are even after being sprayed with glyphosate. regulates crops destined for food, feed, or used to produce rennin for production of Some cultivars of corn and cotton are pharmaceuticals. Thus, EPA does not have cheese and GM yeast has been approved referred to as ‘stacked’, meaning they have authority to regulate a vitamin-enhanced for winemaking . transgenes for both insect resistance and tomato, and FDA would not regulate a HT. According to USDA-ERS (2013), over drought tolerant turfgrass. These federal half of the U.S. corn and cotton acreage was How does GM technology agencies review extensive information planted to stacked cultivars in 2013. differ from other plant submitted by the crop developer, for example, the nature and stability of the breeding techniques? Which GM crops are transgene and its protein product, effects The era of scientific crop improvement grown in Colorado? on non-target organisms in the field dates back to around 1900, when the environment, composition of the food impact of Gregor Mendel’s studies on Corn, alfalfa, and sugar beet are the product, and potential for allergic reaction. trait inheritance in peas became widely major GM crops grown in Colorado, but If the agencies are satisfied that the recognized. Since then, a broad range smaller areas of soybeans and canola are proposed crop does not pose threats to the of techniques has been developed to also planted. The corn, alfalfa, and soybean environment and does not increase risks for improve crop yields, quality, and resistance crops are nearly all used as livestock feed. food or feed safety, the crop is determined to disease, insects, and environmental Sugar beet is used to extract and purify to have nonregulated status, that is, it is stress. Most plant breeding programs rely sugar, and canola is used mostly for approved for commercialization. on manual cross-pollination between edible oil. All GM seeds are targeted to genetically distinct plants to create new commercial growers; no vegetable or fruit combinations of genes. The progeny plants varieties for home production are GM. are intensively evaluated over several generations and the best ones are selected What are potential GM for potential release as new varieties. An crops of the future? example is a tomato variety that is selected for disease resistance and tolerance to cool Some potential applications of GM crop temperatures. Other techniques included technology are: within the conventional plant breeding • Nutritional enhancement: Higher toolbox are development of hybrid varieties vitamin content; more healthful fatty by crossing two parental strains to produce acid profiles; offspring with increased vigor; and induced • Stress tolerance: Tolerance to high and mutations to create useful variation. GM low temperatures, salinity, and drought; technology is much more precise in that • Disease resistance: For example, orange it transfers only the desired gene or genes trees resistant to citrus greening disease to the recipient plant. Another branch of or American chestnut trees resistant to agricultural biotechnology—distinct from fungal blight; GM technology—involves selecting plants part of its DNA into plants and causes for DNA patterns known to be associated crown gall disease. Genetic engineers have For more information on with favorable traits such as higher yield or taken advantage of this DNA transfer GM crops, see the following disease resistance . mechanism while disarming the disease- CSU fact sheets: causing properties. Plant and bacterial cells are co-cultivated in a petri dish under Bt Corn: Health and Environment, Fact The shared DNA code conditions that facilitate gene transfer. This Most organisms store their genetic allows incorporation of genes in a more Sheet No. 0.707 information in the form of DNA molecules controlled manner than with the gene gun; in chromosomes. The sequence of chemical however, it does not work equally well in all Managing Corn Pests with Bt Corn, bases in a DNA strand encodes a specific plant species. Fact Sheet No. 0.708 order of amino acids, which are the building blocks of proteins. Proteins carry Labeling of Genetically Engineered out many functions in cells and tissues, How are whole plants Foods, Fact Sheet No. 9.371 which together are responsible for an obtained from plant cells organism’s characteristics. Because most or tissues? life forms share this same language of Insertion of transgenes is generally References heredity—and due to scientific advances an inefficient process, with only a few in molecular biology—it is now possible to percent of plant cells or tissues successfully Council for Agricultural Science and transfer a gene from one species to another, integrating the foreign gene. Various Technology (CAST). 2014. The for example from a bacterium to a plant, strategies are used to identify the small potential impacts of mandatory and have it function in its new host. percentage of cells/tissues that have actually labeling for genetically engineered been transformed.