SPECIAL TOPICS IN MODERN GENETICS 5 Genetically Modified Foods hroughout the ages, humans have used selective of opposition and violence. On August 8, 2013, 400 protest- breeding techniques to create plants and animals ers broke through security fences surrounding a field trial of with desirable genetic traits. By selecting organisms Golden Rice in the Bicol region of the Philippines. Within 15 Twith naturally occurring or mutagen-induced variations minutes, they had uprooted and trampled most of the GM and breeding them to establish the phenotype, we have rice plants. The attackers argued that Golden Rice was a evolved varieties that now feed our growing populations threat to human health and biodiversity and would lead to and support our complex civilizations. Western corporate control of local food crops. Although we have had tremendous success shuffling Opposition to GM foods is not unique to Golden Rice. genes through selective breeding, the In 2013, approximately two million people process is a slow one. When recombinant marched against GM foods in rallies held DNA technologies emerged in the 1970s “Genetic engineering in 52 countries. Some countries have out- and 1980s, scientists realized that they ONLY of animals and right bans on all GM foods, whereas others could modify agriculturally significant plants promised embrace the technologies. Opponents cite organisms in a more precise and rapid an exciting new safety and environmental concerns, while way—by identifying and cloning genes some scientists and commercial interests that confer desirable traits, then introduc- phase in scientific extol the almost limitless virtues of GM ing these genes into organisms. Genetic agriculture, foods. The topic of GM food attracts hyper- engineering of animals and plants prom- with increased bole and exaggerated rhetoric, informa- ised an exciting new phase in scientific productivity, reduced tion, and misinformation—on both sides of agriculture, with increased productivity, the debate. reduced pesticide use, and enhanced pesticide use, and So, what are the truths about GM SPECIAL TOPIC 5 SPECIAL TOPIC flavor and nutrition. enhanced flavor and foods? In this Special Topic chapter, we Beginning in the 1990s, scientists cre- nutrition.” will introduce the science behind GM foods ated a large number of genetically modi- and examine the promises and problems fied (GM) food varieties. The first one, approved for sale in 1994, was the Flavr Savr tomato—a tomato that stayed firm and ripe longer than non-GM toma- toes. Soon afterward, other GM foods were developed: papaya and zucchini with resistance to virus infection,REVIEW canola con- taining the tropical oil laurate, corn and cotton plants with resistance to insects, and soybeans and sugar beets with tol- erance to agricultural herbicides. By 2012, more than 200 dif- ferent GM crop varieties had been created. Worldwide, GM crops are planted on 170 million hectares of arable land, with a global value of $15 billion for GM seeds. Although many people see great potential for GM foods—to help address malnutrition in a world with a grow- ing human population and climate change—others question the technology,FOR oppose GM food development, and some- times resort to violence to stop the introduction of GM vari- ST Figure 5–1 Anti-GM protesters attacking a field of eties (ST Figure 5.1). Even Golden Rice—a variety of rice genetically-modified maize in southwestern France. In July 2004, that contains the vitamin A precursor and was developed hundreds of activists opposed to GM crops destroyed plants on a humanitarian nonprofit basis to help alleviate vitamin being tested by the US biotech company Pioneer Hi-Bred A deficiencies in the developing world—has been the target International. 724 M30_KLUG8915_11_ST05_pp724-737.indd 724 10/06/14 5:38 PM ST 5 WHat ARE GM FOODS? 725 of the new technologies. We will look at some of the con- ST TABLE 5.1 Some GM Crops Approved for Food, Feed, or troversies and present information to help us evaluate the Cultivation in the United States* complex questions that surround this topic. Number of Crop Varieties GM Characteristics Soybeans 19 Tolerance to glyphosate herbicide Tolerance to glufosinate herbicide What Are GM Foods? Reduced saturated fats Enhanced oleic acid GM foods are derived from genetically modified orga- Enhanced omega-3 fatty acid nisms (GMOs), specifically plants and animals of agricul- Maize 68 Tolerance to glyphosate herbicide tural importance. GMOs are defined as organisms whose Tolerance to glufosinate herbicide genomes have been altered in ways that do not occur natu- Bt insect resistance rally. Although the definition of GMOs includes organisms Enhanced ethanol production that have been genetically modified by selective breeding, the Cotton 30 Tolerance to glyphosate herbicide most commonly used definition refers to organisms modi- Bt insect resistance fied through genetic engineering or recombinant DNA tech- Potatoes 28 Bt insect resistance nologies. Genetic engineering allows one or more genes to be Canola 23 Tolerance to glyphosate herbicide cloned and transferred from one organism to another—either Tolerance to glufosinate herbicide between individuals of the same species or between those of Enhanced lauric acid unrelated species. It also allows an organism’s endogenous Papaya 4 Resistance to papaya ringspot virus genes to be altered in ways that lead to enhanced or reduced ONLY Sugar beets 3 Tolerance to glyphosate herbicide expression levels. When genes are transferred between unre- Rice 3 Tolerance to glufosinate herbicide lated species, the resulting organism is called transgenic. 5 SPECIAL TOPIC Zucchini 2 Resistance to zucchini, watermelon, The term cisgenic is sometimes used to describe gene trans- squash and cucumber mosaic viruses fers within a species. In contrast, the term biotechnology is a Alfalfa 2 Tolerance to glyphosate herbicide more general one, encompassing a wide range of methods that manipulate organisms or their components—such as isolating Plum 1 Resistance to plum pox virus enzymes or producing wine, cheese, or yogurt. Genetic modi- fication of plants or animals is one aspect of biotechnology. * Information from the International Service for the Acquisition of Agri-Biotech Applications, www.isaaa.org. In 2012, it was estimated that GM crops were grown in approximately 30 countries on 11 percent of the arable land on Earth. The majority of these GM crops (almost 90 GM food animal was approved for consumption, although percent) are grown in five countries—the United States, a GM salmon variety was nearing market approval in the Brazil, Argentina, Canada, and India. Of these five, the United States (Box 1). A number of agriculturally impor- United States accounts for approximately half of the acre- tant animals such as goats and sheep have been genetically age devoted to GM crops. According to the U.S. Depart- modified to produce pharmaceutical products in their milk. ment of Agriculture, 93 percent of soybeans and 88 percent The use of transgenic animals as bioreactors is discussed of maize grown in the United StatesREVIEW are from GM crops. In earlier in the text (see Chapter 22). the United States, more than 70 percent of processed foods contain ingredients derived from GM crops. Herbicide-Resistant GM Crops Soon after the release of the Flavr Savr tomato in the Weed infestations destroy about 10 percent of crops world- 1990s, agribusinesses devoted less energy to designing GM wide. To combat weeds, farmers often apply herbicides foods to appeal directly to consumers. Instead, the market before seeding a crop and between rows after the crops are shifted toward farmers, to provide crops that increased pro- growing. As the most efficient broad-spectrum herbicides ductivity. By 2012, approximately 200 different GM crop also kill crop plants, herbicide use may be difficult and lim- varieties were approved for use as food or livestock feed ited. Farmers also use tillage to control weeds; however, till- in the United States. However, only about two dozen are age damages soil structure and increases erosion. widelyFOR planted. These include varieties of soybeans, corn, Herbicide-tolerant varieties are the most widely planted sugar beets, cotton, canola, papaya, and squash. ST Table of GM crops, making up approximately 70 percent of all 5.1 lists some of the common GM food crops available for GM crops. The majority of these varieties contain a bac- planting in the United States. Of these GM crops, by far the terial gene that confers tolerance to the broad-spectrum most widely planted are varieties that are herbicide tolerant herbicide glyphosate—the active ingredient in commer- or insect resistant. At the time of writing this chapter, no cial herbicides such as Roundup®. Studies have shown that M30_KLUG8915_11_ST05_pp724-737.indd 725 20/05/14 5:58 PM 726 5 SPECIAL topic: GENeticallY MODIFIED FOODS BOX 1 The Tale of GM Salmon— Downstream Effects? Despite these assurances, envi- wild populations. A study published ronmental groups are planning to in 2013 shows that it is possible for fight the sale of GM salmon. Some the AquAdvantage salmon to breed grocery chains in the United States successfully with a close relative, the have banned GM fish, and legisla- brown trout.* In laboratory condi- t took 18 years and about $60 tors in several western U.S. states are tions, the hybrids grew more quickly million, but the first GM animal trying to block the approval of the than either the GM or non-GM varie- to be approved as human food— AquAdvantage salmon based on fears ties, and in closed stream-like systems, Ithe AquAdvantage salmon—may soon that the accidental release of these the hybrids outcompeted both paren- hit the U.S. market. fish could contaminate wild salmon tal fish varieties for food supplies. The AquAdvantage salmon is an populations with transgenes and dis- The authors point out that these Atlantic salmon that is genetically turb normal ecosystems.