Transgenic Soybean

Genetically modified soybean is a soybean (Glycine max) that has had DNA introduced into it using genetic engineering techniques.[1]:5 Soy is widely planted genetically modified crop that is used to produce genetically modified food.

Genetic modification in plants

To modify a soybean’s genetic makeup, the gene to be introduced into the soybean must first be isolated. If the gene does not display an obvious phenotype, or visible characteristic, a marker gene must be linked to it so the modified cells and unmodified cells can be distinguished. According to Dr. Peter Celec, a professor in the Slovakian Comenius University’s Department of Molecular Biology, the “marker genes typically confer resistance to a selective agent, often an antibiotic,” so the unmodified cells can easily be killed off to leave only modified cells behind, and the “other [gene] is meant to confer a desirable phenotype, which is often agronomic (herbicide, pest, stress resistance) or related to food quality (shelf-life, taste, nutritional value).”[2]:533 Once the gene to be put into the soybean’s DNA is isolated, there are several ways to insert the gene, though the most popular are by “biolistics,” by using Agrobacterium, by electroporation.

Biolistics

Biolistics, more formally known as ballistic bombardment, is a process in which particles of a heavy metal element, such as tungsten or gold, are coated with the gene to be adopted by the plant and then fired, with gunpowder, into a sample of plant cells, as described by Professor Sibel Roller of South Bank University, London, and Susan Harlander, a vice president of Pillsbury’s research and development department. These particles penetrate the cell walls, leaving the genes free to code into the plant’s DNA. As the description implies, with its very uncomplicated and explosive process, this is one of the oldest methods of genetic engineering, as it was developed in 1990.[1]:6

Agrobacterium

Agrobacterium tumefaciens is a type of bacteria that transfers its DNA via horizontal gene transfer to create tumors in plants. This makes it very useful to genetic engineering. Gene transfer using it happens when “a restriction enzyme is used to cut non-virulent plasmid DNA derived from A. tumefaciens and thus create an insertion point, into which the gene can be ligated. The engineered plasmid is then put into a strain of A. tumefaciens, which contains a ‘helper’ plasmid and plant cells are treated with the recombinant bacterium” in culture.[2] While this looks like a complicated concept, it is really only a genetic engineering version of cut and paste.

Electroporation

Electroporation is exactly what its namesake implies—it is the creation of pores by using electricity. Specifically, it is when a pulsed magnetic field is used to create pores in plant cells, “through which genes can be taken up, and in the form of naked DNA incorporated into the plant genome.”[2]

Gene knockout

Gene knockout, also known as antisense technology or gene neutralization, is used when a gene in a plant is undesirable or inhibits the function of the new gene that will be introduced. To “knock out” this gene, a noncoding strand of DNA (DNA that does not translate into any genes) is used to silence the undesirable trait.[2]:533

Examples of transgenic soybeans

The genetic makeup of a soybean gives it a wide variety of uses, thus keeping it in high demand. First, manufacturers only wanted to use transgenics to be able to grow more soy at a minimal cost to meet this demand, and to fix any problems in the growing process, but they eventually found they could modify the soybean to contain healthier components, or even focus on one aspect of the soybean to produce in larger quantities. These phases became known as the first and second generation of genetically modified (GM) foods. As Dr. Celec describes, “benefits of the first generation of GM foods were oriented towards the production process and companies, the second generation of GM foods offers, on contrary, various advantages and added value for the consumer,” including “improved nutritional composition or even therapeutic effects.”[2]:533

Roundup Ready Soybean

Main article: Roundup Ready soybean

The Roundup Ready soybean, also known as soybean GTS 40-3-2, is a transgenic soybean that has been immunized to the Roundup herbicide. Since the soybean’s natural trypsin inhibitors provide protection against pests, the only major problem in soy farming was weeds,[3] thus making soybean 40-3-2 revolutionary. According to Dr. Gerhardt Wenzel, a professor at the Technische Universität in Munich, Germany and a deputy member of the “Zentrale Komission für die Biologische Sicherheit” (ZKBS), the glyphosate in the herbicide would inhibit the soybean plant’s EPSPS gene, which is involved in the maintenance of the “biosynthesis of aromatic metabolites,” and cause the plant to die along with the weeds for which the herbicide was meant.[4]:57 A plasmid which was transferred to the soybean cells through the cauliflower mosaic virus was soon developed to provide immunity to glyphosate-containing herbicides, and, after this process was perfected, the Roundup Ready soybean was ready, first hitting the US market in 1996.[4]:55

Bt Soybean

Monsanto developed a soybean expressing Cry1Ac protein from Bacillus thuringiensis and the glyphosate-resistance gene, which completed the Brazilian regulatory process in 2010.[5][6][7]

Genetic modification to improve soybean oil

According to Dr. Wenzel, the “soybean is the crop with the best amino acid composition within all cultivated protein crops.”[4]:55 Since amino acids are directly used in the genetic formation of proteins and fatty acids, this makes the soybean invaluable in oil production. The food industry wanted both an increase in soy oil per soybean and an alteration in the types of oils the soybean produced. Tom E. Clemente, from the University of Nebraska’s Department of Biochemistry, describes the unmodified soybean as follows:

Commodity soybean oil is composed of five fatty acids: palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3). The percentage of these five fatty acids in soybean oil averages 10%, 4%, 18%, 55%, and 13%, respectively. This fatty acid profile results in low oxidative stability that limits the uses of soybean oil in food products and industrial applications. Oxidative breakdown of soybean oil, for example, results in rancidity and off flavors in food products.[8]:1030

The main goals in genetic modification of the soybean were thus to improve oxidative stability by changing the mass percentage of certain fatty acids, which would provide a more useful oil, and to increase the overall amount of oil produced.

Increasing oxidative stability

The main fatty acids that would need to be increased to achieve oxidative stability (without creating trans or polyunsaturated fatty acids) were oleic acid and stearic acid, and the main fatty acid to be decreased was linolenic acid.[8]:1031 To accomplish this, genetic engineers and food scientists, according to Anthony J. Kinney and Susan Knowlton of DuPont Agricultural Products, there were two keys: First, silencing, or knocking out, the delta 12 desaturase gene; and second, preventing the formation of the plant’s delta 9 desaturase enzyme.[9] Doing this increases levels of oleic and stearic acid in soybeans. This combination of fatty acids creates an oil that is ideal for the food industry, because it creates a healthier oil that can be used for frying products, nut roasting, and carrying food colors or flavors.[8]:1032 DuPont has actually announced the creation of a high oleic fatty acid soybean, with levels of oleic acid greater than 80%, to be released into the market in 2010.[8]:1038

Increasing amount of oil produced

Even a small change in the amount of oil a soybean produces could affect industry profits marginally, so manufacturers are motivated to create soybeans that produce a greater amount of oil. However, the protein produced by soybeans is also in high demand, so the main problem scientists and companies faced was creating higher oil content without disrupting protein content. According to Clemente, “the only transgenic success reported to date for enhancement of soybean oil content was achieved by the introduction of a seed-specific transgene for a DGAT2-type enzyme from the oil-accumulating fungus Umbelopsis ramanniana. In these studies, the oil content was increased from approximately 20% of the seed weight to approximately 21.5%.”[8]:1037 Though 1.5% does not sound like much, but given the size of the soybean industry, that small increase causes millions of dollars more in sales.

Regulation

Main article: Regulation of the release of genetic modified organisms

The regulation of genetic engineering concerns the approaches taken by governments to assess and manage the risks associated with the development and release of genetically modified crops. There are differences in the regulation of GM crops between countries, with some of the most marked differences occurring between the USA and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety.[10][11]

Controversy

There is broad scientific consensus that food on the market derived from GM crops poses no greater risk to human health than conventional food.[12][13][14][15][16][17] GM crops also provide a number of ecological benefits.[18]

Critics have objected to GM crops per se on several grounds, including ecological concerns, and economic concerns raised by the fact these organisms are subject to intellectual property law (although this latter issue applies equally to any plant variety). GM crops also are involved in controversies over GM food with respect to whether food produced from GM crops is safe and whether GM crops are needed to address the world's food needs. See the genetically modified food controversies article for discussion of issues about GM crops and GM food. These controversies have led to litigation, international trade disputes, and protests, and to restrictive legislation in most countries.[19]

References

  1. United States Free full-text. National Academies Press. See pp11ff on need for better standards and tools to evaluate GM food.
  2. Tamar Haspel for the Washington Post. October 15, 2013. Genetically modified foods: What is and isn’t true
  3. Winter CK and Gallegos LK (2006). Safety of Genetically Engineered Food. University of California Agriculture and Natural Resources Communications, Publication 8180.
  4. Dr. Christopher Preston, AgBioWorld 2011. Peer Reviewed Publications on the Safety of GM Foods.

Further reading

Anthony, Kinney J. and Susan Knowlton. “Designer Oils: The High Oleic Acid Soybean.” Genetic Modification in the Food Industry: A Strategy for Food Quality Improvement. Ed. Roller, Sibel and Susan Harlander. London: Blackie, 1998. 193-213.

Deng, Ping-Jian, et al. “The Definition, Source, Manifestation and Assessment of Unintended Effects in Genetically Modified Plants.” Journal of the Science of Food and Agriculture. 88.14 (2008): 2401-2413.

Domingo, Jose’ L. “Toxicity Studies of Genetically Modified Plants: A Review of the Published Literature.”Critical Reviews in Food Science and Nutrition. 47.8 (2007): 721-733.

“Genetically Modified Soybean.” GMO Compass. Federal Ministry of Education and Research, Dec 2008. Web. 22 Nov. 2009.

Kuiper, Harry A., et al. “Assessment of the Food Safety Issues Related to Genetically Modified Foods.” Plant Journal. 27.6 (Sep 2001): 503-28.

“Molecular Pharming.” GMO Safety. Federal Ministry of Education and Research, Oct 2009. Web. 22 Nov. 2009.

See also

  • GTS 40-3-2
  • Vistive Gold

External links

  • GMO Safety: USA: ‘Superweeds’ encouraged by genetically modified plants?
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