What if your survival and that of your family depended on growing your own crops?
And what if you were starting with wild plants? No seeds from a seed catalog. No started plants from a garden center or farm market. It’s just you and the plants you can find in the wilderness. How would you cultivate and multiply them to ensure their—and your—survival? What difficulties would nature present?
Around 10,000-12,000 years ago, as hunting and gathering gave way to farming, those are some of the challenges our ancestors faced. Ever since then, we have been selecting the best plants and seeds and genetically altering them to suit our needs: making them taste better, yield more, resist disease, tolerate a variety of soil conditions, and many other characteristics. Since the mid-1800s, scientists have discovered and used increasingly sophisticated methods of genetically changing crop plants.
Methods we use to modify crops
Traditional breeding – The earliest and best-known method of altering crops is selective breeding, or artificial selection. This involves crossing plants and selecting offspring based on preferred traits. Nearly all crops have been modified in this manner. Thousands of genes are affected using this technique, and undesirable traits may accompany desired ones. Because of this imprecision, it can take years or even decades to achieve a crop with the looked-for characteristics.
Mutagenesis – Beginning in the 1920s, scientists began investigating the effects of radiation on plants. They discovered that exposing plants or seeds to X-rays or gamma rays induced mutations which could be beneficial. While plants do naturally produce spontaneous mutations on their own, radiation breeding, or mutagenesis, sped up the process and allowed scientists to examine and produce thousands of new crop varieties. Mutagenesis is responsible for a popular variety of Ruby Red grapefruit known as Rio Red and a high-yielding rice variety called Calrose 76. As with any mutation—whether natural or human-induced—the number of genes affected with this technique is unpredictable.
Advanced breeding – More recent variations of selective breeding combine the tools of biotechnology with the “old” method of artificial selection. Breeders can now locate and identify specific traits within the plant genome and use this information to choose which plants to cross-breed. This can minimize the time required in selective breeding: waiting for a plant to produce seeds, and then growing the seeds to see if the new plants show the traits being sought. While the number of genes affected with this process are similar to that of traditional breeding, the results are more predictable.
GM plant breeding or GMOs – GMO stands for “genetically modified organism.” As is true of the breeding tools described above, genetic modification is a process used to modify plants. It is not an ingredient in the resulting crop. Because we humans have modified virtually every organism we use, “genetically modified organism” would accurately describe practically all of our food and our domesticated animals, too. Because of human intervention, the enormous, delectable ears of sweet corn we enjoy today bear no resemblance to teosinte, corn’s tiny ancestor. Our sweet, adorable Yorkshire Terriers look and act nothing like wild wolves. Nevertheless, “GMO” is the acronym used to describe only the most precise methods of breeding. One of these methods is RNA interference, in which selected genes can be switched on or off. The other is transgenic breeding, in which specific genes are inserted from another source. RNA interference impacts just one or two genes in a given crop, while transgenic breeding currently focuses on anywhere from 1-8 genes. Of the plant breeding techniques described above, safety testing is only required for the most precise methods: RNA interference and transgenic breeding. Three U.S. regulatory agencies supervise the development and testing of these crops: the Food & Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and the Environmental Protection Agency (EPA).
GMOs in the grocery store
In the grocery store you are most likely to encounter crops modified with GMO techniques in packaged goods containing ingredients from corn or soybeans. If you buy summer squash such as zucchini or yellow crookneck squash, or if you purchase papaya, it may have been transgenically modified to be virus-resistant.
It’s worth noting that refined sweeteners, oils, and alcohols do not contain any detectable genetic material (DNA or proteins). So, for example, granulated sugar made from sugar cane is chemically identical to granulated sugar from GMO sugar beets.
Another grocery item which owes its existence to transgenic techniques is cheese. Most hard cheeses are made using genetically engineered chymosin, an enzyme which makes milk curdle. (Previous to the development of recombinant chymosin, it was obtained from the inner lining of a veal calf’s fourth stomach.)
For marketing purposes, more and more food products are labeled “nonGMO,” “No GMOs,” or “GMO-free.” But many of these items don’t exist as a transgenic variety in any case. There are no GMO tomatoes, strawberries, or oats, for example—so a non-GMO label on any of these items is irrelevant.
At present, there are just eight crops from genetically modified or transgenic seeds commercially available in the U.S. They are: alfalfa, canola, corn (field and sweet), cotton, papaya, squash, soybeans, and sugar beets. Two more—Arctic apples and Simplot potatoes—were recently approved by the FDA but will take some time to reach the market. GMO technology is a process, not an ingredient. A GMO papaya is still a papaya.
■ Sources/for more information: GMO Answers, How Are GMOs Created?, https://youtu. be/2G-yUuiqIZ0 Genetic Literacy Project, How crops are genetically modified—Are GMOs more dangerous?, http://bit. ly/1Nseweu Genetic Literacy Project, Cheese: The GMO food die-hard GMO opponents love, http://bit.ly/1bUb2QU New York Times, Useful Mutants, Bred with Radiation, http://nyti.ms/1gcACTz The Washington Post, Scientists breed a better seed, trait by trait, http://wapo.st/1J0LWZN Wikipedia, Papaya ringspot virus, http://bit.ly/1i1vraj
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