The Grapevine

The Natural GMO: Bacteria Genetically Modified Sweet Potatoes 8,000 Years Ago

sweet potato fries
Guess what: Your favorite bar food is a GMO that was altered by bacteria thousands of years ago. Photo courtesy of Shutterstock

The terms “natural” and GMOs should never sit side-by-side when describing a food product — at least according to anti-GMO advocates. But a new study brings to our attention that a few truly natural GMOs — crops whose genomes were naturally altered through bacteria — exist. And one of them is a very common vegetable: the sweet potato.

Researchers at the International Potato Center in Lima, Peru, embarked on a project to find the genes from bacteria found in 291 sweet potato varieties. The scientists discovered that bacteria likely served as genetic engineers themselves, up to 8,000 years ago, when they inserted themselves into the sweet potato’s ancestor. In short, bacteria were making GMOs way before we figured out how to use bacteria to make GMOs.

“People have been eating a GMO for thousands of years without knowing it,” Jan Kreuze, a virologist who led the study, told NPR. Another example is corn: Ancient farmers in Mexico specifically chose the larger versions of maize’s ancestor, which were tiny compared to modern corn stalks. Over time, they bred it into what it looks like now.

Agrobacterium: The Original Genetic Engineers

The authors write in their abstract, “Agrobacterium rhizogenes and Agrobacterium tumefaciens are plant pathogenic bacteria capable of transferring DNA fragments bearing functional genes into the host plant genome. This naturally occurring mechanism has been adapted by plant biotechnologists to develop genetically modified crops that today are grown on more than 10 percent of the world’s arable land, although their use can result in considerable controversy.” So there you have it: Even before humans began messing with crop genes, the bacteria we currently harness were doing it.

Sweet potatoes, unlike regular potatoes, aren’t tubers — instead, they’re swollen parts of the root. The scientists believe that the bacteria genes altered the plant’s ancestor to the point where the root was changed into something edible. Once people began farming sweet potatoes thousands of years ago, they chose the puffed up roots (with the bacteria genes) over others because they were tastier, resulting in making the genetically modified sweet potato widespread.

The authors believe that the study might bring some comfort to people who are concerned about the safety of GMOs. Greg Jaffe, GMO expert at the Center for Science in the Public Interest in Washington, told NPR that he wasn’t at all surprised by the findings. “Anyone who’s familiar with genetic engineering wouldn’t be surprised that the [bacteria] Agrobacterium inserted some DNA into some crops.” As a result, there’s likely to be other common crops that were genetically altered — naturally — by bacteria thousands of years ago.

The Controversy

So why are we still scared of GMOs, and why the vicious controversy? Aside from those who are concerned that GMO use increases the use of pesticides and herbicides, there are people who worry that giant food companies manufacturing GMO products make these seeds intellectual property. Others simply feel as though companies “playing God” is immoral and unnatural. But research, for the most part, has shown that GMOs are safe — although not enough research has been done yet. One recent study found that widespread anti-GMO sentiment could be rooted in misguided popular psychology and ethics instead of science.

But as Beth Skwarecki writes on Lifehacker, there are better ways to attack the negatives of the food system than focusing primarily on GMOs.

There are serious problems with our food system and the way it’s based on industrial agriculture. Subsidies support sugar-laden and processed foods, while people on low incomes have trouble affording healthy, sustainably grown produce. Meanwhile, needed farmland is being turned into housing developments, massive amounts of pesticides and fertilizers are finding their way into the environment, and corporate giants like Monsanto have far too much power.

Passing around infographics about which GMO-containing foods to boycott, or putting tons of effort into passing GMO labeling laws, isn’t going to do anything to solve these problems. They will just make it easier for already-privileged people to buy food they feel good about—which may well be just as bad for their health and the environment as the food they’re avoiding.

Source: Kyndt T, Quispe D, Zhai H, Jarret R, Ghislain M, Liu Q. The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop. Proceedings of the National Academy of Sciences of the United States of America. 2015.

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