Contrary to scientific consensus, the public at large continues to harbor concerns over the consumption of foods containing  Genetically Modified Organisms, or GMOs. To make matters worse, scientists have now discovered we have unknowingly been eating GMO foods for more than 10,000 years. Indeed, it seems our overambitious ancestors may have even selected for crops with these controversial modifications.

Copyright Bailey PeckWhile performing small RNA-sequencing on sweet potatoes, Tyna Kendt et al. (PNAS, 2015) stumbled upon reads with sequence similarity to genes found in Agrobacterium. This genus of bacteria is commonly used by plant biologists for genetic engineering as it has the ability to transfer DNA from its own genome to plants. In fact, Agrobacteria were used to make many of the first GMO crops in the United States, including soybeans, corn, wheat, and rice. However, in the case of sweet potatoes, the pesky geneticists had nothing to do with it. Instead it seems that during the original domestication of sweet potatoes, our ancestral farmers preferred sweet potatoes containing bacterial DNA conspicuously located inside one of the sweet potato’s F-box genes. And if that isn’t dirty enough for you, these same bacterial DNA insertions were found in all cultivated sweet potatoes from South America to Oceania. Importantly, the wild relatives of the modern sweet potato were conspicuously GMO-free, at least of this particular bacterial insertion. While Kendt et al. (2015) did not find any particular sweet potato trait to be associated with the bacterial gene insertion, the universal presence of the insertion suggest an early selection for these potatoes.

While 10,000 years of domestication and cultivation of a GMO food doesn’t seem like enough time to make any sweeping conclusions regarding the safety of consuming and growing these crops, scientists and health officials may have found some new fodder.


Peer edited by Kristin Sellers and Dan Albaugh

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This article was co-published on the TIBBS Bioscience Blog.

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