Tina Kyndta and collaborators ((Kyndt T, Quispe D, Zhai H, Jarret R, Ghislain M, Liu Q, Gheysen G, & Kreuze JF (2015). 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 PMID: 25902487)) have found that all cultivated sweetpotatoes are naturally transgenic because they contain transfer DNA (T-DNA) sequences from Agrobacterium. Gene-transfer via Agrobacterium is a naturally occurring process, that is used to make genetically modified crops in the lab. We did not know that one of our main food crops was once naturally transformed via the same process.
Kyndta et al. did not find any T-DNA in the wild relatives of sweetpotato, suggesting that the transformation(s) provided a beneficial trait that was selected for during domestication. The introduced genes are intact and expressed in different organs of the “Huachano” variety that they studied in detail, but we’ll have to wait for future expression studies to find out about the benefit of these paleo-GMOs.
The authors also suggest that, as people have been eating these swollen roots for millennia, we might now consider all transgenic crops to be “natural”. I don’t know about that. Didn’t most of these people suffer and die young? I predict that sweetpotato consumption will plummet now that the word is out.