In a paper titled “Nature’s GM sweet potato and the rock from space,” English investigative science writer Claire Robinson tackles the intentions of British biotech entrepreneur Jonathan Jones. Jones hoped to dismantle safety testing and assessment for genetically modified (GM) foods. He justified his intentions, arguing that Nature herself genetically engineered the sweet potato. Robinson explained why his logic doesn’t stand up. Read the story at gmwatch.org/en/106-news/latest-news/16216.

Crop Comments: Free-Ranging Plant Genes: Equal to Laboratory Manipulation?Jones cited a recent paper, showing that genes from soil microbe Agrobacterium were found in a non-GM variety of sweet potato. Genetic engineers use Agrobacterium to ferry GM genes, or transgenes, into host organisms, a practice called horizontal gene transfer (HGT). That paper’s writer asserted that Nature had long been conducting genetic engineering (GE) on her own; thus, concerns about GE done in the lab are unwarranted.

Jones also cited an article from the journal Ars Technica, “Genetically modified crops? Nature got there first: The sweet potato has been genetically engineered by bacteria.” One of the concerns about GM crops is that they are engineered with genes from unrelated organisms, but the new paper showed that “this has occurred naturally” in sweet potatoes. Authors hoped that their finding “could affect the current consumer distrust of the safety of transgenic food crops” and “influence the public’s current perception that transgenic crops are ‘unnatural.’”

Clearly on a roll, Jones – assigned to Sainsbury Laboratory in Norwich, England – jumped on the natural GE bandwagon. He published an article in Nature repeating the lobbying message of the original paper. Headlined “Sweet! A naturally transgenic crop,” Jones wrote, “One of the world’s most important staple crops, the sweet potato, is a naturally transgenic plant, genetically modified thousands of years ago by a soil bacterium. This surprising discovery may influence the public view of GM crops.”

He concluded, “Where does this leave those anxious about GM crops? Hopefully, less anxious. GM proponents have long referred to Agrobacterium as nature’s natural genetic engineer. No clearer example can be imagined for the safety of the Agrobacterium-mediated DNA transfer process than the fact that all cultivated sweet potato genotypes carry an ancient GM event and that the results of that event have been eaten with impunity for centuries by millions of people.”

Robinson stated that the axe Jones grinds can be summed up as an equation in question form: “Naturally GM sweet potato = no need for GM regulations?” Jones’s concerns about public perception had led directly to his lobbying pitch, which was directed against Europe’s precaution-based GMO regulations. The authors of the sweet potato paper, Jones said, showed that “we have been eating the products of GE for millennia” and thus “demonstrate that there is no longer – if there ever was – any rationale for intense safety scrutiny for every crop line that has arisen from use of GM methods.”

Robinson countered with the equation question. Quoting her further: “Scientists have known for decades that horizontal gene transfer can happen in nature. What Jones misses is the vital difference between this ‘natural genetic engineering’ and what happens in the lab. The former happens over evolutionary time; the latter happens with commercially driven speed. Any harmful mutations that occur as a result of a ‘natural’ horizontal gene transfer event – for example, those resulting in a toxic plant – will be selected out over the long process of co-evolution of humans and their food crops.

“There may well have been collateral damage in the form of a few poisonings and deaths along the way; we don’t know. What is certain is that the sweet potatoes we are left with now passed the test of co-evolution with humans over years, decades or millennia, and were chosen by our ancestors to be bred selectively.”

Dr. Michael Hansen of Consumers Union responded, “The notion that this natural engineering of sweet potatoes shows that GM technology is perfectly safe is false. Since we weren’t around to document the early history of these sweet potatoes, we have no idea if they caused problems … Let’s assume that the first ‘natural’ GM sweet potato, in addition to having some of the Agrobacterium DNA present, also caused a gene to be turned on that produced birth defects, sterility or reduced fertility. As further breeding occurred there would be variable levels of this particular toxin among sweet potatoes. People eating the sweet potatoes with high levels of the toxin would have fewer viable offspring, so the process of natural selection – the co-evolution of people and the food plants they domesticate – would result in a shift toward decreasing the level of the toxin in sweet potatoes, due to the strong selection pressure against higher toxin levels.”

Hansen continued, “Since Agrobacterium DNA has no direct link to the toxin, there would be no selection pressure to remove the Agrobacterium DNA. Thus, it would persist in the modern traditional varieties developed from the initial naturally transformed sweet potato and enable scientists to arrive at their findings. But far from reassuring us that genetic engineering is safe, all that can be concluded from the Nature paper is that scientists have no idea what the history of the development of this sweet potato might be, or what effects it might have had on human or animal consumers during its evolution.”

Robinson led readers to Dr. Jack Heinemann, genetics professor, University of Canterbury, New Zealand, who stressed, “When people move genes into plants, we move constructs that we have pieced together from an average of eight different species simultaneously. In my 25 years of work on HGT, I’ve seen no precedent for this kind of transfer so quickly. When HGT occurs in nature, nature has a chance to react, respond and adjust over many millennia to initially very small descendant populations. When we do it, nature is immediately bombarded by millions of hectares of new organisms in only a few years.”