Biotech entrepreneur Jonathan Jones wants to dismantle safety testing and assessment for GM foods, based on the argument that nature herself genetically engineered the sweet potato. Claire Robinson explains why his logic doesn’t stand up

Earlier this year a paper was published showing that genes from the soil bacterium Agrobacterium had been found in a non-GM variety of sweet potato. Agrobacterium is used by genetic engineers to ferry in GM genes, or transgenes, into host organisms. Such transfer of genes is called horizontal gene transfer, or HGT for short. The message of the new paper was that nature had long been doing genetic engineering of her own, so concerns about the genetic engineering done in the lab are misplaced.

As an article for Arstechnica put it, “Genetically modified crops? Nature got there first: The sweet potato has been genetically engineered by bacteria”. The article said that 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 the sweet potato. The authors said they 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’”.

Now the British genetic engineer and biotech entrepreneur Jonathan Jones, of the Sainsbury Laboratory in Norwich, has jumped on the “natural genetic engineering” bandwagon. He has published an article in Nature repeating the lobbying message of the original paper. Headlined, “Sweet! A naturally transgenic crop”, Jones says, “One of the world's most important staple crops, the sweet potato, is a naturally transgenic plant that was genetically modified thousands of years ago by a soil bacterium. This surprising discovery may influence the public view of GM crops.”

Lest the Luddite GMO-fearing public miss the reassuring message, Jones rams it home:

“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.”

“Naturally GM” sweet potato = no need for GMO regulations?

Jones’s concerns about public perception lead directly to his lobbying point, which is directed against Europe’s precaution-based GMO regulations. The authors of the sweet potato paper, Jones says, have shown that “we have been eating the products of genetic engineering for millenia” 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.”

Sadly, however, Jones’s grasp of industry-friendly lobbying points appears to be firmer than his grasp of evolutionary science. Scientists have known for decades that horizontal gene transfer can happen in nature, so the sweet potato discovery adds little to that knowledge.

What Jones misses is the vital difference between this “natural genetic engineering” and what happens in the lab. The former happens over evolutionary time and 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.

We cannot assume that this was a benign process. There may well have been collateral damage in the form of a few poisonings and deaths along the way: we have no way of knowing. All that is certain is that the sweet potatoes we are left with now are those that passed the test of co-evolution with humans over years, decades, or millennia, and were selected by our ancestors to be bred on.

As Dr Michael Hansen of Consumers Union told GMWatch at the time the sweet potato paper was published:

“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, as an effect of insertional mutagenesis, caused a gene to be turned on that produced birth defects, sterility, or reduced fertility. As the 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 are domesticating) 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.

“Since the 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, enabling the team of scientists to arrive at their findings and write the paper under discussion. But far from reassuring us that genetic engineering is safe, all that can be concluded from the new paper is that the 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.”

“Nature can squash us with a rock from space”

Dr Jack Heinemann, professor of genetics at the University of Canterbury, New Zealand, emphasised that modern lab-based GM is a radical departure from “natural” genetic engineering and that all GM crops and foods must be subjected to safety assessments and testing:

“When people move genes into plants, we move constructs that we have pieced together from an average of 8 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.

“Of course nature can also create organisms – by HGT or other means – that are capable of causing us harm. But that is no reason for us to do it unwittingly to ourselves. Nature can squash us with a rock from space, causing injuries indistinguishable from a car crash. This is not a reason to stop motor vehicle safety testing or recommend removing seat belts.”

It seems unlikely that Jones and his fellow biotech entrepreneurs are open-minded enough to consider these crucial points. We must do our utmost to ensure that Europe’s GMO regulations and labelling requirements stand protected from the damage that their blinkered mindset could cause.