What is genetic modification, really?

By Steven Hussey

If you think you’ve managed to stay clean of them GMOs (genetically modified organisms) by going “organic”, chances are you’ve unknowingly been eating them or wearing them. But don’t worry. After more than three decades of experimentation there’s still no convincing evidence that GMOs are harmful. It’s the paranoia of groups like Woolworths, who explicitly state this lack of evidence, yet choose to rid their fresh produce of the stuff because of concerned customers. Most people don’t know that genetic engineering is usually applied as an investigative tool in genetics to figure out what genes do rather than to make food. And most people would welcome GMOs that we don’t eat, such as the improved trees that may produce our future biofuels. Fear of new technologies is simply a lack of understanding about the unknown. Hell, people were afraid to install electricity in their homes once upon a time, out of concern that it might jump out of the walls and fry them to a crisp! But safety aside, many people are fundamentally anti-GMO because they think it undermines God (especially if you’re the current Pope) or because they don’t have a clue about what it is.

Genetic modification is the introduction of one or more genes into an organism to improve a certain trait, or to produce a certain product. Sometimes the gene(s) come from a different species (sometimes even human genes are introduced into bacteria — this has made human insulin production possible for diabetics). Alternatively, a gene(s) from the same organism is isolated, improved, and re-introduced into the organism. There is nothing unusual about genes from one organism (such as bacteria) being transferred to a very distant relative, say, a plant. Indeed, some bacteria actually “mate” with plants. Agrobacterium is one such bacterial anomaly: it integrates its own genes into the DNA of plants, forcing them to produce cancers, which it then feeds off. In fact, genetic engineers have hijacked Agrobacterium to do the work for them. They’ve taken out the cancer-causing genes, replaced it with whatever gene they want to introduce into a plant, and Agrobacterium will without complaint carry out the task.

Every molecular tool that we use for genetic modification comes from nature. We can cut up DNA precisely to engineer almost whatever we want. But we need enzymes to do this: naturally occurring molecular machines that recognise defined DNA sequences and cut them into pieces like scissors. There are thousands of types available in nature. Similarly, we can also make as many copies of a gene as we need, a central technique that makes genetic modification possible. Again, the enzyme we use comes from a bacterium that thrives in near-boiling waters, and can duplicate DNA at the high temperatures needed to create a chain reaction of replicating DNA molecules. A visit to any molecular biology lab will reveal that genetic engineering requires modest equipment, nothing like what CSI may suggest. And that’s because we use nature’s molecular tools for almost everything.

Almost without exception, when a gene is prepared for genetic modification, it is introduced into E. coli bacteria to preserve it intact, much like keeping a backup of important files. It is almost trivial how easy it is to introduce DNA into E. coli. Is it unnatural? Not in the slightest. Bacteria are the most genetically promiscuous organisms known on earth, the whores of the molecular world. This is because bacteria can literally absorb whatever pieces of DNA they come across (such as DNA from dead organisms), incorporate it into their own genomes, and thereby acquire a diverse genetic repertoire.

I’m dismayed why selective breeding, which has been practised since the age of agriculture more than 10 000 years ago, is seen as inherently safe. What we call maize today is not found in nature, but was instead developed from a pitiful relative called teosinte. It was bred into its current status over thousands of years. Similarly, you will not find modern cabbage, Brussels sprouts, cauliflower or broccoli in nature, because they were bred from one species, Brassica oleracea. Mankind has for millennia manipulated (albeit slowly) the animals and plants he found useful, from wolves (today, a kaleidoscope of dog breeds) to cows to potatoes. But this breeding, although using a natural process, suffers from complete blindness on the breeder’s part. To illustrate, when developing disease-resistant crops, breeders usually “breed in” a resistant gene from wild relatives of domesticated varieties by cross-breeding them. However, hundreds if not thousands of other genes accompany the desired gene and inevitably get incorporated into the target crop. The breeder usually has no clue what these genes are or what their effects are. These crops are only tested for disease resistance but are generally regarded as safe for consumption.

Conversely, genetic modification is a meticulous science: the genetic engineer knows precisely which gene(s) is being introduced, and only the desired gene(s) is introduced into the host organism. The engineer also has a thorough understanding of what the gene(s) does. It does not suffer from the blindness of conventional breeding. Shockingly, there is one process not classified as genetic modification that is widely practised: that of arbitrarily mutating crop plants and selecting for mutants with desired traits. Usually, the nature of the mutation is unknown. It is also highly likely that these crops will carry mutations in non-target genes with completely unknown effects. And it is fully accepted in classical plant breeding.

I argue that GMO technology, in itself, is a concise and predictable science, much less influenced by uncontrolled factors as is the case in conventional breeding. Genetic engineers harness the tools of nature to perform it, and it is in principle no more artificial than conventional breeding. The potential that GMO technology yields are considerable: it is thought that the only way we could possibly produce enough vaccines for the world is by using plants to make them for us cheaply and abundantly. But as with all technologies, one can practice it in ethical and unethical ways. One can drive a car ethically or unethically, and indeed, cars kill thousands every year while it is still to be shown that someone died of a GMO. Yet you will not find lobbyists trying to get cars off the road despite their obvious danger. I find it almost humorous that the good-willed mothers that vehemently avoid GMO food on their grocery list also apply a synthetic factory of chemicals to their faces every morning. To oppose GMO technology because of its unknown long-term effects, then, is simply a double standard.

Steven is an MSc student in the wood and fibre molecular genetics programme at the Department of Genetics, Forestry and Agricultural Biotechnology Institute (Fabi) at the University of Pretoria.