The slightly soggy ziplock bags are labelled “Red Giant” and “Southern Giant Curl”. Bunches of green leaves, not unlike watercress, strain the plastic. They are about seven days from full maturity, the person who sent them stressed in an email, so they will not have achieved their optimal flavour profile. Somewhat gingerly your correspondent tastes one, then the other, making sure to give them a proper chew and plenty of time with the taste buds.
They are gene-edited mustard greens. Usually mustard greens produce a sharp-tasting molecule called allyl isothiocyanate, but in these leaves, the responsible gene has been switched off using a version of CRISPR. The result is a mild taste and a pleasant umami scent; both work nicely in a cheese sandwich. They were grown by Bayer, a multinational pharmaceutical and biotech firm, but were developed by Pairwise, one of a handful of biotechs bringing gene editing to agriculture. It has also developed a seedless blackberry and is working on corn, wheat, soy and rapeseed that are resistant to disease and adapted to some of the effects of global warming.
Such goals may sound familiar. Proponents of genetically modified (GM) crops made similar promises 30 years ago about seeds which had new genes added to them. And they had successes. Most American corn is genetically modified; for the most part it has a gene for herbicide resistance added which means that fields can be sprayed with weed-killer without the crops being bothered (see chart). Almost half of arable land in Latin America yields similarly modified produce.
This is good for companies which sell weedkiller and weedkiller-resistant seed, and it is good for farmers who use their wares to increase their yields. But it has also proved controversial. By 2013 there were worldwide protests against Monsanto, then a massive producer of GM seeds, and widespread public scepticism towards the GM concept itself. Europe has never warmed to the idea, and its fierce regulatory standards have dampened the technology’s use in developing countries which want to sell into European markets.
This time it’s…different
Keen to avoid a rerun, companies and scientists hope to persuade consumers and officials that gene-edited food is altogether different from the GM sort: gene editing is its own distinct technology and, if allowed to, it will bring benefits to consumers, society and the climate in a way that GM never managed to.
Scientifically, gene editing is indeed different. For a GM plant, a gene from another species has been inserted into its genome—such as, in some GM corn, a gene from a microbe which bestows resistance to corn-eating insects. Because the gene comes from a foreign organism, GM plants are known as “transgenic”, literally genes from “the other side”. With gene-edited plants, scientists can tweak the plants’ own genes by editing in small mutations, in effect creating changes that could have happened naturally. That means they can improve plants without DNA from other organisms.
Gene editing can thus be thought of as equivalent to fantastically fortuitous breeding. Plants can have complicated genetics: where humans have one genome, common wheat, for example, has three. That means that a beneficial mutation often has to happen in all three genomes to have an impact. In nature that rarely happens; CRISPR can do it all at once.
Cristobal Uauy, a geneticist, grows such gene-edited wheat at the John Innes Centre, a research institute in England. He is growing several strains in buildings where he adjusts temperature and humidity to simulate different climate conditions. Some are optimised for yield, with more grains on the same plant; some are edited to have healthier, fibre-like starch; and some are tweaked to have higher amounts of accessible iron.
Gene-edited crops may help adaptation to climate change
The centre, funded primarily by the British government, operates on the thesis that editing the foods that people already eat will improve public health. People love white bread—why not make it better for them? The same goes for tomatoes. Cathie Martin, another geneticist at the centre, makes a CRISPR edit that enables a precursor to vitamin D to build up in tomatoes. Once the fruit are exposed to sunlight the precursor transforms into the real vitamin, ready to be consumed in a soup, salad or pasta sauce.
Pairwise takes a different tack, that of making healthier foods more enticing—hence the less pungent mustard greens. This approach also shows up in the handful of gene-edited products already developed by others, which include a variety of non-browning fruits and vegetables, such as a non-browning avocado, sure to delight brunch-goers everywhere.
Gene-edited crops may also help adaptation to climate change. Take rice. Scientists from the Innovative Genomics Institute at the University of California, Berkeley, used CRISPR to limit the pores through which rice loses water, making it more drought-resistant. They are also editing rice to better capture carbon from the atmosphere and store it in the ground. Others at the institute hope to edit the methane-making microbes that live in rice paddies, generating 10% of the world’s methane emissions. And gene-editing biotechs are working on less resource-intensive versions of soy, potatoes, bananas and more.
What will consumers and politicians make of GE crops? A decade after the Monsanto protests, some governments appear ready to embrace the new technology. In 2023 the British Parliament passed the Precision Breeding Act which will give gene-edited crops streamlined access to the English market. EU lawmakers, previously known for their GM-scepticism, may follow. Though the EU strictly regulates plants made through gene technology, a proposal is under consideration to exclude edited plants with only simple modifications from those rules. Similar steps are being taken in America, Brazil, Japan and India (see map).
Slow down, you move too fast
Not everyone is keen. In Europe some national authorities are alarmed at the EU proposal. “Any reference to ‘naturalness’ [of edited crops] is misleading and not a proxy for reduced risk,” Germany’s Federal Agency for Nature Conservation argued in a policy brief in 2024. The agencies want an assessment of risks from edited plants, such as for insects or other plants. A more drought-resistant plant, for example, might outcompete its native “natural” counterparts. Edited microbes will face more scrutiny, owing to their propensity to share their genes with other microbes, possibly spreading edits further than intended.
To some opponents, edited plants are just another chapter of the GM book. There is overlap in cast. The boss of Pairwise, Tom Adams, spent 20 years at Monsanto before the company was bought by Bayer. In fact Monsanto was an original investor in Pairwise. Many researchers now working on gene editing either used to or still dabble in GM plant-making themselves. Such connections, along with the novelty of the science, may fuel critiques from populist political figures.
But the key question for editing will not be whether it is a rerun of GM. It will be whether gene-edited crops can help crack challenges in public health and the climate? Judging by the recent enthusiasm, some policymakers seem to be coming round. ■