Genome Editing

Genome editing: special technology to produce normal agricultural crops

Recently, the European Commission opened the door to genome editing. We see this decision as a victory for science, for farmers, nature, and the consumer. To secure a good harvest, farmers depend on strong plant varieties. These crops are made increasingly robust year after year through selective breeding.

In a traditional breeding process, two plants with desirable traits are crossed. For instance, a tomato variety with tasty fruit but vulnerable to a virus is crossed with a variety that is virus-resistant. Offspring from this cross are then selected for those that exhibit both desirable traits: delicious and resistant to the virus. A new plant variety is thus created. Classical breeding is akin to Darwin's 'survival of the fittest', yet with human intervention. During this process, the DNA of the plants is significantly shuffled, leading to the creation of plant varieties with new characteristics that previously did not exist in our food crops. But what if a particular characteristic is not available? Consider if a virus sickens all tomato varieties. In such cases, traditional breeding still offers a glimmer of hope. The DNA code of plants changes very slightly from one generation to the next. Such a tiny, random change could result in a plant suddenly becoming resistant to the virus. 

Crops can also be achieved through transgenic breeding. For example, by copying a specific piece of DNA code (a gene) from a wild potato species and inserting it into the DNA of cultivated potatoes, varieties resistant to fungus have been developed. The outcome of transgenic breeding is known as a 'genetically modified organism' or GMO for short. A GMO is defined as an organism whose DNA has been altered using a technique that does not occur naturally. Both classical and transgenic breeding techniques have their pros and cons. Transgenic breeding allows for the introduction of desirable traits from different species, an impossibility with classical breeding. A while ago, the cultivation and consumption of 'golden rice' was approved in the Philippines. Through transgenic breeding, several rice varieties received two extra pieces of DNA code for the production of provitamin A, which gives the rice grain a yellow (or golden) hue. In the body, provitamin A is converted into vitamin A, a crucial nutrient for the eyes and overall health. Such rice varieties are not a luxury in a country where one in five children under the age of five suffers from a vitamin A deficiency.

Breeding techniques are continually being developed and refined. CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated proteins) is a revolutionary gene-editing technology that allows scientists to edit DNA sequences with high precision, efficiency, and flexibility. The system was adapted from a natural defense mechanism found in many bacteria and archaea. Genome editing in plants through CRISPR-Cas allows for the modification of a plant's DNA sequence (genome) at very precise locations. A similar adjustment in the DNA can, in theory, also occur spontaneously in a plant in the field and be captured through classical selection.

The first commercial crops bred through genome editing are now a reality. In the USA, soybeans have been genome-edited to produce oils with a longer shelf life. In Japan, tomatoes have been grown that have an extra healthy composition thanks to CRISPR-Cas. In the coming years, we expect hundreds of plant varieties to be developed through genome editing. Often these varieties are developed by government institutions or smaller companies. They are working on developing avocados that brown less quickly, strawberry plants with a higher yield, plant varieties that are more resistant to viruses, or that contain lower amounts of allergens.

Unfortunately, transgenic breeding has encountered substantial opposition. Anti-GMO campaigns convinced the public, and consequently, European politics followed suit. In 2001, stringent laws were enacted, making it almost impossible to cultivate or sell transgenic plants. Now, CRISPR-Cas presents the EU with a dilemma. Since the genome editing of agricultural crops is carried out in a laboratory, the European Court of Justice ruled in 2018 that such crops fall under GMO legislation.

However, at the end of April 2023, the European Commission published a report stating that the existing European GMO legislation from 2001 is not suitable for assessing plant varieties bred with new technologies. Moreover, the Commission believes that genome editing can promote sustainable food production. This report is causing the current GMO legislation to teeter.

The fact that Europe is now expressing a positive stance on genome editing has organizations traditionally against GMOs bristling with incomprehension, with Greenpeace leading the charge. A frequently heard argument is that breeding through transgenic techniques or genome editing is artificial. But what, then, should we make of greenhouses, irrigation, or planting crops in rows? Such practices do not naturally occur in the wild. And what about the outcomes of classical breeding? Without human intervention, there would be no cauliflowers, cucumbers, or wheat. 

We at PSB do not consider a crop made virus-resistant in a lab to be any less natural than one bred in the field. Just as we would not judge someone conceived through IVF differently because they started their embryonic phase on a petri dish or God forbid spent a few months in a freezer. Another argument is the concern that genome editing might encourage monocultures. Indeed, monoculture agriculture benefits from stronger plants, but so does mixed cultivation. And small farmers and hobby gardeners also benefit from robust plants. The argument about monocultures is really an argument against breeding per se, and thus, a non-argument. Agriculture cannot remain profitable without breeding.

Another criticism is that transgenic breeding and genome editing could be dangerous and full of unknowns, and that we should therefore adhere to the precautionary principle. However, this argument does not align with the scientific consensus. True, some may challenge the scientific consensus. But the fact remains that the overwhelming majority of experts agree on the safety of transgenic breeding and genome editing applications. In this regard, the debate reminds us of the importance of vaccination in combating infectious diseases and the anthropogenic causes of climate change. With genome editing, the number of unknown changes in DNA is much smaller than with classical breeding. Hence, genome editing is even safer than classical breeding, which is already considered safe. From this perspective, a positive European report on genome editing is a victory for science. If Europe now also takes logical next steps and permits genome editing in agricultural crops, we can soon talk about a victory for the farmer, nature, and the consumer.

Ruben Vanholmepostdoctoral researcher at VIB-UGent and Yves Van de Peer, Scientific Director of PSB and Professor at Ghent University. Text based on an article originally published in Knack.