New genomic techniques: "Important element for environment-friendly new farming"

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CRISPR-Cas and other new genomic techniques (NGT) could help produce particularly robust wheat, corn and soybean plants faster and cheaper than before – and make agriculture more environmentally friendly. Because interventions in the plant genome are very strictly regulated, an EU proposal for a law is now on the table that provides for relaxations for NGT plants. Companies and scientists welcome this, but criticism has come from nature conservation groups and the German Environment Minister Steffi Lemke (Bündnis 90/Die Grünen), among others.

Christoph Tebbe is a microbiologist and expert in soil ecology at the Thünen Institute in Braunschweig, Germany, and was also a scientific advisor to EU authorities on the environmental effects of genetically modified crops for many years. In an interview with MIT Technology Review, he explains his view of the arguments.

Mr. Tebbe, how do the NGT, the new genomic techniques differ from those to which the EU regulations on genetically modified organisms (GMOs) have applied since 2001?

Plants modified with "old" genetic engineering contain foreign genes. A classic is the so-called Bt corn, which was also approved in Europe after almost 20 years of safety tests. A gene coding for a biodegradable insecticide was inserted into its genome. This insecticide can be produced naturally by bacteria and is also used in organic farming to repel insects. However, the introduction of such foreign genes will remain strictly regulated in the EU.

With CRISPR and other NGTs, however, certain characteristics of plants are usually altered by switching their own genes on or off or by modifying them. In the DNA, often only a few bases are swapped. Some are removed or some are added, but - as the EU proposal states - the latter only within a species.

In this way, the information on a gene from a wild apple could be restored in a cultivated apple in which this gene has been unintentionally modified by classical cultivation. This could then be used to produce varieties that are particularly robust to diseases, pests or drought. Compared with conventional cultivation methods, such molecular techniques are many times faster and more targeted. And: NGT plants cannot be distinguished from conventionally cultivated plants using typical PCR techniques.

The question of labeling

What does this mean for control and labeling in order to guarantee that fields are free of genetic engineering, as required by the state of Lower Saxony, for example?

Since these NGT plants cannot be distinguished from natural mutations - because they do not contain any genes foreign to the species - labeling of the seed by the manufacturers is particularly important. However, the lack of detection also applies to the so-called mutagenesis processes in conventional breeding, as far as I know. X-rays and toxic chemicals are used to force as many mutations as possible and thus increase the probability that one or the other desired variant is among them. In none of these cases would PCR tests, i.e. gene analyses, provide any clues to the history of the origin of a variety.

What about the residual risks that CRISPR and co. could generate questionable mutations that could, for example, destroy sensitive ecosystems? Criticism of this kind comes from nature conservation associations, the German Federal Agency for Nature Conservation and also from the German Federal Environment Minister.

Any mutation by NGT could also be achieved by conventional breeding. Therefore, I do not see a higher risk. And the EU proposal does distinguish between two categories of genetic manipulation using these techniques. The first category includes seeds whose genetic material - according to the manufacturer - has been modified in only 20 places. In this case, according to the proposal, it is the same as in nature and the seed is therefore treated like a natural variety and does not require regulation. The only requirement is that companies label their seeds to enable organic farmers to avoid these plants, which they are opposed to. Consumers can therefore still choose whether they want to use NGT products or not.

The second category includes plants that have been modified to a greater extent. Stricter rules apply to them - but they are also often not as strict as after GMOs for the "old" genomic techniques. For example, in most cases there is no need to clarify questions about horizontal gene transfer to non-species, such as soil bacteria. This is because, by their very nature, the risk does not exist if no genes at all have been added from other organisms, but only, for example, genes have been removed. With these distinctions, the risk for ecological side effects would be no different than for conventionally bred varieties.

Where does the criterion of 20 base pairs as a threshold between the first and second category come from?

This is basically an arbitrary figure, a consensus negotiated by technical experts during discussions in the committees. However, from my perspective, it is quite plausible in the order of magnitude and does justice to the precautionary principle, because such selective mutations are also naturally conceivable and do not show any increased recombination of genes compared to conventional varieties.