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CRISPR-Cas and other new genetic engineering tools (NGT) could help to produce particularly robust wheat, corn and soy 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 relaxation for NGT plants. Companies and scientists welcome this, criticism comes from nature conservation associations and the Federal Environment Minister Steffi Lemke (Bündnis 90/Die Grünen), among others.
Christoph Tebbe is a microbiologist and an expert in soil ecology at the Thünen Institute in Braunschweig. In an interview with MIT Technology Review, he explains his view of the arguments.
Mr. Tebbe, how do the NGT, the new genetic engineering tools, differ from those to which the EU regulations on genetically modified organisms (GMO) have applied since 2001?
The plants modified with “old” genetic engineering contain alien genes. A classic is the so-called Bt maize, which was also approved in Europe after almost 20 years of safety tests. A gene that encodes a biodegradable insecticide was inserted into its genome. This insecticide can be formed naturally by bacteria and is also used in organic farming to repel insects. However, the introduction of such alien genes will remain strictly regulated in the EU.
With CRISPR and other NGTs, however, certain properties of plants are usually changed by turning their own genes on or off or by changing them. Often just a few bases are swapped in the DNA. Some are taken out or some are added, but – according to the EU proposal – the latter only within one species.
In this way, the information on a gene from a wild apple could be restored in a cultivated apple in which this gene was unintentionally modified through classical breeding. This allows varieties to be produced that are particularly resistant to diseases, harmful organisms or drought. Compared to conventional breeding methods, such molecular processes are many times faster and more targeted. And: NGT plants cannot be distinguished from conventionally bred plants using the typical PCR techniques.
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The issue of labeling
What does that mean for control and labeling in order to guarantee the freedom from genetic engineering on the fields, 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 foreign genes – it is particularly important for the manufacturer to label the seed. As far as I know, the missing possibility of proof also applies to the so-called mutagenesis methods in conventional breeding. 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. genetic analyses, provide information about the origin of a variety.
What about the residual risks that CRISPR and Co. create questionable mutations that can destroy sensitive ecosystems, for example? Criticism of this kind comes from nature conservation associations, from the Federal Agency for Nature Conservation and also from the Federal Minister for the Environment.
Any mutation by the NGT could also be achieved through conventional breeding. So I don’t see a higher risk. And the EU proposal distinguishes between two categories of genetic manipulation using these techniques. The first category includes seeds whose genome – according to the manufacturer – has only been changed in 20 places. In this case, according to the proposal, it is like in nature and the seed is therefore treated like a natural variety, so it does not need any regulation. The only requirement is that companies label their seeds to enable organic farming to avoid these plants, which they are opposed to. So consumers can still choose whether they want to use NGT products or not.
The second category includes plants that have been more heavily modified. Stricter rules apply to them – but often not as strict as the GMO for the “old” genetic engineering tools. For example, in most cases no questions about horizontal gene transfer to alien species, such as soil bacteria, need to be clarified. Because the risk naturally does not exist if no genes from other organisms have been added at all, but only genes have been removed, for example. With these distinctions, the risk for ecological side effects would be no different than with conventionally bred varieties.
Where does the criterion of 20 base pairs as a threshold between the first and second categories come from?
It’s basically an arbitrary number, a consensus negotiated during discussions in expert panels. From my point of view, however, it is quite plausible in terms 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.
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