Currently, genome editing has mostly been earmarked for medical applications, but its use in plant breeding could potentially be very promising. However, there is the controversial question of whether plants that have been subject to genome editing will fall under the GMO bracket. According to international scientists, among them Detlef Weigel of the German Max Planck Institute for Developmental Biology in Tübingen, this won’t be the case. They have proposed a regulatory framework for genome editing in plants that was published in the journal Nature Genetics (2016 online publication).

Floods, heat and fungal infestations are stress factors that affect the growth of plants and reduce the yield. Plant researchers aim to develop plants that are resistant to these damaging factors. Now, using the latest gene editing technology CRISPR/Cas9, plant scientists are euphoric that they can use the genetic “scissors” to simply target and change specific genes. But isn’t fiddling with plants using genome editing tools genetic engineering? The researchers, including Detlef Weigel, director at the German Max Planck Institute for Developmental Biology in Tübingen are convinced that these technologies will be put to good use and have great potential for plant research. In reports of genome editing, metaphors such as genome surgery or genetic scalpel are often used. “The conventional genetic engineering of plants can be compared to open-heart surgery when opening up the entire chest,” explains Weigel. Genome editing on the other hand is a more minimally invasive procedure, argues Weigel, because one can precisely determine where in the genome a change is meant to happen.

Changing genes quickly and precisely

The advantage of genome editing: this technology can determine precisely determine at what point the genetic changes are to be carried out. Usually, it is sufficient to replace or remove just a single letter in the DNA. Using this minimal genetic intervention, crops may be altered such as wheat, rice or corn so that they are more resistant to fungal attack or suffer less from the heat. As part of a study published in the journal Nature Genetics, the researchers also addressed the disadvantages of conventional genetic engineering techniques. Planting genes from other plant species or organisms, has been possible for a long time. But which genes ultimately end up in the genome cannot be controlled. Therefore, according to Weigel, many candidates would have to be screened until you have a plant with the desired properties.

At the same time, the researchers reference the standard tools of plant cultivation – such as the crossing of plants or the use of chemicals or radiation – where mutations are also triggered in the genome. According to the study, the achievements of plant breeding are not always better and “finding promising specimens” is also a very lengthy and costly process. Compared to plants that are cultivated with genome editing, these products may be marketed without market authorisation.

No special regulations for approval

In their appeal, Weigel and his research colleagues speak out for a change in thinking in the approval of genome-edited plants. After which, these plants should, in principle, not be treated differently from products of conventional breeding. Weigel makes reference to the German genetic engineering law that classifies only organisms that have been genetically engineered, whose “genetic material has been altered in a way that does not occur naturally by crossing and or natural recombination.” The legislation then has no reason to assess the plants produced by genome editing unlike conventional breeding products.

Documenting the development process

In view of the above, Weigel and his colleagues from China and the US are submitting proposals on what should be taken into account during the development of gene-edited plants. During the development phase, they advise on minimising the risk of propagation in open land. Secondly, the resulting DNA changes should be accurately documented and thirdly, it has to be taken into account that CRISPR/Cas9 techniques may in the beginning require insertion of foreign DNA, if this is the case, it has to be documented that the foreign DNA has been completely removed without a trace. Finally, if a gene has been replaced by a gene from a different species, it should be stated how close the two species are related to each other.

According to the study, all these points should be strictly adhered to upon approval of new plant species. The European Union has not finalised their assessment, but in both Germany and Sweden, the responsible authorities have already declared that certain genome-edited varieties in principle are the same as plant varieties of conventional breeding. "An important aim of breeding is to make the supply of agricultural products more sustainable. Genome editing can, for example, help when breeding for resitance to fungal infection without the use of chemical pesticides. We cannot miss out on such opportunities,” explains Weigel.