New breeding methods have come to supplement the plant breeder’s traditional toolbox. They show potential for a significant reduction of the response time of plant breeding to the many new challenges in agriculture: climate change, pests, scarcity of essential inputs, to name only a few. Timely breeding solutions are more crucial than ever, but the conventional breeding cycle lasts 10 to 15 years. Naturally, breeders are eager to employ any method that might accelerate this process. The precision of genome editing methods allows to develop plants that could also have been bred using conventional crossing and selection, even though it would have taken longer to achieve the same result. In the PILTON research project, 55 mostly medium-sized plant breeding companies have joined hands to explore these techniques in a practical breeding context and to showcase the potential and analyse issues involved in the use of such methods. The method used is CRISPR/Cas and the objective is wheat enhanced with multiple and durable tolerances against fungi.
The challenges facing agriculture are known to everyone: Climate change, dwindling resources and new societal expectations combine to create major challenges. It is a real conundrum how farmers are to produce the same yields and qualities, but in a more sustainable and environmentally friendly way, while the legislator restricts the use of necessary inputs like plant protection products or fertilizers. Awareness for the problems facing plant breeders, however, is less widespread. Plant breeders basically face the same problems, they are farmers, after all, plus the difficulties inherent in their specific field of expertise. They try to find solutions to these problems by crossing. From the offspring, they are selecting plants that precisely combine the desired set of features that help the plant to survive and to thrive even under these unstable, ever more unfavourable and unpredictable cultivation conditions. On average, the cycle from pre-breeding research to a marketable plant variety takes, depending on the crop species, between 10 and 15 years. Many of these years are dedicated to achieving genetic stability after, at long last, the desiredcombination of characteristics has been observed in a plant. Cycle times of 10+ years, it must be said, are a long shot in ever less predictable environments and therefore future needs in agriculture.
Genome editing methods: The prospect of fast-track breeding
If it were possible to change the genetics only minimally, and only where intended, thus leaving all other desirable traits unaltered, this might create a shortcut around the many years of selection needed in conventional breeding. Yet however much the breeders would like to use gene editing techniques, the legislator has placed high obstacles on their path. In 2018, the European Court of Justice classified plants developed with the help of new breeding methods as genetically modified organisms (GMO). In view of the high regulatory burden that comes with this classification, it is unrealistic that these methods are going to be used in plant breeding, to the detriment of clearly both agriculture and society at large. From a scientific standpoint, the undifferentiated classification of plants derived from new breeding methods as GMOs is technically wrong. Plants that cannot be distinguished from conventionally bred varieties or a natural mutation should not be regulated as GMOs. This decision is liable to prevent European plant breeders effectively from gaining the experience necessary to apply the new methods successfully.
Shortly after the ECJ ruling, German plant breeders decided to initiate a proof-of-concept project to showcase the potential of these methods. This was in response to a request often made, heedless of the fact that the development of a plant variety, especially with not yet tried-and-tested methods, is a huge investment that nobody can and will afford without any prospect for later commercial use. More than 80 per cent of the plant breeding companies in Germany are small and medium-sized companies. Such a project is the only way to gain knowledge in such a big topic.
Carefully selected sample project
Despite these difficulties, an expert group of experienced breeders, scientists and communication experts was set up to analyse project ideas and to brainstorm on how an NBT project could be implemented. The response was huge. Twenty-two project proposals referring to a total of 13 different crop species were submitted. The group of experts evaluated these ideas under the aspects of added social value, positive ecological and economic effects. They also screened them with a feasibility filter: Was it, at that time, realistic to expect that a genome editing technique could be applied to the species in question? Could the crop species be worked on in the breeding companies involved?
The project was initiated for two reasons: First for demonstration purposes, successful completion of the project in the foreseeable future should not be per se impossible. Secondly to generate genetic material for the breeders. For the same reasons, economic relevance of the crop and difficulty to achieve the same aim with conventional methods were important criteria, too. Project proposals that required long-term basic research or any extensive precursory steps were deemed unsuitable. In the end, the evaluation process of all these individual components resulted in the wheat project named PILTON.
Wheat is the crop plant with the largest cultivation area in Germany and Europe, and it is one of the essential staple crops in our global society. The PILTON project is also designed to demonstrate and quantify the potential to significantly reduce the use of plant protection products. Furthermore, the project should demonstrate how it is possible for plant breeding companies to use genome editing methods, in the light of intellectual property implications.
The project seeks to achieve a durable tolerance in wheat simultaneously against a variety of fungal diseases. The necessary breeding steps include targeted mutagenesis with Cas endonucleases. The genetic modifications are limited exclusively to individual wheat genes already present in the wheat genome. If successful, this could showcase how the use of new breeding methods can directly benefit society, the economy, and the environment.
PILTON was launched in 2020. The name is an acronym for the German full title and stands for “fungal tolerance of wheat by means of new breeding methods”. Fifty-five mostly medium-sized plant breeding companies are involved in the project, which has been initiated by the German Federation for Plant Innovation (GFPi), a sister organisation of the German Plant Breeders’ Association (BDP) which is dedicated to research. BDP gives its communicative support to the project. The large number of participating companies demonstrate the tremendous interest in the topic among plant breeding companies of all sizes. This can be seen as a first result: Genome editing methods hold promise.
Read Part 2 here.
