Transgene-Free Genome Editing in Plants

Genome editing has revolutionized genetics and breeding likewise. Especially in plant breeding, it opened new ways to address traits with never known specificity. In many cases genome editing tools are provided by classical transgenic methods, i.e., by Agrobacterium-based delivery, but it is also possible to perform genome editing without the use of a transgene by providing proteins, or nucleic acid protein complexes. These methods have the big advantage that transgene organisms can be avoided at any time; even transgenic intermediates are not needed. However, transgene-free methods are technically challenging, and editing rates are often lower compared to classical methods. Nevertheless, it offers great opportunities to produce plants without the need of any transgene, simplifying the regulatory processes in many jurisdictions around the globe. In this chapter, we present methods and delivery methods that can be used for transgene-free editing and present first promising examples.