Transgene-Free Genome Editing in Tomato and Potato Plants Using CRISPR-Cas9 Cytidine Base Editor

Plant scientists are now using genome editing tools to explore on gene function and develop crops for improvement of traits. One of the technical challenges in using such tools is to efficiently induce precise and predictable targeted point mutations for crop breeding. Thus, new additional tools have been developed such as cytidine base editors (CBEs), which are CRISPR-Cas9 derived tools used to direct cytidine to thymine base conversion. In dicots, the most stable genomic integration of CRISPR-Cas9 is through Agrobacterium-mediated transformation. However, elimination of the foreign DNA may be hard to accomplish, particularly in vegetatively propagated plants.

Florian Veillet from Institut National de la Recherche Agronomique in France, together with other researchers targeted the acetolactate synthase (ALS) gene in tomato and potato by a CBE using Agrobacterium-mediated transformation. They successfully edited the targeted cytidine bases, which led to chlorsulfuron-resistant plants with precise base edition efficiency of up to 71% in tomato. They also produced 12.9% and 10% edited (transgene-free) tomato and potato plants, respectively. This approach decreases the unwanted effects that may be caused by random integration of transgenes into the host genome.

The new approach used in the study is expected to introduce new perspectives for genome engineering by co-edition of the ALS with other genes, leading to transgene-free plants with new traits.

Read more findings in the International Journal of Molecular Sciences.