Targeted mutagenesis using the Agrobacterium tumefaciens-mediated CRISPR-Cas9 system in common wheat

Recently, the CRISPR/Cas9 system has been widely used to precisely edit plant genomes. Due to the difficulty in Agrobacterium-mediated genetic transformation of wheat, the reported applications in CRISPR/Cas9 system were all based on the biolistic transformation.

In the present study, we efficiently applied targeted mutagenesis in common wheat (Triticum aestivum L.) protoplasts and transgenic T0 plants using the CRISPR/Cas9 system delivered via Agrobacterium tumefaciens. Seven target sites in three genes (Pinb, waxy and DA1) were selected to construct individual expression vectors. The activities of the sgRNAs were evaluated by transforming the constructed vectors into wheat protoplasts. Mutations in the targets were detected by Illumina sequencing. Genome editing, including insertions or deletions at the target sites, was found in the wheat protoplast cells. The highest mutation efficiency was 6.8% in the DA1 gene. The CRISPR/Cas9 binary vector targeting the DA1 gene was then transformed into common wheat plants by Agrobacterium tumefaciens-mediated transformation, resulting in efficient target gene editing in the T0 generation. Thirteen mutant lines were generated, and the mutation efficiency was 54.17%. Mutations were found in the A and B genomes of the transgenic plants but not in the D genome. In addition, off-target mutations were not detected in regions that were highly homologous to the sgRNA sequences.

Our results showed that our Agrobacterium-mediated CRISPR/Cas9 system can be used for targeted mutations and facilitated wheat genetic improvement.