An Optimized Editing Approach for Wheat Genes by Improving sgRNA Design and Transformation Strategies

Hexaploid wheat has a large genome, making it difficult for transgenes to produce phenotypes due to gene redundancy and tight linkage among genes. Multiple gene copies typically necessitate multiple targeting events during gene editing, followed by several generations of self-crossing to achieve homozygous genotypes. The high cost of transgenesis in wheat is another issue, which hinders the easy availability of gene-edited materials in wheat. In this study, we developed a comprehensive approach to improve wheat gene editing efficiency. First, we established a protoplast-based system to evaluate the relative efficiency of gene editing targets, which enabled the rapid and effective selection of optimal sgRNAs. We then compared two transformation strategies: biolistic bombardment and Agrobacterium-mediated transformation for generating edited wheat lines. Although biolistic bombardment showed higher initial editing efficiency, Agrobacterium-mediated transformation proved more effective for obtaining homozygous mutants. Notably, we discovered that deploying the same sgRNA through different vectors enhanced editing efficiency, whereas overlapping but distinct sgRNAs exhibited interference effects. Finally, we optimized the VITF-edit (virus-induced transgene free editing) technique using BSMV delivery to establish a relatively simple and easily applied wheat gene editing method for general laboratories.