Efficient multiplex genome editing by CRISPR/Cas9 in common wheat.

Common wheat has a large genome with three subgenomes (A, B and D), making it challenging to create mutations at multiple genomic sites simultaneously. The CRISPR/Cas9 system offers a game changing tool for editing crop genomes (Chen et al., 2019). Three main strategies have been developed to produce multiple single guide RNAs (sgRNAs), including the conventional multiplex system with tandem repeats of separate U3 or U6 promoters (TRSP), the tRNA processing system (Xie et al., 2015), and the ribozyme processing system (Gao and Zhao, 2014).