The promoters driving both Cas9 and sgRNAs are quite important for efficient
genome editing by CRISPR-Cas9 in plants. The team of Chao Feng from the
Chinese Academy of Sciences tested the combination of maize dmc1 gene
promoter and the U3 promoter for the Cas9 and sgRNA, respectively.

Three loci in the maize genome were selected for targeting. The T0 plants
developed were efficiently edited at the target sites with mutants
accounting for about 66%. The mutations in T0 plants were found to be stably
transmitted to the T1 generation. Analysis also indicated that no off$B!>(B
target mutations were detected at potential off-target sites.

These results show that the dmc1 promoter-controlled CRISPR-Cas9 system is
highly efficient for maize. This study provides evidence that the
optimization of the promoters for the CRISPR-Cas9 system can enhance the
efficiency of targeted genome editing in plants.



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