Homologous recombination has been broadly applied in genome editing of prokaryotes with high efficiency and accuracy. However, this way is limited in realizing larger-scale genome editing with large DNA fragments or numerous genes because DNA editing template construction is a relatively complicated procedure1. Derived from the immune system present in bacteria and archaea, CRISPR technology as an efficient genome-scale editing tool has revolutionized conventional genetic engineering methods and unprecedentedly facilitated strain engineering2. Consequently, the CRISPR/Cas9 system has rapidly become a transformative and powerful tool for editing genomes in many organisms.
