Dear Editor,rnGenome editing,especially the newly developed CRISPR technology,is now widely implemented for diverse medical and agricultural applications(Puchta,2018).However,for genome editing,the DNA cassettes encoding the editing components are usually assembled and delivered into the cells of organisms(Cong et al.,2013).In most cases,these components will be integrated into the organism genome,which enables efficient genome editing and selection of the modified material.However,the integration of these exo-genous components becomes unnecessary after genome editing and therefore increases the chance of producing un-wanted off-target mutations.In addition,some studies also detected multiple insertions of plasmid vector components on the genome.All those unwanted insertions might lead to safety problems in the genome-edited organism and will be subject to strict regulatory(Li et al.,2019).For example,the genome-edited hornless calves,which had been predicted to be the world's first genome-edited animal approved for marketing,were detected to contain unintended hetero-zygous integration of the plasmid.This casts a shadow over the previously anticipated industrialization of genome-edited animals(Young et al.,2020).