The efficiency of plant cytidine base-editing systems is limited, and unwanted mutations frequently occur in transgenic plants. We increased the cytidine editing frequency and fidelity of the plant base editor 3(BE3) and targeted activation-induced cytidine deaminase(CDA)(target-AID) systems by coexpressing three copies of free uracil–DNA glycosylase(UDG) inhibitor(UGI). The editing efficiency of the improved BE3 and CDA systems reached as high as 88.9% and 85.7%, respectively, in regenerated rice plants, with a very low frequency of unwanted mutations. The low editing frequency of the BE3 system in the GC context could be overcome by the modified CDA system. These results provide a highfidelity and high-efficiency solution for rice genomic base editing.
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Key Laboratory of Rice Genetics & Breeding of Anhui Province Institute of Rice Research Anhui Academy of Agricultural Science Hefei 230031 Anhui China;