ACKNOWLEDGEMENTS
The authors wish to thank the National Key Research and Development Program of China (2018YFA0901301 and 2018YFC0406303), the National Natural Science Foundation of China (21590812, 21607146, 51878638 and 51821006), and the International Partnership Program of Chinese Academy of Sciences (GJHZ1845) for supporting this work. The authors also thank Prof. Quan-Jiang Ji from Shanghai Technological University, China, for the kind donation of the plasmid pnCasPA-BEC.