“…To expand the editing scope, we replaced the Sp Cas9 in the base editors with Cas orthologs or evolved Sp Cas9 variants with relaxed protospacer adjacent motif (PAM) recognition ( Hua et al., 2019a , Hua et al., 2019b , Qin et al., 2019a , Ren et al., 2019 , Zhong et al., 2019 , Wang et al., 2020 ). Furthermore, the efficiency of base editors was enhanced by modification of fusion protein structure, utilization of deaminase orthologs, or development of selection-enriched systems ( Li et al., 2018 , Li et al., 2020c , Zong et al., 2018 , Qin et al., 2019b , Hua et al., 2020 , Xu et al., 2020a ). Editing by base editors has outperformed HDR-mediated substitutions in plants in terms of efficiency and product purity.…”