High-efficiency plastome base editing in rice with TAL cytosine deaminase.

Dear Editor, Genome editing has been widely applied in nuclei but not so in or-ganelles such as the mitochondria and chloroplasts.The chal-lenge for organelle genome editing is the limited accessibility of editing reagents to the compartments of organelles(Zhu et al.,2020).Recently,fusion proteins of cytidine deaminase domain(DddAtox)and transcription activator-like effectors(TALEs)have been developed for DNA base editing in mitochondria of human cells and mice(Mok et al.,2020;Lee et al.,2021).The DddAtox-derived base editors(DdCBEs)function in pairs,each consisting of a mitochondrial targeting sequence,TALE,a split half of DddAtox,and an uracil glycosylase inhibitor(UGI).The split halves of DddAtox heterodimerize to catalyze the deamination of cytosines of double-stranded DNA,resulting in efficient C·G to T·A conversions(Mok et al.,2020).