Fig. 1

Summary of genome editing techniques using engineered nucleases. The first two nucleases are made by a fusion of a zinc-finger protein and TALE to the restriction enzyme FokI, producing ZFN and TALEN, respectively (a). In contrast, Cas9 contains nuclease domains for the cleavage of DNA and RNA binding domains for the guide RNAs, which offer simplicity and better accuracy compared to the predecessors. All three nucleases produce DSBs, and INDELs can be produced via error-prone DNA repair NHEJ. When donor DNAs (red) are provided, knock-in events can be produced via either NHEJ or HDR. Other types of nucleases were summarized (b), including meganucleases and targetrons. Timeline of the major nucleases and their use in genome editing were summarized in c. Their first reports are shown in shades, and those of microalgal genome editing are shown in solid boxes