Target-AID is a synthetic complex of Cas9 that is paired to an activation-induced cytidine deaminase (AID), which enables targeted nucleotide substitution (C to T or G to A). In a previous study, the team of Zenpei Shimatani from Kobe University in Japan reported the development of herbicide tolerant rice (Oryza sativa) callus via introduction of desired point mutations into target genes through Target-AID.
In this study, the team aimed to establish Target-AID as a plant breeding technique by proving that the introduced mutations in plants regenerated from the transformed callus can be inherited to subsequent generations. Analysis revealed that the regenerated plants as well as their progenies inherited the induced mutations, leading to a generation of selectable marker-free (SMF) herbicide tolerant rice plants.
These findings demonstrate that Target-AID can be developed into novel plant breeding technology, which enables improvement of traits and can be used in combination with targeted base editing systems such as the CRISPR-Cas9 system.