Expanded base editing in rice and wheat using a Cas9-adenosine deaminase fusion

Chao Li, Yuan Zong, Yanpeng Wang, Shuai Jin, Dingbo Zhang, Qianna Song, Rui Zhang, Caixia Gao

Nucleotide base editors in plants have been limited to conversion of cytosine to thymine. Here, we describe a new plant adenine base editor based on an evolved tRNA adenosine deaminase fused to the nickase CRISPR/Cas9, enabling A•T to G•C conversion at frequencies up to 7.5% in protoplasts and 59.1% in regenerated rice and wheat plants. An endogenous gene is also successfully modified through introducing a gain-of-function point mutation to directly produce an herbicide-tolerant rice plant. With this new adenine base editing system, it is now possible to precisely edit all base pairs, thus expanding the toolset for precise editing in plants.