Development of TALE-adenine base editors in plants

Area of Science:

• Molecular Biology
• Plant Science
• Genome Editing

Background:

• Base editors precisely modify DNA without double-strand breaks.
• TALE-adenine base editors (TALE-ABEs) facilitate A•T-to-G•C editing, but their plant applications beyond chloroplasts and DddA's role are unclear.

Purpose of the Study:

• To investigate TALE-ABE editing capabilities in plants, specifically in *Nicotiana benthamiana* and rice.
• To elucidate the functional role of the cytosine deaminase DddA in enhancing adenine deaminase activity on double-stranded DNA.

Main Methods:

• Engineered TALE-ABEs with various deaminase fusion architectures were tested in *Nicotiana benthamiana* and rice.
• Adenine base editing efficiencies were analyzed using a *β-glucuronidase* reporter system in rice protoplasts.
• Regenerated rice plants with chloroplast genome mutations were generated using TALE-ABE.

Main Results:

• The cytosine deaminase DddA was shown to enhance the activity of single-stranded DNA-specific deaminases (TadA8e or APOBEC3A) on double-stranded DNA.
• Precise adenine editing with high product purity was achieved in rice protoplasts.
• Successful regeneration of rice plants with targeted A•T-to-G•C mutations in the chloroplast genome was accomplished.

Conclusions:

• TALE-ABEs are effective tools for precise A•T-to-G•C editing in plant nuclear and organellar genomes.
• This technology offers new avenues for crop improvement and potential gene therapy applications.