Double-stranded DNA introduction into intact plants using peptide-DNA complexes

Introducing exogenous genes into plant cells is an essential technique in many fields in plant science and biotechnology. Despite their huge advantages, disadvantages of current transfection methods include the requirement of expensive equipment, risk of gene damage, low transformation efficiency, transgene size limitations, and limitations of applicable plant types. Recently developed peptide-based gene carriers can deliver plasmid and double-stranded RNA. However, the delivery of double-stranded DNA (dsDNA), specifically PCR products, has not been studied. As dsDNA is handled in several plant science labs, peptide-based gene carriers are expected to be applicable to dsDNA in addition to plasmid DNA and double-stranded RNA. Here, we demonstrate dsDNA introduction into intact Nicotiana benthamiana leaves by using an ionic complex of a fusion peptide comprising (KH)(9) and Bp100 with dsDNA encoding Renilla luciferase as a reporter gene. The buffer condition for the complex preparation and infiltration significantly affected the transfection efficiency; this is because the structure of the complex in various protonated conditions contributed to the transfection efficiency. Structures of the complex and peptide are key factors for improving the peptide-based gene delivery system for plants.