High aspect ratio graphene oxide: a highly efficient plasmid DNA deliverer for plant seed

Plant genetic engineering plays a central role in crop improvement and the biosynthesis of natural products. However, the plant cell wall, as a natural barrier, restricts the effective delivery of exogenous biomolecules, especially the delivery of plasmid DNA into the interior of plant cells.

Here, we introduce a novel form of graphene oxide characterized by a high aspect ratio, synthesized through low-voltage, low-current, and prolonged electrochemical oxidation in a 0.5 mol/L NaOH aqueous solution. To evaluate the efficacy of HARGO in delivering exogenous genes, the Poa crymophila Keng seeds were immersed and germinated in a solution containing HARGO and plasmid DNA pEG100-PcNAC2-EGFP.

The high aspect ratio graphene oxide (HARGO) exhibits advantageous characteristics, including a small lateral dimension and single-atom layer thickness (0.414 nm), which can directly penetrate plant tissues and even cell walls. Notably, HARGO can physically adsorb plasmid DNA and facilitate its entry into plant cells for gene delivery without requiring chemical modifications such as polyethylene glycol (PEG) or polyethyleneimine (PEI). Fluorescence signals corresponding to EGFP were successfully observed in the emerged seedlings, with a positive transformation rate reaching 90%.

These findings offer a novel tissue culture-free plasmid DNA delivery tool for plant genetic engineering, which will significantly impact the advancement of plant biotechnology.