A Polymeric Nanoparticle System for the Delivery of CRISPR/Cas9 Components into Arabidopsis Pollen

Efficient and heritable genome editing in plants remains constrained by transformation bottlenecks and reliance on tissue culture-based regeneration. Targeting the male germline offers a promising alternative for DNA-free genome modification. Here, we report a polymeric nanoparticle platform for the delivery of RNA-based CRISPR/Cas9 components into Arabidopsis thaliana pollen, establishing a foundation for sperm transfection-assisted genome editing (STAGE)-like approaches in plants. Poly(2-dimethylaminoethyl methacrylate) (PDMAEMA)-based polyplexes were designed to independently encapsulate Cas9 mRNA and ATTO 550-labeled guide RNA, forming nanoparticles with hydrodynamic diameters of ∼146 nm and condensed cores of 20-30 nm. Following internalization and cytosolic release, Cas9 mRNA translation enabled the nuclear localization of ATTO 550-labeled gRNA, as confirmed by confocal imaging and fluorescence lifetime (TauSense) analysis. Fluorescent signals corresponding to the CRISPR RNPs were detected in both vegetative and sperm cell nuclei, with higher accumulation in the vegetative nucleus. Together, these results demonstrate the feasibility of RNA-mediated delivery and intracellular assembly of CRISPR/Cas9 RNPs in plant male gametophytes. By bypassing tissue culture and DNA integration, this nanoparticle-based approach establishes a framework for a more efficient mechanism for introducing heritable genome modifications in plants.