Muellner, M. | Search bioRxiv

bioRxiv2026

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. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=91 SRC="FIGDIR/small/733037v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@170f7a5org.highwire.dtl.DTLVardef@1929c6forg.highwire.dtl.DTLVardef@5c4a94org.highwire.dtl.DTLVardef@1243cc8_HPS_FORMAT_FIGEXP M_FIG C_FIG

Plant Biology↗

bioRxiv2022

Wheat pollen uptake of CRISPR/Cas9 RNP-PDMAEMA nanoassemblies results in targeted loss of gene function in progeny

The utility of CRISPR in plants has remained limited by the dual difficulties of delivering the molecular machinery to target cells and the use of somatic cell techniques that require tissue culture-based de novo organogenesis. We developed 5-10 nm isodiametric polyplex nanoassemblies, comprising poly [2-(dimethylamino)ethylmethacrylate] PDMAEMA (PD) polycationic linear homopolymers and CRISPR/Cas9 ribonucleoproteins (RNPs), that enable endocytosis-driven RNP uptake into pollen grains. Pollen from wheat plants (genotype Gladius+Sr50), homozygous for monogenic Sr50-mediated resistance to stem rust (Puccinia graminis f. sp. tritici -Pgt), were incubated with RNP/PD nanoassemblies targeting the dominant, Sr50 rust resistance gene. The treated pollen grains were then used to fertilize Gladius+Sr50 florets and the resulting M1 plants were tested for loss of Sr50 function via rust resistance screens. The identification of fully susceptible M1 seedlings indicated that the Sr50 RNPs acted on both alleles, indicating they were transferred via the treated pollen to the zygote. The ability to readily deliver CRISPR RNPs to reproductive cells via biodegradable, polymeric nanocomplexes has significant implications for the efficiency of gene editing in plants.

plant biology↗