Ghosh, S.; Shekhar, V.; Gupta, S.; Bhatia, D. D.; Sankaranarayanan, S.

Delivering biomolecules into pollen tubes that deliver sperm cells for plant fertilization remains technically challenging due to thick cell walls and rapid polarized growth, hindering reproductive engineering. DNA nanotechnology offers a promising alternative over current delivery methods due to their biocompatibility, programmable design, low cytotoxicity, and stimulus-responsive properties, yet their application in plants remains underexplored. Here, we provide the first demonstration of tetrahedral DNA nanostructures (TDNs) as nanocarriers for active, endocytosis-mediated uptake into Arabidopsis pollen tubes, enabling spermidine delivery that shortens pollen tube elongation through actin reorganization and ROS modulation. TDN-treated pollen tubes grew through the Arabidopsis stigma and style, underwent capacitation, and maintained attraction to ovules in a semi-in-vivo assay, preserving reproductive fitness. Furthermore, we demonstrate that functionalization of TDNs with nuclear localization signal peptide significantly enhances nuclear localization. Collectively, these findings establish DNA nanostructures as effective nanocarriers for targeted biomolecule delivery and precise pollen tube modulation, advancing crop reproductive engineering.