A Self-Reporting\nNanosensor for Detecting Bacterial\nExploitation in Plants through Extracellular DNA

Detection of extracellular DNA (exDNA) released by invasive\npathogens\nis crucial for understanding biotic stress in plants but remains challenging\ndue to the lack of practical sensing tools. This study introduces\na fluorescent nanosensor for remote, noninvasive detection of exDNA\nin plant tissues. Comprising GelGreen and polyethylenimine-modified\nsilica nanoparticles, the nanosensor forms a self-reporting nanoplatform\nthat simultaneously captures exDNA and generates signals. DNA-induced\ncross-linking causes nanosensor aggregation, producing detectable\nfluorescence measurable by confocal microscopy and flow cytometry\nwith sensitivity at ng mL<sup>–1</sup> levels. After injection,\nthe nanosensors reside in the apoplastic space, capturing exDNA over\nextended periods and providing stable fluorescence signals. The study\nalso demonstrates that invasive bacteria trigger nanosensor aggregation\nin plant leaves via bacterial surface DNA, rapidly activating the\nnanosensors. This underscores the role of exDNA in pathogen infections\nand highlights the potential of this nanosensor for advancing plant\nnanotechnology and pathophysiological research.