A Self-Reporting Nanosensor for Detecting Bacterial Exploitation in Plants through Extracellular DNA

Detection of extracellular DNA (exDNA) released by invasive pathogens is crucial for understanding biotic stress in plants but remains challenging due to the lack of practical sensing tools. This study introduces a fluorescent nanosensor for remote, noninvasive detection of exDNA in plant tissues. Comprising GelGreen and polyethylenimine-modified silica nanoparticles, the nanosensor forms a self-reporting nanoplatform that simultaneously captures exDNA and generates signals. DNA-induced cross-linking causes nanosensor aggregation, producing detectable fluorescence measurable by confocal microscopy and flow cytometry with sensitivity at ng mL^-1 levels. After injection, the nanosensors reside in the apoplastic space, capturing exDNA over extended periods and providing stable fluorescence signals. The study also demonstrates that invasive bacteria trigger nanosensor aggregation in plant leaves via bacterial surface DNA, rapidly activating the nanosensors. This underscores the role of exDNA in pathogen infections and highlights the potential of this nanosensor for advancing plant nanotechnology and pathophysiological research.