Monitoring Plant Health with Near Infrared Fluorescent H2O2 Nanosensors

Abstract

Nanotechnology-based sensors are promising tools for optimizing plant performance and use of resources in agriculture by equipping plants with capabilities to report when they are under stress and require intervention. Herein, we interfaced near infrared (nIR) fluorescent nanosensors with plant leaves that report hydrogen peroxide (H2O2), a key signaling molecule associated with the onset of plant environmental and pathogen stresses. For this purpose, we used single-walled carbon nanotubes (SWCNT) as non-photobleaching fluorescent building blocks for H2O2 nanoscale sensors with a nIR fluorescent emission (> 800 nm) in a ultra-low background region that is ideal for high-sensitivity remote sensing and imaging. SWCNTs were functionalized with a DNA aptamer that binds to hemin, resulting in nIR fluorescence nanosensor response that is quenched by H2O2 in a dose dependent way within the plant physiological range (10-100 H2O2 µM). The in vivo sensor sensitivity for H2O2 (10 µM) allows it to reversibly report signs of stress in plants exposed to UV-B, high light, and a microbial pathogen related peptide (flg 22), but not mechanical leaf wounding. The sensor response was imaged in leaves by a standoff nIR camera, which reported remotely changes in sensor nIR emission up on stress. Such nanotechnology-based sensors report plant signaling molecules associated with early signs of stress and will impact our understanding of plant stress communication, provide novel tools for precision agriculture, and reduce undesirable losses of agrochemicals in the environment.