A water-soluble phosphorus-dipyrromethene fluorescent probes for visualization of hydrogen sulfide in plants under abiotic stresses

Abstract

Hydrogen sulfide (H₂S) usually acts as a gaseous signaling molecule that plays an essential role in regulating plant physiological activities. Consequently, in-situ detection of H₂S in plants is of great significance for studying the physiological mechanisms of H₂S within the plant system. In this study, a highly water-soluble probe with long-wavelength emission for in-situ detection of H₂S in plants was synthesized. The ring-forming structure of phosphorus atom improves its water solubility. By introducing 2,4-dimethoxyphenyl to the boron-dipyrromethene (BODIPY) structure, DPOD-NO₂ possesses a large Stokes Shift (76 nm). Furthermore, the long-wavelength emission at 616 nm reduces the interference from plant self-fluorescence. The nitro group was chosen as the recognition group, and the specific recognition of H₂S was achieved through the intramolecular charge transfer (ICT) mechanism. The DPOD-NO₂ shows excellent linearity within the H₂S concentration range of 0.1 to 90 μM, with a detection limit of 0.063 μM. Importantly, DPOD-NO₂ enabled successfully in situ detection and imaging of H₂S in plants due to its excellent biocompatibility and detection performance. The imaging results reveal the variations in H₂S content within the root systems of wheat seedlings under Al³⁺ stress, drought stress, and flooding stress. Consequently, this work presents a novel probe for further exploring the role and mechanism of H₂S in plants’ responses to environmental stresses.