NIR Fluorescent Probe for In Situ Bioimaging of Endogenous H 2 S in Rice Roots under Al 3+ and Flooding Stresses

Hydrogen sulfide (H 2 S) is one of the typical reactive sulfur species, which exhibits an important role in regulating both physiological and pathological processes. Recent studies indicate that H 2 S also serves as a key signaling molecule in a broad range of regulatory processes in plants. However, in situ imaging and detection of the levels of H 2 S in plant tissues remains a challenge. In this work, a NIR fluorescent probe ( HBTP-H 2 S ) was synthesized to achieve H 2 S imaging in living plant tissues. HBTP-H 2 S exhibited high sensitivity toward H 2 S with a large Stokes shift (250 nm). HBTP-H 2 S could be applied to HeLa cells to detect the fluctuation of endogenous H 2 S levels in response to physiological stimulations. Importantly, HBTP-H 2 S was utilized for direct H 2 S imaging of rice roots and revealed the upregulation of H 2 S signaling in response to aluminum ions and flooding stresses. Our work thus provides a new tool to investigate H 2 S-involved signal interaction and protective resistance of crops under environmental stresses.