A Dual-Channel Fluorescent Probe for Visualizing Glutathione Dynamics in Plants under Abiotic Stress

Glutathione (GSH), as an important class of antioxidants, exhibits a close correlation with cellular oxidative stress. Usually, GSH serves as an essential biomarker for evaluating redox homeostasis in plants. In this work, we developed a GSH-specific fluorescent probe by employing the aza-IR780 cyanine scaffold as the near-infrared fluorophore, the naphthalimide block as the visible light fluorophore, and sulfonamide as the GSH-responsive unit. The optical performance showed that this probe could highly selectively detect GSH in both visible light (emission at 498 nm) and near-infrared (emission at 780 nm) channels and was not interfered by other amino acid species. The results of the plant imaging experiment showed that this probe could visualize the root tip tissues of plants, as well as GSH in the entire plant. When plants are subjected to abiotic stress, they upregulate GSH expression to combat the redox imbalance induced by oxidative stress. The results of plant imaging studies under abiotic stress show that this probe can monitor the GSH dynamics in the root tip tissues and the entire plant of Arabidopsis thaliana under high-temperature stress, drought stress, and salt stress with a high signal-to-noise ratio, which were exactly similar to its response behavior under oxidative stress conditions. These findings indicate that this probe can serve as an effective and visual molecular tool for analyzing the dynamics of plant oxidative stress.