An ICT-based ratiometric fluorescent probe for tracking and imaging SO 2 during Cd-induced stress in plants

Cadmium (Cd) is a common and highly toxic heavy metal that poses a significant threat to plant growth and development, as well as human and animal health through the food chain. In contrast, sulfur dioxide (SO 2 ) and its derivatives, which are major air pollutants, can also have beneficial effects on plant resistance and seed germination at low concentrations. However, the role of SO 2 in the process of plant response to stress and adversity remain poorly understood. Herein, we have developed an ICT-based and D-π-A structure ratiometric fluorescent probe, TPE-BA, with the photoluminescence properties of AIE. This probe exhibited high sensitivity and excellent selectivity for detecting SO 2 in living plants. Probe TPE-BA showed a fast response time and has been used to detect exogenous changes in SO 2 levels in plants by fluorescence imaging. In addition, the process of Cys metabolism produces endogenous SO 2 were confirmed in the roots of tobacco seedlings. The results suggested that there is an imbalance of oxidative stress levels and an upregulation of SO 2 levels during the response of tobacco seedlings to Cd-induced stress, indicating that SO 2 plays a crucial role as a signaling molecule in plant response to stress.