Multi-Channel System for Simultaneous In Situ Monitoring of Ion Flux and Membrane Potential in Plant Electrophysiology

Simultaneous detection of both ion flux and membrane potential in vivo and in situ in plants is a challenging research task. To explore the mechanisms of plant electrical activity, researchers urgently need to understand and determine the types of ions and the ion fluxes that pass in and out of cells during polarization and repolarization, but the required measurements are very difficult to perform. In this paper, we have developed a versatile system that can detect the ionic flux and the membrane potential, in vivo and in situ, simultaneously. The system uses a self-referencing ion-selective glass microelectrode and a membrane potential glass microelectrode as sensors. These sensors are linked through a preamplifier with high input impedance to a specific dynamic measurement system that can amplify small extracellular concentration gradient signals and realize simultaneous measurement of both the ion flux and the membrane potential. In addition, an interpolation fitting algorithm has been proposed to reduce the artifacts that are present in the in situ measurements during plant growth. The hydrogen ion fluxes in wheat roots were measured using the self-referencing ion-selective microelectrodes, and the proposed system was used to measure NaCl stimulation-induced changes in the membrane potentials and hydrogen ion fluxes of wheat root epidermal cells. The results demonstrate that the system can meet the ion flux and membrane potential measurement requirements.