Malate Detection Using Nanoelectrochemistry

Chemical signaling is important for many plant processes and functions such as photosynthesis, ion permeability, energy transfer, and information exchange between cellular compartments. Malate and other transmitters are essential for reduction/oxidation state regulation that controls the metabolic changes in plants and assists in homeostasis and optimal growth especially in changing environments. The examination of chemical signaling in plants is important for agriculture in not only monitoring plant health for crop production, but it is also crucial for plant reproduction and flowering. Currently, there is not a lot of research examining the dynamics and fluxes of molecules that are responsible for plant signaling in real time from guard cells and transmitter release from plant vacuoles. The goal of our research is to examine malate and other transmitter fluxes from a single chloroplast as well as guard cells and vacuoles using scanning electrochemical microscopy, optical-electron microscopy, and mass spectrometry. These techniques will allow high spatiotemporal and sensitive examination of plant cellular components on a nanometer scale in real time. We have developed a method and sensor to detect malate at the interface between two immiscible electrolyte solutions (ITIES) using a nanoelectrode to monitor changes in electrical current and potential. We determined that there is an increase in electrical current with an increase in malate concentration. Using this information, we will be able use a variety of bioimaging techniques to further study malate flux from a single chloroplast as well as plant stomatal movement in the presence of different environmental stimuli.