Multi Electrode Arrays (MEAs) and the electrical network of the roots

Electrically excitable cells are present in many multicellular organisms, especially in brains of animals, but also in lower animals such as sponges, which lack central nervous system and in animals having excitable epithelia, which can conduct signals via neuroid conduction. In plants, most cells are electrically excitable and active, releasing and propagating action potentials (APs), which may affect such central physiological processes as photosynthesis and respiration. The first report describing electrical signals in plants was published over 200 years ago on carnivorous plants. Since then, many researchers have made detailed analyses of the electrical activity of single cells by using microelectrodes for intracellular recordings. However, such techniques cannot address integrated issues of how large assembly of cells can combine information both spatially and temporally. This can be possible using a multi electrode array (MEA) approach, intensively used in neuroscience for any electrogenic animal tissues, and, here presented as its first application, also for plants tissues. The system allows non-invasive, long time and multisite recording and stimulation with high spatiotemporal resolution. After a short description of the MEA technique in terms of hardware and background, the chapter mainly focuses on the application of this technique in plant electrophysiology by showing some recent works concerning the study of both the intense spontaneous electrical activities and the stimulation-elicited bursts of locally propagating electrical signals generated by the root apex.