The power of ionic movements in plants

The movement of ion-driven electrogenic events known as plant action potentials in the Venus flytrap Dionaea muscipula has first been recognized in Darwin's time. Besides electrophysiological techniques making use of current- and voltage-recording electrodes, today an ever-growing spectrum of tools has become available, that  report online changes in membrane potential and ion concentration. This represents a big step forward, particularly in comparison to the 'dark' times when calcium-signaling studies could not take advantage of Ca²⁺ reporters. Very recently, the first tools from a potpourri of light-gated ion channels routinely used in neurobiology took the plant signaling field to a new level. This kind of genetically encoded, noninvasive opto-tools can be activated by light and provide for remote controlling the membrane potential and ionic second messengers such as Ca²⁺ and H⁺. In future studies, such optogenetic tools in combination with the appropriate reporters for ionic and electrical impulses will allow studying membrane-delimited early steps in plant signal transduction. Moreover, this toolbox will help us tackle the question of how, for example, Ca²⁺ and/or electrical signatures are assessed in terms of local and long-distance information management.