Memristors: Memory elements in potato tubers

Cyclic voltammetry of volatile memristors in the Venus flytrap: short-term memory

Plants have sensory, short-term and long-term memory. Possible candidates for memory in plants are memristors; resistors with memory. Memristors have been found in seeds, plants, flowers and fruits. The electrostimulation of plants by bipolar periodic waves can induce electrical responses with fingerprints of volatile or non-volatile memristors. Here, we show that the electrostimulation of the Venus flytrap (Dionaea muscipula Ellis) by unipolar sinusoidal or triangular periodic electrical trains induces electrical responses in plants with fingerprints of volatile memristors. The discovery of volatile generic memristors in plants opens new directions in the modelling and understanding of electrical phenomena in the plant kingdom.

Sunpatiens compact hot coral: memristors in flowers

Leon Chua postulated the theory of a memristor - a resistor with memory - in 1971, and the first solid-state memristor was built in 2008. Memristors exist in vivo as components of plasma membranes in plants, fruits, roots and seeds. A memristor is a nonlinear element; its current-voltage characteristic is similar to that of a Lissajous pattern. Here, we found memristors in flowers. Electrostimulation by bipolar periodic sinusoidal or triangular waves of an androecium, a spur, petals and a pedicel in Sunpatiens flowers induces hysteresis loops with a pinched point at low frequencies between 0.1mHz and 1mHz. At high frequencies, the pinched hysteresis loop transforms to a non-pinched hysteresis loop instead of a single line I=U/R for ideal memristors because the amplitude of electrical current depends on capacitance of a flower's tissue and electrodes, frequency and direction of scanning. The discovery of memristors in Sunpatiens (Impatiens spp.) creates a new direction in the modelling and understanding of electrophysiological phenomena in flowers.

Electrotonic potentials in Aloe vera L.: Effects of intercellular and external electrodes arrangement

Electrostimulation of plants can induce plant movements, activation of ion channels, ion transport, gene expression, enzymatic systems activation, electrical signaling, plant-cell damage, enhanced wound healing, and influence plant growth. Here we found that electrical networks in plant tissues have electrical differentiators. The amplitude of electrical responses decreases along a leaf and increases by decreasing the distance between polarizing Pt-electrodes. Intercellular Ag/AgCl electrodes inserted in a leaf and extracellular Ag/AgCl electrodes attached to the leaf surface were used to detect the electrotonic potential propagation along a leaf of Aloe vera. There is a difference in duration and amplitude of electrical potentials measured by electrodes inserted in a leaf and those attached to a leaf's surface. If the external reference electrode is located in the soil near the root, it changes the amplitude and duration of electrotonic potentials due to existence of additional resistance, capacitance, ion channels and ion pumps in the root. The information gained from this study can be used to elucidate extracellular and intercellular communication in the form of electrical signals within plants.

Electrophysiology of pumpkin seeds: Memristors in vivo

Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds.