Generation, transmission, and physiological effects of electrical signals in plants

Abstract

This review explores the relationship between electrical long-distance signaling and the potential consequences for physiological processes in plants. Electrical signals such as action potentials (APs) and variation potentials (VPs) can be generated by spontaneous changes in temperature, light, touch, soil water content, by electrical as well as chemical stimulation or by wounding. An AP is evoked when the stimulus is sufficiently great to depolarize the membrane to below a certain threshold, while VPs are mostly induced by wounding, which induces a hydraulic wave transmitted through the xylem, thereby causing a local electrical response in the neighboring symplastic cells. Once generated, the signal can be transmitted over short distances from cell-to-cell through plasmodesmata, and after having reached the phloem it can also be propagated over long distances along the sieve tube plasma membrane. Such electrical messages may have a large impact on distant cells, as numerous well-documented physiological effects of long-distance electrical signaling have been shown. Electrical signals, for instance, affect phloem transport as well as photosynthesis, respiration, nutrient uptake, and gene expression.