Rapid, Long-Distance Electrical and Calcium Signaling in Plants

Abstract

Plants integrate activities throughout their bodies using long-range signaling systems in which stimuli sensed by just a few cells are translated into mobile signals that can influence the activities in distant tissues. Such signaling can travel at speeds well in excess of millimeters per second and can trigger responses as diverse as changes in transcription and translation levels, posttranslational regulation, alterations in metabolite levels, and even wholesale reprogramming of development. In addition to the use of mobile small molecules and hormones, electrical signals have long been known to propagate throughout the plant. This electrical signaling network has now been linked to waves of Ca(2+) and reactive oxygen species that traverse the plant and trigger systemic responses. Analysis of cell type specificity in signal propagation has revealed the movement of systemic signals through specific cell types, suggesting that a rapid signaling network may be hardwired into the architecture of the plant.

Interplay of Plasma Membrane and Vacuolar Ion Channels, Together with BAK1, Elicits Rapid Cytosolic Calcium Elevations in Arabidopsis during Aphid Feeding

“…Since the feeding site [Ca 2+ ] cyt elevations are attenuated, but not abolished in the tpc1-2 mutant, it appears that release of vacuolar Ca 2+ by TPC1 is downstream of and dependent on extracellular Ca 2+ release by the GLRs. This finding agrees with work showing that TPC1 activity is positively regulated by [Ca 2+ ] cyt (Hedrich and Neher, 1987;Ward and Schroeder, 1994;Allen and Sanders, 1996;Guo et al, 2016;Kintzer and Stroud, 2016) and plays a role in systemically propagating Ca 2+ -induced Ca 2+ release (Dubiella et al, 2013;Evans et al, 2016;Gilroy et al, 2016;Choi et al, 2016). Consequently, TPC1 appears to be activated by GLR-mediated Ca 2+ influx and involved in the cell-to-cell spread of Ca 2+ during biotic interactions.…”

Beyond APs and VPs: evidences of chaos and self-organized criticality in electrical signals in plants

“…Different types of signals, such as hormones, ROS, Ca 2+ and electrical signals, compose the plant's signaling network 3,4 . Specifically, there are three types of electrical signals in plants: APs (action potentials), VPs (variation potentials), and SPs (system potentials).…”

“…Like VPs, SPs have a magnitude and duration that are depended on the stimulus, but they are initiated via membrane hyperpolarization through the sustained activation of the proton pump. SPs are dependent of experimental conditions, and then they may occur under a very specific set of environmental conditions 4,11 .…”

“…However, quite often mixed electrical potential waves (EPWs) are recorded, for instance, as result of overlapping APs and VPs, which impedes proper signal analysis 14 . It is also important to note that even though APs, VPs and SPs most likely occur through distinct molecular mechanisms, these phenomena can arise within Thus, we have hypothesized that the complexity of the massive ionic flow through plant tissues could be similar to the complexity observed in the human brain, since they share analogous (but non homologous) mechanisms of membrane depolarization/re-polarization based on transmembrane ion fluxes, linking electrically a plenty of cells and engendering a complex network of information transmission 4,17 .…”

Recent Progress in Understanding the Role of Reactive Oxygen Species in Plant Cell Signaling

“…ROS and calcium waves constitute important components of rapid systemic signaling in plants (e.g. Suzuki et al, 2013;Choi et al, 2016;Evans et al, 2016;Carmody et al, 2016). In addition to RBOHs, which play a key role in mediating systemic signaling, a role for xanthine dehydrogenase was recently proposed in this response .…”