Multivariate characterization of spontaneously generated electrical signals evoked by electrical stimulation in abscisic acid mutant tomato plants

In vivo monitoring of electrical activity between plant tissues and organs can be used to study information transport mechanisms and physiological responses to external stimuli. These signals are mainly characterized as action potential (AP) and variation potential (VP), related to long- and short-distance signaling, respectively. Spontaneous action potentials (SAPs) may also occur in the absence of known stimuli at frequencies adjusted to environmental conditions. By contrast, the mechanism of spontaneous depolarizations (SDs) remain unknown. In this work, spontaneous generation and evocation of electrical signals via electrical stimulation were monitored for 72 h using Ag/AgCl electrodes inserted into the stem and petioles of two mutant tomatoes, cv. Micro-Tom notabilis (MTnot) and MTsp12::NCED (MTNCED), and wild type (MTwt). MTnot generated more SAPs than did MTwt and MTNCED, propagated through the stem and petioles, with a transmission speed of 0.50 cm min(- 1). SDs propagation occurred mainly in the early morning, most often in MTwt. MTNCED gave a lower number of SDs that were associated with membrane depolarization level. The electrical stimuli promoted the generation of APs in all studied genotypes. Mutants MTnot and MTNCED were less sensitive to electrical stimulation, requiring greater stimuli to reach the excitation threshold.

Automated summary

Monitoring electrical signals generated in plant tissues and organs can provide insights into information transport mechanisms and physiological responses to external stimuli. Action potentials and variation potentials play key roles in long- and short-distance signaling, respectively. Spontaneous action potentials may occur in the absence of known stimuli, while the mechanism behind spontaneous depolarizations remains unclear.