To survive in a dynamic environment growing fixed to the ground, plants have developed mechanisms for monitoring and perceiving the environment. When a stimulus is perceived, a series of signals are induced and can propagate away from the stimulated site. Three distinct types of systemic signaling exist, i.e., (i) electrical, (ii) hydraulic, and (iii) chemical, which differ not only in their nature but also in their propagation speed. Naturally, plants suffer influences from two or more stimuli (biotic and/or abiotic). Stimuli combination can promote the activation of new signaling mechanisms that are explicitly activated, as well as the emergence of a new response. This study evaluated the behavior of electrical (electrome) and hydraulic signals after applying simple and combined stimuli in common bean plants. We used simple and mixed stimuli applications to identify biochemical responses and extract information from the electrical and hydraulic patterns. Time series analysis, comparing the conditions before and after the stimuli and the oxidative responses at local and systemic levels, detected changes in electrome and hydraulic signal profiles. Changes in electrome are different between types of stimulation, including their combination, and systemic changes in hydraulic and oxidative dynamics accompany these electrical signals.

Selective attention is an important cognitive phenomenon that allows organisms to flexibly engage with certain environmental cues or activities while ignoring others, permitting optimal behaviour. It has been proposed that selective attention can be present in many different animal species and, more recently, in plants. The phenomenon of attention in plants would be reflected in its electrophysiological activity, possibly being observable through electrophytographic (EPG) techniques. Former EPG time series obtained from the parasitic plant Cuscuta racemosa in a putative state of attention towards two different potential hosts, the suitable bean (Phaseolus vulgaris) and the unsuitable wheat (Triticum aestivum), were revisited. Here, we investigated the potential existence of different band frequencies (including low, delta, theta, mu, alpha, beta, and gamma waves) using a protocol adapted from neuroscientific research. Average band power (ABP) was used to analyse the energy distribution of each band frequency in the EPG signals, and time dispersion analysis of features (TDAF) was used to explore the variations in the energy of each band. Our findings indicated that most band waves were centred in the lower frequencies. We also observed that C. racemosa invested more energy in these low-frequency waves when suitable hosts were present. However, we also noted peaks of energy investment in all the band frequencies, which may be linked to extremely low oscillatory electrical signals in the entire tissue. Overall, the presence of suitable hosts induced a higher energy power, which supports the hypothesis of attention in plants. We further discuss and compare our results with generic neural systems.

Fruits, like other parts of the plant, appear to have a rich electrical activity that may contain information. Here, we present data showing differences in the electrome complexity of tomato fruits through ripening and discuss possible physiological processes involved. The complexity of the signals, measured through approximate entropy, varied along the fruit ripening process. When analyzing the fruits individually, a decrease in entropy values was observed when they entered the breaker stage, followed by a tendency to increase again when they entered the light red stage. Consequently, the data obtained showed a decrease in signal complexity in the breaker stage, probably due to some physiological process that ends up predominating to the detriment of others. This result may be linked to processes involved in ripening, such as climacteric. Electrophysiological studies in the reproductive stage of the plant are still scarce, and research in this direction is of paramount importance to understand whether the electrical signals observed can transmit information from reproductive structures to other modules of plants. This work opens the possibility of studying the relationship between the electrical activity and fruit ripening through the analysis of approximate entropy. More studies are necessary to understand whether there is a correlation or a cause-response relationship in the phenomena involved. There is a myriad of possibilities for the applicability of this knowledge to different areas, from understanding the cognitive processes of plants to achieving more accurate and sustainable agriculture.

Plants can retain information from previous stressful events, adjusting their systemic responses through priming and stress memory. However, the role of bioelectrical signaling in modulating systemic acquired acclimation (SAA) under recurrent salt stress remains poorly understood. Here, we investigated the physiological, biochemical, molecular, and electrophysiological responses of Sorghum bicolor exposed to single and repeated salinity events (120 mM NaCl) using a split-root system, allowing spatial separation of local and systemic stress signaling by selectively salinizing one or both root compartments. Results indicated that recurrent stress (S-S) induced a priming effect. Transpiration and stomatal conductance increased by ∼43 % and 46 % compared to control (C-C) and other treatments. In contrast, water-use efficiency (A/E) was nearly 90 % higher in C-C and non-recurrent stress (S 2nd cycle-S 2nd cycle) than in S-S, while intrinsic (A/g_s) was 60 % higher in non-recurrent-stressed plants compared to S-S. SOD activity in S-S was 50 % higher than in non-recurrent-stressed groups, whereas POD activity in S 2nd cycle-S 2nd cycle, reached 175 % above S-S. APX1 expression was strongly downregulated in S-S. Electrophysiological analyses revealed early and transient responses under recurrent stress, with ApEn reaching ∼0.6 within the first 10 min after stimulus and DFA stabilizing around 1.0. In contrast, non-recurrent stress led to delayed responses (>60 min), reduced complexity (ApEn ∼0.2), and higher DFA values (>1.5). Our integrative approach, combining split-root design, electrophysiology, and molecular biology, provides evidence for a dynamic electrome-based memory that enhances stress acclimation.