Is the co-option of jasmonate signalling for botanical carnivory a universal trait for all carnivorous plants?

The carnivorous plants in the order Caryophyllales co-opted jasmonate signalling from plant defence to botanical carnivory. However, carnivorous plants have at least 11 independent origins, and here we ask whether jasmonate signalling has been co-opted repeatedly in different evolutionary lineages. We experimentally wounded and fed the carnivorous plants Sarracenia purpurea (order Ericales), Cephalotus follicularis (order Oxalidales), Drosophyllum lusitanicum (order Caryophyllales), and measured electrical signals, phytohormone tissue level, and digestive enzymes activity. Coronatine was added exogenously to confirm the role of jasmonates in the induction of digestive process. Immunodetection of aspartic protease and proteomic analysis of digestive fluid was also performed. We found that prey capture induced accumulation of endogenous jasmonates only in D. lusitanicum, in accordance with increased enzyme activity after insect prey or coronatine application. In C. follicularis, the enzyme activity was constitutive while in S. purpurea was regulated by multiple factors. Several classes of digestive enzymes were identified in the digestive fluid of D. lusitanicum. Although carnivorous plants from different evolutionary lineages use the same digestive enzymes, the mechanism of their regulation differs. All investigated genera use jasmonates for their ancient role, defence, but jasmonate signalling has been co-opted for botanical carnivory only in some of them.

Osmoelectric siphon models for signal and water dispersal in wounded plants.

When attacked by herbivores, plants produce electrical signals which can activate the synthesis of the defense mediator jasmonate. These wound-induced membrane potential changes can occur in response to elicitors that are released from damaged plant cells. We list plant-derived elicitors of membrane depolarization. These compounds include the amino acid l-glutamate (Glu), a potential ligand for GLUTAMATE RECEPTOR-LIKE (GLR) proteins that play roles in herbivore-activated electrical signaling. How are membrane depolarization elicitors dispersed in wounded plants? In analogy with widespread turgor-driven cell and organ movements, we propose osmoelectric siphon mechanisms for elicitor transport. These mechanisms are based on membrane depolarization leading to cell water shedding into the apoplast followed by membrane repolarization and water uptake. We discuss two related mechanisms likely to occur in response to small wounds and large wounds that trigger leaf-to-leaf electrical signal propagation. To reduce jasmonate pathway activation, a feeding insect must cut through tissues cleanly. If their mandibles become worn, the herbivore is converted into a robust plant defense activator. Our models may therefore help to explain why numerous plants produce abrasives which can blunt herbivore mouthparts. Finally, if verified, the models we propose may be generalizable for cell to cell transport of water and pathogen-derived regulators.

Selective Light Measurement in the Control of Reference LED Sources.

This paper describes an original adaptive multispectral LED light source that utilizes miniature spectrometer to control its flux in real time. Current measurement of the flux spectrum is necessary in high-stability LED sources. In such cases, it is important the spectrometer work effectively with the system that controls the source and the whole system. Therefore, as important as flux stabilization is the integration of the integrating sphere-based design with the electronic module and power subsystem. Since the problem is interdisciplinary, the paper mainly focuses on presenting the solution of the flux measurement circuit. In particular, the proprietary way of operating the MEMS optical sensor as a real-time spectrometer was proposed. Then, the implementation of the sensor handling circuit, which determines the spectral measurements accuracy and thus the output flux quality, is described. Also presented is the custom method of coupling the analog part of the flux measurement path with the analog-to-digital conversion system and the control system based on the FPGA. The description of the conceptual solutions was supported by the results of simulation and laboratory tests at selected points of the measurement path. The presented concept allows to build adaptive LED light sources in the spectral range from 340 nm to 780 nm with adjustable spectrum and flux value, with electrical power up to 100 W, with adjustable flux value in the range of 100 dB, operating in constant current or pulsed mode.

Advances in immunoassay-based strategies for mycotoxin detection in food: From single-mode immunosensors to dual-mode immunosensors.

Mycotoxin contamination in foods and other goods has become a broad issue owing to serious toxicity, tremendous threat to public safety, and terrible loss of resources. Herein, it is necessary to develop simple, sensitive, inexpensive, and rapid platforms for the detection of mycotoxins. Currently, the limitation of instrumental and chemical methods cannot be massively applied in practice. Immunoassays are considered one of the best candidates for toxin detection due to their simplicity, rapidness, and cost-effectiveness. Especially, the field of dual-mode immunosensors and corresponding assays is rapidly developing as an advanced and intersected technology. So, this review summarized the types and detection principles of single-mode immunosensors including optical and electrical immunosensors in recent years, then focused on developing dual-mode immunosensors including integrated immunosensors and combined immunosensors to detect mycotoxins, as well as the combination of dual-mode immunosensors with a portable device for point-of-care test. The remaining challenges were discussed with the aim of stimulating future development of dual-mode immunosensors to accelerate the transformation of scientific laboratory technologies into easy-to-operate and rapid detection platforms.

Electrical impulse characterization along actin filaments in pathological conditions.

We present an interactive Mathematica notebook that characterizes the electrical impulses along actin filaments in both muscle and non-muscle cells for a wide range of physiological and pathological conditions. The simplicity of the theoretical formulation, and high performance of the Mathematica software, enable the analysis of multiple conditions without computational restrictions. The program is based on a multi-scale (atomic → monomer → filament) approach capable of accounting for the atomistic details of a protein molecular structure, its biological environment, and their impact on the travel distance, velocity, and attenuation of monovalent ionic wave packets propagating along microfilaments. The interactive component allows investigators to choose the experimental conditions (intracellular Vs in vitro), nucleotide state (ATP Vs ADP), actin isoform (alpha, gamma, beta, and muscle or non-muscle cell), as well as a conformation model that covers a variety of mutants and wild-type (the control) actin filament. We used the computational tool to analyze environmental changes such as temperature effects and pH changes of the surrounding solutions, as well as structural changes to an actin monomer due to radius changes. Additionally, we investigated for the first time the electrostatic consequences of actin mutations from different disease conditions. These studies may provide an unprecedented molecular understanding of why and how age, inheritance, and disease conditions induce dysfunctions in the biophysical mechanisms underlying the propagation of electrical signals along actin filaments.

Histological and impedance changes of skeletal muscle by whole-body critical irradiation in a rat model.

In this study, the electrical resistance of the whole body and histological changes of skeletal muscle were investigated in rats according to the increase in radiation dose. A total of 15 male Sprague-Dawley rats (5-weeks-old) were randomly divided into 5 groups (each, n = 3). Each group received 1 Gy, 5 Gy, 10 Gy and 20 Gy systemic exposure, and the non-irradiated group was used as a control for morphological comparison. After attaching an electrode clip to the forelimb of the rat, an AC frequency was applied before and 4 days after irradiation using an impedance/gain-phase analyzer, and the measurement system was automatically controlled with LabVIEW. Comparing to before irradiation after 4 days, the difference in the average impedance values at 1 Gy, 5 Gy, 10 Gy, and 20 Gy was 1188±989 ohm, 3076±2251 ohm, 7650±6836 ohm, and 10478±6250 ohm, respectively. By comparing the normal group and the experimental group, muscle fiber atrophy and collagen fibers around blood vessels were observed (p < 0.05, control group vs 5 Gy or more high-dose group). These results confirmed the previously reported morphological changes of skeletal muscle and our hypothesis that whole-body impedance measurement enables to reflect tissue changes after irradiation.

Functional characterization and physiological roles of the single Shaker outward K+ channel in Medicago truncatula.

The model legume Medicago truncatula possesses a single outward Shaker K+ channel, whereas Arabidopsis thaliana possesses two channels of this type, named AtSKOR and AtGORK, with AtSKOR having been shown to play a major role in K+ secretion into the xylem sap in the root vasculature and with AtGORK being shown to mediate the efflux of K+ across the guard cell membrane, leading to stomatal closure. Here we show that the expression pattern of the single M. truncatula outward Shaker channel, which has been named MtGORK, includes the root vasculature, guard cells and root hairs. As shown by patch-clamp experiments on root hair protoplasts, besides the Shaker-type slowly activating outwardly rectifying K+ conductance encoded by MtGORK, a second K+ -permeable conductance, displaying fast activation and weak rectification, can be expressed by M. truncatula. A knock-out (KO) mutation resulting in an absence of MtGORK activity is shown to weakly reduce K+ translocation to shoots, and only in plants engaged in rhizobial symbiosis, but to strongly affect the control of stomatal aperture and transpirational water loss. In legumes, the early electrical signaling pathway triggered by Nod-factor perception is known to comprise a short transient depolarization of the root hair plasma membrane. In the absence of the functional expression of MtGORK, the rate of the membrane repolarization is found to be decreased by a factor of approximately two. This defect was without any consequence on infection thread development and nodule production in plants grown in vitro, but a decrease in nodule production was observed in plants grown in soil.

Rapid movements in plants.

Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in animals relies on the contraction machinery of muscles, many plant movements use turgor pressure as the primary driving force together with secondarily generated elastic forces. The movement of stomata is the best-characterized model system for studying turgor-driven movement, and many gene products responsible for this movement, especially those related to ion transport, have been identified. Similar gene products were recently shown to function in the daily sleep movements of pulvini, the motor organs for macroscopic leaf movements. However, it is difficult to explain the mechanisms behind rapid multicellular movements as a simple extension of the mechanisms used for unicellular or slow movements. For example, water transport through plant tissues imposes a limit on the speed of plant movements, which becomes more severe as the size of the moving part increases. Rapidly moving traps in carnivorous plants overcome this limitation with the aid of the mechanical behaviors of their three-dimensional structures. In addition to a mechanism for rapid deformation, rapid multicellular movements also require a molecular system for rapid cell-cell communication, along with a mechanosensing system that initiates the response. Electrical activities similar to animal action potentials are found in many plant species, representing promising candidates for the rapid cell-cell signaling behind rapid movements, but the molecular entities of these electrical signals remain obscure. Here we review the current understanding of rapid plant movements with the aim of encouraging further biological studies into this fascinating, challenging topic.

Fish forewarning of comprehensive toxicity in water environment based on Bayesian sequential method.

Environmental impact of pollutants can be analyzed effectively by acquiring fish behavioral signals in water with biological behavior sensors. However, a variety of factors, such as the complexity of biological organisms themselves, the device error and the environmental noise, may compromise the accuracy and timeliness of model predictions. The current methods lack prior knowledge about the fish behavioral signals corresponding to characteristic pollutants, and in the event of a pollutant invasion, the fish behavioral signals are poorly discriminated. Therefore, we propose a novel method based on Bayesian sequential, which utilizes multi-channel prior knowledge to calculate the outlier sequence based on wavelet feature followed by calculating the anomaly probability of observed values. Furthermore, the relationship between the anomaly probability and toxicity is analyzed in order to achieve forewarning effectively. At last, our algorithm for fish toxicity detection is verified by integrating the data on laboratory acceptance of characteristic pollutants. The results show that only one false positive occurred in the six experiments, the present algorithm is effective in suppressing false positives and negatives, which increases the reliability of toxicity detections, and thereby has certain applicability and universality in engineering applications.

[Prediction of epilepsy based on common spatial model algorithm and support vector machine double classification].

At present the prediction method of epilepsy patients is very time-consuming and vulnerable to subjective factors, so this paper presented an automatic recognition method of epilepsy electroencephalogram (EEG) based on common spatial model (CSP) and support vector machine (SVM). In this method, the CSP algorithm for extracting spatial characteristics was applied to the detection of epileptic EEG signals. However, the algorithm did not consider the nonlinear dynamic characteristics of the signals and ignored the time-frequency information, so the complementary characteristics of standard deviation, entropy and wavelet packet energy were selected for the combination in the feature extraction stage. The classification process adopted a new double classification model based on SVM. First, the normal, interictal and ictal periods were divided into normal and paroxysmal periods (including interictal and ictal periods), and then the samples belonging to the paroxysmal periods were classified into interictal and ictal periods. Finally, three categories of recognition were realized. The experimental data came from the epilepsy study at the University of Bonn in Germany. The average recognition rate was 98.73% in the first category and 99.90% in the second category. The experimental results show that the introduction of spatial characteristics and double classification model can effectively solve the problem of low recognition rate between interictal and ictal periods in many literatures, and improve the identification efficiency of each period, so it provides an effective detecting means for the prediction of epilepsy.

Anaesthesia with diethyl ether impairs jasmonate signalling in the carnivorous plant Venus flytrap (Dionaea muscipula).

BACKGROUND AND AIMS: General anaesthetics are compounds that induce loss of responsiveness to environmental stimuli in animals and humans. The primary site of action of general anaesthetics is the nervous system, where anaesthetics inhibit neuronal transmission. Although plants do not have neurons, they generate electrical signals in response to biotic and abiotic stresses. Here, we investigated the effect of the general volatile anaesthetic diethyl ether on the ability to sense potential prey or herbivore attacks in the carnivorous plant Venus flytrap (Dionaea muscipula). METHODS: We monitored trap movement, electrical signalling, phytohormone accumulation and gene expression in response to the mechanical stimulation of trigger hairs and wounding under diethyl ether treatment. KEY RESULTS: Diethyl ether completely inhibited the generation of action potentials and trap closing reactions, which were easily and rapidly restored when the anaesthetic was removed. Diethyl ether also inhibited the later response: jasmonic acid (JA) accumulation and expression of JA-responsive genes (cysteine protease dionain and type I chitinase). However, external application of JA bypassed the inhibited action potentials and restored gene expression under diethyl ether anaesthesia, indicating that downstream reactions from JA are not inhibited. CONCLUSIONS: The Venus flytrap cannot sense prey or a herbivore attack under diethyl ether treatment caused by inhibited action potentials, and the JA signalling pathway as a consequence.

Jasmonate action in plant defense against insects.

Herbivorous insects represent one of the major threats to sessile plants. To cope with herbivore challenges, plants have evolved sophisticated defense systems, in which the lipid-derived phytohormone jasmonate plays a crucial role. Perception of insect attack locally and systemically elicits rapid synthesis of jasmonate, which is perceived by the F-box protein COI1 to further recruit JAZ repressors for ubiquitination and degradation, thereby releasing transcription factors that subsequently activate plant defense against insect attack. Here, we review recent progress in understanding the molecular basis of jasmonate action in plant defense against insects.

The role of electrical and jasmonate signalling in the recognition of captured prey in the carnivorous sundew plant Drosera capensis.

The carnivorous sundew plant (Drosera capensis) captures prey using sticky tentacles. We investigated the tentacle and trap reactions in response to the electrical and jasmonate signalling evoked by different stimuli to reveal how carnivorous sundews recognize digestible captured prey in their traps. We measured the electrical signals, phytohormone concentration, enzyme activities and Chla fluorescence in response to mechanical stimulation, wounding or insect feeding in local and systemic traps. Seven new proteins in the digestive fluid were identified using mass spectrometry. Mechanical stimuli and live prey induced a fast, localized tentacle-bending reaction and enzyme secretion at the place of application. By contrast, repeated wounding induced a nonlocalized convulsive tentacle movement and enzyme secretion in local but also in distant systemic traps. These differences can be explained in terms of the electrical signal propagation and jasmonate accumulation, which also had a significant impact on the photosynthesis in the traps. The electrical signals generated in response to wounding could partially mimic a mechanical stimulation of struggling prey and might trigger a false alarm, confirming that the botanical carnivory and plant defence mechanisms are related. To trigger the full enzyme activity, the traps must detect chemical stimuli from the captured prey.

Triggering a false alarm: wounding mimics prey capture in the carnivorous Venus flytrap (Dionaea muscipula).

In the carnivorous plant Venus flytrap (Dionaea muscipula), the sequence of events after prey capture resembles the well-known plant defence signalling pathway in response to pathogen or herbivore attack. Here, we used wounding to mimic prey capture to show the similarities and differences between botanical carnivory and plant defence mechanisms. We monitored movement, electrical signalling, jasmonate accumulation and digestive enzyme secretion in local and distal (systemic) traps in response to prey capture, the mechanical stimulation of trigger hairs and wounding. The Venus flytrap cannot discriminate between wounding and mechanical trigger hair stimulation. Both induced the same action potentials, rapid trap closure, hermetic trap sealing, the accumulation of jasmonic acid (JA) and its isoleucine conjugate (JA-Ile), and the secretion of proteases (aspartic and cysteine proteases), phosphatases and type I chitinase. The jasmonate accumulation and enzyme secretion were confined to the local traps, to which the stimulus was applied, which correlates with the propagation of electrical signals and the absence of a systemic response in the Venus flytrap. In contrast to plant defence mechanisms, the absence of a systemic response in carnivorous plant may represent a resource-saving strategy. During prey capture, it could be quite expensive to produce digestive enzymes in the traps on the plant without prey.

Long-distance plant signaling pathways in response to multiple stressors: the gap in knowledge.

Plants require the capacity for quick and precise recognition of external stimuli within their environment for survival. Upon exposure to biotic (herbivores and pathogens) or abiotic stressors (environmental conditions), plants can activate hydraulic, chemical, or electrical long-distance signals to initiate systemic stress responses. A plant's stress reactions can be highly precise and orchestrated in response to different stressors or stress combinations. To date, an array of information is available on plant responses to single stressors. However, information on simultaneously occurring stresses that represent either multiple, within, or across abiotic and biotic stress types is nascent. Likewise, the crosstalk between hydraulic, chemical, and electrical signaling pathways and the importance of each individual signaling type requires further investigation in order to be fully understood. The overlapping presence and speed of the signals upon plant exposure to various stressors makes it challenging to identify the signal initiating plant systemic stress/defense responses. Furthermore, it is thought that systemic plant responses are not transmitted by a single pathway, but rather by a combination of signals enabling the transmission of information on the prevailing stressor(s) and its intensity. In this review, we summarize the mode of action of hydraulic, chemical, and electrical long-distance signals, discuss their importance in information transmission to biotic and abiotic stressors, and suggest future research directions.

The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding.

Jasmonates are lipid mediators that control defence gene expression in response to wounding and other environmental stresses. These small molecules can accumulate at distances up to several cm from sites of damage and this is likely to involve cell-to-cell jasmonate transport.Also, and independently of jasmonate synthesis, transport and perception, different long distance wound signals that stimulate distal jasmonate synthesis are propagated at apparent speeds of several cm min­1 to tissues distal to wounds in a mechanism that involves clade 3 GLUTAMATE RECEPTOR-LIKE (GLR) genes. A search for jasmonate synthesis enzymes that might decode these signals revealed LOX6, a lipoxygenase that is necessary for much of the rapid accumulation of jasmonic acid at sites distal to wounds. Intriguingly, the LOX6 promoter is expressed in a distinct niche of cells that are adjacent to mature xylem vessels,a location that would make these contact cells sensitive to the release of xylem water column tension upon wounding. We propose a model in which rapid axial changes in xylem hydrostatic pressure caused by wounding travel through the vasculature and lead to slower,radially dispersed pressure changes that act in a clade 3 GLR-dependent mechanism to promote distal jasmonate synthesis.

Real-time, in vivo intracellular recordings of caterpillar-induced depolarization waves in sieve elements using aphid electrodes.

Plants propagate electrical signals in response to artificial wounding. However, little is known about the electrophysiological responses of the phloem to wounding, and whether natural damaging stimuli induce propagating electrical signals in this tissue. Here, we used living aphids and the direct current (DC) version of the electrical penetration graph (EPG) to detect changes in the membrane potential of Arabidopsis sieve elements (SEs) during caterpillar wounding. Feeding wounds in the lamina induced fast depolarization waves in the affected leaf, rising to maximum amplitude (c. 60 mV) within 2 s. Major damage to the midvein induced fast and slow depolarization waves in unwounded neighbor leaves, but only slow depolarization waves in non-neighbor leaves. The slow depolarization waves rose to maximum amplitude (c. 30 mV) within 14 s. Expression of a jasmonate-responsive gene was detected in leaves in which SEs displayed fast depolarization waves. No electrical signals were detected in SEs of unwounded neighbor leaves of plants with suppressed expression of GLR3.3 and GLR3.6. EPG applied as a novel approach to plant electrophysiology allows cell-specific, robust, real-time monitoring of early electrophysiological responses in plant cells to damage, and is potentially applicable to a broad range of plant-herbivore interactions.

Early detection of dark-affected plant mechanical responses using enhanced electrical signals.

BACKGROUND: Mechanical damage to plants triggers local and systemic electrical signals that are eventually decoded into plant defense responses. These responses are constantly affected by other environmental stimuli in nature, for instance, light fluctuation. In recent years, studies on decoding plant electrical signals powered by various machine learning models are increasing in a sense of early prediction or detection of different environmental stresses that threaten plant growth or crop yields. However, the main bottleneck is the low-throughput nature of plant electrical signals, making it challenging to obtain a substantial amount of training data. Consequently, training these models with small datasets often leads to unsatisfactory performance. RESULTS: In the present work, we set out to decode wound-induced electrical signals (also termed slow wave potentials, SWPs) from plants that are deprived of light to different extents. Using non-invasive electrophysiology, we separately collected sets of local and distal SWPs from the treated plants. Then, we proposed a workflow based on few-shot learning to automatically identify SWPs. This workflow incorporates data preprocessing, feature extraction, data augmentation and classifier training. We established the integral and the first-order derivative as features for efficiently classifying SWPs. We then proposed an Adversarial Autoencoder (AAE) structure to augment the SWP samples. Combining them, the Random Forest classifier allowed remarkable classification accuracies of 0.99 for both local and systemic SWPs. In addition, in comparison to two other reported methods, our proposed AAE structure enabled better classification results using our tested features and classifiers. CONCLUSIONS: The results of this study establish new features for efficiently classifying wound-induced electrical signals, which allow for distinguishing dark-affected local and systemic plant wound responses. We also propose a new data augmentation structure to generate virtual plant electrical signals. The methods proposed in this study could be further applied to build models for crop plants using electrical signals as inputs, and also to process other small-scale signals.

pH change accompanying long-distance electrical signal controls systemic jasmonate biosynthesis.

Local damaging stimuli cause a rapid increase in the content of the defense phytohormone jasmonic acid (JA) and its biologically active derivative jasmonoyl-L-isoleucine (JA-Ile) in undamaged distal tissues. The increase in JA and JA-Ile levels was coincident with a rapid decrease in the levels of the precursor 12-oxo-phytodienoic acid (OPDA). The propagation of a stimulus-induced long-distance electrical signal, variation potential (VP), which is accompanied by intracellular changes in pH and Ca2+ levels, preceded systemic changes in jasmonate content. The decrease in pH during VP, mediated by transient inactivation of the plasma membrane H+-ATPase, induced the conversion of OPDA to JA, probably by regulating the availability of the OPDA substrate to JA biosynthetic enzymes. The regulation of systemic synthesis of JA and JA-Ile by the Ca2+ wave accompanying VP most likely occurs by the same mechanism of pH-induced conversion of OPDA to JA due to Ca2+-mediated decrease in pH as a result of H+-ATPase inactivation. Thus, the transient increase in intracellular Ca2+ levels and the transient decrease in intracellular pH are most likely the key mechanisms of VP-mediated regulation of jasmonate production in systemic tissues upon local stimulation.