As prey and pollinators, insects increase reproduction and allow for outcrossing in the carnivorous plant Dionaea muscipula.

PREMISE: Understanding the factors that limit reproductive success is a key component of plant biology. Carnivorous plants rely on insects as both nutrient sources and pollinators, providing a unique system for studying the effects of both resource and pollen limitation on plant reproduction. METHODS: We conducted a field experiment using wild-growing Dionaea muscipula J. Ellis (Droseraceae) in which we manipulated prey and pollen in a factorial design and measured flower production, number of fruits, and number of seeds. Because understanding reproduction requires knowledge of a plant species' reproductive and pollination biology, we also examined the pollination system, per-visit pollinator effectiveness, and pollen-ovule (P/O) ratio of D. muscipula. RESULTS: Plants that received supplemental prey produced more flowers than control plants. They also had a higher overall fitness estimate (number of flowers × fruit set (total fruits/total flowers) × seeds per fruit), although this benefit was significant only when prey supplementation occurred in the previous growing season. Neither pollen supplementation nor the interaction between pollen and prey supplementation significantly affected overall plant fitness. CONCLUSIONS: This study reinforces the reliance of D. muscipula on adequate prey capture for flower, fruit, and seed production and a mobile pollen vector for reproduction, indicating the importance of considering insects as part of an effective conservation management plan for this species.

Expert assessment of illegal collecting impacts on Venus flytraps and priorities for research on illegal trade.

Illegal collecting of wild Venus flytraps (Dionaea muscipula) for the horticultural trade represents a persistent threat to populations of the species across their endemic range in the coastal plain of North and South Carolina (United States). Although wild collecting of Venus flytraps is not a novel threat, there has been very little research on the impacts of collecting on the species' conservation to date or why an illegal trade persists alongside a legal one. We drew on qualitative expert stakeholder elicitation to contextualize the threat of illegal collecting to the long-term conservation of Venus flytraps in relation to other anthropogenic threats. Expert elicitation included botanical and conservation researchers, cognizant state and federal agency staff, land managers, and conservation nonprofit actors. The workshop included mapping of supply chain structures and prioritization of social and environmental harms. Expert consensus determined illegal collecting is an ongoing problem for Venus flytrap conservation, but habitat destruction, degradation, and fire suppression are the most significant threats to flytrap conservation. Supply chain analysis showed that observable social and environmental harms of the trade are focused at the supply stage and that less is known about transit and demand stages. Key research gaps identified include a lack of understanding of plant laundering practices relevant to a range of desirable plant taxa; the role of commercial nurseries in illicit horticultural supply chains; motivations for engaging in Venus flytrap collecting; and the persistent demand for illegally harvested plants when cultivated, legally obtainable plants are readily available. Our findings and methodology are relevant to a range of ornamental plants affected by illegal trade for which robust social data on illegal collecting drivers are lacking.

Evaluación experta del impacto de la colecta ilegal de venus atrapamoscas y las prioridades de investigación sobre el mercado ilegal Resumen La colecta ilegal de venus atrapamoscas (Dionaea muscipula) silvestres para el mercado de horticultura representa una amenaza constante para las poblaciones de la especie a lo largo de su distribución endémica en la planicie costera de Carolina del Norte y del Sur, Estados Unidos. Aunque esta colecta no es una amenaza novedosa, a la fecha se ha investigado muy poco sobre su impacto en la conservación de la especie o por qué el mercado ilegal persiste a la par del legal. Partimos del conocimiento cualitativo de los actores expertos para contextualizar la amenaza de la colecta ilegal para la conservación a largo plazo de la venus atrapamoscas en relación con otras amenazas antropogénicas. Este conocimiento involucró a investigadores de la conservación y la botánica, personal consciente de agencias federales y estatales y actores de la conservación sin fines de lucro. El taller incluyó el mapeo de las estructuras de las cadenas de suministro y la priorización de los daños sociales y ambientales. El consenso de los expertos determinó que la colecta ilegal es un problema continuo para la conservación de la venus atrapamoscas, pero la destrucción y degradación del hábitat, así como la contención de incendios son las amenazas más significativas. El análisis de las cadenas de suministro mostró que los daños ambientales y sociales observables en el mercado se enfocan en la fase de suministro y que se sabe poco sobre las fases de tránsito y demanda. Los vacíos de investigación más importantes incluyen la falta de entendimiento de las prácticas de lavado de plantas relevantes para un rango de taxones deseables de plantas; el papel de los viveros comerciales en las cadenas de suministro de la horticultura ilícita; los motivos para participar en la colecta de venus atrapamoscas; y la demanda continua de plantas cosechadas ilegalmente cuando ya hay disponibilidad de plantas cultivadas que se obtienen legalmente. Nuestros descubrimientos y metodología son relevantes para una gama de plantas ornamentales afectadas por el mercado ilegal para las cuales hay carencia de datos sociales sólidos sobre los factores de colecta ilegal.

Distinctive plastome evolution in carnivorous angiosperms.

BACKGROUND: Independent origins of carnivory in multiple angiosperm families are fabulous examples of convergent evolution using a diverse array of life forms and habitats. Previous studies have indicated that carnivorous plants have distinct evolutionary trajectories of plastid genome (plastome) compared to their non-carnivorous relatives, yet the extent and general characteristics remain elusive. RESULTS: We compared plastomes from 9 out of 13 carnivorous families and their non-carnivorous relatives to assess carnivory-associated evolutionary patterns. We identified inversions in all sampled Droseraceae species and four species of Utricularia, Pinguicula, Darlingtonia and Triphyophyllum. A few carnivores showed distinct shifts in inverted repeat boundaries and the overall repeat contents. Many ndh genes, along with some other genes, were independently lost in several carnivorous lineages. We detected significant substitution rate variations in most sampled carnivorous lineages. A significant overall substitution rate acceleration characterizes the two largest carnivorous lineages of Droseraceae and Lentibulariaceae. We also observe moderate substitution rates acceleration in many genes of Cephalotus follicularis, Roridula gorgonias, and Drosophyllum lusitanicum. However, only a few genes exhibit significant relaxed selection. CONCLUSION: Our results indicate that the carnivory of plants have different effects on plastome evolution across carnivorous lineages. The complex mechanism under carnivorous habitats may have resulted in distinctive plastome evolution with conserved plastome in the Brocchinia hechtioides to strongly reconfigured plastomes structures in Droseraceae. Organic carbon obtained from prey and the efficiency of utilizing prey-derived nutrients might constitute possible explanation.

Demystifying the Venus flytrap action potential.

All plants are electrically excitable, but only few are known to fire a well-defined, all-or-nothing action potential (AP). The Venus flytrap Dionaea muscipula displays APs with an extraordinarily high firing frequency and speed, enabling the capture organ of this carnivorous plant to catch small animals as fast as flies. The number of APs triggered by the prey is counted and serves as the basis for decisions within the flytrap's hunting cycle. The archetypical Dionaea AP lasts 1 s and consists of five phases: Starting from the resting state, an initial cytosolic Ca2+ transient is followed by depolarization, repolarization and a transient hyperpolarization (overshoot) before the original membrane potential is finally recovered. When the flytrap matures and becomes excitable, a distinct set of ion channels, pumps and carriers is expressed, each mastering a distinct AP phase.

A single touch can provide sufficient mechanical stimulation to trigger Venus flytrap closure.

The carnivorous Venus flytrap catches prey by an ingenious snapping mechanism. Based on work over nearly 200 years, it has become generally accepted that two touches of the trap's sensory hairs within 30 s, each one generating an action potential, are required to trigger closure of the trap. We developed an electromechanical model, which, however, suggests that under certain circumstances one touch is sufficient to generate two action potentials. Using a force-sensing microrobotic system, we precisely quantified the sensory-hair deflection parameters necessary to trigger trap closure and correlated them with the elicited action potentials in vivo. Our results confirm the model's predictions, suggesting that the Venus flytrap may be adapted to a wider range of prey movements than previously assumed.

The Venus flytrap trigger hair-specific potassium channel KDM1 can reestablish the K+ gradient required for hapto-electric signaling.

The carnivorous plant Dionaea muscipula harbors multicellular trigger hairs designed to sense mechanical stimuli upon contact with animal prey. At the base of the trigger hair, mechanosensation is transduced into an all-or-nothing action potential (AP) that spreads all over the trap, ultimately leading to trap closure and prey capture. To reveal the molecular basis for the unique functional repertoire of this mechanoresponsive plant structure, we determined the transcriptome of D. muscipula's trigger hair. Among the genes that were found to be highly specific to the trigger hair, the Shaker-type channel KDM1 was electrophysiologically characterized as a hyperpolarization- and acid-activated K+-selective channel, thus allowing the reuptake of K+ ions into the trigger hair's sensory cells during the hyperpolarization phase of the AP. During trap development, the increased electrical excitability of the trigger hair is associated with the transcriptional induction of KDM1. Conversely, when KDM1 is blocked by Cs+ in adult traps, the initiation of APs in response to trigger hair deflection is reduced, and trap closure is suppressed. KDM1 thus plays a dominant role in K+ homeostasis in the context of AP and turgor formation underlying the mechanosensation of trigger hair cells and thus D. muscipula's hapto-electric signaling.

Snapping mechanics of the Venus flytrap (Dionaea muscipula).

The mechanical principles for fast snapping in the iconic Venus flytrap are not yet fully understood. In this study, we obtained time-resolved strain distributions via three-dimensional digital image correlation (DIC) for the outer and inner trap-lobe surfaces throughout the closing motion. In combination with finite element models, the various possible contributions of the trap tissue layers were investigated with respect to the trap's movement behavior and the amount of strain required for snapping. Supported by in vivo experiments, we show that full trap turgescence is a mechanical-physiological prerequisite for successful (fast and geometrically correct) snapping, driven by differential tissue changes (swelling, shrinking, or no contribution). These are probably the result of the previous accumulation of internal hydrostatic pressure (prestress), which is released after trap triggering. Our research leads to an in-depth mechanical understanding of a complex plant movement incorporating various actuation principles.

Differences in the Occurrence of Cell Wall Components between Distinct Cell Types in Glands of Drosophyllum lusitanicum.

Carnivorous plants are mixotrophs that have developed the ability to lure, trap, and digest small organisms and utilize components of the digested bodies. Leaves of Drosophyllum lusitanicum have two kinds of glands (emergences): stalked mucilage glands and sessile digestive glands. The stalked mucilage glands perform the primary role in prey lure and trapping. Apart from their role in carnivory, they absorb water condensed from oceanic fog; thus, plants can survive in arid conditions. To better understand the function of carnivorous plant emergences, the molecular composition of their cell walls was investigated using immunocytochemical methods. In this research, Drosophyllum lusitanicum was used as a study system to determine whether cell wall immunocytochemistry differs between the mucilage and digestive glands of other carnivorous plant species. Light and electron microscopy were used to observe gland structure. Fluorescence microscopy revealed the localization of carbohydrate epitopes associated with the major cell wall polysaccharides and glycoproteins. The mucilage gland (emergence) consists of a glandular head, a connecting neck zone, and stalk. The gland head is formed by an outer and inner layer of glandular (secretory) cells and supported by a layer of endodermoid (barrier) cells. The endodermoid cells have contact with a core of spongy tracheids with spiral-shaped thickenings. Lateral tracheids are surrounded by epidermal and parenchymal neck cells. Different patterns of cell wall components were found in the various cell types of the glands. Cell walls of glandular cells generally are poor in both low and highly esterified homogalacturonans (HGs) but enriched with hemicelluloses. Cell walls of inner glandular cells are especially rich in arabinogalactan proteins (AGPs). The cell wall ingrowths in glandular cells are significantly enriched with hemicelluloses and AGPs. In the case of cell wall components, the glandular cells of Drosophyllum lusitanicum mucilage glands are similar to the glandular cells of the digestive glands of Aldrovanda vesiculosa and Dionaea muscipula.

The Localization of Cell Wall Components in the Quadrifids of Whole-Mount Immunolabeled Utricularia dichotoma Traps.

Utricularia (bladderworts) are carnivorous plants. They produce small hollow vesicles, which function as suction traps that work underwater and capture fine organisms. Inside the traps, there are numerous glandular trichomes (quadrifids), which take part in the secretion of digestive enzymes, the resorption of released nutrients, and likely the pumping out of water. Due to the extreme specialization of quadrifids, they are an interesting model for studying the cell walls. This aim of the study was to fill in the gap in the literature concerning the immunocytochemistry of quadrifids in the major cell wall polysaccharides and glycoproteins. To do this, the localization of the cell wall components in the quadrifids was performed using whole-mount immunolabeled Utricularia traps. It was observed that only parts (arms) of the terminal cells had enough discontinuous cuticle to be permeable to antibodies. There were different patterns of the cell wall components in the arms of the terminal cells of the quadrifids. The cell walls of the arms were especially rich in low-methyl-esterified homogalacturonan. Moreover, various arabinogalactan proteins also occurred. Cell walls in glandular cells of quadrifids were rich in low-methyl-esterified homogalacturonan; in contrast, in the aquatic carnivorous plant Aldrovanda vesiculosa, cell walls in the glandular cells of digestive glands were poor in low-methyl-esterified homogalacturonan. Arabinogalactan proteins were found in the cell walls of trap gland cells in all studied carnivorous plants: Utricularia, and members of Droseraceae and Drosophyllaceae.

Carnivorous Plants from Nepenthaceae and Droseraceae as a Source of Secondary Metabolites.

Carnivorous plants are able to attract small animals or protozoa and retain them in their specialized traps. Later, the captured organisms are killed and digested. The nutrients contained in the prey bodies are absorbed by the plants to use for growth and reproduction. These plants produce many secondary metabolites involved in the carnivorous syndrome. The main purpose of this review was to provide an overview of the secondary metabolites in the family Nepenthaceae and Droseraceae, which were studied using modern identification techniques, i.e., high-performance liquid chromatography or ultra-high-performance liquid chromatography with mass spectrometry and nuclear magnetic resonance spectroscopy. After literature screening, there is no doubt that tissues of species from the genera Nepenthes, Drosera, and Dionaea are rich sources of secondary metabolites that can be used in pharmacy and for medical purposes. The main types of the identified compounds include phenolic acids and their derivatives (gallic, protocatechuic, chlorogenic, ferulic, p-coumaric acids, gallic, hydroxybenzoic, vanillic, syringic caffeic acids, and vanillin), flavonoids (myricetin, quercetin, and kaempferol derivatives), including anthocyanins (delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, and cyanidin), naphthoquinones (e.g., plumbagin, droserone, and 5-O-methyl droserone), and volatile organic compounds. Due to the biological activity of most of these substances, the importance of the carnivorous plant as a pharmaceutical crop will increase.

Biological Potential of Carnivorous Plants from Nepenthales.

Since Charles Darwin and his book carnivorous plants have aroused interest and heated debate. In addition, there is growing interest in this group of plants as a source of secondary metabolites and in the application of their biological activity. The aim of this study was to trace the recent literature in search of the application of extracts obtained from families Droseraceae, Nepenthaceae, and Drosophyllaceae to show their biological potential. The data collected in the review clearly indicate that the studied Nepenthales species have great biological potential in terms of antibacterial, antifungal, antioxidant, anti-inflammatory, and anticancer use. We proposed that further investigations should include: (i) bioactivity-guided investigations of crude plant extract to connect a particular type of action with a specific compound or a group of metabolites; (ii) a search for new bioactive properties of carnivorous plants; (iii) establishment of molecular mechanisms associated with specific activity. Furthermore, further research should be extended to include less explored species, i.e., Drosophyllum lusitanicum and especially Aldrovanda vesiculosa.

Autonomous snapping and jumping polymer gels.

Snap-through buckling is commonly used in nature for power-amplified movements. While natural examples such as Utricularia and Dionaea muscipula can autonomously reset their snapping structures, bio-inspired analogues require external mediation for sequential snap events. Here we report the design principles for self-repeating, snap-based polymer jumping devices. Transient shape changes during the drying of a polymer gel are exploited to generate mechanical constraint and an internal driving force for snap-through buckling. Snap-induced shape changes alter environmental interactions to realize multiple, self-repeating snap events. The underlying mechanisms are understood through controlled experiments and numerical modelling. Using these lessons, we create snap-induced jumping devices with power density outputs (specific power ≈ 312 W kg-1) that are similar to high-performing jumping organisms and engineered robots. These results provide the demonstration of an autonomous, self-repeating, high-speed movement, marking an important advance in the development of environmental energy harvesting, high-power motion that is important for microscale robots and actuated devices.

Signaling and transport processes related to the carnivorous lifestyle of plants living on nutrient-poor soil.

In Eukaryotes, long-distance and rapid signal transmission is required in order to be able to react fast and flexibly to external stimuli. This long-distance signal transmission cannot take place by diffusion of signal molecules from the site of perception to the target tissue, as their speed is insufficient. Therefore, for adequate stimulus transmission, plants as well as animals make use of electrical signal transmission, as this can quickly cover long distances. This update summarises the most important advances in plant electrical signal transduction with a focus on the carnivorous Venus flytrap. It highlights the different types of electrical signals, examines their underlying ion fluxes and summarises the carnivorous processes downstream of the electrical signals.

Cytokinins and auxins in organs of aquatic carnivorous plants: what do they reflect?

BACKGROUND AND AIMS: Aquatic carnivorous plants have typical rootless linear shoots bearing traps and exhibit steep physiological polarity with rapid apical growth. The aim was to analyse auxin and cytokinin metabolites in traps, leaves/shoots and shoot apices in several species of genera Aldrovanda and Utricularia to elucidate how the hormonal profiles reflect the specific organ functions and polarity. METHODS: The main auxin and cytokinin metabolites were analysed in miniature samples (>2 mg dry weight) of different organs of Aldrovanda vesiculosa and six Utricularia species using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry. KEY RESULTS: Total contents of biologically active forms (free bases, ribosides) of all four main endogenously occurring cytokinin types were consistently higher in traps than in leaves in four Utricularia species with monomorphic shoots and/or higher than in shoots in two Utricularia species with dimorphic shoots. In Aldrovanda traps, the total content of different cytokinin forms was similar to or lower than that in shoots. In U. australis leaves, feeding on prey increased all cytokinin forms, while no consistent differences occurred in Aldrovanda. In four aquatic Utricularia species with monomorphic shoots, the content of four auxin forms was usually higher in traps than in leaves. Zero IAA content was determined in U. australis leaves from a meso-eutrophic site or when prey-fed. CONCLUSIONS: Different cytokinin and auxin profiles estimated in traps and leaves/shoots of aquatic carnivorous plants indicate an association with different dominant functions of these organs: nutrient uptake by traps versus photosynthetic function of traps. Interplay of cytokinins and auxins regulates apical dominance in these plants possessing strong polarity.

Stellate Trichomes in Dionaea muscipula Ellis (Venus Flytrap) Traps, Structure and Functions.

The digestive organs of carnivorous plants have external (abaxial) glands and trichomes, which perform various functions. Dionaea muscipula Ellis (the Venus flytrap) is a model carnivorous plant species whose traps are covered by external trichomes. The aim of the study was to fill in the gap regarding the structure of the stellate outer trichomes and their immunocytochemistry and to determine whether these data support the suggestions of other authors about the roles of these trichomes. Light and electron microscopy was used to show the trichomes' structure. Fluorescence microscopy was used to locate the carbohydrate epitopes that are associated with the major cell wall polysaccharides and glycoproteins. The endodermal cells and internal head cells of the trichomes were differentiated as transfer cells, and this supports the idea that stellate trichomes transport solutes and are not only tomentose-like trichomes. Trichome cells differ in the composition of their cell walls, e.g., the cell walls of the internal head cells are enriched with arabinogalactan proteins (AGPs). The cell walls of the outer head cells are poor in both low and highly homogalacturonans (HGs), but the immature trichomes are rich in the pectic polysaccharide (1-4)-ß-D-galactan. In the immature traps, young stellate trichomes produce mucilage which may protect the trap surface, and in particular, the trap entrance. However, the role of these trichomes is different when the outer head cells collapse. In the internal head cells, a thick secondary wall cell was deposited, which together with the thick cell walls of the outer head cells played the role of a large apoplastic space. This may suggest that mature stellate trichomes might function as hydathodes, but this should be experimentally proven.

Response of physiological parameters in Dionaea muscipula J. Ellis teratomas transformed with rolB oncogene.

BACKGROUND: Plant transformation with rol oncogenes derived from wild strains of Rhizobium rhizogenes is a popular biotechnology tool. Transformation effects depend on the type of rol gene, expression level, and the number of gene copies incorporated into the plant's genomic DNA. Although rol oncogenes are known as inducers of plant secondary metabolism, little is known about the physiological response of plants subjected to transformation. RESULTS: In this study, the physiological consequences of rolB oncogene incorporation into the DNA of Dionaea muscipula J. Ellis was evaluated at the level of primary and secondary metabolism. Examination of the teratoma (transformed shoots) cultures of two different clones (K and L) showed two different strategies for dealing with the presence of the rolB gene. Clone K showed an increased ratio of free fatty acids to lipids, superoxide dismutase activity, synthesis of the oxidised form of glutathione, and total pool of glutathione and carotenoids, in comparison to non-transformed plants (control). Clone L was characterised by increased accumulation of malondialdehyde, proline, activity of superoxide dismutase and catalase, total pool of glutathione, ratio of reduced form of glutathione to oxidised form, and accumulation of selected phenolic acids. Moreover, clone L had an enhanced ratio of total triglycerides to lipids and accumulated saccharose, fructose, glucose, and tyrosine. CONCLUSIONS: This study showed that plant transformation with the rolB oncogene derived from R. rhizogenes induces a pleiotropic effect in plant tissue after transformation. Examination of D. muscipula plant in the context of transformation with wild strains of R. rhizogenes can be a new source of knowledge about primary and secondary metabolites in transgenic organisms.

Transformed tissue of Dionaea muscipula J. Ellis as a source of biologically active phenolic compounds with bactericidal properties.

The Venus flytrap (Dionaea muscipula J. Ellis) is a carnivorous plant able to synthesize large amounts of phenolic compounds, such as phenylpropanoids, flavonoids, phenolic acids, and 1,4-naphtoquinones. In this study, the first genetic transformation of D. muscipula tissues is presented. Two wild-type Rhizobium rhizogenes strains (LBA 9402 and ATCC 15834) were suitable vector organisms in the transformation process. Transformation led to the formation of teratoma (transformed shoot) cultures with the bacterial rolB gene incorporated into the plant genome in a single copy. Using high-pressure liquid chromatography, we demonstrated that transgenic plants were characterized by an increased quantity of phenolic compounds, including 1,4-naphtoquinone derivative, plumbagin (up to 106.63 mg × g-1 DW), and phenolic acids (including salicylic, caffeic, and ellagic acid), in comparison to non-transformed plants. Moreover, Rhizobium-mediated transformation highly increased the bactericidal properties of teratoma-derived extracts. The antibacterial properties of transformed plants were increased up to 33% against Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli and up to 7% against Pseudomonas aeruginosa. For the first time, we prove the possibility of D. muscipula transformation. Moreover, we propose that transformation may be a valuable tool for enhancing secondary metabolite production in D. muscipula tissue and to increase bactericidal properties against human antibiotic-resistant bacteria. KEY POINTS: • Rhizobium-mediated transformation created Dionaea muscipula teratomas. • Transformed plants had highly increased synthesis of phenolic compounds. • The MBC value was connected with plumbagin and phenolic acid concentrations.

Functional organisation of the endomembrane network in the digestive gland of the Venus flytrap: revisiting an old story with a new microscopy toolbox.

Up-to-date imaging approaches were used to address the spatiotemporal organisation of the endomembrane system in secretory cells of Dionaea muscipula. Different 'slice and view' methodologies were performed on resin-embedded samples to finally achieve a 3D reconstruction of the cell architecture, using ultrastructural tomography, array tomography, serial block face-scanning electron microscopy (SBF-SEM), correlation, and volume rendering at the light microscopy level. Observations of cryo-fixed samples by high-pressure freezing revealed changes of the endomembrane system that occur after trap activation and prey digestion. They provide evidence for an original strategy that adapts the secretory machinery to a specific and unique case of stimulated exocytosis in plant cells. A first secretion peak is part of a rapid response to deliver digestive fluids to the cell surface, which delivers the needed stock of digestive materials 'on site'. The second peak of activity could then be associated with the reconstruction of the Golgi apparatus (GA), endoplasmic reticulum (ER) and vacuolar machinery, in order to prepare for a subsequent round of prey capture. Tubular continuum between ER and Golgi stacks observed on ZIO-impregnated tissues may correspond to an efficient transfer mechanism for lipids and/or proteins, especially for use in rapidly resetting the molecular GA machinery. The occurrence of one vacuolar continuum may permit continuous adjustment of cell homeostasy. The subcellular features of the secretory cells of Dionaea muscipula outline key innovations in the organisation of plant cell compartmentalisation that are used to cope with specific cell needs such as the full use of the GA as a protein factory, and the ability to create protein reservoirs in the periplasmic space. Shape-derived forces of the pleiomorphic vacuole may act as signals to accompany the sorting and entering flows of the cell.

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.

Functional-morphological analyses of the delicate snap-traps of the aquatic carnivorous waterwheel plant (Aldrovanda vesiculosa) with 2D and 3D imaging techniques.

BACKGROUND AND AIMS: The endangered aquatic carnivorous waterwheel plant (Aldrovanda vesiculosa) catches prey with 3-5-mm-long underwater snap-traps. Trapping lasts 10-20 ms, which is 10-fold faster than in its famous sister, the terrestrial Venus flytrap (Dionaea muscipula). After successful capture, the trap narrows further and forms a 'stomach' for the digestion of prey, the so-called 'sickle-shaped cavity'. To date, knowledge is very scarce regarding the deformation process during narrowing and consequent functional morphology of the trap. METHODS: We performed comparative analyses of virtual 3D histology using computed tomography (CT) and conventional 2D histology. For 3D histology we established a contrasting agent-based preparation protocol tailored for delicate underwater plant tissues. KEY RESULTS: Our analyses reveal new structural insights into the adaptive architecture of the complex A. vesiculosa snap-trap. In particular, we discuss in detail the arrangement of sensitive trigger hairs inside the trap and present actual 3D representations of traps with prey. In addition, we provide trap volume calculations at different narrowing stages. Furthermore, the motile zone close to the trap midrib, which is thought to promote not only the fast trap closure by hydraulics but also the subsequent trap narrowing and trap reopening, is described and discussed for the first time in its entirety. CONCLUSIONS: Our research contributes to the understanding of a complex, fast and reversible underwater plant movement and supplements preparation protocols for CT analyses of other non-lignified and sensitive plant structures.