Water Translocation Research Articles

Impact of Irrigation and Fertigation Schedules on Physical and Biochemical Properties of Apple Under High-Density Plantation

ABSTRACT Over the 2-year period of study (2019–2020), the impact of different irrigation and fertigation schedules on the physical and biochemical properties of apple under high-density plantation was investigated. The quality of fruits is considerably influenced by irrigation and fertigation. Drip fertigation levels unveiled significant effect on fruit length (65.43 mm), fruit breadth (72.32 mm), and fruit weight (187.53 g). The application of 100% ETc with 100% AD (NPK) during fertigation enhanced both fruit size and weight. Under uniform application of water, photosynthesis increased, which improved the assimilate partitioning. Growth hormones, including cytokinins, gibberellins, and auxins, are generated at optimal and uniform nutrient distribution, which promotes nutrients uptake and assimilates water translocation, resulting in increased fruit size and weight. Drip irrigation and fertigation treatments produced fruits with better color. A higher dose of NPK applied via drip fertigation system produced higher levels of anthocyanin and ascorbic acid content in fruits over conventional approaches. Merging new orchard designs with a high-coloring strain of an apple cultivar and more efficient irrigation and fertigation systems results in higher productivity with better fruit quality and less water consumption.

Unveiling morphophysiological and metabolic adaptive strategies of the CAM epiphytic bromeliad Acanthostachys pitcairnioides to drought

Ongoing climate changes are expected to intensify drought periods in tropical regions, directly impacting epiphytic bromeliads that depend on intermittent water availability. This study aimed to elucidate if Acanthostachys pitcairnioides, an epiphytic bromeliad of Atlantic Forest, tolerates extended drought periods and the potential strategies involved in its tolerance and recovery capacity. We suppressed irrigation for 42 days, rehydrated plants for four days, and evaluated leaf water status, and photochemical, metabolic, and anatomical changes. During the initial 28 days of drought, translocation of water from hydrenchyma to chlorenchyma, higher chlorophyll content, and accumulation of abscisic and salicylic acid and antioxidants contributed to maintaining the cell turgor and functionality of photosynthetic apparatus. At 42 days, a significant reduction in leaf water content to 45.5% was accompanied by a 2.5-fold increase in non-photochemical quenching and enhanced levels of carotenoids, anthocyanins, osmoregulators (proline, myo-inositol, and trehalose), and phytohormones (abscisic acid and jasmonates). After rewatering, water storage in the hydrenchyma and almost all pigments, hormones, and metabolites were restored to pre-stress conditions. Leaf succulence, carbohydrate and organic acid accumulation, and carbon isotope data (δ13C−14.5‰) provide evidence of induction of CAM metabolism by water limitation in A. pitcairnioides. Our findings indicate the prevalence of water accumulation strategy during the first half of the drought stress. At the end of the drought period, the complete depletion of water from the hydrenchyma favored the osmotic adjustment. Considering this set of tolerance strategies and the rapid recovery after rehydration, A. pitcairnioides can successfully withstand environments with restricted water availability.

Self-Assembled Hydrazide-Based Nanochannels: Efficient Water Translocation and Salt Rejection.

Nature has ingeniously developed specialized water transporters that effectively reject ions, including protons, while transporting water across membranes. These natural water channels, known as aquaporins (AQPs), have inspired the creation of Artificial Water Channels (AWCs). However, replicating superfast water transport with synthetic molecular structures that exclude salts and protons is a challenging task. This endeavor demands the coexistence of a suitable water-binding site and a selective filter for precise water transportation. Here, we present small-molecule hydrazides 1b-1d that self-assemble into a rosette-type nanochannel assembly through intermolecular hydrogen bonding and π-π stacking interactions, and selectively transport water molecules across lipid bilayer membranes. The experimental analysis demonstrates notable permeability rates for the 1c derivative, enabling approximately 3.18 × 108 water molecules to traverse the channel per second. This permeability rate is about one order of magnitude lower than that of AQPs. Of particular significance, the 1c ensures exclusive passage of water molecules while effectively blocking salts and protons. MD simulation studies confirmed the stability and water transport properties of the water channel assembly inside the bilayer membranes at ambient conditions.

Exploitation of Grafting for Abiotic and Biotic Stress Management in Vegetable Crops: A Review

Growing vegetables is often impacted by various abiotic and biotic stresses that can hinder growth and yield. Abiotic stresses, such as salinity, water stress, and temperature fluctuations, and biotic stresses, including diseases, pests, and nematodes, pose significant threats to agriculture. Grafting, a horticultural technique, offers a promising solution to overcome these challenges. In cases of salinity stress, grafting with salt-tolerant rootstocks can limit the transport of harmful ions to the shoot and help store them in the roots, mitigating ion toxicity. Water stress, including drought and water logging, can be addressed by grafting with drought-tolerant rootstocks, which can reduce yield losses and enhance photosynthesis under adverse water conditions. Grafting can also improve nutrient uptake, translocation of water, and osmoregulation, thereby assisting plants in surviving under water stress. High and low-temperature stresses, which can disrupt plant metabolism, membrane stability, and growth, can also be addressed through grafting. Grafted plants with temperature-tolerant rootstocks may indirectly enhance tolerance to extreme temperatures. Additionally, grafted plants can adapt to varying temperature conditions by promoting root growth, nutrient absorption, and the production of specific compounds that protect against temperature-related damage. Heavy metal stress, which can contaminate crops and impact human health, can be alleviated by using rootstocks that control the uptake and transport of heavy metals, reducing their toxicity to plants. Furthermore, grafting can effectively combat biotic stresses. By selecting disease-resistant rootstocks, plants can be protected against soil-borne diseases, pests, and nematodes, thereby increasing yields and sustainability in agriculture.

Antibacterial and Antiviral Properties of Chenopodin-Derived Synthetic Peptides.

Antimicrobial peptides have been developed based on plant-derived molecular scaffolds for the treatment of infectious diseases. Chenopodin is an abundant seed storage protein in quinoa, an Andean plant with high nutritional and therapeutic properties. Here, we used computer- and physicochemical-based strategies and designed four peptides derived from the primary structure of Chenopodin. Two peptides reproduce natural fragments of 14 amino acids from Chenopodin, named Chen1 and Chen2, and two engineered peptides of the same length were designed based on the Chen1 sequence. The two amino acids of Chen1 containing amide side chains were replaced by arginine (ChenR) or tryptophan (ChenW) to generate engineered cationic and hydrophobic peptides. The evaluation of these 14-mer peptides on Staphylococcus aureus and Escherichia coli showed that Chen1 does not have antibacterial activity up to 512 µM against these strains, while other peptides exhibited antibacterial effects at lower concentrations. The chemical substitutions of glutamine and asparagine by amino acids with cationic or aromatic side chains significantly favoured their antibacterial effects. These peptides did not show significant hemolytic activity. The fluorescence microscopy analysis highlighted the membranolytic nature of Chenopodin-derived peptides. Using molecular dynamic simulations, we found that a pore is formed when multiple peptides are assembled in the membrane. Whereas, some of them form secondary structures when interacting with the membrane, allowing water translocations during the simulations. Finally, Chen2 and ChenR significantly reduced SARS-CoV-2 infection. These findings demonstrate that Chenopodin is a highly useful template for the design, engineering, and manufacturing of non-toxic, antibacterial, and antiviral peptides.

Effect of freeze–thaw cycles on the macrostructure and failure mechanisms of fiber-reinforced clay using industrial computed tomography

Freeze–thaw cycling is a critical issue in cold-climate engineering because these cycles impact the mechanical properties of soils due to the translocation of water and ice at temperatures near 0 °C. Reinforcement methods have been developed to decrease these adverse effects, including the use of polypropylene (PP) fibers. However, few macrostructural investigations have been able to demonstrate the underlying physical basis for their effectiveness. This study used computed tomography (CT) images of clay samples reinforced with 2% PP fibers and subjected to unconfined compression and Brazilian tests before and after up to 10 closed-system freeze–thaw cycles (FTCs). Significant effects of the FTCs on soil structure include a reduction in macropores and an increase in mesopores. The addition of PP fibers reduces this change in the number of macropores from 28% to 18% following 10 FTCs. Unreinforced samples also show more localized propagation of shear/tensile cracks during tests than reinforced samples as a result of having a higher failure strength and ductility. The bridging effect of fibers, deviation of the failure path, and formation of microcracks around fibers are clearly illustrated in the CT images. This study provides significant insights relevant to engineering design in cold regions.

The dynamic changes in phytoplankton and environmental factors within Dongping Lake (China) before and after the South-to-North Water Diversion Project

Dongping Lake is one of the most important regulation and storage lakes along the eastern route of the South-to-North Water Diversion Project in China, the water quality condition of which directly influences the safety of water diverting, because it serves as a Yangtze River water redistribution control point. However, the changes in algae, and in environmental factors affecting their community structures, before and after the water diversion project are rarely reported. In this study, the temporal variations of phytoplankton abundance were examined based on monthly samples collected at three stations from May 2010 to April 2022. The total abundance of algae greatly decreased after the water diversion project was implemented, with a relatively stable biodiversity and evenness before and after the water translocation. Multiple statistical methods were used together with the water quality indices (WQIs) and the nutrient status index (TSIM) to evaluate overall water condition and analyse relationships among environmental factors. The WQIs demonstrated a general “Good” water quality with a seasonal differentiation, and that water conditions during water transfer periods were better than during non-water transfer periods, which may be ascribed to the improved hydraulic conditions and purified water environment during water transfer periods. Redundancy analysis showed that water temperature, ammonia nitrogen, water transparency, and total phosphorus were the most important environmental factors, with relatively decreased contribution rates towards phytoplankton communities after the water translocation. Importantly, some dominant phytoplankton genera of Chlorophyta, Bacillariophyceae, and Cyanophyceae were similarly affected by water transparency, and nitrogen and phosphorus nutrients in summer after the water translocation. These research findings helped us gain a comprehensive understanding of the changing patterns of water quality and microalgae and their relationships before and after the water diversion project, providing a guidance for future lake management in regulating hydraulic conditions and improving water quality of Dongping Lake.

Effects of different plant polysaccharides as fat substitutes on the gel properties, microstructure and digestion characteristics of myofibrillar protein

This study aimed to investigate the effects of different plant polysaccharides (inulin, κ-carrageenan, and konjac glucomannan) as fat substitutes on the gel properties, microstructure, and digestion characteristics of myofibrillar protein (MP). The results revealed that incorporating inulin, κ-carrageenan, and konjac glucomannan significantly improved the water holding capacity, texture profiles, and rheological behavior of MP gels while limiting water fluidity. Among them, the MP-konjac glucomannan gel (1%, w/w) showed superior water retention and gel strength, demonstrating the most notable restriction on water translocation. Microstructural analysis observed that the MP gels with inulin, κ-carrageenan, and konjac glucomannan displayed a dense and well-clustered network structure, resulting in a more even distribution and compact gel structure. However, including 1.5% and 2% konjac glucomannan in MP mixed gels resulted in block-like clustering and larger agglomeration. Furthermore, the protein digestibility assessment indicated that polysaccharides incorporation significantly reduced the digestibility of MP, with konjac glucomannan demonstrating higher digestibility compared to inulin and κ-carrageenan groups. Overall, incorporating konjac glucomannan at a 1% incorporation (w/w) can effectively serve as a fat substitute in muscle food. This study will provide valuable insights for utilizing konjac glucomannan as a fat substitute in meat products.

Effect of Cadmium on flag leaf morpho-physiological traits in three Mediterranean hulless barley varieties

In Morocco, the use of phosphate fertilizer in farming system represents a source of cadmium that accumulates in soil and would affect negatively the growth and yield. Cadmium toxicity decreases nutrients and water translocation and absorption, it leads to an increase in oxidative harm, affects the metabolism of plants, and inhibits plant morpho-physiology as well. This experiment was conducted to examine the impacts of various concentrations of Cd (0, 15, 30 mg leg-1) in the flag leaf of three hulless barley varieties: Assiya (Morocco), Tombari (Tunisia), and Gizal30 (Egypt). Several morpho-physiological parameters were measured at vegetative stage encompassing measurements like Flag leaf length (FLL), Flag leaf area (FLA), Flag leaf width (FLW), and Flag leaf dry weight (FLDW), water relative content (RWC), total chlorophyll content (SPAD), and Fluorescence (Fv/Fm). ANOVA analysis showed that all morphological traits (except for FLDW) were primarily affected by the variety effect (>62% of total variance). In contrast, the treatment of Cd largely influenced physiological traits (>90% of total variance). Moreover, the interaction between the two factors was in general of lower importance. Comparison among varieties showed significant differences for all traits. In fact, the Moroccan variety (Assiya) displayed the highest values for physiological and morphological parameters.

Root water uptake and water transport to above-ground organs compensate for winter water losses and prevent shoot dehydration in apple trees

Plants need to maintain a minimum moisture content in their tissues to preserve their living functions not only during the growing season but also during periods of dormancy. Whereas water uptake of trees during the growing season has been widely investigated, very little attention has been paid to tree water uptake and losses during winter dormancy. A study was therefore conducted aiming at quantifying root water uptake of apple trees in winter, comparing the water content of two groups of field-grown apple trees for two winter seasons. One group of trees was isolated from its roots by a transversal cut at the base of the trunk and the other was left intact. In an additional experiment, deuterium-enriched water was added to the soil of potted apple trees during winter dormancy, to monitor water uptake and translocation within the plant. The field experiment revealed incrementing moisture losses of annual shoots in late winter, driven by the rising evaporative demand of the atmosphere. Trees with unimpaired water transport systems compensated shoot water losses by root water uptake and internal translocation, whereas trees with severed trunks only partially mitigated losses by internal translocation from trunk and larger branches. Root water uptake during winter dormancy was also confirmed in the potted tree experiment with deuterium-enriched water. This work provides evidence that water flow along the soil-plant-atmosphere continuum in apple trees takes place also in winter, with possible impacts on tree survival during prolonged periods of soil or trunk freezing.

Performance of Mango Trees under the Spraying of Some Biostimulants

Ensuring the sustainability of horticultural production is crucial to meeting consumer demand, and the most effective approach involves enhancing the efficient utilization of resources to support the production of wholesome foods. Plant biostimulants are substances defined by their ability, when applied to plants or the rhizosphere, to enhance root development, resulting in heightened vigor. They facilitate the more effective uptake and translocation of nutrients and water throughout the growing season. Additionally, these biostimulants contribute to improved plant health and quality by supplying essential nutrients that stimulate overall growth and metabolic processes. Therefore, this study was performed to examine the impact of some biostimulants on the possibility of improving vegetative growth, yield, fruit quality, and the leaf mineral content of mango cv. Keitt. Mango trees were sprayed with Putrescine at 25, 50, and 100 mg/L; Brassinosteroids at 0.5, 1, and 2 mg/L; and Chitosan at 500, 1000, and 1500 mg/L four times starting from mid-April, with three-week intervals during the seasons of 2021 and 2022. The results showed that the foliar application of these three biostimulants improved the growth, yield, and fruit quality of mango trees as opposed to untreated trees during two study seasons. The results also showed that the foliar application of 1500 mg/L of Chit, 2 mg/L of Brs, and 100 mg/L of Put gave the highest increments for inducing the number, length, and thickness of shoots, leaf area, and leaf chlorophyll over the other applied treatments. In addition, it also heightened the fruit set, fruit yield, and the fruit’s physical and chemical characteristics in both experimental seasons.

Estimating uptake and internal transport dynamics of irrigation water in apple trees using deuterium-enriched water

With future climatic scenarios foreseeing increased crop water demands and reduced irrigation water availability, a deeper knowledge on the dynamics of water uptake and translocation inside plants is needed. Little is known about the time interval existing between the irrigation water supply and the presence of irrigation water inside trees, and whether the dripper localization can affect water uptake and translocation dynamics. Another research gap concerns the redistribution of irrigation water in the canopy following irrigation localized to one side of the tree.A field and a pot experiment were designed to gain more insight into this context. In the field experiment, we tested the effect of different drip irrigation layouts on the extent and velocity of water uptake by apple trees. Trees were irrigated using deuterium-enriched water using one, two, or four drippers per tree. Samples were collected from different heights in the canopy at regular intervals following the irrigation event. In the pot experiment, the soil was saturated with labelled water and samples were collected at different time intervals and heights along the tree stem. Labelled water was detected in the lowest stem section of potted trees after 1 h from irrigation. In field-grown trees, labelled water appeared in the shoots after 4 h and 6 h in the bottom and top part of the canopy, respectively. By increasing the number of drippers per tree, the fraction of irrigation water in the shoots increased accordingly. However, uptake and transport velocity were unaffected by the number of drippers, averaging 0.60–0.65 m h-1. In trees that were irrigated from one side only, irrigation water could be found on the opposite side in the top part of the canopy. Our results suggest that the localization and amount of irrigation water can significantly influence root water uptake in apple trees.

Selective Water Pore Recognition and Transport through Self-Assembled Alkyl-Ureido-Trianglamine Artificial Water Channels.

In nature, aquaporins (AQPs) are proteins known for fast water transport through the membrane of living cells. Artificial water channels (AWCs) synthetic counterparts with intrinsic water permeability have been developed with the hope of mimicking the performances and the natural functions of AQPs. Highly selective AWCs are needed, and the design of selectivity filters for water is of tremendous importance. Herein, we report the use of self-assembled trianglamine macrocycles acting as AWCs in lipid bilayer membranes that are able to transport water with steric restriction along biomimetic H-bonding-decorated pores conferring selective binding filters for water. Trianglamine [(±)Δ, (mixture of diastereoisomers) and (R,R)3Δ and (S,S)3Δ], trianglamine hydrochloride (Δ.HCl), and alkyl-ureido trianglamines (n = 4, 6, 8, and 12) [(±)ΔC4, (±)ΔC8, (±)ΔC6, and (±)ΔC12] were synthesized for the studies presented here. The single-crystal X-ray structures confirmed that trianglamines form a tubular superstructure in the solid state. The water translocation is controlled via successive selective H-bonding pores (a diameter of 3 Å) and highly permeable hydrophobic vestibules (a diameter of 5 Å). The self-assembled alkyl-ureido-trianglamines achieve a single-channel permeability of 108 water molecules/second/channel, which is within 1 order of magnitude lower than AQPs with good ability to sterically reject ions and preventing the proton transport. Trianglamines present potential for engineering membranes for water purification and separation technologies.

Telescoping-Solvation-Box Protocol-Based Umbrella Sampling Method for Potential Mean Force Estimation.

Previously, it was shown that the telescoping box scheme, in combination with adaptive steered molecule dynamics (ASMD), can be used to estimate the potential of mean force (PMF) with a decrease in computational cost associated with large solvation boxes. Since ASMD reduces to umbrella sampling (US) in the limit of infinitely slow pulling velocity, a hypothesis was made that the telescoping box scheme can be extended to include the US method. The hypothesis was tested using the unfolding pathway of a polyalanine peptide in a water box and translocation of α-tocopherol through the human membrane. Two different approaches were tried: telescoping US (TELUS), in which the number of solvent molecules was linearly coupled to the reaction coordinate, and Block-TELUS, which was a compromise between the fixed solvation box of the US and the window-wise variable solvation box of TELUS. In the case of polyalanine peptide in a water box, both approaches gave overlapping potential of mean force (PMF) concerning the benchmark US-PMF. Window-wise comparison of properties like root-mean-square inner product, Ramachandran plot, α-helix content, and hydrogen bond formation was used to verify that both approaches captured the same dynamics as the US method. Applying the Block-TELUS protocol in the system with diffusing α-tocopherol through the bilayer resulted in overlapping PMF to its US benchmark. A comparison between the window-wise orientation of the chromanol headgroup also produced almost identical results. This study concluded that with the careful application of telescoping solvation boxes, a less computationally expensive US could be performed for systems where the effect of distant solvent molecules on the configurational space sampled in the window depends on the value of the reaction coordinate.

Recent Advances in Microbial-Assisted Remediation of Cadmium-Contaminated Soil.

Soil contamination with cadmium (Cd) is a severe concern for the developing world due to its non-biodegradability and significant potential to damage the ecosystem and associated services. Industries such as mining, manufacturing, building, etc., rapidly produce a substantial amount of Cd, posing environmental risks. Cd toxicity in crop plants decreases nutrient and water uptake and translocation, increases oxidative damage, interferes with plant metabolism and inhibits plant morphology and physiology. However, various conventional physicochemical approaches are available to remove Cd from the soil, including chemical reduction, immobilization, stabilization and electro-remediation. Nevertheless, these processes are costly and unfriendly to the environment because they require much energy, skilled labor and hazardous chemicals. In contrasting, contaminated soils can be restored by using bioremediation techniques, which use plants alone and in association with different beneficial microbes as cutting-edge approaches. This review covers the bioremediation of soils contaminated with Cd in various new ways. The bioremediation capability of bacteria and fungi alone and in combination with plants are studied and analyzed. Microbes, including bacteria, fungi and algae, are reported to have a high tolerance for metals, having a 98% bioremediation capability. The internal structure of microorganisms, their cell surface characteristics and the surrounding environmental circumstances are all discussed concerning how microbes detoxify metals. Moreover, issues affecting the effectiveness of bioremediation are explored, along with potential difficulties, solutions and prospects.

Self-Assembling Peptide-Appended Metallomacrocycle Pores for Selective Water Translocation.

Artificial water channels selectively transport water, excluding all ions. Unimolecular channels have been synthesized via complex synthetic steps. Ideally, simpler compounds requesting less synthetic steps should efficiently lead to selective channels by self-assembly. Herein, we report a self-assembled peptide-bound Ni2+ metallomacrocycle, 1, in which rim-peptide-bound units are connected to a central macrocycle obtained via condensation in the presence of Ni2+ ions. Compound 1 achieves a single-channel permeability up to 107-108 water/s/channel and insignificant ion transport, which is 1 order of magnitude lower than those for aquaporins. Molecular simulations probe that spongelike aggregates can form to generate transient cluster water pathways through the bilayer. Altogether, adaptive metallosupramolecular self-assembly is an efficient and simple way to construct selective channel superstructures.

Nitrogen nutrition and xylem sap composition in Zea mays: effect of urea, ammonium and nitrate on ionomic and metabolic profiles

In plants the communication between organs is mainly carried out via the xylem and phloem. The concentration and the molecular species of some phytohormones, assimilates and inorganic ions that are translocated in the xylem vessel play a key role in the systemic nutritional signaling in plants. In this work the composition of the xylem sap of maize was investigated at the metabolic and ionomic level depending on the N form available in the nutrient solution. Plants were grown up to 7 days in hydroponic system under N-free nutrient solution or nutrient solution containing N in form of nitrate, urea, ammonium or a combination of urea and ammonium.For the first time this work provides evidence that the ureic nutrition reduced the water translocation in maize plants more than mineral N forms. This result correlates with those obtained from the analyses of photosynthetic parameters (stomatal conductance and transpiration rate) suggesting a parsimonious use of water by maize plants under urea nutrition. A peculiar composition in amino acids and phytohormones (i.e. S, Gln, Pro, ABA) of the xylem sap under urea nutrition could explain differences in xylem sap exudation in comparison to plants treated with mineral N forms. The knowledge improvement of urea nutrition will allow to further perform good agronomic strategies to improve the resilience of maize crop to water stress.

Trash or treasure: Rhizome conservation during drought

Abstract The role of storage carbohydrates in plant carbon economy is currently disputed as possibly passive accumulation when other resources are limiting growth, or part of a conservative growth strategy as insurance for regrowth and stress response. One indication may be the fate of carbohydrates in senescing rhizomes, as either translocated to be retained in the live and growing end of the rhizome or kept within the senescing rhizome end and lost into the soil for it to decompose. To examine carbohydrate storage in senescing rhizomes, eight rhizomatous species were grown in a split‐pot design with one compartment containing the forward‐growing and younger end of the rhizome and another containing the older end. Both compartments were either watered (control) or the older one was left un‐watered (drought treatment) to trigger rhizome senescence and potential carbohydrate translocation. Plant growth, root traits, and non‐structural carbohydrate types and concentrations were assessed in four sequential harvests. Drought treatment plants had higher rhizome dry matter content. Younger rhizome parts produced higher new rhizome and above‐ground biomass than older rhizome parts. Carbohydrate concentrations in rhizomes remained consistent for both treatments, younger and older rhizome parts, and all harvests, probably because of the translocation of water from the watered to the dry compartment to prevent senescence and rhizome loss. Contrary to expectations, the experimental treatment did not trigger rhizome senescence: plants responded by conserving the rhizome and resources within, rather than by losing their older parts. The invariant composition and concentration of carbohydrates within the rhizome suggest that rhizomes are essential plant organs and the storage carbohydrates they contain are necessary for regrowth after stress. Read the free Plain Language Summary for this article on the Journal blog.

Translocation and Utilization Mechanisms of Leaf Intracellular Water in Karst Plants Orychophragmus violaceus (L.) O. E. Schulz and Brassica napus L.

Orychophragmus violaceus (L.) O. E. Schulz adapts to karst environments through a variety of adaptability mechanisms. However, the leaf intracellular water translocation and utilization mechanism is still unknown. This study hypothesizes that plants adapt to dehydration by synergistically adjusting the leaf anatomy, cell elasticity and intracellular water translocation. Leaf structure, elastic modulus (Em), physiological capacitance (CP), impedance (Z), water potential (ΨL), leaf tensity (LT) and chlorophyll fluorescence parameters of the detached leaves in plants of O. violaceus and Brassica napus L. were measured at each water loss time (0, 1, 2, 3, 4 and 5 h). The uniform leaves were randomly selected from five different plants for each species. The cell vacuole volume and translocation resistance of intracellular water could be represented by the electrophysiological parameters, such as CP and Z. The results indicated that timely shrinkage of O. violaceus leaves and mesophyll cells together with the increased water translocation resistance retained the intracellular water and maintained the turgor pressure. Water within sponge parenchyma could also be translocated into palisade parenchyma. The PSII reaction center was kept stable, and the photosynthetic activity of O. violaceus was clearly inhibited at 3 h. Palisade parenchyma of B. napus leaves increased quickly to improve the intercellular water translocation due to the strong cell stiffness. Gradually increasing intracellular water translocation resistance and recovery of the cell elasticity slowed down the leaf water loss, which, however, could not timely stop the damage on the PSII reaction center and the photochemical efficiency. The photochemical efficiency was seriously inhibited at 4 h and 5 h. The response mechanism of intracellular water to dehydration can be investigated with the help of leaf electrophysiological traits. However, the direct determination of plant drought resistance using electrophysiological information can still not be realized at present and needs further research.

In Vitro Membrane Platform for the Visualization of Water Impermeability across the Liquid-Ordered Phase under Hypertonic Conditions.

Passive water penetration across the cell membrane by osmotic diffusion is essential for the homeostasis of cell volume, in addition to the protein-assisted active transportation of water. Since membrane components can regulate water permeability, controlling compositional variation during the volume regulatory process is a prerequisite for investigating the underlying mechanisms of water permeation and related membrane dynamics. However, the lack of a viable in vitro membrane platform in hypertonic solutions impedes advanced knowledge of cell volume regulation processes, especially cholesterol-enriched lipid domains called lipid rafts. By reconstituting the liquid-ordered (Lo) domain as a likeness of lipid rafts, we verified suppressed water permeation across the Lo domains, which had yet to be confirmed with experimental demonstrations despite a simulation approach. With the help of direct transfer of the Lo domains from vesicles to supported lipid membranes, the biological roles of lipid composition in suppressed water translocation were experimentally confirmed. Additionally, the improvement in membrane stability under hypertonic conditions was demonstrated based on molecular dynamics simulations.