Changes In Turgor Pressure Research Articles

The Relationship between Turgor Pressure Change and Cell Hydraulics of Midrib Parenchyma Cells in the Leaves of Zea mays.

Leaf dehydration decreases water potential and cell turgor pressure. Therefore, changes in cell turgor pressure may regulate water transport across plant cell membranes. Using a cell pressure probe, the hydraulic properties of parenchyma cells in the midrib of maize (Zea mays L.) leaves were measured (half time of water exchange in cells as a measure of hydraulic conductivity Lp). Using intact plants with root systems encased in a pressure chamber, the root systems were pressurized and the turgor pressure in leaf cells increased by increments up to 0.3 MPa. However, the increase in the cell turgor did not increase but stabilized values. Increased water potential in leaf cells seemed to have stabilizing effects on the probably due to enhanced water availability. When the cell turgor decreased by 0.1 MPa to 0.3 MPa with releasing the pressure in the pressure chamber, was temporarily increased to a large degree, a factor of up to 13 within 30 min.

Modulation of Guard Cell Turgor and Drought Tolerance by a Peroxisomal Acetate–Malate Shunt

In plants, stomatal movements are tightly controlled by changes in cellular turgor pressure. Carbohydrates produced by glycolysis and the tricarboxylic acid cycle play an important role in regulating turgor pressure. Here, we describe an Arabidopsis mutant, bzu1, isolated in a screen for elevated leaf temperature in response to drought stress, which displays smaller stomatal pores and higher drought resistance than wild-type plants. BZU1 encodes a known acetyl-coenzyme A synthetase, ACN1, which acts in the first step of a metabolic pathway converting acetate to malate in peroxisomes. We showed that BZU1/ACN1-mediated acetate-to-malate conversion provides a shunt that plays an important role in osmoregulation of stomatal turgor. We found that the smaller stomatal pores in the bzu1 mutant are a consequence of reduced accumulation of malate, which acts as an osmoticum and/or a signaling molecule in the control of turgor pressure within guard cells, and these results provided new genetic evidence for malate-regulated stomatal movement. Collectively, our results indicate that a peroxisomal BZU1/ACN1-mediated acetate–malate shunt regulates drought resistance by controlling the turgor pressure of guard cells in Arabidopsis.

Enhanced uptake of potassium or glycine betaine or export of cyclic-di-AMP restores osmoresistance in a high cyclic-di-AMP Lactococcus lactis mutant.

The broadly conserved bacterial signalling molecule cyclic-di-adenosine monophosphate (c-di-AMP) controls osmoresistance via its regulation of potassium (K+) and compatible solute uptake. High levels of c-di-AMP resulting from inactivation of c-di-AMP phosphodiesterase activity leads to poor growth of bacteria under high osmotic conditions. To better understand how bacteria can adjust in response to excessive c-di-AMP levels and to identify signals that feed into the c-di-AMP network, we characterised genes identified in a screen for osmoresistant suppressor mutants of the high c-di-AMP Lactococcus ΔgdpP strain. Mutations were identified which increased the uptake of osmoprotectants, including gain-of-function mutations in a Kup family K+ importer (KupB) and inactivation of the glycine betaine transporter transcriptional repressor BusR. The KupB mutations increased the intracellular K+ level while BusR inactivation increased the glycine betaine level. In addition, BusR was found to directly bind c-di-AMP and repress expression of the glycine betaine transporter in response to elevated c-di-AMP. Interestingly, overactive KupB activity or loss of BusR triggered c-di-AMP accumulation, suggesting turgor pressure changes act as a signal for this second messenger. In another group of suppressors, overexpression of an operon encoding an EmrB family multidrug resistance protein allowed cells to lower their intracellular level of c-di-AMP through active export. Lastly evidence is provided that c-di-AMP levels in several bacteria are rapidly responsive to environmental osmolarity changes. Taken together, this work provides evidence for a model in which high c-di-AMP containing cells are dehydrated due to lower K+ and compatible solute levels and that this osmoregulation system is able to sense and respond to cellular water stress.

Stomatal Opening Involves Polar, Not Radial, Stiffening Of Guard Cells

SummaryIt has long been accepted that differential radial thickening of guard cells plays an important role in the turgor-driven shape changes required for stomatal pore opening to occur [1, 2, 3, 4]. This textbook description derives from an original interpretation of structure rather than measurement of mechanical properties. Here we show, using atomic force microscopy, that although mature guard cells display a radial gradient of stiffness, this is not present in immature guard cells, yet young stomata show a normal opening response. Finite element modeling supports the experimental observation that radial stiffening plays a very limited role in stomatal opening. In addition, our analysis reveals an unexpected stiffening of the polar regions of the stomata complexes, both in Arabidopsis and other plants, suggesting a widespread occurrence. Combined experimental data (analysis of guard cell wall epitopes and treatment of tissue with cell wall digesting enzymes, coupled with bioassay of guard cell function) plus modeling lead us to propose that polar stiffening reflects a mechanical, pectin-based pinning down of the guard cell ends, which restricts increase of stomatal complex length during opening. This is predicted to lead to an improved response sensitivity of stomatal aperture movement with respect to change of turgor pressure. Our results provide new insight into the mechanics of stomatal function, both negating an established view of the importance of radial thickening and providing evidence for a significant role for polar stiffening. Improved stomatal performance via altered cell-wall-mediated mechanics is likely to be of evolutionary and agronomic significance.

The effect of blue light on stomatal oscillations and leaf turgor pressure in banana leaves.

Stomatal oscillations are cyclic opening and closing of stomata, presumed to initiate from hydraulic mismatch between leaf water supply and transpiration rate. To test this assumption, mismatches between water supply and transpiration were induced using manipulations of vapour pressure deficit (VPD) and light spectrum in banana (Musa acuminata). Simultaneous measurements of gas exchange with changes in leaf turgor pressure were used to describe the hydraulic mismatches. An increase of VPD above a certain threshold caused stomatal oscillations with variable amplitudes. Oscillations in leaf turgor pressure were synchronized with stomatal oscillations and balanced only when transpiration equaled water supply. Surprisingly, changing the light spectrum from red and blue to red alone at constant VPD also induced stomatal oscillations - while the addition of blue (10%) to red light only ended oscillations. Blue light is known to induce stomatal opening and thus should increase the hydraulic mismatch, reduce the VPD threshold for oscillations and increase the oscillation amplitude. Unexpectedly, blue light reduced oscillation amplitude, increased VPD threshold and reduced turgor pressure loss. These results suggest that additionally, to the known effect of blue light on the hydroactive opening response of stomata, it can also effect stomatal movement by increased xylem-epidermis water supply.

Usefulness of the ZIM-probe technology for detecting water stress in clementine and persimmon trees

Further improvement on irrigation management requires continuous plant water status monitoring. The non-invasive ZIM-probe measures the pressure (Pp) transfer function through a patch of an intact leaf, which is inversely correlated with the turgor pressure. Data are sent wireless in real-time by telemetry to an internet server via a mobile phone network where it is available to be analyzed. In this work, the detection of water stress by measuring relative changes in turgor pressure with the ZIM-probe was evaluated in clementine and persimmon trees. Ten trees of both species were equipped with two ZIM-probes each located at the east side of the canopy. The ZIM-probes were used over several months during which half of the trees were subjected to two drought cycles. Concomitant measurements of stem water potential (ψs) were taken at midday in both orchards during the drought periods. Additionally, determinations of ψs and stomatal conductance (gs) were also performed during 1-2 days at hourly intervals in the clementine and persimmon orchards, respectively, to study the existing relationship of these classical indicators with the leaf turgor pressure. Results showed that diurnal Pp values increased in non-irrigated clementine trees when water restrictions were imposed. Persimmon drought-stressed trees, on the other hand, showed different Pp curve shapes (half and complete inverse curve) depending on the level of stress reached by the trees. There was a tight correlation between the hourly spot measurements of ψs and gs with the probe data. Overall, results show that the ZIM-probe enables the detection of drought stress in clementine and persimmon trees. Nevertheless, different approaches for calculating the water stress level must be used in each of these species due to the higher tendency of persimmon leaves to the inversed Pp curve phenomena.

Fountain streaming contributes to fast tip-growth through regulating the gradients of turgor pressure and concentration in pollen tubes.

Fountain streaming is a typical microfluidic pattern in plant cells, especially for cells with a high aspect ratio such as pollen tubes. Although it has been found that fountain streaming plays crucial roles in the transport of nutrients and metabolites, the positioning of organelles and the mixing of cytoplasms, its implications for the fast tip growth of pollen tubes remain a mystery. To address this, based on the observations of asiatic lily Lilium Casablanca, we developed physical models for reverse fountain streaming in pollen tubes and solved the hydrodynamics and advection-diffusion dynamics of viscous Stokes flow in the shank and apical region of pollen tubes. Theoretical and numerical results demonstrated that the gradients of turgor pressure and concentration of wall materials along the length of pollen tubes provide undamped driving force and high-efficiency materials supply, which are supposed to contribute to the fast tip-growth of pollen tubes. The sample experimental results show that the tip-growth will be abnormal when the gradients of turgor pressure change under osmotic stress induced by different concentrations of PEG-6000 (a dehydrant).

Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall

SummaryStomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape [1]. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils [2], our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO2, substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology.

Linking Turgor with ABA Biosynthesis: Implications for Stomatal Responses to Vapor Pressure Deficit across Land Plants.

Stomatal responses to changes in vapor pressure deficit (VPD) constitute the predominant form of daytime gas-exchange regulation in plants. Stomatal closure in response to increased VPD is driven by the rapid up-regulation of foliar abscisic acid (ABA) biosynthesis and ABA levels in angiosperms; however, very little is known about the physiological trigger for this increase in ABA biosynthesis at increased VPD Using a novel method of modifying leaf cell turgor by the application of external pressures, we test whether changes in turgor pressure can trigger increases in foliar ABA levels over 20 min, a period of time most relevant to the stomatal response to VPD We found in angiosperm species that the biosynthesis of ABA was triggered by reductions in leaf turgor, and in two species tested, that a higher sensitivity of ABA synthesis to leaf turgor corresponded with a higher stomatal sensitivity to VPD In contrast, representative species from nonflowering plant lineages did not show a rapid turgor-triggered increase in foliar ABA levels, which is consistent with previous studies demonstrating passive stomatal responses to changes in VPD in these lineages. Our method provides a new tool for characterizing the response of stomata to water availability.

Repeated cultivation: non-cell disruption extraction of astaxanthin for Haematococcus pluvialis.

The operation of cell disruption is indispensable but cost much in microalgae industry. To be simplified, two different reaction mechanisms await in the cell to respond to moderated or stressed environment. The physical and chemical changes of enzyme and turgor pressure of cell in this conversion play an important role in the enhancement of biomass and metabolites. Repeated turgor pressure (based on the structure and mechanics of cell wall) and converted enzyme system (based on photosynthesis) were used to loosen cell wall and then repeated cultivation of Haematococcus pluvialis for astaxanthin extraction was proposed. There was no significant difference of extraction yield between the broken cell (94.75 ± 3.13%) and non-broken cell (92.32 ± 3.24%) treated by the repeated cultivation. Meanwhile, fed-batch culture according to the relationship among pH and nutrient concentration was used to enhance the biomass of Haematococcus pluvialis with the dry cell weight of 1.63 ± 0.07 g/L.

Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis.

Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3(je5) mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface.

Endosperm turgor pressure decreases during early Arabidopsis seed development.

In Arabidopsis, rapid expansion of the coenocytic endosperm after fertilisation has been proposed to drive early seed growth, which is in turn constrained by the seed coat. This hypothesis implies physical heterogeneity between the endosperm and seed coat compartments during early seed development, which to date has not been demonstrated. Here, we combine tissue indentation with modelling to show that the physical properties of the developing seed are consistent with the hypothesis that elevated endosperm-derived turgor pressure drives early seed expansion. We provide evidence that whole-seed turgor is generated by the endosperm at early developmental stages. Furthermore, we show that endosperm cellularisation and seed growth arrest are associated with a drop in endosperm turgor pressure. Finally, we demonstrate that this decrease is perturbed when the function of POLYCOMB REPRESSIVE COMPLEX 2 is lost, suggesting that turgor pressure changes could be a target of genomic imprinting. Our results indicate a developmental role for changes in endosperm turgor pressure in the Arabidopsis seed.

PLANT SENSORS HELP TO UNDERSTAND TIPBURN IN LETTUCE

Although growers seem to be able to control the incidence of tipburn in soilgrown lettuce (Lactuca spp.), this physiological disorder causes substantial yield losses in hydroponics (up to 50%). Tipburn is generally considered to be a calcium deficiency related disorder, but literature exhibits apparently contradictory findings, because the research always focused on the effects of the environment on the occurrence of tipburn, whereas the plant physiological aspects were seldom included. Therefore, there is a strong need for a plant physiological interpretation of the tipburn disorder, which correlates the different environmental effects to the plant physiological processes. In this study, we present the use of plant sensors to assess the plant physiological response to its environment with respect to the incidence of tipburn. As such, stem diameter and leaf thickness were continuously monitored, because variations in these variables are strongly related to variations in the plant water relations, turgor pressure and growth rate. Leaf thickness measurements were combined with a mechanistic model to detect periods of water deficits or abrupt changes in turgor pressure. This approach could additionally help to monitor root pressure and investigate the hypothesis that root pressure has beneficial effects on the supply of calcium to slowly transpiring leaves. As such, growth rate, supply of calcium to low transpiring leaves and abrupt variations in turgor pressure, all of which are associated with tipburn, could be instantly visualised by these plant sensors and consequently identify environmental drivers for tipburn.

EFFECT OF EXOGENOUS ABSCISIC ACID ON GROWTH AND BIOCHEMICAL CHANGES IN THE HALOPHYTE SUAEDA MARITIMA

Different types of phytohormones are being extensively used to alleviate the adverse effect of salinity stress on plant growth. Among those, Abscisic acid (ABA) is a plant stress hormone and one of the most important signaling molecules in plants. Drought and salinity activate De-novo abscisic acid synthesis prevent further water loss by evaporation through stomata, mediated by changes in the guard cell turgor pressure. Under osmotic stress abscisic acid induce the accumulation of protein involved in the biosynthesis of osmolites which increasing the stress tolerance of plant. In addition, exogenous application of ABA enhances the tolerance of plants or plant cells to cold, heat, drought, anoxia and heavy metal stresses. This study was carried out to study the exogenous abscisic (ABA) acid induced regulatory role on the growth, water content, protein content, chlorophyll content, osmolyte accumulation and protein profiling through SDS PAGE in a halophyte, Suaeda maritima. The osmolyte accumulation of proline and glycine betaine was found to be more in 50 µM ABA concentrations. The protein profiling through SDS PAGE revealed that ̴ 66KDa proteins was not expressed in the control plant and in 10μM ABA treated plants. Interestingly, the ABA treatment induced a new protein of 14.2KDa in 10μM concentration. The ABA treated plants with concentrations 50μM, 100μM and 150μM showed changes in the expression of protein in abundance than the control and 10μM ABA treated plants. The findings in this study indicate that among all the concentrations, 50μM ABA concentration treated plants exhibited higher growth rate.

Latex dilution reaction during the tapping flow course of Hevea brasiliensis and the effect of Ethrel stimulation

The latex dilution reaction during the tapping flow course has been well documented and associated with the facilitation of tapping latex flow. However, its underlying mechanism has not experimentally examined. The latex total solid content, osmotic potential and phloem turgor pressure change during the tapping flow course were simultaneously measured to investigate the cause of water movement during the tapping flow course. It was found that there are three different stages for the laticifer water equilibrium during the tapping flow course. The tapping-induced rapid turgor pressure drop is the cause of the first stage water influx into laticifers, while osmoregulation prevails during water exchange in the second and third stages of tapping flow. Meanwhile, aquaporin expressions were, for the first time, investigated during the tapping flow course. The rapid transcript up-regulation of HbPIP1, HbPIP2;1 and HbPIP2;3 contributes to the latex dilution reaction. However, their activity gating cannot be ruled out. Ethrel stimulation can significantly dilute the corresponding latex fractions during the tapping flow course due to its up-regulations of HbPIP1, HbPIP2;1 and HbPIP2;3. Nevertheless, the latex dilution reaction pattern for the Ethrel treated trees did not change, except for a lower degree of dilution compared with the un-treated trees. All these results suggest that both phloem turgor pressure and aquaporins are involved in the latex dilution reaction during the tapping flow course.

Simultaneous recording of diurnal changes in leaf turgor pressure and stem water status of bread wheat reveal variation in hydraulic mechanisms in response to drought.

Information about water relations within crop canopies is needed to improve our understanding of canopy resource distribution and crop productivity. In this study, we examined the dehydration/rehydration kinetics of different organs of wheat plants using ZIM-probes that continuously monitor water status non-destructively. ZIM-probes were clamped to the flag leaf and penultimate leaf of the same stem to monitor changes in turgor pressure, and a novel stem probe was clamped to the peduncle (just below the spike of the same stem) to monitor changes in stem water status. All organs behaved similarly under well-watered conditions, dehydrating and recovering at the same times of day. When water was withheld, the behaviour diverged, with the leaves showing gradual dehydration and incomplete recovery in leaf turgor pressure during the night, but the stem was affected to a lesser extent. Penultimate leaves were the most severely affected, reaching turgor loss point before the flag leaf. Upon rewatering, turgor pressure recovered but the output patch-pressure of the probes (Pp) oscillated at ~30min periods in all organs of most plants (n=4). Oscillations in Pp were attributed to oscillations in stomatal opening and appear to only occur above a threshold light intensity. The mechanisms identified in this study will be beneficial for crop productivity because the flag leaf is the source of most photoassimilates in developing grains, so the plant's ability to maintain flag leaf hydration at the expense of older leaves should moderate the impact of drought on yield. Stomatal oscillations could increase water use efficiency as the plant attempts to rehydrate after drought.

Finite element modelling of the mechanical behaviour of onion epidermis with incorporation of nonlinear properties of cell walls and real tissue geometry

In the field of agricultural sciences, numerical modelling has proven to be a valuable tool in finding solutions to practical and scientific issues. In the present study a computational model of plant tissue that incorporates micro-scale geometrical features was developed to provide qualitative and quantitative predictions of the mechanical properties of onion (Allium cepa) epidermis. The simulations of cellular structure behaviour under various mechanical load conditions were carried out using the finite element method (FEM). The models were validated against experimental data from a tensile test of the real tissue strips. The models showed capabilities of simulating large strains (up to 25%) with nonlinear behaviour and produced force-strain curves that closely matched the experimental data. Also, a new insight into the relationship between microstructure and mechanical behaviour was provided for this type of material. The incorporation of the real microstructure resulted in a qualitative improvement of the mechanical characteristics obtained from FEM models of plant tissues. The ability to directly simulate the impact of changes in turgor pressure was limited due to the semi-three dimensional representation of tissue. The general behaviour of tissue resulting from the changes in turgor was approximated using the semi-solid protoplast that replaced the cells liquid. On the basis of a sensitivity analysis it was concluded that the validity of the results provided by the model is largely dependent on accurate measurements of cell wall thickness.

RhNAC3, a stress‐associated NAC transcription factor, has a role in dehydration tolerance through regulating osmotic stress‐related genes in rose petals

Petal cell expansion depends on cell wall metabolism, changes in cell turgor pressure and restructuring of the cytoskeleton, and recovery ability of petal cell expansion is defined as an indicator of dehydration tolerance in flowers. We previously reported that RhNAC2, a development-related NAC domain transcription factor, confers dehydration tolerance through regulating cell wall-related genes in rose petals. Here, we identify RhNAC3, a novel rose SNAC gene, and its expression in petals induced by dehydration, wounding, exogenous ethylene and abscisic acid (ABA). Expression studies in Arabidopsis protoplasts and yeast show that RhNAC3 has transactivation activity along its full length and in the carboxyl-terminal domain. Silencing RhNAC3 in rose petals by virus-induced gene silencing (VIGS) significantly decreased the cell expansion of rose petals under rehydration conditions. In total, 24 of 27 osmotic stress-related genes were down-regulated in RhNAC3-silenced rose petals, while only 4 of 22 cell expansion-related genes were down-regulated. Overexpression of RhNAC3 in Arabidopsis gave improved drought tolerance, with lower water loss of leaves in transgenic plants. Arabidopsis ATH1 microarray analysis showed that RhNAC3 regulated the expression of stress-responsive genes in overexpressing lines, and further analysis revealed that most of the RhNAC3-up-regulated genes were involved in the response to osmotic stress. Comparative analysis revealed that different transcription regulation existed between RhNAC3 and RhNAC2. Taken together, these data indicate that RhNAC3, as a positive regulator, confers dehydration tolerance of rose petals mainly through regulating osmotic adjustment-associated genes.

Nanomechanics measurements of live bacteria reveal a mechanism for bacterial cell protection: the polysaccharide capsule in Klebsiella is a responsive polymer hydrogel that adapts to osmotic stress

A global health problem concerns the evolution of antibiotic-resistant bacteria. A characteristic of these super bug pathogens is their ability to form an exopolysaccharide matrix, the capsule, allowing them to resist antibiotic treatment and other environmental stresses. Here we apply atomic force microscopy (AFM) to interrogate living bacterial cells and provide the first in situ measurements of the biophysical behaviour of the capsule in physiologically relevant conditions. We prepared live Klebsiella pneumoniae, a common pathogen that has evolved super bug strains. We measured how capsule, cell wall and cell cytoplasm of wild type and capsule-deficient bacterial cells respond when indented by an AFM tip, under extreme osmotic conditions. By developing a mechanical model for the indentation of bacteria and fitting the force profiles to this model, we discovered that the organisation and hydration of the capsule alter in response to the osmotic environment, but surprisingly there is no change in cytoplasmic turgor pressure. The capsule deficient mutants however, experience extreme change in turgor pressure under altered osmotic conditions. Our results provide new insight on the biophysical behaviour of the bacterial capsule, demonstrating that it is a polymer hydrogel that acts as an ion sponge to dampen the impact of osmotic stress. Nano-mechanical screening for additives to medical plastics that alter the properties of this ion sponge represents a new way to address the problems associated with antibiotic-resistant bacteria.

A non-invasive plant-based probe for continuous monitoring of water stress in real time: a new tool for irrigation scheduling and deeper insight into drought and salinity stress physiology

The non-invasive, magnetic leaf patch clamp pressure probe (also termed ZIM-probe) allows for the first time to measure continuously turgor pressure changes of plant leaves over long periods of time with high precision and in real time. The probe has become an important tool in plant physiology, molecular biology and ecology, but also in agriculture because the probe is very robust and user-friendly. Growers receive the information about the water status of their plants by wireless telemetry, mobile network and internet on an as-needed basis and can thus adjust very precisely both the timing of irrigation and the quantity of water to apply. Effects of air and leaf temperature, relative humidity, illumination and wind on turgor pressure can be monitored very sensitively both under indoor and outdoor conditions. Even the effects of blue and red light as well as of oscillations of stomata aperture on turgor pressure can be monitored by the probe with high sensitivity. Similarly, water deficit due to increase of the osmotic pressure in the nutrition solutions resulted in significant changes of the probe signals. Multiple probe readings open up new possibilities to resolve (together with other techniques) the mechanisms of short- and long-distance water transport, particularly how plants can cope with water shortage. The applications of the magnetic probe are numerous and one can expect highly interesting developments in plant water relations in the nearest future.