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1.
A. M. Hetherington 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1998,353(1374):1489-1494
Stomatal guard cells have proven to be an attractive system for dissecting the mechanisms of stimulus-response coupling in plants. In this review we focus on the intracellular signal transduction pathways by which extracellular signals bring about closure and opening of the stomatal pore. It is proposed that guard cell signal transduction pathways may be organized into functional arrays or signalling cassettes that contain elements common to a number of converging signalling pathways. The purpose of these signalling cassettes may be to funnel extracellular signals down onto the ion transporters that control the fluxes of ions that underlie stomatal movements. Evidence is emerging that specificity in guard cell signalling may be, in part, encoded in complex spatio-temporal patterns of increases in the concentration of cytosolic-free calcium ([Ca2+]cyt). It is suggested that oscillations in [Ca2+]cyt may generate calcium signatures that encode information concerning the stimulus type and strength. New evidence is presented that suggests that these calcium signatures may integrate information when many stimuli are present. 相似文献
2.
Byeong Wook Jeon Biswa R. Acharya Sarah M. Assmann 《The Plant journal : for cell and molecular biology》2019,99(2):231-244
Cytosolic calcium concentration ([Ca2+]cyt) and heterotrimeric G‐proteins are universal eukaryotic signaling elements. In plant guard cells, extracellular calcium (Cao) is as strong a stimulus for stomatal closure as the phytohormone abscisic acid (ABA), but underlying mechanisms remain elusive. Here, we report that the sole Arabidopsis heterotrimeric Gβ subunit, AGB1, is required for four guard cell Cao responses: induction of stomatal closure; inhibition of stomatal opening; [Ca2+]cyt oscillation; and inositol 1,4,5‐trisphosphate (InsP3) production. Stomata in wild‐type Arabidopsis (Col) and in mutants of the canonical Gα subunit, GPA1, showed inhibition of stomatal opening and promotion of stomatal closure by Cao. By contrast, stomatal movements of agb1 mutants and agb1/gpa1 double‐mutants, as well as those of the agg1agg2 Gγ double‐mutant, were insensitive to Cao. These behaviors contrast with ABA‐regulated stomatal movements, which involve GPA1 and AGB1/AGG3 dimers, illustrating differential partitioning of G‐protein subunits among stimuli with similar ultimate impacts, which may facilitate stimulus‐specific encoding. AGB1 knockouts retained reactive oxygen species and NO production, but lost YC3.6‐detected [Ca2+]cyt oscillations in response to Cao, initiating only a single [Ca2+]cyt spike. Experimentally imposed [Ca2+]cyt oscillations restored stomatal closure in agb1. Yeast two‐hybrid and bimolecular complementation fluorescence experiments revealed that AGB1 interacts with phospholipase Cs (PLCs), and Cao induced InsP3 production in Col but not in agb1. In sum, G‐protein signaling via AGB1/AGG1/AGG2 is essential for Cao‐regulation of stomatal apertures, and stomatal movements in response to Cao apparently require Ca2+‐induced Ca2+ release that is likely dependent on Gβγ interaction with PLCs leading to InsP3 production. 相似文献
3.
M. A. Hossain W. Ye S. Munemasa Y. Nakamura I. C. Mori Y. Murata 《Plant biology (Stuttgart, Germany)》2014,16(6):1140-1144
Methyl jasmonate (MeJA) signalling shares several signal components with abscisic acid (ABA) signalling in guard cells. Cyclic adenosine 5′‐diphosphoribose (cADPR) and cyclic guanosine 3′,5′‐monophosphate (cGMP) are second messengers in ABA‐induced stomatal closure. In order to clarify involvement of cADPR and cGMP in MeJA‐induced stomatal closure in Arabidopsis thaliana (Col‐0), we investigated effects of an inhibitor of cADPR synthesis, nicotinamide (NA), and an inhibitor of cGMP synthesis, LY83583 (LY, 6‐anilino‐5,8‐quinolinedione), on MeJA‐induced stomatal closure. Treatment with NA and LY inhibited MeJA‐induced stomatal closure. NA inhibited MeJA‐induced reactive oxygen species (ROS) accumulation and nitric oxide (NO) production in guard cells. NA and LY suppressed transient elevations elicited by MeJA in cytosolic free Ca2+ concentration ([Ca2+]cyt) in guard cells. These results suggest that cADPR and cGMP positively function in [Ca2+]cyt elevation in MeJA‐induced stomatal closure, are signalling components shared with ABA‐induced stomatal closure in Arabidopsis, and that cADPR is required for MeJA‐induced ROS accumulation and NO production in Arabidopsis guard cells. 相似文献
4.
Robert S. Siegel Shaowu Xue Yoshiyuki Murata Yingzhen Yang Noriyuki Nishimura Angela Wang Julian I. Schroeder 《The Plant journal : for cell and molecular biology》2009,59(2):207-220
Stomatal closure in response to abscisic acid depends on mechanisms that are mediated by intracellular [Ca2+] ([Ca2+]i), and also on mechanisms that are independent of [Ca2+]i in guard cells. In this study, we addressed three important questions with respect to these two predicted pathways in Arabidopsis thaliana. (i) How large is the relative abscisic acid (ABA)‐induced stomatal closure response in the [Ca2+]i‐elevation‐independent pathway? (ii) How do ABA‐insensitive mutants affect the [Ca2+]i‐elevation‐independent pathway? (iii) Does ABA enhance (prime) the Ca2+ sensitivity of anion and inward‐rectifying K+ channel regulation? We monitored stomatal responses to ABA while experimentally inhibiting [Ca2+]i elevations and clamping [Ca2+]i to resting levels. The absence of [Ca2+]i elevations was confirmed by ratiometric [Ca2+]i imaging experiments. ABA‐induced stomatal closure in the absence of [Ca2+]i elevations above the physiological resting [Ca2+]i showed only approximately 30% of the normal stomatal closure response, and was greatly slowed compared to the response in the presence of [Ca2+]i elevations. The ABA‐insensitive mutants ost1‐2, abi2‐1 and gca2 showed partial stomatal closure responses that correlate with [Ca2+]i‐dependent ABA signaling. Interestingly, patch‐clamp experiments showed that exposure of guard cells to ABA greatly enhances the ability of cytosolic Ca2+ to activate S‐type anion channels and down‐regulate inward‐rectifying K+ channels, providing strong evidence for a Ca2+ sensitivity priming hypothesis. The present study demonstrates and quantifies an attenuated and slowed ABA response when [Ca2+]i elevations are directly inhibited in guard cells. A minimal model is discussed, in which ABA enhances (primes) the [Ca2+]i sensitivity of stomatal closure mechanisms. 相似文献
5.
Two guard cell‐preferential MAPKs,MPK9 and MPK12, regulate YEL signalling in Arabidopsis guard cells
M. A. Salam F. Jammes M. A. Hossain W. Ye Y. Nakamura I. C. Mori J. M. Kwak Y. Murata 《Plant biology (Stuttgart, Germany)》2013,15(3):436-442
We report that two mitogen‐activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate abscisic acid (ABA)‐induced stomatal closure in Arabidopsis thaliana. Yeast elicitor (YEL) induced stomatal closure accompanied by intracellular reactive oxygen species (ROS) accumulation and cytosolic free calcium concentration ([Ca2+]cyt) oscillation. In this study, we examined whether these two MAP kinases are involved in YEL‐induced stomatal closure using MAPKK inhibitors, PD98059 and U0126, and MAPK mutants, mpk9, mpk12 and mpk9 mpk12. Both PD98059 and U0126 inhibited YEL‐induced stomatal closure. YEL induced stomatal closure in the mpk9 and mpk12 mutants but not in the mpk9 mpk12 mutant, suggesting that a MAPK cascade involving MPK9 and MPK12 functions in guard cell YEL signalling. However, YEL induced extracellular ROS production, intracellular ROS accumulation and cytosolic alkalisation in the mpk9, mpk12 and mpk9 mpk12 mutants. YEL induced [Ca2+]cyt oscillations in both wild type and mpk9 mpk12 mutant. These results suggest that MPK9 and MPK12 function redundantly downstream of extracellular ROS production, intracellular ROS accumulation, cytosolic alkalisation and [Ca2+]cyt oscillation in YEL‐induced stomatal closure in Arabidopsis guard cells and are shared with ABA signalling. 相似文献
6.
Hossain MA Munemasa S Nakamura Y Mori IC Murata Y 《Journal of plant physiology》2011,168(16):1901-1908
Methyl jasmonate (MeJA) induces stomatal closure similar to abscisic acid (ABA), and MeJA signaling in guard cells shares some signal components with ABA signaling. As part of this process, MeJA as well as ABA induce the elevation and oscillation of cytosolic free-calcium concentrations ([Ca2+]cyt) in guard cells. While abscisic acid-induced [Ca2+]cyt oscillation has been extensively studied, MeJA-induced [Ca2+]cyt oscillation is less well understood. In this study, we investigated the effects of K252a (a broad-range protein kinase inhibitor) and okadaic acid (OA, a protein phosphatase 1 and 2A inhibitor) on MeJA-induced [Ca2+]cyt oscillation in guard cells of Arabidopsis thaliana ecotype Columbia expressing the Ca2+ reporter yellow cameleon 3.6. The protein kinase inhibitor K252a abolished MeJA-induced stomatal closure and reduced MeJA-elicited [Ca2+]cyt oscillation. The protein phosphatase inhibitor OA, on the other hand, did not inhibit these processes. These results suggest that MeJA signaling involves activation of K252a-sensitive protein kinases upstream of [Ca2+]cyt oscillation but not activation of an OA-sensitive protein phosphatase in guard cells of A. thaliana ecotype Columbia. 相似文献
7.
The inward K+ channels (IKin) of guard cells are inhibited upon application of abscisic acid (ABA). It has been postulated that IKin inhibition requires an elevation in cytosolic free Ca2+ levels ([Ca2+]c) because: (i) experimental increases in [Ca2+] c can mimic the ABA effect, and; (ii) ABA can trigger an elevation of [Ca2+]c in guard cells. However, not all guard cells respond to ABA with a [Ca2+]c increase, and the magnitude of the increases that do occur is variable. Therefore, an obligate role for Ca2+ in the regulation of downstream effectors of ABA response, such as the IKin channels, remains in question. In this study, we developed a methodology for simultaneous patch clamping and confocal ratiometric
Ca2+ imaging of Vicia faba L. guard-cell protoplasts. This allowed us to directly assess the relationship between ABA-induced changes in [Ca2+]c and IKin inhibition. In the presence of extracellular Ca2+, the extent of [Ca2+]c elevation correlated with the extent of IKin inhibition. However, upon chelation of either extracellular Ca2+, [Ca2+]c, or both, extracellular Ca2+ and [Ca2+]c, [Ca2+]c elevation did not occur in response to ABA yet IKin currents were still strongly inhibited. These data illustrate that Ca2+-independent regulation is involved in ABA-inhibition of stomatal opening processes.
Received: 17 September 1999 / Accepted: 26 October 1999 相似文献
8.
Two guard cell mitogen‐activated protein kinases,MPK9 and MPK12, function in methyl jasmonate‐induced stomatal closure in Arabidopsis thaliana
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W. Ye M. A. Hossain M. Uraji Y. Nakamura I. C. Mori J. M. Kwak Y. Murata 《Plant biology (Stuttgart, Germany)》2015,17(5):946-952
Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell‐preferential mitogen‐activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9‐1 and mpk12‐1 single mutants as well as wild‐type plants, but not in mpk9‐1 mpk12‐1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA‐induced stomatal closure in wild‐type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9‐1, mpk12‐1 and mpk9‐1 mpk12‐1 mutants, as well in wild‐type plants. Furthermore, MeJA triggered elevation of cytosolic Ca2+ concentration ([Ca2+]cyt) in the mpk9‐1 mpk12‐1 double mutant as well as wild‐type plants. Activation of S‐type anion channels by MeJA was impaired in mpk9‐1 mpk12‐1. Together, these results indicate that MPK9 and MPK12 function upstream of S‐type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca2+]cyt elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells. 相似文献
9.
Plant guard cells gate CO2 uptake and transpirational water loss through stomatal pores. As a result of decades of experimental investigation, there is an abundance of information on the involvement of specific proteins and secondary messengers in the regulation of stomatal movements and on the pairwise relationships between guard cell components. We constructed a multi-level dynamic model of guard cell signal transduction during light-induced stomatal opening and of the effect of the plant hormone abscisic acid (ABA) on this process. The model integrates into a coherent network the direct and indirect biological evidence regarding the regulation of seventy components implicated in stomatal opening. Analysis of this signal transduction network identified robust cross-talk between blue light and ABA, in which [Ca2+]c plays a key role, and indicated an absence of cross-talk between red light and ABA. The dynamic model captured more than 1031 distinct states for the system and yielded outcomes that were in qualitative agreement with a wide variety of previous experimental results. We obtained novel model predictions by simulating single component knockout phenotypes. We found that under white light or blue light, over 60%, and under red light, over 90% of all simulated knockouts had similar opening responses as wild type, showing that the system is robust against single node loss. The model revealed an open question concerning the effect of ABA on red light-induced stomatal opening. We experimentally showed that ABA is able to inhibit red light-induced stomatal opening, and our model offers possible hypotheses for the underlying mechanism, which point to potential future experiments. Our modelling methodology combines simplicity and flexibility with dynamic richness, making it well suited for a wide class of biological regulatory systems. 相似文献
10.
MacRobbie EA 《The Journal of membrane biology》2006,210(2):131-142
Water loss from plants is determined by the aperture of stomatal pores in the leaf epidermis, set by the level of vacuolar
accumulation of potassium salt, and hence volume and turgor, of a pair of guard cells. Regulation of ion fluxes across the
tonoplast, the key to regulation of stomatal aperture, can only be studied by tracer flux measurements. There are two transport
systems in the tonoplast. The first is a Ca2+-activated channel, inhibited by phenylarsine oxide (PAO), responsible for the release of vacuolar K+(Rb+) in response to the “drought” hormone, abscisic acid (ABA). This channel is sensitive to pressure, down-regulated at low
turgor and up-regulated at high turgor, providing a system for turgor regulation. ABA induces a transient stimulation of vacuolar
ion efflux, during which the flux tracks the ion content (volume, turgor), suggesting ABA reduces the set-point of a control
system. The second system, which is PAO-insensitive, is responsible for an ion flux from vacuole to cytoplasm associated with
inward water flow following a hypo-osmotic transfer. It is suggested that this involves an aquaporin as sensor, and perhaps
also as responder; deformation of the aquaporin may render it ion-permeable, or, alternatively, the deformed aquaporin may
signal to an associated ion channel, activating it. Treatment with inhibitors of aquaporins, HgCl2 or silver sulfadiazine, produces a large transient increase in ion release from the vacuole, also PAO-insensitive. It is
suggested that this involves the same aquaporin, either rendered directly ion-permeable, or signalling to activate an associated
ion channel. 相似文献
11.
Daeshik Cho Sun A. Kim Yoshiyuki Murata Sangmee Lee Seul-Ki Jae Hong Gil Nam June M. Kwak 《The Plant journal : for cell and molecular biology》2009,58(3):437-449
Cytosolic Ca2+ ([Ca2+]cyt) mediates diverse cellular responses in both animal and plant cells in response to various stimuli. Calcium oscillation amplitude and frequency control gene expression. In stomatal guard cells, [Ca2+]cyt has been shown to regulate stomatal movements, and a defined window of Ca2+ oscillation kinetic parameters encodes necessary information for long‐term stomatal movements. However, it remains unknown how the encrypted information in the cytosolic Ca2+ signature is decoded to maintain stomatal closure. Here we report that the Arabidopsis glutamate receptor homolog AtGLR3.1 is preferentially expressed in guard cells compared to mesophyll cells. Furthermore, over‐expression of AtGLR3.1 using a viral promoter resulted in impaired external Ca2+‐induced stomatal closure. Cytosolic Ca2+ activation of S‐type anion channels, which play a central role in Ca2+‐reactive stomatal closure, was normal in the AtGLR3.1 over‐expressing plants. Interestingly, AtGLR3.1 over‐expression did not affect Ca2+‐induced Ca2+ oscillation kinetics, but resulted in a failure to maintain long‐term ‘Ca2+‐programmed’ stomatal closure when Ca2+ oscillations containing information for maintaining stomatal closure were imposed. By contrast, prompt short‐term Ca2+‐reactive closure was not affected in AtGLR3.1 over‐expressing plants. In wild‐type plants, the translational inhibitor cyclohexamide partially inhibited Ca2+‐programmed stomatal closure induced by experimentally imposed Ca2+ oscillations without affecting short‐term Ca2+‐reactive closure, mimicking the guard cell behavior of the AtGLR3.1 over‐expressing plants. Our results suggest that over‐expression of AtGLR3.1 impairs Ca2+ oscillation‐regulated stomatal movements, and that de novo protein synthesis contributes to the maintenance of long‐term Ca2+‐programmed stomatal closure. 相似文献
12.
Guard cell photosynthesis is critical for stomatal turgor production,yet does not directly mediate CO2‐ and ABA‐induced stomatal closing
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Tamar Azoulay‐Shemer Axxell Palomares Andisheh Bagheri Maria Israelsson‐Nordstrom Cawas B. Engineer Bastiaan O. R. Bargmann Aaron B. Stephan Julian I. Schroeder 《The Plant journal : for cell and molecular biology》2015,83(4):567-581
Stomata mediate gas exchange between the inter‐cellular spaces of leaves and the atmosphere. CO2 levels in leaves (Ci) are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2]. [CO2] in leaves mediates stomatal movements. The role of guard cell photosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. We have generated transgenic Arabidopsis plants that are chlorophyll‐deficient in guard cells only, expressing a constitutively active chlorophyllase in a guard cell specific enhancer trap line. Our data show that more than 90% of guard cells were chlorophyll‐deficient. Interestingly, approximately 45% of stomata had an unusual, previously not‐described, morphology of thin‐shaped chlorophyll‐less stomata. Nevertheless, stomatal size, stomatal index, plant morphology, and whole‐leaf photosynthetic parameters (PSII, qP, qN, FV′/FM′) were comparable with wild‐type plants. Time‐resolved intact leaf gas‐exchange analyses showed a reduction in stomatal conductance and CO2‐assimilation rates of the transgenic plants. Normalization of CO2 responses showed that stomata of transgenic plants respond to [CO2] shifts. Detailed stomatal aperture measurements of normal kidney‐shaped stomata, which lack chlorophyll, showed stomatal closing responses to [CO2] elevation and abscisic acid (ABA), while thin‐shaped stomata were continuously closed. Our present findings show that stomatal movement responses to [CO2] and ABA are functional in guard cells that lack chlorophyll. These data suggest that guard cell CO2 and ABA signal transduction are not directly modulated by guard cell photosynthesis/electron transport. Moreover, the finding that chlorophyll‐less stomata cause a ‘deflated’ thin‐shaped phenotype, suggests that photosynthesis in guard cells is critical for energization and guard cell turgor production. 相似文献
13.
Background
Stomatal guard cells are the regulators of gas exchange between plants and the atmosphere. Ca2+-dependent and Ca2+-independent mechanisms function in these responses. Key stomatal regulation mechanisms, including plasma membrane and vacuolar ion channels have been identified and are regulated by the free cytosolic Ca2+ concentration ([Ca2+]cyt).Scope
Here we show that CO2-induced stomatal closing is strongly impaired under conditions that prevent intracellular Ca2+ elevations. Moreover, Ca2+ oscillation-induced stomatal closing is partially impaired in knock-out mutations in several guard cell-expressed Ca2+-dependent protein kinases (CDPKs) here, including the cpk4cpk11 double and cpk10 mutants; however, abscisic acid-regulated stomatal movements remain relatively intact in the cpk4cpk11 and cpk10 mutants. We further discuss diverse studies of Ca2+ signalling in guard cells, discuss apparent peculiarities, and pose novel open questions. The recently proposed Ca2+ sensitivity priming model could account for many of the findings in the field. Recent research shows that the stomatal closing stimuli abscisic acid and CO2 enhance the sensitivity of stomatal closing mechanisms to intracellular Ca2+, which has been termed ‘calcium sensitivity priming’. The genome of the reference plant Arabidopsis thaliana encodes for over 250 Ca2+-sensing proteins, giving rise to the question, how can specificity in Ca2+ responses be achieved? Calcium sensitivity priming could provide a key mechanism contributing to specificity in eukaryotic Ca2+ signal transduction, a topic of central interest in cell signalling research. In this article we further propose an individual stomatal tracking method for improved analyses of stimulus-regulated stomatal movements in Arabidopsis guard cells that reduces noise and increases fidelity in stimulus-regulated stomatal aperture responses ( Box 1). This method is recommended for stomatal response research, in parallel to previously adopted blind analyses, due to the relatively small and diverse sizes of stomatal apertures in the reference plant Arabidopsis thaliana.Box 1. Improved resolution of stimulus-induced stomatal movements in guard cells by tracking of individual stomatal apertures
Arabidopsis guard cells have become a prime model system for analysing signal transduction, since early research combining genetic and ion channel analyses in this system (Ichida et al., 1997; Pei et al., 1997, 1998; Roelfsema and Prins, 1997). Arabidopsis stomata are small relative to other stomatal model systems and stomatal apertures of various plant types including Arabidopsis are known to show variability in the size of individual stomatal complexes and also variability in the opening apertures of stomata of similar size in a given leaf (Gorton et al., 1988; Mott and Buckley, 2000; Mott and Peak, 2007). Thus stomatal aperture measurements are expected to show a clear degree of statistical variation. Use of blind experiments, in which the genotype and, when possible, the stimulus being applied to guard cells is unknown to the experimenter (Murata et al., 2001) has been employed by several laboratories, has become a standard in the field and has aided in addressing the above limitations of the range of stomatal aperture sizes found under any given condition.Research in our laboratory has shown that a major additional improvement in experiments can be made, by adding imaging of the same individual stomatal apertures over time (Allen et al., 2001; Mori et al., 2006; Vahisalu et al., 2008; Siegel et al., 2009), while performing blind experiments. In such ‘stomatal tracking’ experiments the lower side of a leaf is attached to a glass coverslip in an extracellular incubation medium (Webb et al., 2001; Young et al., 2006). The mesophyll and upper leaf epidermis are removed surgically for better optical resolution of stomatal apertures in the intact lower leaf epidermis (Young et al., 2006). For stimulus-induced stomatal closing analyses, a field of well-opened stomata is located and images are captured (e.g. using Scion Image software) for later analyses and data storage. The bottom (dry side) of coverslips can be marked with colour marker pens to label grids in the regions where apertures where imaged, for finding these same stomata subsequently if needed. Images of the same stomatal apertures are taken over time and can be stored for later analyses of individual stomatal apertures and for deposition of image files. While this approach has been used as a standard for imposed Ca2+ oscillation studies (Allen et al., 2001; Mori et al., 2006; Vahisalu et al., 2008; Fig. 4), we have found that this method also substantially improves stomatal movement response analyses to any given stimulus (Siegel et al., 2009; see Figs 1 and 4 and, Box Fig. 1). For example, while individual stomata are known to have diverse apertures (e.g. Box Fig. 1C), the relative responses of wide open stomata and smaller stomatal apertures to ABA or to CO2 were comparable (Fig. 1 and Box Fig. 1; Siegel et al., 2009). Note that this method has previously been proposed and used in Vicia faba (Gorton et al., 1988), for which stomata exhibit relatively weak ABA and CO2 responses, compared with, for example, Arabidopsis. We propose that this simple image-capturing approach, together with blind analyses, be used as a standard for stomatal response research in arabidopsis. Our research experience with this method shows that this approach will aid in greatly improving resolution and robustness and in defining the functions of individual Ca2+-independent and Ca2+-dependent components and mechanisms in stomatal response analyses. Open in a separate windowBox Fig. 1.ABA-induced stomatal closing of individually tracked stomatal apertures. (A) Average individually tracked stomatal apertures in the presence of 50 µm Ca2+ (open triangles) and in the presence of 200 nm free Ca2+ (open squares) in the bath solution from three experiments are shown and were normalized to the stomatal apertures at time = 0. (B, C) ABA-induced stomatal closing in the presence of 50 µm Ca2+ in five individually tracked stomatal apertures. In (A; open triangles) normalized stomatal apertures of the same stomata depicted in (B) and (C) are shown. Methods used in these experiments tracking individual stomatal apertures are described in Siegel et al. (2009). ABA-induced stomatal closing experiments are reproduced from Siegel et al. (2009) with permission of the publisher. 相似文献14.
A theoretical model of calcium signaling is presented that simulates oscillations of cytoplasmic calcium concentration ([Ca2+]cyt) in stomatal guard cells under the action of abscisic acid. The model is based on the kinetics of inositol 1,4,5-trisphosphate-sensitive calcium channels of endoplasmic reticulum and cyclic ADP-ribose-sensitive calcium channels of the tonoplast. The operation of two energy-dependent pumps—the Ca2+-ATPase of the endoplasmic reticulum and the Ca2+/H+ antiporter of the tonoplast—is also included in the model. It is shown that the removal of excessive Ca2+ from the cytoplasm by the tonoplast Ca2+/H+ antiporter is the main factor accounting for generation of [Ca2+]cyt oscillations at a wide range of ABA concentrations (0.01–1 M). The long period of [Ca2+]cyt oscillations in plant cells is explained by a slow release from inhibition of inositol 1,4,5-trisphosphate-gated calcium channels. 相似文献
15.
CDPKs CPK6 and CPK3 function in ABA regulation of guard cell S-type anion- and Ca(2+)-permeable channels and stomatal closure 总被引:1,自引:0,他引:1
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Mori IC Murata Y Yang Y Munemasa S Wang YF Andreoli S Tiriac H Alonso JM Harper JF Ecker JR Kwak JM Schroeder JI 《PLoS biology》2006,4(10):e327
Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca2+ in guard cell ion channel regulation. However, genetic mutants in Ca2+ sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca2+-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell–expressed CDPK genes, CPK3 and CPK6 , showed gene disruption phenotypes. ABA and Ca2+ activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca2+-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca2+-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca2+ oscillation experiments revealed that Ca2+-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca2+-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca2+-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling. 相似文献
16.
17.
Plant cells maintain high Ca2+ concentration gradients between the cytosol and the extracellular matrix, as well as intracellular compartments. During evolution, the regulatory mechanisms, maintaining low cytosolic free Ca2+ concentrations, most likely provided the backbone for the development of Ca2+‐dependent signalling pathways. In this review, the current understanding of molecular mechanisms involved in Ca2+ homeostasis of plants cells is evaluated. The question is addressed to which extent the mechanisms, controlling the cytosolic Ca2+ concentration, are linked to Ca2+‐based signalling. A large number of environmental stimuli can evoke Ca2+ signals, but the Ca2+‐induced responses are likely to differ depending on the stimulus applied. Two mechanisms are put forward to explain signal specificity of Ca2+‐dependent responses. A signal may evoke a specific Ca2+ signature that is recognized by downstream signalling components. Alternatively, Ca2+ signals are accompanied by Ca2+‐independent signalling events that determine the specificity of the response. The existence of such parallel‐acting pathways explains why guard cell responses to abscisic acid (ABA) can occur in the absence, as well as in the presence, of Ca2+ signals. Future research may shed new light on the relation between parallel acting Ca2+‐dependent and ‐independent events, and may provide insights in their evolutionary origin. 相似文献
18.
Eiji Okuma Md. Sarwar Jahan Shintaro Munemasa Mohammad Anowar HossainDaichi Muroyama Mohammad Mahbub IslamKen’ichi Ogawa Megumi Watanabe-SugimotoYoshimasa Nakamura Yasuaki ShimoishiIzumi C. Mori Yoshiyuki Murata 《Journal of plant physiology》2011,168(17):2048-2055
We found that glutathione (GSH) is involved in abscisic acid (ABA)-induced stomatal closure. Regulation of ABA signaling by GSH in guard cells was investigated using an Arabidopsis mutant, cad2-1, that is deficient in the first GSH biosynthesis enzyme, γ-glutamylcysteine synthetase, and a GSH-decreasing chemical, 1-chloro-2,4-dinitrobenzene (CDNB). Glutathione contents in guard cells decreased along with ABA-induced stomatal closure. Decreasing GSH by both the cad2-1 mutation and CDNB treatment enhanced ABA-induced stomatal closure. Glutathione monoethyl ester (GSHmee) restored the GSH level in cad2-1 guard cells and complemented the stomatal phenotype of the mutant. Depletion of GSH did not significantly increase ABA-induced production of reactive oxygen species in guard cells and GSH did not affect either activation of plasma membrane Ca2+-permeable channel currents by ABA or oscillation of the cytosolic free Ca2+ concentration induced by ABA. These results indicate that GSH negatively modulates a signal component other than ROS production and Ca2+ oscillation in ABA signal pathway of Arabidopsis guard cells. 相似文献
19.
Early ABA Signaling Events in Guard Cells 总被引:1,自引:0,他引:1
The plant hormone abscisic acid (ABA) regulates a wide variety of plant physiological and developmental processes, particularly
responses to environmental stress, such as drought. In response to water deficiency, plants redistribute foliar ABA and/or
upregulate ABA synthesis in roots, leading to roughly a 30-fold increase in ABA concentration in the apoplast of stomatal
guard cells. The elevated ABA triggers a chain of events in guard cells, causing stomatal closure and thus preventing water
loss. Although the molecular nature of ABA receptor(s) remains unknown, considerable progress in the identification and characterization
of its downstream signaling elements has been made by using combined physiological, biochemical, biophysical, molecular, and
genetic approaches. The measurable events associated with ABA-induced stomatal closure in guard cells include, sequentially,
the production of reactive oxygen species (ROS), increases in cytosolic free Ca2+ levels ([Ca2+]i), activation of anion channels, membrane potential depolarization, cytosolic alkalinization, inhibition of K+ influx channels, and promotion of K+ efflux channels. This review provides an overview of the cellular and molecular mechanisms underlying these ABA-evoked signaling
events, with particular emphasis on how ABA triggers an “electronic circuitry” involving these ionic components. 相似文献
20.
Patrice Meimoun Guillaume Vidal Anne-Sophie Bohrer Arnaud Lehner Daniel Tran Jo?l Briand Fran?ois Bouteau Jean-Pierre Rona 《Plant signaling & behavior》2009,4(9):830-835
In Arabidopsis thaliana cell suspension,abscisic acid (aBa) induces changes in cytosolic calcium concentration ([Ca2+]cyt) which are the trigger for aBa-induced plasma membrane anion current activation, H+-aTPase inhibition, and subsequent plasma membrane depolarization. In the present study, we took advantage of this model to analyze the implication of intracellular Ca2+ stores in aBa signal transduction through electrophysiological current measurements, cytosolic Ca2+ activity measurements with the apoaequorin Ca2+ reporter protein and external pH measurement. Intracellular Ca2+ stores involvement was determined by using specific inhibitors of CICR channels: the cADP-ribose/ryanodine receptor (Br-cADPR and dantrolene) and of the inositol trisphosphate receptor (). In addition experiments were performed on epidermal strips of A. thaliana leaves to monitor stomatal closure in response to ABA in presence of the same pharmacology. Our data provide evidence that ryanodine receptor and inositol trisphosphate receptor could be involved in ABA-induced (1) Ca2+ release in the cytosol, (2) anion channel activation and H+-ATPase inhibition leading to plasma membrane depolarization and (3) stomatal closure. Intracellular Ca2+ release could thus contribute to the control of early events in the ABA signal transduction pathway in A. thaliana. U73122相似文献