Modulation of frequency and height of cytosolic calcium spikes by plasma membrane anion channels in guard cells

2021 ◽  
Author(s):  
Md Tahjib-Ul-Arif ◽  
Shintaro Munemasa ◽  
Toshiyuki Nakamura ◽  
Yoshimasa Nakamura ◽  
Yoshiyuki Murata
Keyword(s):  
Plasma Membrane ◽  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Cytosolic Calcium ◽  
Peak Height ◽  
Extracellular Calcium ◽  
Wild Type ◽  
Anion Channels ◽  
In The Wild

Abstract Cytosolic calcium ([Ca2+]cyt) elevation activates plasma membrane anion channels in guard cells, which is required for stomatal closure. However, involvement of the anion channels in the [Ca2+]cyt elevation remains unclear. We investigated the involvement using Arabidopsis thaliana anion channel mutants, slac1-4 slah3-3 and slac1-4 almt12-1. Extracellular calcium induced stomatal closure in the wild-type plants but not in the anion channel mutant plants whereas extracellular calcium induced [Ca2+]cyt elevation both in the wild-type guard cells and in the mutant guard cells. The peak height and the number of the [Ca2+]cyt spike were lower and larger in the slac1-4 slah3-3 than in the wild-type and the height and the number in the slac1-4 almt12-1 were much lower and much larger than in the wild-type. These results suggest that the anion channels are involved in the regulation of [Ca2+]cyt elevation in guard cells.

scholarly journals Optogenetic control of the guard cell membrane potential and stomatal movement by the light-gated anion channel GtACR1

2021 ◽  
Vol 7 (28) ◽  
pp. eabg4619
Author(s):  
Shouguang Huang ◽  
Meiqi Ding ◽  
M. Rob G. Roelfsema ◽  
Ingo Dreyer ◽  
Sönke Scherzer ◽  
...  
Keyword(s):  
Guard Cell ◽  
Stomatal Closure ◽  
Green Light ◽  
Anion Channel ◽  
Guard Cells ◽  
Wild Type ◽  
Anion Channels ◽  
Light Pulses ◽  
Cell Turgor ◽  
Open Question

Guard cells control the aperture of plant stomata, which are crucial for global fluxes of CO2 and water. In turn, guard cell anion channels are seen as key players for stomatal closure, but is activation of these channels sufficient to limit plant water loss? To answer this open question, we used an optogenetic approach based on the light-gated anion channelrhodopsin 1 (GtACR1). In tobacco guard cells that express GtACR1, blue- and green-light pulses elicit Cl− and NO3− currents of −1 to −2 nA. The anion currents depolarize the plasma membrane by 60 to 80 mV, which causes opening of voltage-gated K+ channels and the extrusion of K+. As a result, continuous stimulation with green light leads to loss of guard cell turgor and closure of stomata at conditions that provoke stomatal opening in wild type. GtACR1 optogenetics thus provides unequivocal evidence that opening of anion channels is sufficient to close stomata.

scholarly journals Molecular basis for the R-type anion channel QUAC1 activity in guard cells

2021 ◽  
Author(s):  
Li Qin ◽  
Ling-hui Tang ◽  
Jia-shu Xu ◽  
Xian-hui Zhang ◽  
Yun Zhu ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Channel Activity ◽  
Cytoplasmic Domains ◽  
Anion Channels ◽  
Channel Activation ◽  
Environmental Stimuli ◽  
Functional Analyses

SUMMARYThe rapid (R)-type anion channel plays a central role in controlling stomatal closure in plant guard cells, thus regulating the exchange of water and photosynthetic gas (CO2) in response to environmental stimuli. The activity of the R- type anion channel is regulated by malate. However, the molecular basis of the R-type anion channel activity remains elusive. Here, we describe the first cryo-EM structure of the R-type anion channel QUAC1 at 3.5 Å resolution in the presence of malate. The structure reveals that the QUAC1 is a symmetrical dimer, forming a single electropositive T-shaped pore for passing anions across the membrane. The transmembrane and cytoplasmic domains are assembled into a twisted bi-layer architecture, with the associated dimeric interfaces nearly perpendicular. Our structural and functional analyses reveal that QUAC1 functions as an inward rectifying anion channel and suggests a mechanism for malate-mediated channel activation. Altogether, our study uncovers the molecular basis for a novel class of anion channels and provides insights into the gating and modulation of the R-type anion channel.

Plasma membrane ion channel regulation during abscisic acid-induced closing of stomata

1992 ◽  
Vol 338 (1283) ◽  
pp. 83-89 ◽  
Keyword(s):  
Plasma Membrane ◽  
Abscisic Acid ◽  
Ion Channels ◽  
Patch Clamp ◽  
Integrated Control ◽  
Anion Channel ◽  
Guard Cells ◽  
Anion Channels ◽  
Higher Plant ◽  
Ion Channel Regulation

The plant growth regulator abscisic acid triggers closing of stomata in the leaf epidermis in response to water stress. Recent tracer flux studies, patch-clamp studies, fluorometric Ca 2+ measurements and microelectrode experiments have provided insight into primary transduction mechanisms by which abscisic acid causes stomatal closing. Data show that abscisic acid activates non-selective Ca 2+ permeable ion channels in the plasma membrane of guard cells. The resulting elevation in the free Ca 2+ concentration in the cytosol of guard cells, and the resulting membrane depolarization as well as other unidentified Ca 2+ independent mechanisms are suggested to contribute to activation of voltage- and second messenger-dependent anion channels and outward rectifying K + channels. Recent data suggest the involvement of two types of anion channels in the regulation of stomatal movements, which provide highly distinct mechanisms for anion efflux and depolarization. A novely characterized ‘S-type’ anion channel is likely to provide a key mechanism for long-term depolarization and sustained anion efflux during closing of stomata. Patch-clamp studies have revealed the presence of a network of K + , anion and non-selective Ca 2+ -permeable channels in the plasma membrane of a higher plant cell. The integrated control of these guard cell ion channels by abscisic acid can provide control over K + and anion efflux required for stomatal closing.

scholarly journals Anion channel sensitivity to cytosolic organic acids implicates a central role for oxaloacetate in integrating ion flux with metabolism in stomatal guard cells

2011 ◽  
Vol 439 (1) ◽  
pp. 161-170 ◽  
Author(s):  
Yizhou Wang ◽  
Michael R. Blatt
Keyword(s):  
Plasma Membrane ◽  
Organic Acids ◽  
Organic Acid ◽  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Solute Flux ◽  
Stomatal Guard Cells ◽  
The Impact

Stomatal guard cells play a key role in gas exchange for photosynthesis and in minimizing transpirational water loss from plants by opening and closing the stomatal pore. The bulk of the osmotic content driving stomatal movements depends on ionic fluxes across both the plasma membrane and tonoplast, the metabolism of organic acids, primarily Mal (malate), and its accumulation and loss. Anion channels at the plasma membrane are thought to comprise a major pathway for Mal efflux during stomatal closure, implicating their key role in linking solute flux with metabolism. Nonetheless, little is known of the regulation of anion channel current (ICl) by cytosolic Mal or its immediate metabolite OAA (oxaloacetate). In the present study, we have examined the impact of Mal, OAA and of the monocarboxylic acid anion acetate in guard cells of Vicia faba L. and report that all three organic acids affect ICl, but with markedly different characteristics and sidedness to their activities. Most prominent was a suppression of ICl by OAA within the physiological range of concentrations found in vivo. These findings indicate a capacity for OAA to co-ordinate organic acid metabolism with ICl through the direct effect of organic acid pool size. The findings of the present study also add perspective to in vivo recordings using acetate-based electrolytes.

scholarly journals Identification of SLAC1 anion channel residues required for CO2/bicarbonate sensing and regulation of stomatal movements

2018 ◽  
Vol 115 (44) ◽  
pp. 11129-11137 ◽  
Author(s):  
Jingbo Zhang ◽  
Nuo Wang ◽  
Yinglong Miao ◽  
Felix Hauser ◽  
J. Andrew McCammon ◽  
...  
Keyword(s):  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Channel Activity ◽  
Plant Leaves ◽  
In Planta ◽  
Anion Channels ◽  
Accelerated Molecular Dynamics ◽  
Bicarbonate Ions ◽  
Stomatal Movements

Increases in CO2 concentration in plant leaves due to respiration in the dark and the continuing atmospheric [CO2] rise cause closing of stomatal pores, thus affecting plant–water relations globally. However, the underlying CO2/bicarbonate (CO2/HCO3−) sensing mechanisms remain unknown. [CO2] elevation in leaves triggers stomatal closure by anion efflux mediated via the SLAC1 anion channel localized in the plasma membrane of guard cells. Previous reconstitution analysis has suggested that intracellular bicarbonate ions might directly up-regulate SLAC1 channel activity. However, whether such a CO2/HCO3− regulation of SLAC1 is relevant for CO2 control of stomatal movements in planta remains unknown. Here, we computationally probe for candidate bicarbonate-interacting sites within the SLAC1 anion channel via long-timescale Gaussian accelerated molecular dynamics (GaMD) simulations. Mutations of two putative bicarbonate-interacting residues, R256 and R321, impaired the enhancement of the SLAC1 anion channel activity by CO2/HCO3− in Xenopus oocytes. Mutations of the neighboring charged amino acid K255 and residue R432 and the predicted gate residue F450 did not affect HCO3− regulation of SLAC1. Notably, gas-exchange experiments with slac1-transformed plants expressing mutated SLAC1 proteins revealed that the SLAC1 residue R256 is required for CO2 regulation of stomatal movements in planta, but not for abscisic acid (ABA)-induced stomatal closing. Patch clamp analyses of guard cells show that activation of S-type anion channels by CO2/HCO3−, but not by ABA, was impaired, indicating the relevance of R256 for CO2 signal transduction. Together, these analyses suggest that the SLAC1 anion channel is one of the physiologically relevant CO2/HCO3− sensors in guard cells.

Hydrogen sulfide induced by hydrogen peroxide mediates brassinosteroid-induced stomatal closure of Arabidopsis thaliana

2021 ◽  
Vol 48 (2) ◽  
pp. 195 ◽  
Author(s):  
Yinli Ma ◽  
Luhan Shao ◽  
Wei Zhang ◽  
Fengxi Zheng
Keyword(s):  
Hydrogen Peroxide ◽  
Arabidopsis Thaliana ◽  
Hydrogen Sulfide ◽  
Stomatal Closure ◽  
Guard Cells ◽  
H2o2 Production ◽  
Wild Type ◽  
Synthesis Inhibitor ◽  
In The Wild ◽  
H2s Production

The role of hydrogen sulfide (H2S) and its relationship with hydrogen peroxide (H2O2) in brassinosteroid-induced stomatal closure in Arabidopsis thaliana (L.) Heynh. were investigated. In the present study, 2,4-epibrassinolide (EBR, a bioactive BR) induced stomatal closure in the wild type, the effects were inhibited by H2S scavenger and synthesis inhibitors, and H2O2 scavengers and synthesis inhibitor. However, EBR failed to close the stomata of mutants Atl-cdes, Atd-cdes, AtrbohF and AtrbohD/F. Additionally, EBR induced increase of L-/D-cysteine desulfhydrase (L-/D-CDes) activity, H2S production, and H2O2 production in the wild type, and the effects were inhibited by H2S scavenger and synthesis inhibitors, and H2O2 scavengers and synthesis inhibitor respectively. Furthermore, EBR increased H2O2 levels in the guard cells of AtrbohD mutant, but couldn’t raise H2O2 levels in the guard cells of AtrbohF and AtrbohD/F mutants. Next, scavengers and synthesis inhibitor of H2O2 could significantly inhibit EBR-induced rise of L-/D-CDes activity and H2S production in the wild type, but H2S scavenger and synthesis inhibitors failed to repress EBR-induced H2O2 production. EBR could increase H2O2 levels in the guard cells of Atl-cdes and Atd-cdes mutants, but EBR failed to induce increase of L-/D-CDes activity and H2S production in AtrbohF and AtrbohD/F mutants. Therefore, we conclude that H2S and H2O2 are involved in the signal transduction pathway of EBR-induced stomatal closure. Altogether, our data suggested that EBR induces AtrbohF-dependent H2O2 production and subsequent AtL-CDes-/AtD-CDes-catalysed H2S production, and finally closes stomata in A. thaliana.

scholarly journals Arabidopsis NPF4.6 and NPF5.1 Control Leaf Stomatal Aperture by Regulating Abscisic Acid Transport

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 885
Author(s):  
Takafumi Shimizu ◽  
Yuri Kanno ◽  
Hiromi Suzuki ◽  
Shunsuke Watanabe ◽  
Mitsunori Seo
Keyword(s):  
Abscisic Acid ◽  
Plant Hormone ◽  
Leaf Surface ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Cell Types ◽  
Acid Transport ◽  
Wild Type ◽  
Vascular Tissues ◽  
Abscisic Acid Transport

The plant hormone abscisic acid (ABA) is actively synthesized in vascular tissues and transported to guard cells to promote stomatal closure. Although several transmembrane ABA transporters have been identified, how the movement of ABA within plants is regulated is not fully understood. In this study, we determined that Arabidopsis NPF4.6, previously identified as an ABA transporter expressed in vascular tissues, is also present in guard cells and positively regulates stomatal closure in leaves. We also found that mutants defective in NPF5.1 had a higher leaf surface temperature compared to the wild type. Additionally, NPF5.1 mediated cellular ABA uptake when expressed in a heterologous yeast system. Promoter activities of NPF5.1 were detected in several leaf cell types. Taken together, these observations indicate that NPF5.1 negatively regulates stomatal closure by regulating the amount of ABA that can be transported from vascular tissues to guard cells.

Sevoflurane but not propofol provided dual effects of cell survival in human neuroblastoma SH-SY5Y cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Xue Gao ◽  
Xiu Wang ◽  
Lei Zhang ◽  
Ge Liang ◽  
Rachel Mund ◽  
...  
Keyword(s):  
Cell Survival ◽  
Prolonged Exposure ◽  
Calcium Influx ◽  
Cell Damage ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Mitochondrial Calcium ◽  
General Anesthetics ◽  
Wild Type ◽  
Human Neuroblastoma

Background: We have hypothesized that the most commonly used intravenous (propofol) and inhalational (sevoflurane) general anesthetics affect cell survival concentration and duration dependently with different potency associated with their differential potency to affect intracellular calcium homeostasis. Methods: Human neuroblastoma SH-SY5Y cells stably transfected with either wild type or M146L mutant human presenilin 1 were cultured and exposed to equipotent of propofol or sevoflurane. Cell viability, cytosolic and mitochondrial calcium were measured. Results: Sevoflurane but not propofol, at clinically relevant concentrations and durations, promoted cell survival. Prolonged exposure (24 hours) of 1% sevoflurane resulted in significant cell damage in both types of cells. Both sevoflurane and propofol had significantly higher cell response rates to the elevation of cytosolic calcium or mitochondrial calcium in the presence of extracellular calcium. With the contribution of calcium influx, sevoflurane but not equipotent 1 MAC propofol, caused a significantly greater increase in peak and overall calcium in Alzheimer’s mutation cell than in wild type cells, but significantly more increase in overall mitochondrial calcium concentrations in wild type than mutation cells. In the absence of extracellular calcium influx, sevoflurane, but not propofol, caused more significant elevations of overall mitochondrial calcium concentration in mutation cells than control cells. Conclusion: Calcium influx contributed to the general anesthetics mediated elevation of cytosolic or mitochondrial calcium, which is especially true for propofol. Sevoflurane has a greater potency to either promote or inhibit cell survival than propofol, which may be associated with its ability to affect cytosolic or mitochondrial calcium.

scholarly journals Overexpression of Plasma Membrane H+-ATPase in Guard Cells Enhances Light-Induced Stomatal Opening, Photosynthesis, and Plant Growth in Hybrid Aspen

2021 ◽  
Vol 12 ◽  
Author(s):  
Shigeo Toh ◽  
Naoki Takata ◽  
Eigo Ando ◽  
Yosuke Toda ◽  
Yin Wang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Transgenic Plants ◽  
Woody Plants ◽  
Stem Elongation ◽  
Guard Cells ◽  
Gus Expression ◽  
Stomatal Opening ◽  
Wild Type ◽  
Exchange System ◽  
Gas Exchange System

Stomata in the plant epidermis open in response to light and regulate CO2 uptake for photosynthesis and transpiration for uptake of water and nutrients from roots. Light-induced stomatal opening is mediated by activation of the plasma membrane (PM) H+-ATPase in guard cells. Overexpression of PM H+-ATPase in guard cells promotes light-induced stomatal opening, enhancing photosynthesis and growth in Arabidopsis thaliana. In this study, transgenic hybrid aspens overexpressing Arabidopsis PM H+-ATPase (AHA2) in guard cells under the strong guard cell promoter Arabidopsis GC1 (AtGC1) showed enhanced light-induced stomatal opening, photosynthesis, and growth. First, we confirmed that AtGC1 induces GUS expression specifically in guard cells in hybrid aspens. Thus, we produced AtGC1::AHA2 transgenic hybrid aspens and confirmed expression of AHA2 in AtGC1::AHA2 transgenic plants. In addition, AtGC1::AHA2 transgenic plants showed a higher PM H+-ATPase protein level in guard cells. Analysis using a gas exchange system revealed that transpiration and the photosynthetic rate were significantly increased in AtGC1::AHA2 transgenic aspen plants. AtGC1::AHA2 transgenic plants showed a>20% higher stem elongation rate than the wild type (WT). Therefore, overexpression of PM H+-ATPase in guard cells promotes the growth of perennial woody plants.

scholarly journals Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Yi Liu ◽  
Tobias Maierhofer ◽  
Katarzyna Rybak ◽  
Jan Sklenar ◽  
Andy Breakspear ◽  
...  
Keyword(s):  
Stomatal Closure ◽  
Anion Channel ◽  
Anion Channels ◽  
Slow Type ◽  
Leaf Level ◽  
Short Signal ◽  
Molecular Patterns ◽  
Fungal Immunity ◽  
Anti Fungal ◽  
Full Activation

In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.

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