scholarly journals Ozone Altered Stomatal/Guard Cell Function: Whole Plant and Single Cell Analysis

2000 ◽  
Author(s):  
Eva J. Pell ◽  
Sarah M. Assmann ◽  
Amnon Schwartz ◽  
Hava Steinberger
Keyword(s):  
Hydrogen Peroxide ◽  
Gas Exchange ◽  
Vicia Faba ◽  
Guard Cell ◽  
Cell Function ◽  
Stomatal Closure ◽  
Relative Sensitivity ◽  
Guard Cells ◽  
Stomatal Opening ◽  
K Channels

Original objectives (revisions from original proposal are highlighted) 1. Elucidate the direct effects O3 and H2O2 on guard cell function, utilizing assays of stomatal response in isolated epidermal peels and whole cell gas exchange. 2. Determine the mechanistic basis of O3 and H2O2 effects on the plasma membrane through application of the electrophysiological technique of patch clamping to isolated guard cells. 3. Determine the relative sensitivity of Israeli cultivars of economically important crops to O3 and determine whether differential leaf conductance responses to O3 can explain relative sensitivity to the air pollutant: transfer of technological expertise to Israel. Background to the topic For a long time O3 has been known to reduce gas exchange in plants; it has however been unclear if O3 can affect the stomatal complex directly. Ion channels are essential in stomatal regulation, but O3 has never before been shown to affect these directly. Major conclusions, solution, achievements 1. Ozone inhibits light-induced stomatal opening in epidermal peels isolated from Vicia faba, Arabidopsis thaliana and Nicotiana tabacum in V. faba plants this leads to reduced assimilation without a direct effect on the photosynthetic apparatus. Stomatal opening is more sensitive to O3 than stomatal closure. 2. Ozone causes inhibition of inward K+ channels (involved in stomatal opening) while no detectable effect is observed o the outward K+ channels (stomatal closure). 3. Hydrogen peroxide inhibits stomatal opening and induces stomatal closure in epidermal peels isolated from Vicia faba. 4. Hydrogen peroxide enhances stomatal closure by increasing K+ efflux from guard cells via outward rectifying K+ channels. 5. Based on epidermal peel experiments we have indirectly shown that Ca2+ may play a role in the guard cell response to O3. However, direct measurement of the guard cell [Ca2+]cyt did not show a response to O3. 6. Three Israeli cultivars of zucchini, Clarita, Yarden and Bareqet, were shown to be relatively sensitive to O3 (0.12 ml1-1 ). 7. Two environmentally important Israeli pine species are adversely affected by O3, even at 0.050 ml1-1 , a level frequently exceeded under local tropospheric conditions. P. brutia may be better equipped than P. halepensis to tolerate O3 stress. 8. Ozone directly affects pigment biosynthesis in pine seedlings, as well as the metabolism of O5 precursors, thus affecting the allocation of resources among various metabolic pathways. 9. Ozone induces activity of antioxidant enzymes, and of ascorbate content i the mesophyll and epidermis cells of Commelina communis L. Implications, both scientific and agricultural We have improved the understanding of how O3 and H2O2 do affect guard cell and stomatal function. We have shown that economical important Israeli species like zucchini and pine are relatively sensitive to O3.

scholarly journals K+ transport properties of K+ channels in the plasma membrane of Vicia faba guard cells.

1988 ◽  
Vol 92 (5) ◽  
pp. 667-683 ◽  
Author(s):  
J I Schroeder
Keyword(s):  
Plasma Membrane ◽  
Transport Properties ◽  
Vicia Faba ◽  
Guard Cell ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Whole Cell ◽  
K Channels ◽  
K Transport ◽  
K Currents

Electrical properties of the plasma membrane of guard cell protoplasts isolated from stomates of Vicia faba leaves were studied by application of the whole-cell configuration of the patch-clamp technique. The two types of K+ currents that have recently been identified in guard cells may allow efflux of K+ during stomatal closing, and uptake of K+ during stomatal opening (Schroeder et al., 1987). A detailed characterization of ion transport properties of the inward-rectifying (IK+,in) and the outward-rectifying (IK+,out) K+ conductance is presented here. The permeability ratios of IK+,in and IK+,out currents for K+ over monovalent alkali metal ions were determined. The resulting permeability sequences (PK+ greater than PRb+ greater than PNa+ greater than PLi+ much greater than PCs+) corresponded closely to the ion specificity of guard cell movements in V. faba. Neither K+ currents exhibited significant inactivation when K+ channels were activated for prolonged periods (greater than 10 min). The absence of inactivation may permit long durations of K+ fluxes, which occur during guard cell movements. Activation potentials of inward K+ currents were not shifted when external K+ concentrations were changed. This differs strongly from the behavior of inward-rectifying K+ channels in animal tissue. Blue light and fusicoccin induce hyperpolarization by stimulation of an electrogenic pump. From slow-whole-cell recordings it was concluded that electrogenic pumps require cytoplasmic substrates for full activation and that the magnitude of the pump current is sufficient to drive K+ uptake through IK+,in channels. First, direct evidence was gained for the hypothesis that IK+,in channels are a molecular pathway for K+ accumulation by the finding that IK+,in was blocked by Al3+ ions, which are known to inhibit stomatal opening but not closing. The results presented in this study strongly support a prominent role for IK+,in and IK+,out channels in K+ transport across the plasma membrane of guard cells.

Cytokinin- and auxin-induced stomatal opening involves a decrease in levels of hydrogen peroxide in guard cells of Vicia faba

2006 ◽  
Vol 33 (6) ◽  
pp. 573 ◽  
Author(s):  
Xi-Gui Song ◽  
Xiao-Ping She ◽  
Jun-Min He ◽  
Chen Huang ◽  
Tu-sheng Song
Keyword(s):  
Hydrogen Peroxide ◽  
Vicia Faba ◽  
Laser Scanning ◽  
Guard Cells ◽  
Laser Scanning Confocal Microscopy ◽  
Stomatal Opening ◽  
Scanning Confocal Microscopy ◽  
Diphenylene Iodonium ◽  
The Relationship ◽  
Exogenous H2o2

Previous studies have shown that cytokinins and auxins can induce the opening of stomata. However, the mechanism of stomatal opening caused by cytokinins and auxins remains unclear. The purpose of this paper is to investigate the relationship between hydrogen peroxide (H2O2) levels in guard cells and stomatal opening induced by cytokinins and auxins in Vicia faba. By means of stomatal bioassay and laser-scanning confocal microscopy, we provide evidence that cytokinins and auxins reduced the levels of H2O2 in guard cells and induced stomatal opening in darkness. Additionally, cytokinins not only reduced exogenous H2O2 levels in guard cells caused by exposure to light, but also abolished H2O2 that had been generated during a dark period, and promoted stomatal opening, as did ascorbic acid (ASA, an important reducing substrate for H2O2 removal). However, unlike cytokinins, auxins did not reduce exogenous H2O2, did not abolish H2O2 that had been generated in the dark, and therefore did not promote reopening of stoma induced to close in the dark. The above-mentioned effects of auxins were similar to that of diphenylene iodonium (DPI, an inhibitor of the H2O2-generating enzyme NADPH oxidase). Taken together our results indicate that cytokinins probably reduce the levels of H2O2 in guard cells by scavenging, whereas auxins limit H2O2 levels through restraining H2O2 generation, inducing stomatal opening in darkness.

Hydrogen sulfide may function downstream of hydrogen peroxide in salt stress-induced stomatal closure in Vicia faba

2019 ◽  
Vol 46 (2) ◽  
pp. 136 ◽  
Author(s):  
Yinli Ma ◽  
Wei Zhang ◽  
Jiao Niu ◽  
Yu Ren ◽  
Fan Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Sulfide ◽  
Salt Stress ◽  
Vicia Faba ◽  
Laser Scanning ◽  
Stomatal Closure ◽  
Guard Cells ◽  
H2o2 Production ◽  
Diphenylene Iodonium ◽  
Cysteine Desulfhydrase

The roles of hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) in signalling transduction of stomatal closure induced by salt stress were examined by using pharmacological, spectrophotographic and laser scanning confocal microscopic (LSCM) approaches in Vicia faba L. Salt stress resulted in stomatal closure, and this effect was blocked by H2S modulators hypotaurine (HT), aminooxy acetic acid (AOA), hydroxylamine (NH2OH), potassium pyruvate (C3H3KO3) and ammonia (NH3) and H2O2 modulators ascorbic acid (ASA), catalase (CAT), diphenylene iodonium (DPI). Additionally, salt stress induced H2S generation and increased L-/D-cysteine desulfhydrase (L-/D-CDes, pyridoxalphosphate-dependent enzyme) activity in leaves, and caused H2O2 production in guard cells, and these effects were significantly suppressed by H2S modulators and H2O2 modulators respectively. Moreover, H2O2 modulators suppressed salt stress-induced increase of H2S levels and L-/D-CDes activity in leaves as well as stomatal closure of V. faba. However, H2S modulators had no effects on salt stress-induced H2O2 production in guard cells. Altogether, our data suggested that H2S and H2O2 probably are involved in salt stress-induced stomatal closure, and H2S may function downstream of H2O2 in salt stress-induced stomatal movement in V. faba.

Ethylene inhibits darkness-induced stomatal closure by scavenging nitric oxide in guard cells of Vicia faba

2011 ◽  
Vol 38 (10) ◽  
pp. 767 ◽  
Author(s):  
Xi-Gui Song ◽  
Xiao-Ping She ◽  
Juan Wang ◽  
Yi-Chao Sun
Keyword(s):  
Nitric Oxide ◽  
Vicia Faba ◽  
Plant Hormone ◽  
No Reduction ◽  
Enzyme Commission ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Physiological Data ◽  
Oxide Synthase

The plant hormone ethylene regulates many aspects of plant growth and development. Despite the well-known relationship between ethylene and stress signalling, the involvement of ethylene in regulating stomatal movement is not completely explored. Here, the role and association between nitric oxide (NO) reduction and the inhibition of darkness-induced stomatal closure by ethylene was studied. Physiological data are provided that both ethylene-releasing compound 2-chloroethylene phosphonic acid (ethephon, ETH) and 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, reduced the levels of NO in Vicia faba L. guard cells, and then induced stomatal opening in darkness. In addition, ACC and ETH not only reduced NO levels in guard cells caused by exogenous NO (derived from sodium nitroprusside, SNP) in light, but also abolished NO that had been generated during a dark period and promoted stomatal opening. Interestingly, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) and hemoglobin (Hb), NO scavenger and the potent scavenger of NO/carbon monoxide (CO), respectively, also reduced NO levels by SNP and darkness. However, the above-mentioned effects of ACC and ETH were dissimilar to that of nitric oxide synthase (enzyme commission 1.14.13.39) inhibitor NG-nitro-L-Arg-methyl ester (L-NAME), which could neither reduce NO levels by SNP nor abolish NO that had been generated in the dark. Thus, it is concluded that ethylene reduces the levels of NO in V. faba guard cells via a pattern of NO scavenging, then induces stomatal opening in the dark.

Hydrogen sulfide may function downstream of hydrogen peroxide in mediating darkness-induced stomatal closure in Vicia faba

2018 ◽  
Vol 45 (5) ◽  
pp. 553 ◽  
Author(s):  
Yinli Ma ◽  
Jiao Niu ◽  
Wei Zhang ◽  
Xiang Wu
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Hydrogen Sulfide ◽  
Vicia Faba ◽  
Stomatal Closure ◽  
Guard Cells ◽  
H2o2 Accumulation ◽  
Vicia Faba L ◽  
Cysteine Desulfhydrase ◽  
The Relationship

The relationship between hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) during darkness-induced stomatal closure in Vicia faba L. was investigated by using pharmacological, spectrophotographic and lasers canning confocal microscopic approaches. Darkness-induced stomatal closure was inhibited by H2S scavenger hypotaurine (HT), H2S synthesis inhibitors aminooxy acetic acid (AOA) and hydroxylamine (NH2OH) and potassium pyruvate (N3H3KO3) and ammonia (NH3), which are the products of L-/D-cysteine desulfhydrase (L-/D-CDes). Moreover, darkness induced H2S generation and increased L-/D-CDes activity in leaves of V. faba. H2O2 scavenger and synthesis inhibitors suppressed darkness-induced increase of H2S levels and L-/D-CDes activity as well as stomatal closure in leaves of V. faba. However, H2S scavenger and synthesis inhibitors had no effect on darkness-induced H2O2 accumulation in guard cells of V. faba. From these data it can be deduced that H2S is involved in darkness-induced stomatal closure and acts downstream of H2O2 in V. faba.

scholarly journals A multi-phase flux balance model reveals flexibility of guard cell central carbon metabolism

2020 ◽  
Author(s):  
Joshua XL Tan ◽  
C. Y. Maurice Cheung
Keyword(s):  
Guard Cell ◽  
Cell Function ◽  
Cell Metabolism ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Diel Cycle ◽  
Balance Model ◽  
Metabolic Processes ◽  
Flux Balance ◽  
Opening And Closing

SummaryExperimental research in guard cell metabolism has revealed the roles of the accumulation of various metabolites in guard cell function, but a comprehensive understanding of their metabolism over the diel cycle is still incomplete, given the limitations of current experimental methods. In this study, we constructed a four-phase flux balance model of guard cell metabolism to investigate the changes in guard cell metabolism over the diel cycle, including the day and night and stomata opening and closing. Our model demonstrated the metabolic flexibility in guard cells, showing that multiple metabolic processes can contribute to the synthesis and metabolism of malate and sucrose as osmolytes during stomatal opening and closing. We showed that guard cells can adapt to varying light availability and sucrose uptake from the apoplast during the day by operating in a mixotrophic mode with a switch between sucrose synthesis via the Calvin-Benson cycle and sucrose degradation via the oxidative pentose phosphate pathway. During stomatal opening, our model predicted an alternative flux mode of the Calvin-Benson cycle with all dephosphorylating steps diverted to diphosphate—fructose-6-phosphate 1-phosphotransferase to produce PPi, which is used to pump protons across the tonoplast for the accumulation of osmolytes. An analysis of the energetics of the use of different osmolytes in guard cells showed that malate and Cl- are similarly efficient as the counterion of K+ during stomatal opening.Significance statementThis work presents the first four-phase metabolic model for predicting guard cell metabolism over the diel cycle, which predicted an alternative flux model of the Calvin-Benson cycle that maximises the production of PPi during stomatal opening. While multiple metabolic processes were shown be important in synthesising and metabolising osmolytes in guard cells of different experimental systems, our model demonstrated that these processes can operate simultaneously and at different rates depending on conditions.

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