scholarly journals The Regulation of Stomatal Aperture in Tobacco Leaf Epidermal Strips

1972 ◽  
Vol 25 (5) ◽  
pp. 877 ◽  
Author(s):  
DA Thomas
Keyword(s):  
Guard Cell ◽  
Cell Membranes ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Stomatal Aperture ◽  
Bathing Solution ◽  
Bathing Medium ◽  
Tobacco Leaf ◽  
Phosphoenol Pyruvate

Stepwise decreases in the stomatal aperture of tobacco leaf epidermal strips followed stepwise increases in the concentration of KHCOa added to bathing solutions. Removal of KHCOa from the bathing solution resulted in a rapid increase in aperture. The reduction in aperture caused by KHCO., both in the light and dark, can be reversed by the addition of ATP or phosphoenol pyruvate to the bathing solution. The stomatal opening, supported by a NaCl bathing medium, is reduced by the addition of NaHCOa? From the results it is suggested that HCO;/C02t increases the permeability of guard cell membranes causing a net efflux of water or ions or both from the guard cells.

scholarly journals The Regulation of Stomatal Aperture in Tobacco Leaf Epidermal Strips III. The Effect of Atp

1971 ◽  
Vol 24 (3) ◽  
pp. 689 ◽  
Author(s):  
DA Thomas
Keyword(s):  
Guard Cells ◽  
Stomatal Opening ◽  
Stomatal Aperture ◽  
Osmotic Swelling ◽  
Tobacco Leaf

The addition of ATP in the light and dark and ADP in the light to bathing solutions containing K+ can stimulate stomatal opening in tobacco leaf epidermal strips. UTP or AMP do not stimulate opening in the light or dark. The presence of ouabain prevents ATP or ADP stimulating stomatal opening. The additions of Ca2+ and Mg2+, though they reduce stomatal aperture, do not prevent ATP stimulating stomatal opening. Increasing the concentration of ATP presented to the stomata in the dark increases the aperture. The rate of stomatal opening in the presence of ATP is increased in the light. In bathing solutions which contain Na+ as the only cation ATP neither initiates nor maintains stomatal opening. The results are discussed in relation to a postulated light-stimulated, ATPase-mediated accumulation ofK+ in the guard cells which is followed by an influx of water, osmotic swelling, and stomatal opening

scholarly journals The Regulation of Stomatal Aperture in Tobacco Leaf Epidermal Strips I. The Effect of Ions

1970 ◽  
Vol 23 (4) ◽  
pp. 961 ◽  
Author(s):  
DA Thomas
Keyword(s):  
Flow Rate ◽  
Stomatal Opening ◽  
Stomatal Aperture ◽  
Bathing Solution ◽  
Saturation Curve ◽  
Bathing Medium ◽  
Simple Apparatus ◽  
Similar Shape ◽  
Maximal Opening ◽  
Opening And Closing

A simple apparatus has been developed whereby the extent of stomatal opening on isolated epidermal strips can be monitored by measuring the flow rate of bathing solution through the stomata. This apparatus has been used to study the opening and closing response of stomata to various treatments. A supply of ions, particularly K+, was found necessary to initiate and maintain the opening of stomata in the light. In the presence of K+ stomata could be opened in the light and closed in the dark. This cycle could be repeated. The pattern of stomatal opening in the light and closing in the dark showed a similar shape with time to that shown for stomata on leaves. Similar results could be obtained in a bathing medium consisting of KH2P04-Na2HP04 buffer. The best pH found for opening was 8� O. No specificity of stomatal opening was found for the anion associated with K +. The addition of Ca2+ or Mg2+ to the bathing medium caused reductions in aperture. The extent of stomatal opening in response to the concentration of K+ in the range 0-10 mM gave a saturation curve with a concentration for half maximal opening of O� 32 mM. Increasing the concentration of K+ past 10 mM resulted in reductions of aperture.

Ca2+ signalling in stomatal guard cells

2000 ◽  
Vol 28 (4) ◽  
pp. 476-481 ◽  
Author(s):  
M. R. McAinsh ◽  
J. E. Gray ◽  
A. M. Hetherington ◽  
C. P. Leckie ◽  
C. Ng
Keyword(s):  
Signal Transduction ◽  
Guard Cell ◽  
Signal Transduction Pathway ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Cell Turgor ◽  
Stomatal Guard Cells ◽  
External Stimuli ◽  
Spatial And Temporal Characteristics

Ca2+ is a ubiquitous second messenger in the signal transduction pathway(s) by which stomatal guard cells respond to external stimuli. Increases in guard-cell cytosolic free Ca2+ concentration ([Ca2+]cyt) have been observed in response to stimuli that cause both stomatal opening and closure. In addition, several important components of Ca2+-based signalling pathways have been identified in guard cells, including the cADP-ribose and phospholipase C/Ins(1,4,5)P3-mediated Ca2+-mobilizing pathways. The central role of stimulus-induced increases in [Ca2+]cyt in guard-cell signal transduction has been clearly demonstrated in experiments examining the effects of modulating increases in [Ca2+]cyt on alterations in guard-cell turgor or the activity of ion channels that act as effectors in the guard-cell turgor response. In addition, the paradox that Ca2+ is involved in the transduction of signals that result in opposite end responses (stomatal opening and closure) might be accounted for by the generation of stimulus-specific Ca2+ signatures, such that increases in [Ca2+]cyt exhibit unique spatial and temporal characteristics.

Lacking chloroplasts in guard cells ofcrumpled leafattenuates stomatal opening: both guard cell chloroplasts and mesophyll contribute to guard cell ATP levels

2014 ◽  
Vol 37 (9) ◽  
pp. 2201-2210 ◽  
Author(s):  
SHU-WEI WANG ◽  
YING LI ◽  
XIAO-LU ZHANG ◽  
HAI-QIANG YANG ◽  
XUE-FEI HAN ◽  
...  
Keyword(s):  
Guard Cell ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Atp Levels ◽  
Guard Cell Chloroplasts

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.

Potassium involvement not demonstrated in stomatal movements of Paphiopedilum. Qualified confirmation of the Nelson–Mayo report

1982 ◽  
Vol 60 (3) ◽  
pp. 240-244 ◽  
Author(s):  
William H. Outlaw Jr. ◽  
Jill Manchester ◽  
Vincent E. Zenger
Keyword(s):  
Chlorophyll A ◽  
Guard Cell ◽  
Guard Cells ◽  
Stomatal Aperture ◽  
Potassium Content ◽  
Aperture Size ◽  
Stomatal Movements ◽  
Unique Condition

Guard cells of Paphiopedilum leaves lack chlorophyll, a unique condition. Whether potassium fluxes are involved in stomatal movements is controversial. In attempting to resolve this controversy, we have dissected individual guard cell pairs from frozen-dried epidermal peels of three species. These samples were assayed for potassium using quantitative histochemical methodology. We were unable to detect a correlation between guard cell potassium content and stomatal aperture size. With certain reservations, these results indicate potassium is not the major osmoticum causing stomata of these species to open.

scholarly journals Effects of ouabain on fluid transport and electrical properties of Necturus gallbladder. Evidence in favor of a neutral basolateral sodium transport mechanism.

1979 ◽  
Vol 73 (4) ◽  
pp. 385-402 ◽  
Author(s):  
L Reuss ◽  
E Bello-Reuss ◽  
T P Grady
Keyword(s):  
Electrical Properties ◽  
Cell Membranes ◽  
Fluid Transport ◽  
Prolonged Exposure ◽  
Basolateral Membrane ◽  
Bathing Solution ◽  
Na Transport ◽  
Bathing Medium ◽  
Necturus Gallbladder ◽  
Before And After

Net fluid transport (Jv) and electrical properties of the cell membranes and paracellular pathway of Necturus gallbladder epithelium were studied before and after the addition of ouabain (10(-4) M) to the serosal bathing medium. The glycoside inhibited Jv by 70% in 15 min and by 100% in 30 min. In contrast, the potentials across both cell membranes did not decrease significantly until 20 min of exposure to ouabain. At 30 min, the basolateral membrane potential (Vcs) fell only by ca 7 mV. If basolateral Na transport were electrogenic, with a coupling ratio (Na:K) of 3:2, the reductions of Vcs at 15 and 30 min should be 12--15 and 17--21 mV, respectively. Thus, we conclude that the mechanism of Na transport from the cells to the serosal bathing solution is not electrogenic under normal transport conditions. The slow depolarization observed in ouabain is caused by a fall of intracellular K concentration, and by a decrease in basolateral cell membrane K permeability. Prolonged exposure to ouabain results also in an increase in paracellular K selectivity, with no change of P Na/P Cl.

scholarly journals Pathogen-Mediated Stomatal Opening: A Previously Overlooked Pathogenicity Strategy in the Oomycete Pathogen Phytophthora infestans

2021 ◽  
Vol 12 ◽  
Author(s):  
Li-Na Yang ◽  
Hao Liu ◽  
Yan-Ping Wang ◽  
Jenifer Seematti ◽  
Laura J. Grenville-Briggs ◽  
...  
Keyword(s):  
Phytophthora Infestans ◽  
Guard Cell ◽  
Metabolic Pathways ◽  
Guard Cells ◽  
Defense Responses ◽  
Stomatal Opening ◽  
Starch Degradation ◽  
Stomatal Movement ◽  
Oomycete Pathogen ◽  
Antagonistic Interactions

Phytophthora infestans, the most damaging oomycete pathogen of potato, is specialized to grow sporangiophore through opened stomata for secondary inoculum production. However, it is still unclear which metabolic pathways in potato are manipulated by P. infestans in the guard cell–pathogen interactions to open the stomata. Here microscopic observations and cell biology were used to investigate antagonistic interactions between guard cells and the oomycete pathogen. We observed that the antagonistic interactions started at the very beginning of infection. Stomatal movement is an important part of the immune response of potato to P. infestans infection and this occurs through guard cell death and stomatal closure. We observed that P. infestans appeared to manipulate metabolic processes in guard cells, such as triacylglycerol (TAG) breakdown, starch degradation, H2O2 scavenging, and NO catabolism, which are involved in stomatal movement, to evade these stomatal defense responses. The signal transduction pathway of P. infestans-induced stomatal opening likely starts from H2O2 and NO scavenging, along with TAG breakdown while the subsequent starch degradation reinforces the opening process by strengthening guard cell turgor and opening the stomata to their maximum aperture. These results suggest that stomata are a barrier stopping P. infestans from completing its life cycle, but this host defense system can be bypassed through the manipulation of diverse metabolic pathways that may be induced by P. infestans effector proteins.

Fluxes of Potassium and Changes in Malate within Epidermis of Commelina cyanea and their Relationships with Stomatal Aperture

1975 ◽  
Vol 2 (1) ◽  
pp. 85
Author(s):  
C.J Pearson
Keyword(s):  
Positive Relationship ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Stomatal Aperture ◽  
Degree Of Isolation

Stomatal apertures and concentrations of potassium, malate and sugars within the epidermis were measured during stomatal opening and closure; the location of K+ was also estimated by cobaltinitrite staining. The concentration of K+ in the epidermis as a whole did not change during stomatal opening and closure, but K+ migrated between epidermal and guard cells. Concentrations of sugars also remained constant. By contrast, there was a positive relationship between concentration of malate and aperture. These and other results emphasize an appreciable degree of isolation of the epidermis.

XIX.—pH Phenomena in Relation to Stomatal Opening: II–V

1942 ◽  
Vol 61 (3) ◽  
pp. 233-266 ◽  
Author(s):  
J. Small ◽  
M. I. Clarke ◽  
J. Crosbie-Baird
Keyword(s):  
Light Intensity ◽  
Water Relations ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Stomatal Aperture ◽  
Queen's University ◽  
Research Students

The control of stomatal aperture by intensity of light, under normal conditions of water-relations of surrounding cells, has apparently been established by Nutman (1937) for coffee leaves. This control results in the closing of stomatal pores both with too little and with too much illumination. Since photosynthesis in the guard-cells is not known to decrease with increase in light intensity, up to the limit of full sunshine, some other factor or factors are suggested as coming into action.Investigations, in the Department of Botany, Queen's University, Belfast, by three research students have progressively elucidated some of the factors concerned.

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