An anion transporter that functions in stomatal opening

Nitrate Induces Depolarization of Membrane Potential in Guard Cells of Wild-Type but Not chl1 Plants. Depolarization of membrane potentials is represented as an increase in fluorescence. (A) Fluorescence from a representative wild-type guard cell at 0, 15, 30, and 60 s after adding CsNO3 to a final concentration of 100 mM. (B) Fluorescence from a representative mutant (chl1-5) guard cell at 0, 15, 30, and 60 s after adding CsNO3 to a final concentration of 100 mM. (C) Fluorescence from a representative wild-type guard cell at 0, 15, 30, and 60 s after adding KCl to a final concentration of 100 mM. (D) Fluorescence from a representative mutant (chl1-5) guard cell at 0, 15, 30, and 60 s after adding KCl to a final concentration of 100 mM. (E) Quantified fluorescence signals from the stomates for each genotype or treatment. Error bars represent standard deviations (n = 5).

 

The nitrate transporter AtNRT1.1 (CHL1) functions in stomatal opening and contributes to drought susceptibility in Arabidopsis

by Guo F. Q., Young .J, Crawford N. M. (2003)

Fang-Qing Guo, Jared Young, Nigel M. Crawford,

Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116

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in Plant Cell 15: 107–117 – doi:  10.1105/tpc.006312 –

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC143464/

Abstract

The movement of guard cells in stomatal complexes controls water loss and CO₂ uptake in plants. Examination of the dual-affinity nitrate transporter gene AtNRT1.1 (CHL1) revealed that it is expressed and functions in Arabidopsis guard cells. CHL1promoter–β-glucuronidase and CHL1 promoter–green fluorescent protein constructs showed strong expression in guard cells, and immunolocalization experiments with anti-CHL1 antibody confirmed these results.

To assess CHL1 function, chl1 mutant plants grown in the presence of nitrate were examined. Compared with wild-type plants, chl1 mutants had reduced stomatal opening and reduced transpiration rates in the light or when deprived of CO₂ in the dark.

These effects result in enhanced drought tolerance in chl1 mutants. At the cellular level, chl1 mutants showed reduced nitrate accumulation in guard cells during stomatal opening and failed to show nitrate-induced depolarization of guard cells.

In wild-type guard cells, nitrate induced depolarization, and nitrate concentrations increased threefold during stomatal opening.

These results identify an anion transporter that functions in stomatal opening and demonstrate that CHL1 supports stomatal function in the presence of nitrate.

Steady state stomatal response to environment

 

 

Current perspectives of steady state stomatal response to environment

by Hall A. E., Schulze E.-D., Lange O. L. (1976)

• A. E. Hall,
• E.-D. Schulze,
• O. L. Lange,

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In Lange O. L., Kappen L., Schulze E.-D., eds, – Water and Plant Life. Ecological Studies 19. Springer, Berlin, pp 169–185 – https://doi.org/10.1007/978-3-642-66429-8_11 –

https://link.springer.com/chapter/10.1007%2F978-3-642-66429-8_11

Abstract

Plant responses to environment are frequently influenced by stomatal functioning, through effects on plant water use, the development of plant water deficits, net photosynthesis, and temperature relations.

In ecophysiology, predicting stomatal responses to environment and relating these responses to the functioning and physical state of plants are important objectives.

Qualitative and quantitative differences in stomatal behavior between plant species and ecotypes, or at different phenological stages play important roles in plant performance and adaptation.

Two photoreactions and phytochrome in light dependent stomatal opening

 

 

Evidence for two photoreactions and possible involvement of phytochrome in light dependent stomatal opening

by Habermann H. M. (1973)

Helen M. Habermann

Department of Biological Sciences, Goucher College, Baltimore, Maryland 21204

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in Plant Physiol. 51: 543-548 – PMID: 16658366 – PMCID: PMC366302 – 

https://www.ncbi.nlm.nih.gov/pubmed/16658366

Abstract

Leaves of the xantha mutant of Helianthus annuus have a higher rate of transpiration and a lower diffusive resistance in the light than in the dark.

Stomates of this non-photosynthetic mutant open in the light and close in the dark. Comparative studies of tobacco, xantha mutant, and wild-type sunflower stomatal opening over a range of light intensities in isolated portions of the spectrum reveal two patterns of response:

(a) a low intensity opening in the green and far red characterized by partial opening, absence of a threshold, and saturation of the response at low light intensities;

(b) a high intensity response in the blue characterized by a threshold (intensities greater than 100 microwatts per square centimeter needed for opening) and a linear opening response at higher incident light intensities.

In xantha mutant stomates only the low intensity system appears to be operational, while both low and high intensity systems are present in the wild-type sunflower and tobacco. Red light has an inhibiting effect on stomatal opening in both mutant and wild-type sunflowers. They require prior exposure to far red for opening to occur in red light. This red far-red antagonism suggests the involvement of phytochrome.

Stomatal responses to drought and humidity

Fig. 4A-D. Photomicrographs of isolated epidermis of Commelina, x 400, ba r=50 gm. A Guard cells of closed stomata were initially plasmolyzed in 0.6 M mannitol containing 100 mM KC1. B Guard cells recovered from plasmolysis and stomata opened during incubation for 3 h in 0.6 M mannitol, while other epidermal cells remained plasmolyzed. C Guard cells shown in A were not plasmolyzed when transferred to the uniform osmotic environment of 0.4 M mannitol, while other epidermal cells were plasmolyzed. D Guard cells shown in B were turgid and stomata were widely open in 0.4 M mannitol, while the surrounding cells remained plasmolyzed

 

Guard cells of Commelina communis L. do not respond metabolically to osmotic stress in isolated epidermis: implications for stomatal responses to drought and humidity

by Grantz D. A., Schwartz A. (1988)

• David A. Grantz
• Amnon Schwartz

Department of Agricultural Botany, Faculty of Agriculture, Hebrew University of Jerusalem, 76-100, Rehovot, Israel.

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in Planta 174: 166–173 – doi: 10.1007/BF00394768 –

https://www.ncbi.nlm.nih.gov/pubmed/24221472

https://www.semanticscholar.org/paper/Guard-cells-of-Commelina-communis-L.-do-not-respond-Grantz-Schwartz/af1203826bc6dffe18cd5b79dfa54f8320638027/figure/3

Abstract

We investigated the hypothesis that stomatal aperture is regulated by epidermal water status. Detached epidermal peels of Commelina communis L. or leaf disks with epidermis attached were incubated in graded solutions of mannitol (0-1.2 M) containing KCl. In isolated epidermis, guard-cell solute content of open stomata did not decrease in response to desiccation.

Guard cells of closed stomata accumulated solutes to the same extent in all levels of mannitol tested. There was no evidence of stress-induced hydroactive closure nor of inhibition of hydroactive opening, even when guard cells of closed stomata were initially plasmolyzed.

Hydropassive, osmometer-like, changes in stomatal aperture in the isolated epidermis were induced by addition or removal of mannitol, but these did not involve changes in guard-cell solute content. In leaf disks, stomata exhibited clear hydroactive stomatal responses.

Steady-state guard-cell solute content of initially open and initially closed stomata decreased substantially with increasing mannitol. Stomata were completely closed above approx. 0.4 M mannitol, near the turgor-loss point for the bulk leaf tissue.

Stomata of Commelina did not exhibit direct hydroactive responses to environmental or epidermal water status. Stomatal responses to water deficit and low humidity may be indirect, mediated by abscisic acid or other signal metabolite(s) from the mesophyll.

Stomatal movement in Dolichus biflorus Linn. (Fabaceae)

 

 

Studies on stomatal movement in Dolichus biflorus Linn. (Fabaceae)

by Meerabai G., Koteswari B. (2017)

G. Meerrabai, B. Koteswari,

Department of Botany, Rayalaseema University, Kurnool-7, A. P., India

Humanities & Sciences, Brindavan Institute of Science & Technology, Chinna Tekur Road, Kurnool, A. P., India

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in Int. J. Trend Scientific Res. & Dev. (IJTSRD) 1(6): 365-368 – ISSN No: 2456 – 6470 – 

https://www.academia.edu/35941875/Studies_on_Stomatal_Movement_in_Dolichus_biflorus_Linn._Fabaceae_

 

Counting stomata

 

Counting stomata from different types of leaves

by Suthar K., Sutariya K., Yadav P., Menon S. (2017)

Kirti Suthjar, Komal Sutariya, Poola yadav, Sheeba Menon,

Biology Department, K. K. Shah Jarodwala Maninagar Science College, Maninagar, Almedabad

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in Int. J. Trend in Scientific Res. & Dev. (IJTSRD) 1(6): 1068-1075 – ISSN 2456-6470 –

https://www.academia.edu/35945205/Counting_of_Stomata_from_Different_Types_of_Leaves

 

Stomatal and surface conductance of tropical rainforest

 

 

by Dolman A. J., Gash J. H. C., Roberts J., Shuttleworth W. J. (1991)

A. Johannes Dolman, John H. C. Gash, John Roberts, W. James Shuttleworth,

Institute of Hydrology, Wallingford, OX10 8BB, UK

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in Agricultural and Forest Meteorology 54(2–4): 303-318 – https://doi.org/10.1016/0168-1923(91)90011-E –

https://www.sciencedirect.com/science/article/pii/016819239190011E

Abstract

Although the absolute values of stomatal conductance of tropical rainforest vary greatly, there is some similarity in the response to humidity deficit and radiation. Stomatal conductance decreases downward through the canopy of Amazonian rainforest. Using a multi-layer approach and measured profiles of stomatal conductance and weather variables through the canopy, good agreement can be obtained between calculated and observed values of dry canopy evaporation. The relationship between the biological response of stomata to radiation at the leaf level and the response of surface conductance to radiation above the canopy is derived by relating the profile of stomatal conductance through the canopy to the attenuation of radiation. Simple use of responses derived at leaf level will greatly overestimate surface conductance if used with above-canopy radiation measurements.

Three models of surface conductance of the same Amazonian forest, varying in their degree of complexity, were tested against measured evaporation data for the Reserva Ducke forest in Brazil. A simple model with surface conductance varying only with time of day was found to model the observed data slightly better than a more complex environmental model. Using a constant value of surface conductance gave a poorer fit to the data, although the average evaporation can be calculated accurately. It is recommended that the more complex environmental model be used when estimates of evaporation are required under any conditions substantially different from those of the central Amazonian forest where the data were collected.

Stomatal conductance of two tropical trees during the wet season

 

 

Stomatal conductance of two tropical trees during the wet season in Nigeria

by Grace J., Okali D. U. U., Fasehun F. E. (1982)

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in J Appl Ecol 19: 659–670 – DOI: 10.2307/2403497 –

https://www.jstor.org/stable/2403497?seq=1#page_scan_tab_contents

Abstract

(1) Measurements of stomatal conductance were made on teak and Gmelina on 5 days during the wet season in Nigeria. Both species displayed very high conductances but, when compared in the same conditions, values for Gmelina were less than those in teak.

(2) Stomatal conductance was mainly determined by the quantum flux, although the saturation deficit of the air also exerted an effect.

(3) Transpiration rates were calculated from the stomatal conductances, using the Penman-Monteith equation. The rates were high, and imply that almost all the net radiation was used to evaporate water.

(4) Sensitivity analysis showed that transpiration rate for much of the day is insensitive to changes in the stomatal conductance g_s, the aerodynamic conductance g_a or the leaf area index. It is however closely coupled to net radiation.

(5) The future application of the results to other sites is discussed.

Light‐induced alkalinization of the suspending medium of stomatal protoplasts

 

 

Light‐induced alkalinization of the suspending medium of guard cell protoplasts from Vicia faba

by Gotow K., Sakaki T., Kondo N., Kobayashi K., Syôno K (1985)

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in Plant Physiology 79: 825-828 – DOI: https://doi.org/10.1104/pp.79.3.825 –

http://www.plantphysiol.org/content/79/3/825

Abstract

The light-dependent pH changes in the suspending medium of guard cell protoplasts (GCP) from Vicia faba were studied.

Upon illumination, the medium was initially slightly alkalinized and then acidified. The extent of alkalinization was lower in CO₂-free air than in normal air. This initial alkalinization was inhibited by DCMU.

Acidification in CO₂-free air became observable in shorter duration of light exposure than that in normal air. The rate of acidification was higher in CO₂-free air than in normal air. The CO₂ level of the medium decreased in the light, and increased in the dark. ¹⁴CO₂uptake was enhanced 2- to 3-fold by light, but not in the presence of DCMU.

These results indicate that photosynthetic CO₂ fixation does take place in GCP and that the initial alkalinization is due to this photosynthetic CO₂ uptake. Diethylstilbestrol, a nonmitochondrial membrane-bound ATPase inhibitor, inhibited the acidification, suggesting that the acidification resulted from H⁺ extrusion by GCP.

The acidification in light was also prevented by KCN, and partly by DCMU. Possible mechanisms of alkalinization and acidification are discussed in relation to guard cell metabolism.

Influence of GA on stomatal movement

 

 

Influence of gibberellic acid on stomatal movement

by Göring H., Koshuchowa S., Deckert C. (1990)

Horst Göring, ¹² Svetlana Koshuchowa, ¹ Cornelia Deckert, ¹

Humboldt University, Section of Biology, Department of Plant Physiology, Berlin, F.R.G.

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in Biochem. Physiol. Pflanz. 186: 367-374 – https://doi.org/10.1016/S0015-3796(11)80235-0 –

https://www.sciencedirect.com/science/article/pii/S0015379611802350

Summary

The influence of gibberellic acid (GA) on stomatal opening and changes in the content of potassium and starch of guard cells of Vicia faba and Fritillaria imperialis was studied.

GA treatment induced a transient opening of stomata in the dark with a maximum at 5 to 7 h after the beginning of treatment. Although stomata opened nearly to the same extent as in light no substantial accumulation of potassium could be detected by the cobalt nitrite method.

Quantitative determination of the starch content of epidermal peels revealed a transient decrease of about 50% after 5 h.

Since speed and extent of stomatal opening depends on the initial osmotic potential of guard cells, it is proposed that stomatal movement is influenced to a certain degree by the hormonal status of plant tissues.