Inhibition of light-dependent zeaxanthin formation in stomatal guard cells might be one of the regulatory steps mediating the shift from diurnal to nocturnal stomatal opening typical of plants with CAM

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在气孔保卫细胞中抑制依赖光的蔗黄质形成可能是调节步骤之一，导致具有CAM的植物从白天到夜间气孔开放的典型转变。

A inibição da formação de zeaxantina dependente da luz nas células-guarda estomáticas pode ser um dos passos regulatórios que medeiam a transição da abertura estomática diurna para a noturna, típica das plantas com metabolismo CAM.

La inhibición de la formación de zeaxantina dependiente de la luz en las células guardianas estomáticas podría ser uno de los pasos regulatorios que median en el cambio de la apertura estomática diurna a la nocturna, típica de las plantas con CAM.

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Induction of CAM in Mesembryanthemum crystallinum Abolishes the Stomatal Response to Blue Light and Light-Dependent Zeaxanthin Formation in Guard Cell Chloroplasts

Tallman G., Zhu J. X.,Mawson B. T., Amodeo G., Noyuhi Z., Levy K., Zeiger E. (1997)

Gary Tallman, Jianxin Zhu, Bruce T. Mawson, Gabriella Amodeo, Zepedeh Nouhi, Kathleen Levy, Eduardo Zeiger,

Plant and Cell Physiology 38(3): 236–242 – https://doi.org/10.1093/oxfordjournals.pcp.a029158 –

https://academic.oup.com/pcp/article/38/3/236/1928407?login=false

Abstract

Facultative CAM plants such as Mesembryanthemum crystallinum (ice plant) possess C3 metabolism when unstressed but develop CAM under water or salt stress. When ice plants shift from C3 metabolism to CAM, their stomata remain closed during the day and open at night. Recent studies have shown that the stomatal response of ice plants in the C3 mode depends solely on the guard cell response to blue light. Recent evidence for a possible role of the xanthophyll, zeaxanthin in blue light photoreception of guard cells led to the question of whether changes in the regulation of the xanthophyll cycle in guard cells parallel the shift from diurnal to nocturnal stomatal opening associated with CAM induction. In the present study, light-dependent stomatal opening and the operation of the xanthophyll cycle were characterized in guard cells isolated from ice plants shifting from C3 metabolism to CAM. Stomata in epidermis detached from leaves with C3 metabolism opened in response to white light and blue light, but they did not open in response to red light. Guard cells from these leaves showed light-dependent conversion of violaxan-thin to zeaxanthin. Induction of CAM by NaCI abolished both white light- and blue light-stimulated stomatal opening and light-dependent zeaxanthin formation. When guard cells isolated from leaves with CAM were treated with 100 mM ascorbate, pH 5.0 for 1 h in darkness, guard cell zeaxanthin content increased at rates equal to or higher than those stimulated by light in guard cells from leaves in the C3 mode. The ascorbate effect indicates that chloroplasts in guard cells from leaves with CAM retain their competence to operate the xanthophyll cycle, but that zeaxanthin formation does not take place in the light. The data suggest that inhibition of light-dependent zeaxanthin formation in guard cells might be one of the regulatory steps mediating the shift from diurnal to nocturnal stomatal opening typical of plants with CAM.

Paphiopedilum stomata possess both a blue light-mediated opening response a novel phytochrome-mediated opening response

Phytochrome and blue light-mediated stomatal opening in the orchid, Paphiopedilum

by Talbott L. D., Zhu J., Han S. W., Zeiger E. (2002)

Lawrence D. Talbott, Jianxin Zhu, Seung Won Han, Eduardo Zeiger,

===

In Plant Cell Physiol 43: 639–646 – PMID: 12091717 – https://doi.org/10.1093/pcp/pcf075

https://www.ncbi.nlm.nih.gov/pubmed/12091717 

Abstract

Guard cells of the orchid genus, Paphiopedilum have been reported to lack developed chloroplasts and detectable chlorophyll a autofluorescence.

Paphiopedilum stomata lack a photosynthesis-dependent opening response but have a blue light-specific opening. The present study found that low fluence rate green and red light elicited stomatal opening in Paphiopedilum and this opening was reversed by far red light, indicating the presence of a phytochrome-mediated opening response.

Phytochrome-dependent, red light-stimulated opening was largest under low fluence rates and decreased to near zero as fluence rate increased. A recently discovered green light reversibility of blue light-specific stomatal opening was used to probe the properties of the blue light response in Paphiopedilum stomata.

Blue light-stimulated opening was completely reversed by green light in the presence of far red light. Red light enhanced the blue light response of Paphiopedilum guard cells when given as a pretreatment or together with blue light.

Analysis of guard cell pigments showed that guard cells have small amounts of chlorophyll a and b, zeaxanthin, violaxanthin, antheraxanthin and lutein. Zeaxanthin content increased in response to blue light or ascorbate and declined in the dark or under illumination in the presence of dithiothreitol, indicating the presence of an active xanthophyll cycle.

Thus Paphiopedilum stomata possess both a blue light-mediated opening response with characteristics similar to species with normal chloroplast development and a novel phytochrome-mediated opening response.

The properties of the stomatal chloroplast

 

 

The guard cell chloroplast: a perspective for the twenty-first century

Zeiger E., Talbott L. D., Frechilla S., Srivastava A., Zhu J. (2008)

Eduardo Zeiger, Lawrence D. Talbott, Silvia Frechilla, Alaka Srivastava, Jianxin Zhu,

 

in New Phytol 153: 415–424 – https://doi.org/10.1046/j.0028-646X.2001.NPH328.doc.x –

https://nph.onlinelibrary.wiley.com/doi/full/10.1046/j.0028-646X.2001.NPH328.doc.x

Summary

The guard cell chloroplast is the site of perception of blue light and of photosynthetically active radiation, and of at least one of the mechanisms sensing CO₂ in the guard cell.

The guard cell chloroplast has been the focus of intense controversy over its capacity for light sensing and photosynthetic carbon fixation, and the osmoregulatory mechanisms mediating stomatal movements.

It is argued here that a primary reason behind these long‐lived controversies is the remarkable plasticity of the guard cell, which has resulted in responses being generalized as basic properties when opposite responses appear to be the norm under different environmental or experimental conditions.

Examples of guard cell plasticity are described, including variation of chlorophyll fluorescence transients over a daily course, acclimation of the guard cell responses to blue light and CO₂, the shift from potassium to sucrose in daily courses of osmoregulation and the transduction of red light into different osmoregulatory pathways.

Recent findings on the properties of the guard cell chloroplast are also presented, including the role of the chloroplastic carotenoid, zeaxanthin, in blue light photoreception, the blue‐green reversibility of stomatal movements, and the involvement of phytochrome in the stomatal response to light in the orchid, Paphiopedilum.

Stomata from npq1 lack a specific response to blue light

 

 

Stomata from npq1, a zeaxanthin‐less Arabidopsis mutant, lack a specific response to blue light

by Frechilla S., Zhu J., Talbott L. D., Zeiger E. (1999)

Silvia Frechilla, University of California, Los Angeles

Jianxin Zhu, University of California, Los Angeles

Lawrence D. Talbott, University of California, Los Angeles

Eduardo Zeiger, University of California, Los Angeles

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in Plant and Cell Physiology 40: 949-954 – DOI | 10.1093/oxfordjournals.pcp.a029627 – 

https://scinapse.io/papers/2156072438

Abstract

The Arabidopsis mutant npql, which cannot accumulate zeaxanthin because of a defective violaxanthin deepoxidase, was used to investigate the role of zeaxanthin in the stomatal response to blue light.

Neither dark-adapted nor light-treated guard cells or mesophyll cells of the npql mutant contained detectable zeaxanthin. In contrast, wildtype guard cells had a significant zeaxanthin content in the dark and accumulated large amounts of zeaxanthin when illuminated.

The well-documented red light enhancement of blue light-stimulated stomatal opening, in which increasing fluence rates of background red light result in increased response to blue light, was used to probe the specific blue light response of Arabidopsis stomata.

Stomata from the npql mutant did not have a specific blue light response under all fluence rates of background red light tested. On the other hand, stomata from leaves of hy4 (cry 1), an Arabidopsis mutant lacking blue light-dependent inhibition of hypocotyl elongation, had a typical enhancement of the blue light response by background red light.

The lack of a specific blue light response in the zeaxanthinless npql mutant provides genetic evidence for the role of zeaxanthin as a blue light photoreceptor in guard cells.

Blue light sensing by guard cell zeaxanthin has a regulatory role in the light response of stomata

 

 

Role of zeaxanthin in blue light photoreception and the modulation of light-CO2 interactions in guard cells

by Zeiger E., Zhu J. (1998)

===

in J. Exp. Bot. 49: 433–442 – DOI 10.1093/jxb/49.Special_Issue.433 – 

[Cross Ref] – 

https://www.jstor.org/stable/23695976?seq=1#page_scan_tab_contents

Abstract

The stomatal response to blue light is an intrinsic component of the sensory transducing processes mediating light-stimulated stomatal movements. Guard cell chloroplasts have a specific blue light response with an action spectrum that resembles the action spectrum for blue light-stimulated stomatal opening, suggesting a role of guard cell chloroplasts in the sensory transduction of blue light.

The xanthophyll, zeaxanthin has recently been identified as a blue light photoreceptor in guard cells. The inhibitor of zeaxanthin formation, dithiothreitol, inhibits zeaxanthin formation and the stomatal response to blue light in a concentration-dependent fashion. In greenhouse-grown leaves, guard cell zeaxanthin content closely tracks incident radiation and it is positively correlated with stomatal apertures.

The sensitivity of guard cells to blue light co-varies with guard cell zeaxanthin content. A zeaxanthin-less mutant of Arabidopsis is devoid of a typical stomatal response to blue light. At constant light and temperature, changes in ambient [CO2] in a growth chamber caused large changes in stomata aperture and in guard cell zeaxanthin.

The aperturezeaxanthin changes were linearly related over a wide range of [CO2]. Experiments with detached epidermis showed a similar relation among [CO2], stomatal apertures and guard cell zeaxanthin, and DTT inhibited the CO2 response in the light without altering the CO2 response in the dark.

These results indicate that blue light sensing by guard cell zeaxanthin has a regulatory role in the light response of stomata. Zeaxanthin also appears to mediate light-CO2 interactions in guard cells.

Zeaxanthin in blue light photoreception and stomata

 

Role of zeaxanthin in blue light photoreception and the modulation of light-CO2 interactions in guard cells

by Zeiger E., Zhu J. (1998)

Department of Biology,University of California,Los Angeles

CA 90095-1606,USA

Eduardo Zeiger

Jianxin Zhu

in Journal of Experimental Botany 49: 433–442. – doi: 10.1093/jxb/49.Special_Issue.433 –

CrossRef Full Text | Google Scholar – Abstract/FREE Full Text –

https://academic.oup.com/jxb/article-lookup/doi/10.1093/jxb/49.Special_Issue.433

Abstract

The stomatal response to blue light is an intrinsic component of the sensory transducing processes mediating light-stimulated stomatal movements. Guard cell chloroplasts have a specific blue light response with an action spectrum that resembles the action spectrum for blue light-stimulated stomatal opening, suggesting a role of guard cell chloroplasts in the sensory transduction of blue light.

The xanthophyll, zeaxanthin has recently been identified as a blue light photoreceptor in guard cells. The inhibitor of zeaxanthin formation, dithiothreitol, inhibits zeaxanthin formation and the stomatal response to blue light in a concentration-dependent fashion.

In greenhousegrown leaves, guard cell zeaxanthin content closely tracks incident radiation and it is positively correlated with stomatal apertures. The sensitivity of guard cells to blue light co-varies with guard cell zeaxanthin content. A zeaxanthin-less mutant of Arabidopsis is devoid of a typical stomatal response to blue light.

At constant light and temperature, changes in ambient [CO₂] in a growth chamber caused large changes in stomata aperture and in guard cell zeaxanthin. The aperture zeaxanthin changes were linearly related over a wide range of [CO₂].

Experiments with detached epidermis showed a similar relation among [CO₂], stomatal apertures and guard cell zeaxanthin, and DTT inhibited the CO₂ response in the light without altering the CO₂ response in the dark.

These results indicate that blue light sensing by guard cell zeaxanthin has a regulatory role in the light response of stomata. Zeaxanthin also appears to mediate light-CO₂ interactions in guard cells.

Stomatal movements and the guard cell chloroplast

 

The guard cell chloroplast: a perspective for the 21st century.

by Zeiger E., Talbott L. D., Frechilla S., Srivastava A., Zhu J. (2002)

Department of Organismic Biology, Ecology and Evolution, University of California, Los Angeles, 900 Veteran Ave., Los Angeles, CA 90024-1786, USA;

Eduardo Zeiger,

Lawrence D. Talbott,

Silvia Frechilla,

Alaka Srivastava,

Jianxin Zhu

in New Phytologist 153: 415–424. – DOI: 10.1046/j.0028-646X.2001.NPH328.doc.x

CrossRef |CAS | –

http://onlinelibrary.wiley.com/doi/10.1046/j.0028-646X.2001.NPH328.doc.x/abstract

Summary

The guard cell chloroplast is the site of perception of blue light and of photosynthetically active radiation, and of at least one of the mechanisms sensing CO₂ in the guard cell. The guard cell chloroplast has been the focus of intense controversy over its capacity for light sensing and photosynthetic carbon fixation, and the osmoregulatory mechanisms mediating stomatal movements.

It is argued here that a primary reason behind these long-lived controversies is the remarkable plasticity of the guard cell, which has resulted in responses being generalized as basic properties when opposite responses appear to be the norm under different environmental or experimental conditions.

Examples of guard cell plasticity are described, including variation of chlorophyll fluorescence transients over a daily course, acclimation of the guard cell responses to blue light and CO₂, the shift from potassium to sucrose in daily courses of osmoregulation and the transduction of red light into different osmoregulatory pathways.

Recent findings on the properties of the guard cell chloroplast are also presented, including the role of the chloroplastic carotenoid, zeaxanthin, in blue light photoreception, the blue-green reversibility of stomatal movements, and the involvement of phytochrome in the stomatal response to light in the orchid, Paphiopedilum.