A plastid protein crucial for Ca2+-regulated stomatal responses

Authors

  • Stefan Weinl,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany;
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  • Katrin Held,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany;
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  • Kathrin Schlücking,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany;
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  • Leonie Steinhorst,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany;
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  • Sebastian Kuhlgert,

    1. Institut für Biochemie und Biotechnologie der Pflanzen, Universität Münster, Hindenburgplatz 55, 48143 Münster, Germany
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  • Michael Hippler,

    1. Institut für Biochemie und Biotechnologie der Pflanzen, Universität Münster, Hindenburgplatz 55, 48143 Münster, Germany
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  • Jörg Kudla

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany;
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Author for correspondence:
Stefan Weinl
Tel: +49 251/83 24811
Fax: +49 251/83 23311
Email: Stefan.Weinl@uni-muenster.de

Summary

  • • Guard cell movements are regulated by environmental cues including, for example, elevations in extracellular Ca2+ concentration. Here, the subcellular localization and physiological function of the Ca2+-sensing receptor (CAS) protein was investigated.
  • • CAS protein localization was ascertained by microscopic analyses of green fluorescent protein (GFP) fusion proteins and biochemical fractionation assays. Comparative guard cell movement investigations were performed in wild-type and cas loss-of-function mutant lines of Arabidopsis thaliana. Cytoplasmic Ca2+ dynamics were addressed in plants expressing the yellow cameleon reporter protein YC3.6.
  • • This study identified CAS as a chloroplast-localized protein that is crucial for proper stomatal regulation in response to elevations of external Ca2+. CAS fulfils this role through modulation of the cytoplasmic Ca2+ concentration.
  • • This work reveals a novel role of the chloroplast in cellular Ca2+ signal transduction.

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