Use of infrared thermal imaging to isolate Arabidopsis mutants defective in stomatal regulation

Authors

  • Sylvain Merlot,

    1. Institut des Sciences du Végétal, Centre National de la Recherche Scientifique UPR2355, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France,
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    • Present address: Section of Cell and Developmental Biology and Center for Molecular Genetics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0634, USA.

  • Anna-Chiara Mustilli,

    1. Institut des Sciences du Végétal, Centre National de la Recherche Scientifique UPR2355, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France,
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  • Bernard Genty,

    1. Laboratoire d'Ecophysiologie Végétale, Bât. 362, UPRESA 8079, Université Paris Sud/CNRS, 91405 Orsay, France,
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  • Helen North,

    1. Laboratoire de Biologie des Semences, INRA, Route de Saint Cyr, 78026 Versailles Cedex, France,
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  • Valérie Lefebvre,

    1. Laboratoire de Biologie des Semences, INRA, Route de Saint Cyr, 78026 Versailles Cedex, France,
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  • Bruno Sotta,

    1. Physiologie Cellulaire et Moléculaire des Plantes, UMR CNRS 7632, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Cedex 05, Paris, France, and
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  • Alain Vavasseur,

    1. CEA/Cadarache-DSV-DEVM, Laboratoire des Echanges Membranaires et Signalisation, UMR 163 CNRS-CEA, 13108 St Paul-lez-Durance, Cedex, France
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  • Jérôme Giraudat

    Corresponding author
    1. Institut des Sciences du Végétal, Centre National de la Recherche Scientifique UPR2355, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France,
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For correspondence (fax +33 1 69 82 36 95; e-mail jerome.giraudat@isv.cnrs-gif.fr). Present address: CEA/Cadarache-DSV-DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, UMR 163 CNRS-CEA, 13108 St Paul-lez-Durance, Cedex, France.

Summary

In response to drought, plants synthesise the hormone abscisic acid (ABA), which triggers closure of the stomatal pores. This process is vital for plants to conserve water by reducing transpirational water loss. Moreover, recent studies have demonstrated the advantages of the Arabidopsis stomatal guard cell for combining genetic, molecular and biophysical approaches to characterise ABA action. However, genetic dissection of stomatal regulation has been limited by the difficulty of identifying a reliable phenotype for mutant screening. Leaf temperature can be used as an indicator to detect mutants with altered stomatal control, since transpiration causes leaf cooling. In this study, we optimised experimental conditions under which individual Arabidopsis plants with altered stomatal responses to drought can be identified by infrared thermography. These conditions were then used to perform a pilot screen for mutants that displayed a reduced ability to close their stomata and hence appeared colder than the wild type. Some of the mutants recovered were deficient in ABA accumulation, and corresponded to alleles of the ABA biosynthesis loci ABA1, ABA2 and ABA3. Interestingly, two of these novel aba2 alleles were able to intragenically complement the aba2–1 mutation. The remaining mutants showed reduced ABA responsiveness in guard cells. In addition to the previously known abi1–1 mutation, we isolated mutations at two novel loci designated as OST1 (OPEN STOMATA 1) and OST2. Remarkably, ost1 and ost2 represent, to our knowledge, the first Arabidopsis mutations altering ABA responsiveness in stomata and not in seeds.

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