title: Reevaluation of the plant "gemstones": Calcium oxalate crystals sustain photosynthesis under drought conditions.
abstract: Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path "alarm photosynthesis." The so-far "enigmatic," but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants.
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.|b Metabolic Engineering and Systems Biology Laboratory, Institute of Chemical Engineering Sciences, Foundation for Research & Technology-Hellas (FORTH/ICE-HT) , Patras , Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Tooulakou
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Giannopoulos
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: Dimosthenis
authors.initials: D
authors.lastname: Nikolopoulos
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: Panagiota
authors.initials: P
authors.lastname: Bresta
authors.affiliation: c Stable Isotope Unit, Institute of Material Science, National Center for Scientific Research "Demokritos" Athens , Greece.
authors.forename: Elissavet
authors.initials: E
authors.lastname: Dotsika
authors.affiliation: d Department of Pharmacy , University of Patras , Patras , Greece.
authors.forename: Malvina G
authors.initials: MG
authors.lastname: Orkoula
authors.affiliation: d Department of Pharmacy , University of Patras , Patras , Greece.
authors.forename: Christos G
authors.initials: CG
authors.lastname: Kontoyannis
authors.affiliation: e Laboratory of Electron Microscopy, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: Costas
authors.initials: C
authors.lastname: Fasseas
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Liakopoulos
authors.affiliation: b Metabolic Engineering and Systems Biology Laboratory, Institute of Chemical Engineering Sciences, Foundation for Research & Technology-Hellas (FORTH/ICE-HT) , Patras , Greece.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Klapa
authors.affiliation: a Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens , Athens , Greece.
authors.forename: George
authors.initials: G
authors.lastname: Karabourniotis
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D027721:Amaranthus / Q000378:metabolism / Q000502:physiology; D002129:Calcium Oxalate / Q000378:metabolism*; D055864:Droughts; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D054046:Plant Stomata / Q000378:metabolism / Q000502:physiology
chemical_list: D002129:Calcium Oxalate; D000040:Abscisic Acid
keywords: Abscisic acid; alarm photosynthesis; calcium oxalate; drought; stomata