RD20, a Stress-Inducible Caleosin, Participates in Stomatal Control, Transpiration and Drought Tolerance in Arabidopsis thaliana

• Published in: Plant and cell physiology Vol. 51; no. 12; pp. 1975 - 1987
• Main Authors: Aubert, Yann, Vile, Denis, Pervent, Marjorie, Aldon, Didier, Ranty, Benoit, Simonneau, Thierry, Vavasseur, Alain, Galaud, Jean-Philippe
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01-12-2010; Oxford University Press (OUP)
• Subjects: Abscisic Acid - genetics; Abscisic Acid - metabolism; Abscisic Acid - pharmacology; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - physiology; Arabidopsis Proteins - drug effects; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Arabidopsis thaliana; Calcium-Binding Proteins - drug effects; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Calcium-Binding Proteins - physiology; Caleosin; Drought tolerance; Droughts; Environmental Sciences; Flowers - genetics; Flowers - metabolism; Gene Expression Regulation, Plant; Germination - drug effects; Germination - genetics; Life Sciences; Oil bodies; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Stomata - physiology; Plant Transpiration - physiology; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Promoter Regions, Genetic; Salts - adverse effects; Sequence Deletion; Stomata; Water - metabolism; OIL BODIES; CALEOSIN; STOMATA; DROUGHT TOLERANCE; BIOLOGIE DU DEVELOPPEMENT
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcq155

Plants overcome water deficit conditions by combining molecular, biochemical and morphological changes. At the molecular level, many stress-responsive genes have been isolated, but knowledge of their physiological functions remains fragmentary. Here, we report data for RD20, a stress-inducible Arabidopsis gene that belongs to the caleosin family. As for other caleosins, we showed that RD20 localized to oil bodies. Although caleosins are thought to play a role in the degradation of lipids during seed germination, induction of RD20 by dehydration, salt stress and ABA suggests that RD20 might be involved in processes other than germination. Using plants carrying the promoter RD20::uidA construct, we show that RD20 is expressed in leaves, guard cells and flowers, but not in root or in mature seeds. Water deficit triggers a transient increase in RD20 expression in leaves that appeared predominantly dependent on ABA signaling. To assess the biological significance of these data, a functional analysis using rd20 knock-out and overexpressing complemented lines cultivated either in standard or in water deficit conditions was performed. The rd20 knock-out plants present a higher transpiration rate that correlates with enhanced stomatal opening and a reduced tolerance to drought as compared with the wild type. These results support a role for RD20 in drought tolerance through stomatal control under water deficit conditions.