title: Water Deficit Enhances C Export to the Roots in Arabidopsis thaliana Plants with Contribution of Sucrose Transporters in Both Shoot and Roots.
abstract: Root high plasticity is an adaptation to its changing environment. Water deficit impairs growth, leading to sugar accumulation in leaves, part of which could be available to roots via sucrose (Suc) phloem transport. Phloem loading is widely described in Arabidopsis (Arabidopsis thaliana), while unloading in roots is less understood. To gain information on leaf-to-root transport, a soil-based culture system was developed to monitor root system architecture in two dimensions. Under water deficit (50% of soil water-holding capacity), total root length was strongly reduced but the depth of root foraging and the shape of the root system were less affected, likely to improve water uptake. (14)CO2 pulse-chase experiments confirmed that water deficit enhanced carbon (C) export to the roots, as suggested by the increased root-to-shoot ratio. The transcript levels of AtSWEET11 (for sugar will eventually be exported transporter), AtSWEET12, and AtSUC2 (for Suc carrier) genes, all three involved in Suc phloem loading, were significantly up-regulated in leaves of water deficit plants, in accordance with the increase in C export from the leaves to the roots. Interestingly, the transcript levels of AtSUC2 and AtSWEET11 to AtSWEET15 were also significantly higher in stressed roots, underlying the importance of Suc apoplastic unloading in Arabidopsis roots and a putative role for these Suc transporters in Suc unloading. These data demonstrate that, during water deficit, plants respond to growth limitation by allocating relatively more C to the roots to maintain an efficient root system and that a subset of Suc transporters is potentially involved in the flux of C to and in the roots.
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Durand
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: Porcheron
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France.
authors.forename: Nils
authors.identifier: http://orcid.org/0000-0001-9877-3682
authors.initials: N
authors.lastname: Hennion
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Maurousset
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France remi.lemoine@univ-poitiers.fr.
authors.forename: Rémi
authors.initials: R
authors.lastname: Lemoine
authors.affiliation: Université de Poitiers, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7267, Ecologie et Biologie des Interactions, 86073 Poitiers cedex 9, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pourtau
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002244:Carbon / Q000378:metabolism*; D055864:Droughts; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D052585:Phloem / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D025341:Principal Component Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013395:Sucrose / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002244:Carbon; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D013395:Sucrose; D014867:Water; C557299:At5g13170 protein, Arabidopsis; C569466:SWEET11 protein, Arabidopsis; C569467:SWEET12 protein, Arabidopsis; C078729:sucrose transport protein, plant