title: Mother-plant-mediated pumping of zinc into the developing seed.
abstract: Insufficient intake of zinc and iron from a cereal-based diet is one of the causes of 'hidden hunger' (micronutrient deficiency), which affects some two billion people(1,2). Identifying a limiting factor in the molecular mechanism of zinc loading into seeds is an important step towards determining the genetic basis for variation of grain micronutrient content and developing breeding strategies to improve this trait(3). Nutrients are translocated to developing seeds at a rate that is regulated by transport processes in source leaves, in the phloem vascular pathway, and at seed sinks. Nutrients are released from a symplasmic maternal seed domain into the seed apoplasm surrounding the endosperm and embryo by poorly understood membrane transport processes(4-6). Plants are unique among eukaryotes in having specific P1B-ATPase pumps for the cellular export of zinc(7). In Arabidopsis, we show that two zinc transporting P1B-ATPases actively export zinc from the mother plant to the filial tissues. Mutant plants that lack both zinc pumps accumulate zinc in the seed coat and consequently have vastly reduced amounts of zinc inside the seed. Blockage of zinc transport was observed at both high and low external zinc supplies. The phenotype was determined by the mother plant and is thus due to a lack of zinc pump activity in the seed coat and not in the filial tissues. The finding that P1B-ATPases are one of the limiting factors controlling the amount of zinc inside a seed is an important step towards combating nutritional zinc deficiency worldwide.
authors.affiliation: Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark.|Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
authors.forename: Lene Irene
authors.initials: LI
authors.lastname: Olsen
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
authors.forename: Thomas H
authors.identifier: 0000-0003-3511-2806
authors.initials: TH
authors.lastname: Hansen
authors.affiliation: Department of Plant Physiology, Ruhr University Bochum, D-44801 Bochum, Germany.|ECOLAB, Université de Toulouse, CNRS, INPT, UPS, F-31062 Toulouse, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Larue
authors.affiliation: Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark.|Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
authors.forename: Jeppe Thulin
authors.initials: JT
authors.lastname: Østerberg
authors.affiliation: Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark.|Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hoffmann
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.|College of Life Sciences, Northwest A&F University, CN-712100 Yangling, China.
authors.forename: Johannes
authors.initials: J
authors.lastname: Liesche
authors.affiliation: Department of Plant Physiology, Ruhr University Bochum, D-44801 Bochum, Germany.
authors.forename: Ute
authors.identifier: 0000-0001-7870-4508
authors.initials: U
authors.lastname: Krämer
authors.affiliation: LEEL, NIMBE-CEA-CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette Cedex, France.
authors.forename: Suzy
authors.initials: S
authors.lastname: Surblé
authors.affiliation: ECOLAB, Université de Toulouse, CNRS, INPT, UPS, F-31062 Toulouse, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Cadarsi
authors.affiliation: microXAS beamline, Swiss Light Source, CH-5232 Villigen, Switzerland.
authors.forename: Vallerie Ann
authors.initials: VA
authors.lastname: Samson
authors.affiliation: microXAS beamline, Swiss Light Source, CH-5232 Villigen, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grolimund
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Husted
authors.affiliation: Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark.|Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.|Institute of Environmental Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Palmgren
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D000251:Adenosine Triphosphatases; C494967:HMA2 protein, Arabidopsis; C477864:HMA4 protein, Arabidopsis; D015032:Zinc