title: The EXS Domain of PHO1 Participates in the Response of Shoots to Phosphate Deficiency via a Root-to-Shoot Signal.
abstract: The response of shoots to phosphate (Pi) deficiency implicates long-distance communication between roots and shoots, but the participating components are poorly understood. We have studied the topology of the Arabidopsis (Arabidopsis thaliana) PHOSPHATE1 (PHO1) Pi exporter and defined the functions of its different domains in Pi homeostasis and signaling. The results indicate that the amino and carboxyl termini of PHO1 are both oriented toward the cytosol and that the protein spans the membrane twice in the EXS domain, resulting in a total of six transmembrane α-helices. Using transient expression in Nicotiana benthamiana leaf, we demonstrated that the EXS domain of PHO1 is essential for Pi export activity and proper localization to the Golgi and trans-Golgi network, although the EXS domain by itself cannot mediate Pi export. In contrast, removal of the amino-terminal hydrophilic SPX domain does not affect the Pi export capacity of the truncated PHO1 in N. benthamiana. While the Arabidopsis pho1 mutant has low shoot Pi and shows all the hallmarks associated with Pi deficiency, including poor shoot growth and overexpression of numerous Pi deficiency-responsive genes, expression of only the EXS domain of PHO1 in the roots of the pho1 mutant results in a remarkable improvement of shoot growth despite low shoot Pi. Transcriptomic analysis of pho1 expressing the EXS domain indicates an attenuation of the Pi signaling cascade and the up-regulation of genes involved in cell wall synthesis and the synthesis or response to several phytohormones in leaves as well as an altered expression of genes responsive to abscisic acid in roots.
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Stefanie
authors.identifier: http://orcid.org/0000-0002-7232-5889
authors.initials: S
authors.lastname: Wege
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Ghazanfar Abbas
authors.identifier: http://orcid.org/0000-0002-7557-6210
authors.initials: GA
authors.lastname: Khan
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Ji-Yul
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Evangelia
authors.identifier: http://orcid.org/0000-0003-2503-316X
authors.initials: E
authors.lastname: Vogiatzaki
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pradervand
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Isabel
authors.identifier: http://orcid.org/0000-0002-0501-807X
authors.initials: I
authors.lastname: Aller
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.).
authors.forename: Andreas J
authors.identifier: http://orcid.org/0000-0001-8144-4364
authors.initials: AJ
authors.lastname: Meyer
authors.affiliation: Department for Plant Molecular Biology (S.W., G.A.K., J.-Y.J., E.V., Y.P.) and Genomic Technologies Facility, Center for Integrative Genomics (S.P.), University of Lausanne, 1015 Lausanne, Switzerland;Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland (S.P.); andInstitute for Crop Science and Natural Resources, Chemical Signaling, University of Bonn, 53113 Bonn, Germany (I.A., A.J.M.) yves.poirier@unil.ch.
authors.forename: Yves
authors.identifier: http://orcid.org/0000-0001-8660-294X
authors.initials: Y
authors.lastname: Poirier
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010710:Phosphates / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C460111:PHO1 protein, Arabidopsis; D010710:Phosphates