title: ROTUNDA3 function in plant development by phosphatase 2A-mediated regulation of auxin transporter recycling.
abstract: The shaping of organs in plants depends on the intercellular flow of the phytohormone auxin, of which the directional signaling is determined by the polar subcellular localization of PIN-FORMED (PIN) auxin transport proteins. Phosphorylation dynamics of PIN proteins are affected by the protein phosphatase 2A (PP2A) and the PINOID kinase, which act antagonistically to mediate their apical-basal polar delivery. Here, we identified the ROTUNDA3 (RON3) protein as a regulator of the PP2A phosphatase activity in Arabidopsis thaliana. The RON3 gene was map-based cloned starting from the ron3-1 leaf mutant and found to be a unique, plant-specific gene coding for a protein with high and dispersed proline content. The ron3-1 and ron3-2 mutant phenotypes [i.e., reduced apical dominance, primary root length, lateral root emergence, and growth; increased ectopic stages II, IV, and V lateral root primordia; decreased auxin maxima in indole-3-acetic acid (IAA)-treated root apical meristems; hypergravitropic root growth and response; increased IAA levels in shoot apices; and reduced auxin accumulation in root meristems] support a role for RON3 in auxin biology. The affinity-purified PP2A complex with RON3 as bait suggested that RON3 might act in PIN transporter trafficking. Indeed, pharmacological interference with vesicle trafficking processes revealed that single ron3-2 and double ron3-2 rcn1 mutants have altered PIN polarity and endocytosis in specific cells. Our data indicate that RON3 contributes to auxin-mediated development by playing a role in PIN recycling and polarity establishment through regulation of the PP2A complex activity.
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Michael
authors.initials: M
authors.lastname: Karampelias
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Pia
authors.initials: P
authors.lastname: Neyt
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Steven
authors.initials: S
authors.lastname: De Groeve
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Stijn
authors.initials: S
authors.lastname: Aesaert
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Griet
authors.initials: G
authors.lastname: Coussens
authors.affiliation: Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Palacký University, 771 47 Olomouc, Czech Republic;
authors.forename: Jakub
authors.initials: J
authors.lastname: Rolčík
authors.affiliation: Dipartimento di Ecologia, Università della Calabria, 87030 Cosenza, Italy;
authors.forename: Leonardo
authors.initials: L
authors.lastname: Bruno
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Nancy
authors.initials: N
authors.lastname: De Winne
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Annemie
authors.initials: A
authors.lastname: Van Minnebruggen
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; marc.vanmontagu@ugent.be milij@psb.vib-ugent.be.
authors.forename: Marc
authors.initials: M
authors.lastname: Van Montagu
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain;
authors.forename: María Rosa
authors.initials: MR
authors.lastname: Ponce
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain;
authors.forename: José Luis
authors.initials: JL
authors.lastname: Micol
authors.affiliation: Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
authors.forename: Jiří
authors.initials: J
authors.lastname: Friml
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
authors.forename: Geert
authors.initials: G
authors.lastname: De Jaeger
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; marc.vanmontagu@ugent.be milij@psb.vib-ugent.be.
authors.forename: Mieke
authors.initials: M
authors.lastname: Van Lijsebettens
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008954:Models, Biological; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D054648:Protein Phosphatase 2; C116363:PIN1 protein, Arabidopsis; C000609619:SIC protein, Arabidopsis
keywords: Arabidopsis; PIN recycling; PP2A; auxin; plant development