title: ECHIDNA-mediated post-Golgi trafficking of auxin carriers for differential cell elongation.
abstract: The plant hormone indole-acetic acid (auxin) is essential for many aspects of plant development. Auxin-mediated growth regulation typically involves the establishment of an auxin concentration gradient mediated by polarly localized auxin transporters. The localization of auxin carriers and their amount at the plasma membrane are controlled by membrane trafficking processes such as secretion, endocytosis, and recycling. In contrast to endocytosis or recycling, how the secretory pathway mediates the localization of auxin carriers is not well understood. In this study we have used the differential cell elongation process during apical hook development to elucidate the mechanisms underlying the post-Golgi trafficking of auxin carriers in Arabidopsis. We show that differential cell elongation during apical hook development is defective in Arabidopsis mutant echidna (ech). ECH protein is required for the trans-Golgi network (TGN)-mediated trafficking of the auxin influx carrier AUX1 to the plasma membrane. In contrast, ech mutation only marginally perturbs the trafficking of the highly related auxin influx carrier LIKE-AUX1-3 or the auxin efflux carrier PIN-FORMED-3, both also involved in hook development. Electron tomography reveals that the trafficking defects in ech mutant are associated with the perturbation of secretory vesicle genesis from the TGN. Our results identify differential mechanisms for the post-Golgi trafficking of de novo-synthesized auxin carriers to plasma membrane from the TGN and reveal how trafficking of auxin influx carriers mediates the control of differential cell elongation in apical hook development.
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90 183 Umeå, Sweden.
authors.forename: Yohann
authors.initials: Y
authors.lastname: Boutté
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Jonsson
authors.forename: Heather E
authors.initials: HE
authors.lastname: McFarlane
authors.forename: Errin
authors.initials: E
authors.lastname: Johnson
authors.forename: Delphine
authors.initials: D
authors.lastname: Gendre
authors.forename: Ranjan
authors.initials: R
authors.lastname: Swarup
authors.forename: Jirí
authors.initials: J
authors.lastname: Friml
authors.forename: Lacey
authors.initials: L
authors.lastname: Samuels
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Robert
authors.forename: Rishikesh P
authors.initials: RP
authors.lastname: Bhalerao
mesh_terms: D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D049108:Cell Enlargement; D002462:Cell Membrane / Q000378:metabolism; D055032:Electron Microscope Tomography; D006056:Golgi Apparatus / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology* / Q000254:growth & development; D021381:Protein Transport / Q000502:physiology; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D033921:Vesicular Transport Proteins
keywords: IAA; morphogenesis; sorting
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