title: AUX1 promotes lateral root formation by facilitating indole-3-acetic acid distribution between sink and source tissues in the Arabidopsis seedling.
abstract: Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between indole-3-acetic acid (IAA) source and sink tissues. Gas chromatography-selected reaction monitoring-mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.
authors.affiliation: Plant Science Division, School of Biosciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Alan
authors.initials: A
authors.lastname: Marchant
authors.forename: Rishikesh
authors.initials: R
authors.lastname: Bhalerao
authors.forename: Ilda
authors.initials: I
authors.lastname: Casimiro
authors.forename: Jan
authors.initials: J
authors.lastname: Eklöf
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Casero
authors.forename: Malcolm
authors.initials: M
authors.lastname: Bennett
authors.forename: Goran
authors.initials: G
authors.lastname: Sandberg
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division; D015870:Gene Expression; D007210:Indoleacetic Acids / Q000378:metabolism*; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development*
chemical_list: C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010940:Plant Proteins; C034182:1-naphthaleneacetic acid; C030737:indoleacetic acid