title: Cytokinin acts through the auxin influx carrier AUX1 to regulate cell elongation in the root.
abstract: Hormonal interactions are crucial for plant development. In Arabidopsis, cytokinins inhibit root growth through effects on cell proliferation and cell elongation. Here, we define key mechanistic elements in a regulatory network by which cytokinin inhibits root cell elongation in concert with the hormones auxin and ethylene. The auxin importer AUX1 functions as a positive regulator of cytokinin responses in the root; mutation of AUX1 specifically affects the ability of cytokinin to inhibit cell elongation but not cell proliferation. AUX1 is required for cytokinin-dependent changes of auxin activity in the lateral root cap associated with the control of cell elongation. Cytokinin regulates root cell elongation through ethylene-dependent and -independent mechanisms, both hormonal signals converging on AUX1 as a regulatory hub. An autoregulatory circuit is identified involving the control of ARR10 and AUX1 expression by cytokinin and auxin, this circuit potentially functioning as an oscillator to integrate the effects of these two hormones. Taken together, our results uncover several regulatory circuits controlling interactions of cytokinin with auxin and ethylene, and support a model in which cytokinin regulates shootward auxin transport to control cell elongation and root growth.
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Ian H
authors.identifier: 0000-0002-1113-1415
authors.initials: IH
authors.lastname: Street
authors.affiliation: Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA.
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Mathews
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Yamburkenko
authors.affiliation: Department of Agronomy, Tarbiat Modares University, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Sorooshzadeh
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Roshen T
authors.initials: RT
authors.lastname: John
authors.affiliation: Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Nottingham LE12 5RD, UK.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Swarup
authors.affiliation: Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Nottingham LE12 5RD, UK.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Bennett
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Joseph J
authors.identifier: 0000-0002-5766-812X
authors.initials: JJ
authors.lastname: Kieber
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA george.e.schaller@dartmouth.edu.
authors.forename: G Eric
authors.identifier: 0000-0003-4032-2437
authors.initials: GE
authors.lastname: Schaller
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001593:Benzyl Compounds / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D003583:Cytokinins / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011687:Purines / Q000494:pharmacology
chemical_list: C469257:ARR10 protein, Arabidopsis; C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D003583:Cytokinins; D004268:DNA-Binding Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011687:Purines; C036216:ethylene; C480551:benzylaminopurine
keywords: AUX1; Arabidopsis; Auxin; Cytokinin; Ethylene; Root Development