title: The Arabidopsis Auxin Receptor F-Box Proteins AFB4 and AFB5 Are Required for Response to the Synthetic Auxin Picloram.
abstract: The plant hormone auxin is perceived by a family of F-box proteins called the TIR1/AFBs. Phylogenetic studies reveal that these proteins fall into four clades in flowering plants called TIR1, AFB2, AFB4, and AFB6. Genetic studies indicate that members of the TIR1 and AFB2 groups act as positive regulators of auxin signaling by promoting the degradation of the Aux/IAA transcriptional repressors. In this report, we demonstrate that both AFB4 and AFB5 also function as auxin receptors based on in vitro assays. We also provide genetic evidence that AFB4 and AFB5 are targets of the picloram family of auxinic herbicides in addition to indole-3-acetic acid. In contrast to previous studies we find that null afb4 alleles do not exhibit obvious defects in seedling morphology or auxin hypersensitivity. We conclude that AFB4 and AFB5 act in a similar fashion to other members of the family but exhibit a distinct auxin specificity.
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
authors.forename: Michael J
authors.identifier: 0000-0003-0671-2538
authors.initials: MJ
authors.lastname: Prigge
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Greenham
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
authors.forename: Aaron
authors.initials: A
authors.lastname: Santner
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093.
authors.forename: Cristina
authors.initials: C
authors.lastname: Castillejo
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Mutka
authors.affiliation: Genomic Analysis Laboratory, Howard Hughes Medical Institute and The Salk Institute for Biological Studies, La Jolla, California 92037.
authors.forename: Ronan C
authors.initials: RC
authors.lastname: O'Malley
authors.affiliation: Genomic Analysis Laboratory, Howard Hughes Medical Institute and The Salk Institute for Biological Studies, La Jolla, California 92037.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Barbara N
authors.initials: BN
authors.lastname: Kunkel
authors.affiliation: Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California 92093 mestelle@ucsd.edu.
authors.forename: Mark
authors.identifier: 0000-0002-2613-8652
authors.initials: M
authors.lastname: Estelle
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D044783:F-Box Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D053209:Herbicide Resistance / Q000235:genetics; D006540:Herbicides / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010846:Picloram / Q000494:pharmacology*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000235:genetics / Q000378:metabolism
chemical_list: C559638:AFB4 protein, Arabidopsis; C516178:AFB5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D006540:Herbicides; D007210:Indoleacetic Acids; D011956:Receptors, Cell Surface; D010846:Picloram
keywords: Arabidopsis; F-box protein; auxin