title: RACK1 mediates multiple hormone responsiveness and developmental processes in Arabidopsis.
abstract: The scaffold protein RACK1 (Receptor for Activated C Kinase 1) serves as an integrative point for diverse signal transduction pathways. The Arabidopsis genome contains three RACK1 orthologues, however, little is known about their functions. It is reported here that one member of this gene family, RACK1A, previously identified as the Arabidopsis homologue of the tobacco arcA gene, mediates hormone responses and plays a regulatory role in multiple developmental processes. RACK1A expresses ubiquitously in Arabidopsis. Loss-of-function mutations in RACK1A confer defects in multiple developmental processes including seed germination, leaf production, and flowering. rack1a mutants displayed reduced sensitivity to gibberellin and brassinosteroid in seed germination, hypersensitivity to abscisic acid in seed germination and early seedling development, and hyposensitivity to auxin in adventitious and lateral root formation. These results provide the first genetic evidence that RACK1A is involved in multiple signal transduction pathways.
authors.affiliation: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4 Canada. jingui@interchange.ubc.ca
authors.forename: Jin-Gui
authors.initials: JG
authors.lastname: Chen
authors.forename: Hemayet
authors.initials: H
authors.lastname: Ullah
authors.forename: Brenda
authors.initials: B
authors.lastname: Temple
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Liang
authors.forename: Jianjun
authors.initials: J
authors.lastname: Guo
authors.forename: José M
authors.initials: JM
authors.lastname: Alonso
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jones
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000235:genetics; D005875:Gibberellins / Q000494:pharmacology; D005966:Glucuronidase / Q000032:analysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000032:analysis; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D010937:Plant Growth Regulators; D021122:Protein Subunits; C515163:RACK1 protein, Arabidopsis; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D005966:Glucuronidase; D019204:GTP-Binding Proteins