title: SPINDLY is a nuclear-localized repressor of gibberellin signal transduction expressed throughout the plant.
abstract: SPY (SPINDLY) encodes a putative O-linked N-acetyl-glucosamine transferase that is genetically defined as a negatively acting component of the gibberellin (GA) signal transduction pathway. Analysis of Arabidopsis plants containing a SPY::GUS reporter gene reveals that SPY is expressed throughout the life of the plant and in most plant organs examined. In addition to being expressed in all organs where phenotypes due to spy mutations have been reported, SPY::GUS is expressed in the root. Examination of the roots of wild-type, spy, and gai plants revealed phenotypes indicating that SPY and GAI play a role in root development. A second SPY::GUS reporter gene lacking part of the SPY promoter was inactive, suggesting that sequences in the first exon and/or intron are required for detectable expression. Using both subcellular fractionation and visualization of a SPY-green fluorescent protein fusion protein that is able to rescue the spy mutant phenotype, the majority of SPY protein was shown to be present in the nucleus. This result is consistent with the nuclear localization of other components of the GA response pathway and suggests that SPY's role as a negative regulator of GA signaling involves interaction with other nuclear proteins and/or O-N-acetyl-glucosamine modification of these proteins.
authors.affiliation: Department of Plant Biology and Plant Molecular Genetics Institute, University of Minnesota, St. Paul, MN 55108, USA. Steve.Swain@csiro.au
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Swain
authors.forename: Tong-Seung
authors.initials: TS
authors.lastname: Tseng
authors.forename: Tina M
authors.initials: TM
authors.lastname: Thornton
authors.forename: Manjula
authors.initials: M
authors.lastname: Gopalraj
authors.forename: Neil E
authors.initials: NE
authors.lastname: Olszewski
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology*; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D063245:Plant Development; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D010944:Plants / Q000187:drug effects / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; C109555:GAI protein, Arabidopsis; D005875:Gibberellins; D008164:Luminescent Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C101465:SPY protein, Arabidopsis; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid; D005966:Glucuronidase