Arabidopsis SGT1b is required for SCF(TIR1)-mediated auxin response

Plant Cell. 2003 Jun;15(6):1310-9. doi: 10.1105/tpc.010884.

Abstract

The SCF(TIR1) complex is a central regulator of the auxin response pathway in Arabidopsis. This complex functions as a ubiquitin protein ligase that targets members of the auxin/indoleacetic acid (Aux/IAA) family of transcriptional regulators for ubiquitin-mediated degradation in response to auxin. In an attempt to identify additional factors required for SCF(TIR1) activity, we conducted a genetic screen to isolate enhancers of the auxin response defect conferred by the tir1-1 mutation. Here, we report the identification and characterization of the eta3 mutant. The eta3 mutation interacts synergistically with tir1-1 to strongly enhance all aspects of the tir1 mutant phenotype, including auxin inhibition of root growth, lateral root development, hypocotyl elongation at high temperature, and apical dominance. We isolated the ETA3 gene using a map-based cloning strategy and determined that ETA3 encodes SGT1b. SGT1b was identified recently as a factor involved in plant disease resistance signaling, and SGT1 from barley and tobacco extracts was shown to interact with SCF ubiquitin ligases. We conclude that ETA3/SGT1b is required for the SCF(TIR1)-mediated degradation of Aux/IAA proteins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Base Sequence
  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism
  • Cloning, Molecular
  • Cyclopentanes / pharmacology
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Hypocotyl / growth & development
  • Immunity, Innate / genetics
  • Indoleacetic Acids / pharmacology*
  • Molecular Sequence Data
  • Mutation
  • Oxylipins
  • Peptide Synthases / genetics*
  • Peptide Synthases / metabolism
  • Phenotype
  • Plant Roots / growth & development
  • SKP Cullin F-Box Protein Ligases
  • Signal Transduction / genetics

Substances

  • Arabidopsis Proteins
  • Cell Cycle Proteins
  • Cyclopentanes
  • Indoleacetic Acids
  • Oxylipins
  • SGT1b protein, Arabidopsis
  • jasmonic acid
  • indoleacetic acid
  • SKP Cullin F-Box Protein Ligases
  • Peptide Synthases