A fast brassinolide-regulated response pathway in the plasma membrane of Arabidopsis thaliana

Plant J. 2011 May;66(3):528-40. doi: 10.1111/j.1365-313X.2011.04510.x. Epub 2011 Mar 1.


To understand molecular processes in living plant cells, quantitative spectro-microscopic technologies are required. By combining fluorescence lifetime spectroscopy with confocal microscopy, we studied the subcellular properties and function of a GFP-tagged variant of the plasma membrane-bound brassinosteroid receptor BRI1 (BRI1-GFP) in living cells of Arabidopsis seedlings. Shortly after adding brassinolide, we observed BRI1-dependent cell-wall expansion, preceding cell elongation. In parallel, the fluorescence lifetime of BRI1-GFP decreased, indicating an alteration in the receptor's physico-chemical environment. The parameter modulating the fluorescence lifetime of BRI1-GFP was found to be BL-induced hyperpolarization of the plasma membrane. Furthermore, for induction of hyperpolarization and cell-wall expansion, activation of the plasma membrane P-ATPase was necessary. This activation required BRI1 kinase activity, and was mediated by BL-modulated interaction of BRI1 with the P-ATPase. Our results were used to develop a model suggesting that there is a fast BL-regulated signal response pathway within the plasma membrane that links BRI1 with P-ATPase for the regulation of cell-wall expansion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2,4-Dichlorophenoxyacetic Acid / pharmacology
  • Adenosine Triphosphatases
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / metabolism*
  • Brassinosteroids
  • Cell Membrane / enzymology
  • Cell Membrane / physiology*
  • Cell Wall / drug effects
  • Cell Wall / physiology*
  • Cholestanols / pharmacology*
  • Electrophysiology
  • Green Fluorescent Proteins / metabolism
  • Membrane Potentials
  • Phosphorylation
  • Plants, Genetically Modified / drug effects
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / physiology
  • Protein Kinases / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Seedlings / drug effects
  • Seedlings / growth & development
  • Seedlings / physiology
  • Sodium Acetate / pharmacology
  • Steroids, Heterocyclic / pharmacology*
  • Tobacco / drug effects
  • Tobacco / genetics
  • Tobacco / physiology


  • Arabidopsis Proteins
  • Brassinosteroids
  • Cholestanols
  • Recombinant Fusion Proteins
  • Steroids, Heterocyclic
  • Green Fluorescent Proteins
  • 2,4-Dichlorophenoxyacetic Acid
  • Sodium Acetate
  • Protein Kinases
  • BRI1 protein, Arabidopsis
  • Adenosine Triphosphatases
  • brassinolide