Cytokinin Modulates Endocytic Trafficking of PIN1 Auxin Efflux Carrier to Control Plant Organogenesis

Dev Cell. 2011 Oct 18;21(4):796-804. doi: 10.1016/j.devcel.2011.08.014. Epub 2011 Sep 29.


Cytokinin is an important regulator of plant growth and development. In Arabidopsis thaliana, the two-component phosphorelay mediated through a family of histidine kinases and response regulators is recognized as the principal cytokinin signal transduction mechanism activating the complex transcriptional response to control various developmental processes. Here, we identified an alternative mode of cytokinin action that uses endocytic trafficking as a means to direct plant organogenesis. This activity occurs downstream of known cytokinin receptors but through a branch of the cytokinin signaling pathway that does not involve transcriptional regulation. We show that cytokinin regulates endocytic recycling of the auxin efflux carrier PINFORMED1 (PIN1) by redirecting it for lytic degradation in vacuoles. Stimulation of the lytic PIN1 degradation is not a default effect for general downregulation of proteins from plasma membranes, but a specific mechanism to rapidly modulate the auxin distribution in cytokinin-mediated developmental processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Blotting, Western
  • Cell Membrane / metabolism
  • Cytokinins / pharmacology*
  • Endocytosis*
  • Gene Expression Regulation, Plant
  • Indoleacetic Acids / pharmacology*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Organogenesis
  • Plant Growth Regulators / pharmacology
  • Plant Roots / cytology*
  • Plant Roots / metabolism
  • Protein Transport*
  • RNA, Messenger / genetics
  • RNA, Plant / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Seeds / growth & development
  • Seeds / metabolism
  • Vacuoles / metabolism


  • Arabidopsis Proteins
  • Cytokinins
  • Indoleacetic Acids
  • Membrane Transport Proteins
  • PIN1 protein, Arabidopsis
  • Plant Growth Regulators
  • RNA, Messenger
  • RNA, Plant