Mechano-chemical aspects of organ formation in Arabidopsis thaliana: the relationship between auxin and pectin

PLoS One. 2013;8(3):e57813. doi: 10.1371/journal.pone.0057813. Epub 2013 Mar 12.


How instructive signals are translated into robust and predictable changes in growth is a central question in developmental biology. Recently, much interest has centered on the feedback between chemical instructions and mechanical changes for pattern formation in development. In plants, the patterned arrangement of aerial organs, or phyllotaxis, is instructed by the phytohormone auxin; however, it still remains to be seen how auxin is linked, at the apex, to the biochemical and mechanical changes of the cell wall required for organ outgrowth. Here, using Atomic Force Microscopy, we demonstrate that auxin reduces tissue rigidity prior to organ outgrowth in the shoot apex of Arabidopsis thaliana, and that the de-methyl-esterification of pectin is necessary for this reduction. We further show that development of functional organs produced by pectin-mediated ectopic wall softening requires auxin signaling. Lastly, we demonstrate that coordinated localization of the auxin transport protein, PIN1, is disrupted in a naked-apex produced by increasing cell wall rigidity. Our data indicates that a feedback loop between the instructive chemical auxin and cell wall mechanics may play a crucial role in phyllotactic patterning.

Publication types

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

MeSH terms

  • Arabidopsis / cytology
  • Arabidopsis / embryology*
  • Arabidopsis Proteins / metabolism*
  • Indoleacetic Acids / metabolism*
  • Mechanotransduction, Cellular / physiology*
  • Membrane Transport Proteins / metabolism*
  • Pectins / metabolism*
  • Seeds / cytology
  • Seeds / embryology*


  • Arabidopsis Proteins
  • Indoleacetic Acids
  • Membrane Transport Proteins
  • PIN1 protein, Arabidopsis
  • Pectins

Grant support

AP was funded by the Human Frontiers Science Program, Agence Nationale de la Recherche (ANR) Blanc 2009 ANR-09-BLAN-0007-02 ‘GrowPec’, ANR-10-BLAN-1516 2010 ‘Mechastem’. SB is funded by a United States National Science Foundation International Research Fellowship (Award No. OISE-0853105) and the Swiss National Science Foundation. No additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.