Canalization Without Flux Sensors: A Traveling-Wave Hypothesis

Trends Plant Sci. 2007 Sep;12(9):384-90. doi: 10.1016/j.tplants.2007.08.004. Epub 2007 Aug 31.


In 1969, Tsvi Sachs published his seminal hypothesis of vascular development in plants: the canalization hypothesis. A positive feedback loop between the flux of the phytohormone auxin and the cells' auxin transport capacity would canalize auxin progressively into discrete channels, which would then differentiate into vascular tissues. Recent experimental studies confirm the central role of polar auxin flux in plant vasculogenesis, but it is unclear if and by which mechanism plant cells could respond to auxin flux. In this Opinion article, we review auxin perception mechanisms and argue that these respond more likely to auxin concentrations than to auxin flux. We propose an alternative mechanism for polar auxin channeling, which is more consistent with recent molecular observations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Computer Simulation
  • Gene Expression Regulation, Plant
  • Indoleacetic Acids / metabolism
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Models, Biological*
  • Plant Development*
  • Plant Leaves / growth & development


  • Indoleacetic Acids
  • Membrane Transport Proteins