title: Canalization without flux sensors: a traveling-wave hypothesis.
abstract: 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.
authors.affiliation: Department of Plant Systems Biology, VIB, Technologiepark 927, 9052 Ghent, Belgium. roeland.merks@psb.ugent.be
authors.forename: Roeland M H
authors.initials: RM
authors.lastname: Merks
authors.forename: Yves
authors.initials: Y
authors.lastname: Van de Peer
authors.forename: Dirk
authors.initials: D
authors.lastname: Inzé
authors.forename: Gerrit T S
authors.initials: GT
authors.lastname: Beemster
mesh_terms: D003198:Computer Simulation; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D063245:Plant Development; D018515:Plant Leaves / Q000254:growth & development
chemical_list: D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins