Local auxin biosynthesis modulates gradient-directed planar polarity in Arabidopsis

Nat Cell Biol. 2009 Jun;11(6):731-8. doi: 10.1038/ncb1879. Epub 2009 May 17.

Abstract

The coordination of cell polarity within the plane of a single tissue layer (planar polarity) is a crucial task during development of multicellular organisms. Mechanisms underlying establishment of planar polarity, however, differ substantially between plants and animals. In Arabidopsis thaliana, planar polarity of root-hair positioning along epidermal cells is coordinated towards maximum concentration of an auxin gradient in the root tip. This gradient has been hypothesized to be sink-driven and computational modelling suggests that auxin efflux carrier activity may be sufficient to generate the gradient in the absence of auxin biosynthesis in the root. Here, we demonstrate that the Raf-like kinase CONSTITUTIVE TRIPLE RESPONSE1 (CTR1; Refs 8, 9) acts as a concentration-dependent repressor of a biosynthesis-dependent auxin gradient that modulates planar polarity in the root tip. We analysed auxin biosynthesis and concentration gradients in a variety of root-hair-position mutants affected in CTR1 activity, auxin biosynthesis and transport. Our results reveal that planar polarity relies on influx- and efflux-carrier-mediated auxin redistribution from a local biosynthesis maximum. Thus, a local source of auxin biosynthesis contributes to gradient homeostasis during long-range coordination of cellular morphogenesis.

Publication types

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

MeSH terms

  • Animals
  • Arabidopsis Proteins / biosynthesis
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Arabidopsis* / anatomy & histology
  • Arabidopsis* / metabolism
  • Cell Polarity*
  • Genes, Reporter
  • Morphogenesis / physiology*
  • Mutation
  • Plant Roots / cytology
  • Plant Roots / growth & development
  • Plants, Genetically Modified
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism

Substances

  • AUX1 protein, Arabidopsis
  • Arabidopsis Proteins
  • PIN2 protein, Arabidopsis
  • Recombinant Fusion Proteins
  • Protein Kinases
  • CTR1 protein, Arabidopsis