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Nature 426, 147-153 (13 November 2003) | doi:10.1038/nature02085; Received 24 June 2003; Accepted 19 September 2003

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Efflux-dependent auxin gradients establish the apical–basal axis of Arabidopsis

Jir caroní Friml1,4, Anne Vieten1,4, Michael Sauer1,4, Dolf Weijers1,2, Heinz Schwarz3, Thorsten Hamann1,5, Remko Offringa2 & Gerd Jürgens1

  1. Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany
  2. Institute of Biology, Clusius Laboratory, Leiden University, Wassenaarseweg 64, 2333 AL, Leiden, The Netherlands
  3. Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany
  4. These authors contributed equally to this work
  5. Present address: Department of Plant Biology, Carnegie Institution of Washington, 260 Panama street, 94305 Stanford, USA

Correspondence to: Jir caroní Friml1,4 Email: jiri.friml@zmbp.uni-tuebingen.de

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Axis formation occurs in plants, as in animals, during early embryogenesis. However, the underlying mechanism is not known. Here we show that the first manifestation of the apical–basal axis in plants, the asymmetric division of the zygote, produces a basal cell that transports and an apical cell that responds to the signalling molecule auxin. This apical–basal auxin activity gradient triggers the specification of apical embryo structures and is actively maintained by a novel component of auxin efflux, PIN7, which is located apically in the basal cell. Later, the developmentally regulated reversal of PIN7 and onset of PIN1 polar localization reorganize the auxin gradient for specification of the basal root pole. An analysis of pin quadruple mutants identifies PIN-dependent transport as an essential part of the mechanism for embryo axis formation. Our results indicate how the establishment of cell polarity, polar auxin efflux and local auxin response result in apical–basal axis formation of the embryo, and thus determine the axiality of the adult plant.

  1. Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany
  2. Institute of Biology, Clusius Laboratory, Leiden University, Wassenaarseweg 64, 2333 AL, Leiden, The Netherlands
  3. Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany
  4. These authors contributed equally to this work
  5. Present address: Department of Plant Biology, Carnegie Institution of Washington, 260 Panama street, 94305 Stanford, USA

Correspondence to: Jir caroní Friml1,4 Email: jiri.friml@zmbp.uni-tuebingen.de