Auxin-dependent regulation of lateral root positioning in the basal meristem of <i>Arabidopsis</i>

Ive De Smet(Vlaams Instituut voor Biotechnologie), Takuya Tetsumura(University of Nottingham), Bert De Rybel(Vlaams Instituut voor Biotechnologie), Nicolas Frei dit Frey(Vlaams Instituut voor Biotechnologie), Laurent Laplaze(Institut de Recherche pour le Développement), Ilda Casimiro(Universidad de Extremadura), Ranjan Swarup(University of Nottingham), Mirande Naudts(Vlaams Instituut voor Biotechnologie), Steffen Vanneste(Vlaams Instituut voor Biotechnologie), Dominique Audenaert(Vlaams Instituut voor Biotechnologie), Dirk Inzé(Vlaams Instituut voor Biotechnologie), Malcolm J. Bennett(University of Nottingham), Tom Beeckman(Vlaams Instituut voor Biotechnologie)
Development
January 10, 2007
10.1242/dev.02753
Cited by 615

Abstract

In plants, the developmental mechanisms that regulate the positioning of lateral organs along the primary root are currently unknown. We present evidence on how lateral root initiation is controlled in a spatiotemporal manner in the model plant Arabidopsis thaliana. First, lateral roots are spaced along the main axis in a regular left-right alternating pattern that correlates with gravity-induced waving and depends on AUX1, an auxin influx carrier essential for gravitropic response. Second, we found evidence that the priming of pericycle cells for lateral root initiation might take place in the basal meristem, correlating with elevated auxin sensitivity in this part of the root. This local auxin responsiveness oscillates with peaks of expression at regular intervals of 15 hours. Each peak in the auxin-reporter maximum correlates with the formation of a consecutive lateral root. Third, auxin signaling in the basal meristem triggers pericycle cells for lateral root initiation prior to the action of INDOLE-3-ACETIC ACID14 (SOLITARY ROOT).

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