--- res: bibo_abstract: - |- 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. @eng bibo_authorlist: - foaf_Person: foaf_givenName: Jirí foaf_name: Jirí Friml foaf_surname: Friml foaf_workInfoHomepage: http://www.librecat.org/personId=4159519E-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-8302-7596 - foaf_Person: foaf_givenName: Anne foaf_name: Vieten, Anne foaf_surname: Vieten - foaf_Person: foaf_givenName: Michael foaf_name: Sauer, Michael foaf_surname: Sauer - foaf_Person: foaf_givenName: Dolf foaf_name: Weijers, Dolf foaf_surname: Weijers - foaf_Person: foaf_givenName: Heinz foaf_name: Schwarz, Heinz foaf_surname: Schwarz - foaf_Person: foaf_givenName: Thorsten foaf_name: Hamann, Thorsten foaf_surname: Hamann - foaf_Person: foaf_givenName: Remko foaf_name: Offringa, Remko foaf_surname: Offringa - foaf_Person: foaf_givenName: Gerd foaf_name: Jürgens, Gerd foaf_surname: Jürgens bibo_doi: 10.1038/nature02085 bibo_issue: '6963' bibo_volume: 426 dct_date: 2003^xs_gYear dct_publisher: Nature Publishing Group@ dct_title: Efflux dependent auxin gradients establish the apical basal axis of Arabidopsis@ ...