--- res: bibo_abstract: - Plants exhibit an exceptional adaptability to different environmental conditions. To a large extent, this adaptability depends on their ability to initiate and form new organs throughout their entire postembryonic life. Plant shoot and root systems unceasingly branch and form axillary shoots or lateral roots, respectively. The first event in the formation of a new organ is specification of founder cells. Several plant hormones, prominent among them auxin, have been implicated in the acquisition of founder cell identity by differentiated cells, but the mechanisms underlying this process are largely elusive. Here, we show that auxin and its local accumulation in root pericycle cells is a necessary and sufficient signal to respecify these cells into lateral root founder cells. Analysis of the alf4-1 mutant suggests that specification of founder cells and the subsequent activation of cell division leading to primordium formation represent two genetically separable events. Time-lapse experiments show that the activation of an auxin response is the earliest detectable event in founder cell specification. Accordingly, local activation of auxin response correlates absolutely with the acquisition of founder cell identity and precedes the actual formation of a lateral root primordium through patterned cell division. Local production and subsequent accumulation of auxin in single pericycle cells induced by Cre-Lox-based activation of auxin synthesis converts them into founder cells. Thus, auxin is the local instructive signal that is sufficient for acquisition of founder cell identity and can be considered a morphogenetic trigger in postembryonic plant organogenesis.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Joseph foaf_name: Dubrovsky, Joseph G foaf_surname: Dubrovsky - foaf_Person: foaf_givenName: Michael foaf_name: Sauer, Michael foaf_surname: Sauer - foaf_Person: foaf_givenName: Selene foaf_name: Napsucialy-Mendivil, Selene foaf_surname: Napsucialy Mendivil - foaf_Person: foaf_givenName: Maria foaf_name: Ivanchenko, Maria G foaf_surname: Ivanchenko - 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: Svetlana foaf_name: Shishkova, Svetlana foaf_surname: Shishkova - foaf_Person: foaf_givenName: John foaf_name: Celenza, John foaf_surname: Celenza - foaf_Person: foaf_givenName: Eva foaf_name: Eva Benková foaf_surname: Benková foaf_workInfoHomepage: http://www.librecat.org/personId=38F4F166-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-8510-9739 bibo_doi: 10.1073/pnas.0712307105 bibo_issue: '25' bibo_volume: 105 dct_date: 2008^xs_gYear dct_publisher: National Academy of Sciences@ dct_title: Auxin acts as a local morphogenetic trigger to specify lateral root founder cells@ ...