Local auxin sources orient the apical basal axis in arabidopsis embryos Journal Article

Author(s): Robert, Hélène S; Grones, Peter; Stepanova, Anna N; Robles, Linda M; Lokerse, Annemarie S; Alonso, Jose M; Weijers, Dolf; Friml, Jiří
Article Title: Local auxin sources orient the apical basal axis in arabidopsis embryos
Affiliation IST Austria
Abstract: Establishment of the embryonic axis foreshadows the main body axis of adults both in plants and in animals, but underlying mechanisms are considered distinct. Plants utilize directional, cell-to-cell transport of the growth hormone auxin [1, 2] to generate an asymmetric auxin response that specifies the embryonic apical-basal axis [3-6]. The auxin flow directionality depends on the polarized subcellular localization of PIN-FORMED (PIN) auxin transporters [7, 8]. It remains unknown which mechanisms and spatial cues guide cell polarization and axis orientation in early embryos. Herein, we provide conceptually novel insights into the formation of embryonic axis in Arabidopsis by identifying a crucial role of localized tryptophan-dependent auxin biosynthesis [9-12]. Local auxin production at the base of young embryos and the accompanying PIN7-mediated auxin flow toward the proembryo are required for the apical auxin response maximum and the specification of apical embryonic structures. Later in embryogenesis, the precisely timed onset of localized apical auxin biosynthesis mediates PIN1 polarization, basal auxin response maximum, and specification of the root pole. Thus, the tight spatiotemporal control of distinct local auxin sources provides a necessary, non-cell-autonomous trigger for the coordinated cell polarization and subsequent apical-basal axis orientation during embryogenesis and, presumably, also for other polarization events during postembryonic plant life [13, 14].
Journal Title: Current Biology
Volume: 23
Issue 24
ISSN: 0960-9822
Publisher: Cell Press  
Date Published: 2013-12-16
Start Page: 2506
End Page: 2512
DOI: 10.1016/j.cub.2013.09.039
Notes: We thank Y. Zhao, A. Maizel, and NASC for providing seeds; W. Grunewald and K. Wabnik for helpful discussion; and B. Cannoot, N. Smet, and the PSB transformation facility for technical assistance. This work was supported by the European Research Council (project ERC-2011-StG-20101109-PSDP), project “CEITEC - Central European Institute of Technology” (CZ.1.05/1.1.00/02.0068), the European Social Fund (CZ.1.07/2.3.00/20.0043), and the Czech Science Foundation GAČR (GA13-40637S) to J.F.; by National Science Foundation grants (DBI0820755, MCB0923727, and MCB1158181) to J.M.A. and A.N.S.; and by the Netherlands Organization for Scientific Research (NWO; ALW VIDI-864.06.012) to D.W. H.S.R is supported by Employment of Best Young Scientists for International Cooperation Empowerment (CZ.1.07/2.3.00/30.0037), cofinanced by the European Social Fund and the state budget of the Czech Republic.
Open access: no