title: Translatome analyses capture of opposing tissue-specific brassinosteroid signals orchestrating root meristem differentiation.
abstract: The mechanisms ensuring balanced growth remain a critical question in developmental biology. In plants, this balance relies on spatiotemporal integration of hormonal signaling pathways, but the understanding of the precise contribution of each hormone is just beginning to take form. Brassinosteroid (BR) hormone is shown here to have opposing effects on root meristem size, depending on its site of action. BR is demonstrated to both delay and promote onset of stem cell daughter differentiation, when acting in the outer tissue of the root meristem, the epidermis, and the innermost tissue, the stele, respectively. To understand the molecular basis of this phenomenon, a comprehensive spatiotemporal translatome mapping of Arabidopsis roots was performed. Analyses of wild type and mutants featuring different distributions of BR revealed autonomous, tissue-specific gene responses to BR, implying its contrasting tissue-dependent impact on growth. BR-induced genes were primarily detected in epidermal cells of the basal meristem zone and were enriched by auxin-related genes. In contrast, repressed BR genes prevailed in the stele of the apical meristem zone. Furthermore, auxin was found to mediate the growth-promoting impact of BR signaling originating in the epidermis, whereas BR signaling in the stele buffered this effect. We propose that context-specific BR activity and responses are oppositely interpreted at the organ level, ensuring coherent growth.
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Kristina
authors.initials: K
authors.lastname: Vragović
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Ayala
authors.initials: A
authors.lastname: Sela
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Lilach
authors.initials: L
authors.lastname: Friedlander-Shani
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Yulia
authors.initials: Y
authors.lastname: Fridman
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Yael
authors.initials: Y
authors.lastname: Hacham
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel;
authors.forename: Neta
authors.initials: N
authors.lastname: Holland
authors.affiliation: Bioinformatics Knowledge Unit, Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa 3200003, Israel; Center for Research Informatics, Biological Sciences Division, University of Chicago, Chicago, IL 60637; and.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Bartom
authors.affiliation: Crop Computational Biology Laboratory, Donald Danforth Plant Science Center, St. Louis, MO 63132.
authors.forename: Todd C
authors.initials: TC
authors.lastname: Mockler
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel; sigal@technion.ac.il.
authors.forename: Sigal
authors.initials: S
authors.lastname: Savaldi-Goldstein
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000378:metabolism*; D002454:Cell Differentiation; D018519:Meristem / Q000166:cytology*; D018517:Plant Roots / Q000166:cytology*; D014176:Protein Biosynthesis; D015398:Signal Transduction
chemical_list: D060406:Brassinosteroids
keywords: BRI1; auxin; brassinosteroids; intertissue communication; root meristem