title: Positional information by differential endocytosis splits auxin response to drive Arabidopsis root meristem growth.
abstract: In the Arabidopsis root meristem, polar auxin transport creates a transcriptional auxin response gradient that peaks at the stem cell niche and gradually decreases as stem cell daughters divide and differentiate [1-3]. The amplitude and extent of this gradient are essential for both stem cell maintenance and root meristem growth [4, 5]. To investigate why expression of some auxin-responsive genes, such as the essential root meristem growth regulator BREVIS RADIX (BRX) [6], deviates from this gradient, we combined experimental and computational approaches. We created cellular-level root meristem models that accurately reproduce distribution of nuclear auxin activity and allow dynamic modeling of regulatory processes to guide experimentation. Expression profiles deviating from the auxin gradient could only be modeled after intersection of auxin activity with the observed differential endocytosis pattern and positive autoregulatory feedback through plasma-membrane-to-nucleus transfer of BRX. Because BRX is required for expression of certain auxin response factor targets, our data suggest a cell-type-specific endocytosis-dependent input into transcriptional auxin perception. This input sustains expression of a subset of auxin-responsive genes across the root meristem's division and transition zones and is essential for meristem growth. Thus, the endocytosis pattern provides specific positional information to modulate auxin response.
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Santuari
authors.forename: Emanuele
authors.initials: E
authors.lastname: Scacchi
authors.forename: Antia
authors.initials: A
authors.lastname: Rodriguez-Villalon
authors.forename: Paula
authors.initials: P
authors.lastname: Salinas
authors.forename: Esther M N
authors.initials: EM
authors.lastname: Dohmann
authors.forename: Géraldine
authors.initials: G
authors.lastname: Brunoud
authors.forename: Teva
authors.initials: T
authors.lastname: Vernoux
authors.forename: Richard S
authors.initials: RS
authors.lastname: Smith
authors.forename: Christian S
authors.initials: CS
authors.lastname: Hardtke
mesh_terms: D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003198:Computer Simulation; D004705:Endocytosis; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D018519:Meristem / Q000254:growth & development* / Q000378:metabolism; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C483078:BREVIS RADIX protein, Arabidopsis; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators