title: Precise control of plant stem cell activity through parallel regulatory inputs.
abstract: The regulation of columella stem cell activity in the Arabidopsis root cap by a nearby organizing centre, the quiescent centre, has been a key example of the stem cell niche paradigm in plants. Here, we investigate interactions between transcription factors that have been shown to regulate columella stem cells using a simple quantification method for stem cell activity in the root cap. Genetic and expression analyses reveal that the RETINOBLASTOMA-RELATED protein, the FEZ and SOMBRERO NAC-domain transcription factors, the ARF10 and ARF16 auxin response factors and the quiescent centre-expressed WOX5 homeodomain protein each provide independent inputs to regulate the number of columella stem cells. Given the tight control of columella development, we found that these inputs act in a surprisingly parallel manner. Nevertheless, important points of interaction exist; for example, we demonstrate the repression of SMB activity by non-autonomous action of WOX5. Our results suggest that the developmental progression of columella stem cells may be quantitatively regulated by several more broadly acting transcription factors rather than by a single intrinsic stem cell factor, which raises questions about the special nature of the stem cell state in plants.
authors.affiliation: Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands.
authors.forename: Tom
authors.initials: T
authors.lastname: Bennett
authors.affiliation: Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: van den Toorn
authors.affiliation: Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands.
authors.forename: Viola
authors.initials: V
authors.lastname: Willemsen
authors.affiliation: Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands ben.scheres@wur.nl.
authors.forename: Ben
authors.initials: B
authors.lastname: Scheres
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D055153:Stem Cell Niche / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C505216:ARF10 protein, Arabidopsis; C505217:ARF16 protein, Arabidopsis; D029681:Arabidopsis Proteins; C534300:FEZ protein, Arabidopsis; D010940:Plant Proteins; C487568:RBR1 protein, Arabidopsis; C534299:SOMBRERO protein, Arabidopsis; D014157:Transcription Factors
keywords: Plant development; Root cap; Stem cell; Stem cell niche