title: A SCARECROW-based regulatory circuit controls Arabidopsis thaliana meristem size from the root endodermis.
abstract: SCARECROW controls Arabidopsis root meristem size from the root endodermis tissue by regulating the DELLA protein RGA that in turn mediates the regulation of ARR1 levels at the transition zone. Coherent organ growth requires a fine balance between cell division and cell differentiation. Intriguingly, plants continuously develop organs post-embryonically thanks to the activity of meristems that allow growth and environmental plasticity. In Arabidopsis thaliana, continued root growth is assured when division of the distal stem cell and their daughters is balanced with cell differentiation at the meristematic transition zone (TZ). We have previously shown that at the TZ, the cytokinin-dependent transcription factor ARR1 controls the rate of differentiation commitment of meristematic cells and that its activities are coordinated with those of the distal stem cells by the gene SCARECROW (SCR). In the stem cell organizer (the quiescent center, QC), SCR directly suppresses ARR1 both sustaining stem cell activities and titrating non-autonomously the ARR1 transcript levels at the TZ via auxin. Here, we show that SCR also exerts a fine control on ARR1 levels at the TZ from the endodermis by sustaining gibberellin signals. From the endodermis, SCR controls the RGA REPRESSOR OF ga1-3 (RGA) DELLA protein stability throughout the root meristem, thus controlling ARR1 transcriptional activation at the TZ. This guarantees robustness and fineness to the control of ARR1 levels necessary to balance cell division to cell differentiation in sustaining coherent root growth. Therefore, this work advances the state of the art in the field of root meristem development by integrating the activity of three hormones, auxin, gibberellin, and cytokinin, under the control of different tissue-specific activities of a single root key regulator, SCR.
authors: Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università La Sapienza, P.le Aldo Moro, 5, 00185, Rome, Italy. laila.moubayidin@jic.ac.uk.|Crop Genetics Department, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK. laila.moubayidin@jic.ac.uk.
authors: Laila
authors: L
authors: Moubayidin
authors: Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università La Sapienza, P.le Aldo Moro, 5, 00185, Rome, Italy.
authors: Elena
authors: E
authors: Salvi
authors: Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università La Sapienza, P.le Aldo Moro, 5, 00185, Rome, Italy.
authors: Leonardo
authors: L
authors: Giustini
authors: Section Molecular Genetics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.|Faculty of Science, SILS, University of Amsterdam, POSTBUS 94215, 1090 GE, Amsterdam, The Netherlands.
authors: Inez
authors: I
authors: Terpstra
authors: Section Molecular Genetics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.|Plant Developmental Biology, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
authors: Renze
authors: R
authors: Heidstra
authors: Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università La Sapienza, P.le Aldo Moro, 5, 00185, Rome, Italy.
authors: Paolo
authors: P
authors: Costantino
authors: Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università La Sapienza, P.le Aldo Moro, 5, 00185, Rome, Italy.
authors: Sabrina
authors: S
authors: Sabatini
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D005875:Gibberellins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000235:genetics*; D059828:Plant Cells / Q000502:physiology; D018517:Plant Roots / Q000235:genetics* / Q000254:growth & development; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C117138:ARR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D005875:Gibberellins; D007210:Indoleacetic Acids; C508468:RGA protein, Arabidopsis; D012097:Repressor Proteins; C100978:SCR protein, Arabidopsis; D014157:Transcription Factors
keywords: ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1); Differentiation; Gibberellin; Hormones; Root; SCARECROW (SCR)