title: A plausible mechanism, based upon Short-Root movement, for regulating the number of cortex cell layers in roots.
abstract: Formation of specialized cells and tissues at defined times and in specific positions is essential for the development of multicellular organisms. Often this developmental precision is achieved through intercellular signaling networks, which establish patterns of differential gene expression and ultimately the specification of distinct cell fates. Here we address the question of how the Short-root (SHR) proteins from Arabidopsis thaliana (AtSHR), Brachypodium distachyon (BdSHR), and Oryza sativa (OsSHR1 and OsSHR2) function in patterning the root ground tissue. We find that all of the SHR proteins function as mobile signals in A. thaliana and all of the SHR homologs physically interact with the AtSHR binding protein, Scarecow (SCR). Unlike AtSHR, movement of the SHR homologs was not limited to the endodermis. Instead, the SHR proteins moved multiple cell layers and determined the number of cortex, not endodermal, cell layers formed in the root. Our results in A. thaliana are consistent with a mechanism by which the regulated movement of the SHR transcription factor determines the number of cortex cell layers produced in the roots of B. distachyon and O. sativa. These data also provide a new model for ground tissue patterning in A. thaliana in which the ability to form a functional endodermis is spatially limited independently of SHR.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Chin-Mei
authors.initials: CM
authors.lastname: Lee
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Simara
authors.initials: S
authors.lastname: Price
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Amélioration Génétique et Adaptation des Plantes Cultivées (AGAP), F34398 Montpellier, France.
authors.forename: Fanchon
authors.initials: F
authors.lastname: Divol
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Amélioration Génétique et Adaptation des Plantes Cultivées (AGAP), F34398 Montpellier, France.
authors.forename: Sophia
authors.initials: S
authors.lastname: Henry
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Amélioration Génétique et Adaptation des Plantes Cultivées (AGAP), F34398 Montpellier, France.
authors.forename: Germain
authors.initials: G
authors.lastname: Pauluzzi
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Amélioration Génétique et Adaptation des Plantes Cultivées (AGAP), F34398 Montpellier, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Perin
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and gallagkl@sas.upenn.edu.
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: Gallagher
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D058431:Brachypodium / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C100978:SCR protein, Arabidopsis; C410510:SHORT ROOT protein, Arabidopsis; D014157:Transcription Factors
keywords: SCARECROW; SHORT-ROOT; cellular patterning; rice; root development