title: Multiple feedback loops through cytokinin signaling control stem cell number within the Arabidopsis shoot meristem.
abstract: A central unanswered question in stem cell biology, both in plants and in animals, is how the spatial organization of stem cell niches are maintained as cells move through them. We address this question for the shoot apical meristem (SAM) which harbors pluripotent stem cells responsible for growth of above-ground tissues in flowering plants. We find that localized perception of the plant hormone cytokinin establishes a spatial domain in which cell fate is respecified through induction of the master regulator WUSCHEL as cells are displaced during growth. Cytokinin-induced WUSCHEL expression occurs through both CLAVATA-dependent and CLAVATA-independent pathways. Computational analysis shows that feedback between cytokinin response and genetic regulators predicts their relative patterning, which we confirm experimentally. Our results also may explain how increasing cytokinin concentration leads to the first steps in reestablishing the shoot stem cell niche in vitro.
authors.affiliation: Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Gordon
authors.forename: Vijay S
authors.initials: VS
authors.lastname: Chickarmane
authors.forename: Carolyn
authors.initials: C
authors.lastname: Ohno
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Meyerowitz
mesh_terms: D000465:Algorithms; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003198:Computer Simulation; D003583:Cytokinins / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000494:pharmacology; D018520:Plant Shoots / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C401621:CLV2 protein, Arabidopsis; D003583:Cytokinins; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; C116421:WUSCHEL protein, Arabidopsis; D049452:Green Fluorescent Proteins; D011494:Protein Kinases; C421783:WOL protein, Arabidopsis