Multiple feedback loops through cytokinin signaling control stem cell number within the Arabidopsis shoot meristem

• Published in: Proceedings of the National Academy of Sciences - PNAS 2009-09, Vol.106 (38), p.16529-16534
• Main Authors: Gordon, Sean P, Chickarmane, Vijay S, Ohno, Carolyn, Meyerowitz, Elliot M
• Format: Article
• Language: English
• Subjects: Algorithms; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological Sciences; Computational modeling; Computer Simulation; Control loops; Cytokinins; Cytokinins - pharmacology; Flowers & plants; Gene expression; Gene Expression Regulation, Plant - drug effects; genes; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Hormones; In Situ Hybridization; Membrane Proteins - genetics; Membrane Proteins - metabolism; Meristem - genetics; Meristem - metabolism; Meristems; Models, Biological; Multipotent stem cells; Plant Growth Regulators - pharmacology; Plant Shoots - genetics; Plant Shoots - metabolism; Plants; Plants, Genetically Modified; Pluripotent stem cells; Protein Kinases - genetics; Protein Kinases - metabolism; Proteins; Receptors; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Shoot meristems; Signal Transduction; Stem cells; transcription factors; WUS gene; WUSCHEL gene
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0908122106

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.