Experimental Morphology and Morphogenesis Then and Now: A Symposium in Memory of Elizabeth G. Cutter
Feldman, Lewis , Jiang, Keni .
Root Development; from Trichoblasts to the Quiescent Center.
Developmentally, an individual root axis can be subdivided into zones or regions based mainly on the presumed, predominant activity occurring within each of these regions; cell division, cell elongation, or cell differentiation. As a result of increased attention to root development, and especially the application of molecular-genetic approaches, investigators are discovering more about the physiological and biochemical controls underlying this zonal specification. For this talk we will focus on the region of cell division, the root apical meristem (RAM), and shall consider this zone in terms of the special microenvironments (niches) that comprise the RAM. The establishment and maintenance of the RAM is dependent on the specification of the niche and on the attendant development of the quiescent center (QC). The distribution of auxin and the establishment of an auxin maximum are central to niche formation and maintenance. Auxin specifies the niche by directly and/or indirectly affecting gene activities, including reduced expression of metabolism-, redox- and certain cell-cycle associated transcripts within the QC portion of the niche, and enrichment of auxin-associated transcripts within the entire niche. Niche establishment is also associated with the imposition of controls for the state of differentiation of cells of the QC, with processes (repair machinery) for maintaining DNA integrity, and with a role for gene silencing in niche stabilization. Additionally, niche equilibrium is associated with a role for cytokinins in the dividing cells located proximal to, and in direct contact with the QC. We conclude that the coordinated expression of auxin-, redox-, cell cycle- and metabolism-associated genes point to a network of events likely related to niche establishment and maintenance, which thereby provides insights about the stereotypical regional developmental patterns of roots.
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1 - University of California, Plant and Microbial Biology, 111 Koshland Hall, Berkeley, CA, 94720, USA
root apical meristem
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware B/Hyatt
Date: Wednesday, July 11th, 2012
Time: 9:30 AM