Transcriptional regulation of vascular patterning in Arabidopsis thaliana

  • Author / Creator
    Donner, Tyler James
  • The plant vascular system is a network of vascular strands that transport nutrients and signals. Some of these signals control the development of non-vascular tissues surrounding vascular strands; some others coordinate the development of new branches, leaves, and flowers with that of new roots. Thus, understanding how vascular strands form may provide understanding of how tissues and organs are formed and how their formation is integrated within the organism. Available evidence implicates the plant signaling molecule auxin in the control of vascular strand formation, but the molecular details of auxin’s action in this process remain unclear. Leaves are an attractive system to study the mechanisms controlling vascular strand formation because in leaf development strands of vascular cells appear from within a population of seemingly identical cells. Within this population, however, only vascular precursor cells initiate expression of the ARABIPDOPSIS THALIANA HOMEOBOX8 (ATHB8) gene. Under both normal and experimental conditions, domains of ATHB8 expression accurately predict sites of vascular strand formation, suggesting that the mechanisms that control vascular strand formation act prior to initiation of ATHB8 expression. If initiation of ATHB8 expression identifies the termination of the vascular patterning process, identification of the regulatory elements required for expression of ATHB8 and similarly expressed genes, and identification of the transcription factors binding to these regulatory elements, should identify transcriptional controls of leaf vascular patterning. Here I identify three Arabidopsis genes whose initiation of expression overlaps with initiation of ATHB8 expression during leaf vascular development. Further, I show that for three of these four early vascular genes, including ATHB8, initiation of expression depends on different regulatory elements, suggesting that early vascular gene expression is controlled by different regulatory pathways. Finally, I identify the regulatory pathway that initiates ATHB8 expression and contributes to vascular strand formation. My findings define molecular identities of early vascular cells, transcriptional controls of early vascular gene expression, and molecular inputs of auxin signal transduction in leaf vascular patterning.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Biological Sciences
  • Specialization
    • Molecular Biology and Genetics
  • Supervisor / co-supervisor and their department(s)
    • Scarpella, Enrico (Biological Sciences)
  • Examining committee members and their departments
    • Deyholos, Michael (Biological Sciences)
    • Cooke, Janice (Biological Sciences)
    • Mattsson, Jim (Biological Sciences, Simon Fraser University)
    • Waskiewicz, Andrew (Biological Sciences)