Pattern formation is the process by which undifferentiated cells divide and differentiate to generate complex tissues and organs. In plants, pattern formation begins in embryogenesis and continues post-embryonically with the function of the meristems. microRNAs (miRNAs), which are small regulatory RNAs that repress gene expression, are involved in a variety of patterning processes in plants, including the formation and function of the meristems and establishment of polarity. For example, regulation of the class III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP III) transcription factors by miR165/6 is not only involved in the formation and function of the meristems, but also in polarity establishment in the leaf, and in axial patterning during embryogenesis. To gain a better understanding of the role of miRNAs in embryonic patterning, I investigated the tissue-specific functions of the miRNA biogenesis protein SERRATE (SE), which is required for the regulation of the HD-ZIP IIIs via miR165/6. By expressing SE in various domains in se-5 null mutant embryos, I revealed that although SE is expressed throughout the embryonic body, tissue-specific expression of SE from either the upper or lower tier of the embryo is sufficient for correct patterning. This observation suggests a SE-dependent non-cell autonomous and bi-directional mechanism that influences patterning in Arabidopsis embryos. Furthermore, through a suppressor screen of a se-3 loss-of-function mutant allele, I identified mutants in genes that likely function upstream of SE, and downstream or in parallel of the HD-ZIP IIIs. One of those se-3 suppressors is likely to be a mutant in the BELL homeobox gene POUND-FOOLISH (PNF).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:669894 |
| Date | January 2014 |
| Creators | Lagiotis, Georgios |
| Contributors | Tsiantis, Miltos |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:e2abd8c6-924b-4085-bd18-ecd6cebc05de |
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