The leaves of <i>Antirrhinum </i>provide a good model system to study the mechanisms that specify formation of axes during plant development because mutation of the <i>PHANTASTICA </i>gene (<i>PHAN</i>) causes more complete disruption of these features than does mutation of its homologues in <i>Arabidopsis </i>or maize. <i>PHAN</i> encodes a Myb homologue and is expressed in the whole of the developing lateral organs yet the mutant phenotype suggests that it has functions restricted to the dorsal domain as well as in meristem maintenance. Mutants of <i>PHAN </i>in <i>Antirrhinum, Arabidopsis</i> and maize all missexpress <i>knox</i> genes so a related function of <i>PHAN </i>homologues is repression of meristem genes in lateral organs. The yeast 2-hybrid assay was used here to isolate PULP a novel potential modifier of PHAN protein function which, based on expression pattern in plant tissue has potential to interact with PHAN in vivo. The yeast 2-hybrid assay suggested that the interaction between PHAN and PULP is conserved because <i>Arabidopsis</i> PHAN and PULP homologues, AS1 and T20403, interact in the same way. Mutagenesis indicated that the interaction is biologically relevant because a putative T20403 mutant enhanced the <i>as1</i>-<i>1</i> phenotype causing it to resemble that of <i>phan</i>. PULP expression pattern suggested that it may function in collaboration with PHAN in lateral organs but independently of PHAN in stem tissues to repress <i>knox</i> genes. The yeast 2-hybrid assay also revealed potential homotypic and heterotypic interaction between PHAN, AS1 and PHANL1 which could provide a mechanism for PHAN and AS1 repression of <i>knox</i> expression, but taken together with the function of <i>knox</i> gene and Myb homologues in animals and the nature of the genetic pathways important to regulation of growth of the tissue where they are expressed, a degree of functional homology between PHAN and cMyb or aMyb in animals is also suggested.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:659957 |
| Date | January 2002 |
| Creators | Newton, Peter |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15509 |
Page generated in 0.0018 seconds