<i>ASYMMETRIC LEAVES1 </i>(<i>AS1</i>) encodes a MYB transcription factor that is expressed in lateral organs of <i>Arabidopsis </i>where it excludes expression of meristem promoting <i>know</i> genes. This is unlikely to be the only function of <i>AS1</i> as reducing <i>knox </i>expression does not suppress the <i>as1</i> mutant phenotype. To identify additional targets of <i>AS1,</i> gain-of-function and loss-of-function mutant screens were used to identify modifiers of the <i>as1</i> mutant phenotype. A gain of function mutation in the <i>PTL</i> gene was isolated as a potential suppressor of the <i>as1</i> mutant phenotype in petals. Further genetic analysis suggested that <i>AS1 </i>and <i>PTL</i> are unlikely to act in same pathway. <i>symmetrica </i>(<i>sym</i>), a complete suppressor of <i>as1,</i> was isolated in loss-of-function screens. Expression analysis of <i>knox</i> expression in lateral organs of <i>sym</i> mutants suggests that <i>SYM</i> is required for <i>knox</i> upregulation in <i>as1</i> mutant lateral organs. <i>AS2,</i> which is thought to act in a similar position in development to <i>AS1</i> also appeared to interact with <i>SYM </i>as <i>as2</i> mutants were also suppressed in its absence. Triple mutant analysis indicated that <i>SYM</i> may work in a similar position in development to <i>SE</i>, a previously described partial suppresser of <i>as1.</i> In the absence of the <i>knox </i>gene <i>STM</i>, formation of a functional SAM during embryogenesis is prevented due to ectopic expression of <i>AS1 </i>and genes that specify lateral organ fate throughout the apex. However, <i>as1-1 stm-1 </i>double mutants form a functional SAM as lateral organ fate signals are reduced due to the lack of <i>AS1. </i>The SAM of <i>as1-1 sym stm-1 </i>triple mutants is arrested, indicating a redundant role for <i>SYM</i> in meristem function. <i>sym </i>also modified mutants at the <i>PNH</i> locus, suggesting an interaction with the post translational gene silencing machinery. <i>SYM </i>was mapped to an interval of 120 Mb linked to <i>AS1</i> on the long arm of chromosome 2.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649868 |
| Date | January 2003 |
| Creators | Etchells, J. Peter |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14799 |
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