The DAD Genes: Characterisation of branching controls in Petunia x hybrida

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dc.contributor.advisor Snowden, K en
dc.contributor.advisor Plummer, K en
dc.contributor.advisor Putterill, J en Simons, Joanne en 2016-06-15T21:19:27Z en 2006 en
dc.identifier.citation 2006 en
dc.identifier.uri en
dc.description.abstract Branching is one of the major developmental processes that determine the architecture of a plant. Lateral branching is the outgrowth of axillary buds from the main shoot axis of the plant, and in Petunia hybrida this process is controlled by the DECREASED APICAL DOMINANCE (DAD) genes. The three dad mutants are characterised by increased levels of basal branching, and decreased height when compared to wild-type petunia. Double mutant analyses were carried out to determine whether these genes act in the same pathway to control branching. The dad1dad2 and dad2dad3 double mutants were indistinguishable from the dad2 mutant, which indicated that DAD2 acts in the same pathway as DAD1 and DAD3. Grafting experiments confirmed the action of DAD2 in this pathway, potentially with a role in signal reception or transduction. The dad1dad3 double mutant has an additive phenotype with decreased plant height and delayed flowering compared to the single mutants, indicating that these genes do not act in a simple step-wise fashion. The function of the DAD1 and DAD3 genes was investigated by expression analysis using quantitative RT-PCR (qRT-PCR). The genes were expressed in root and stem and showed upregulation in the stem, but not the roots of the dad mutants, suggesting the involvement of a feedback mechanism in the control of gene expression. The expression of DAD1 and DAD3 in the stem of grafted plants was linked with the branching phenotype not the genotype of the scion. A candidate gene (PhMAX2) was investigated to ascertain whether it was the same locus as DAD2. Results from Southern analyses and qRT-PCR experiments, combined with existing sequencing data, indicated that PhMAX2 is unlikely to encode DAD2. The function of the PhMAX2 gene was investigated by construction RNAi transgenic plants with decreased levels of PhMAX2 transcript, which showed a slight increase in branching and decrease in height compared to wild-type petunia. A model is presented that describes how the DAD genes are thought to act together, as well as with internal and external signals, to control the outgrowth of axillary buds into branches in petunia. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99176522814002091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
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dc.title The DAD Genes: Characterisation of branching controls in Petunia x hybrida en
dc.type Thesis en Biological Sciences en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The Author en
dc.rights.accessrights en
pubs.elements-id 530836 en Libraries & Learning Services en Libraries & Learning Services en Research and Collections en Research and Collections en Research Services en Research Services en
pubs.record-created-at-source-date 2016-06-16 en
dc.identifier.wikidata Q111963304

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