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Title: The physiology and transcriptomics underlying dahlia flower senescence
Author: Casey, Matthew
ISNI:       0000 0004 8500 6590
Awarding Body: Royal Holloway, University of London
Current Institution: Royal Holloway, University of London
Date of Award: 2019
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Dahlias are a popular commercial flower due to their variety in colour and morphology. Unfortunately, they are currently not commercially viable as cut flowers due to an unreliable vase-life. Analysis of the cut flower trade suggests that minimum longevity needs to be 10-14 days from harvest to provide time for transport to a pack house and on to the supermarket, three days in-store shelf life, and still allow a 5-day consumer guarantee. Dahlia inflorescences present unique challenges due to their complex composite floral structure: florets develop sequentially within the capitulum hence in each flower head flowers of different ages are represented. Another problem has been the limited data on dahlia and the lack of conclusive data regarding ethylene sensitivity. Therefore it was necessary to address some key questions on dahlia during this project. Firstly, dahlia flower senescence was characterised and cut flower senescence compared to senescence on the plant. The response of cut dahlia to traditional and novel postharvest treatments, including ethylene inhibitors, exogenous phytohormones and sugars, and application methods, including sprays, pulses, and holding solutions was also analysed. It was found that treatment with ethylene action inhibitors and exogenous cytokinins may significantly extend dahlia vase life. Finally, RNA-sequencing has been carried out on material from three different developmental stages of dahlia flowers to examine transcriptomic changes during the process and analyse the process at a molecular level. The differential expression analysis of this data found upregulation of putative genes including ethylene biosynthetic genes and downregulation of cytokinin biosynthetic genes, along with changes in expression in the signalling pathways of both cytokinins and ethylene. This work will provide a database for further research on dahlia flower senescence.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: dahlia ; cut flowers ; transcriptomics ; Transcriptome ; RNA-Sequencing ; senescence