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Senescence or ageing in wallflower petals?

Price, Anna Marie 2004. Senescence or ageing in wallflower petals? PhD Thesis, Cardiff University.

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Senescence is the final event in the life of many plant tissues. It is concerned with remobilisation of metabolites from the senescing organ and is distinct from other forms of cell death. It is a highly regulated process involving structural, biochemical and molecular changes. Gene expression is tightly regulated, with many genes down regulated and others induced. Conversely, ageing is a passive degradation. Petals and leaves are good model organs for developmental studies, as petal development is irreversible and tightly controlled, and leaves are an extensively studied senescent system. Similarities between these organs allow direct comparison of late developmental events to establish whether petals senesce, as leaves do, or age however, important differences in function lead to the hypothesis that petal deterioration and leaf senescence are distinct. Wallflowers were chosen as they are closely related to Arabidopsis and Brassica spp., have large petals, and are commercially relevant ornamental plants. Changes in wallflower morphology and physiology were examined over development. A high degree of gene homology was shown between wallflowers and Arabidopsis by northern blotting. 1632 genes upregulated in old wallflower tissues were cloned using subtractive selective hybridisation and a microarray of these genes, along with 91 Arabidopsis senescence associated genes, was constructed. Probing the microarray with RNA from different leaf and petal developmental stages identified 298 common genes significantly upregulated during both leaf senescence and late petal development, and expression patterns were compared between the two tissues. The expression patterns of selected genes were confirmed by RT-PCR. Late development in petals was shown to be an active process, and was tentatively concluded to be senescence due to upregulation of genes involved with nutrient remobilisation and the strong upregulation of the SAG 12 gene---a molecular marker for leaf senescence that is not upregulated during other forms of death in leaves.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Biosciences
ISBN: 9781303200557
Funders: BBSRC
Date of First Compliant Deposit: 30 March 2016
Last Modified: 10 Oct 2017 15:29

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