Seasonal Fluctuations of Carbyhydrate Metabolizing Enzyme Activities Throughout Tart Cherry Fruit Development
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Authors
Wadland, Lauren
Issue Date
2000
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Carbohydrate metabolism during tart cherry ripening remains to be investigated.
However, extensive carbohydrate metabolism studies of other fruits have provided insight on potential enzymes involved in tart cherry fruit ripening. Information from the
aforementioned studies and the known changes in sugar composition occurring
throughout ripening have allowed for hypotheses of the enzymes that may be involved in
carbohydrate metabolism throughout cherry fruit development. In order to determine the level of carbohydrate metabolizing enzyme activities throughout fruit development, activities of NAD-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), acid invertase (AI), sucrose synthase (SS) and alkaline invertase (ALK) in tart cherry fruits (Prunus cerasus, L.cv. Montmorency) were assayed during the growing season. SDH, a sorbitol metabolizing enzyme, activity was found to increase while sorbitol levels declined. Also, while sucrose levels decreased during development, the sucrose catabolizing enzyme AI activity levels increased dramatically. SOX , SS, and ALK activity levels were negligible. Therefore, AI and SDH were concluded to be the main carbohydrate metabolizing enzymes involved in tart cherry fruit development.
With the aim of revealing the mode of enzyme regulation, RNA blot analysis of AI and SDH were performed to extend the investigation to the level of gene expression.
The levels of AI mRNA were low during the young green stage and high in the mature
dark red stage, paralleling activity levels, implying transcriptional control. The northern
analysis for SDH mRNA was less clear, suggesting other modes of regulation, possibly
post-transcriptional or post-translational controls.
Description
iv, 20 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.