Allan, AEspley, RPlunkett, Blue2012-02-292012https://hdl.handle.net/2292/12291Levels of fruit pigmentation are important both biologically to the plant and commercially to the agronomist and consumer. Anthocyanins, the red, orange, or blue pigments, protect plants from light stress, provide cultivar differentiation, and affect the health attributes of fruit which is important for consumers. Environmental conditions such as temperature and light affect plant anthocyanin accumulation. When apple (Malus x domestica), a temperate crop, is grown in hot conditions anthocyanin levels decrease via a regulatory process that is yet to be elucidated. The transcription factor (TF) MYB10 has been shown to be a primary controller of anthocyanin production, forming a complex with TFs from different classes including a bHLH and a WD40 to regulate the anthocyanin biosynthetic genes. The expression of MYB10 is affected by upstream factors that are regulated by environmental conditions. There are many candidate genes that could potentially regulate this process. The change in anthocyanin levels may be due to increased degradation of regulating factors in the heat or induction of factors by the cold. These anthocyanin regulating TFs may act directly on the promoter of MYB10, through environmentally responsive genes, or perhaps through an alternate network downstream, affecting the enzymes in the anthocyanin biosynthetic pathway themselves. Temperature and light are typically encountered in nature together and therefore are likely to be working in concert to regulate this process. This thesis investigates the regulatory TFs up-stream of MYB10 to determine how transduction of environmental signals leads to anthocyanin accumulation in apple. This is addressed by characterising candidate expression profiles and assessing relative contributions of light and temperature to expression rhythms. Functional analysis of candidate genes, in a model system (tobacco), in response to daily cycles of light and temperature and other TFs are also tested. Results show that there are daily expression profiles displayed by candidate genes in apple peel. Heat treatment is shown to affect the expression of MYB10. Harvesting the apple fruit caused all observed rhythms to cease. COL1 and COL12 are identified as prime candidates for linking environment conditions with MYB10 expression. Promoters of COL1 and 12 are shown to be activated by various TFs and cycling of the COL promoters is demonstrated in the tobacco system.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.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttps://creativecommons.org/licenses/by-nc-sa/3.0/nz/ThesisCopyright: The authorhttp://purl.org/eprint/accessRights/OpenAccessQ112891146