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Gene expression and daylength regulation of bulb formation in onion (Allium cepa L.)
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Cheng, Wei (2019) Gene expression and daylength regulation of bulb formation in onion (Allium cepa L.). PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3493127~S15
Abstract
Onion bulb initiation is photoperiod-dependent, which is crucial for adapting new varieties for growth at different latitudes as well as aiding germplasm screening for choice of current varieties. Although much is known about the physiological aspects of onion development, little work has been done on the genetics. This project primarily aims to gain further understanding of the molecular mechanisms involved in the onion bulbing process based on the parallels with well characterised functional clock genes in Arabidopsis flowering pathway, and additionally to identify some novel genes differentially expressed in bulb tissues. A comprehensive set of spatial, diurnal and developmental quantitative expression experiments were carried out to investigate the bulbing response with different onion varieties under varied day-lengths.
All onion homologues of Arabidopsis thaliana flowering time genes showed the spatial expression patterns consistent with their role in Arabidopsis, together with clear diurnal expression patterns peaking at different times of the day for both long/short-day onions, indicating that their role in a daylength dependent bulbing process at the molecular level. Particularly, under intermediate daylengths, AcFT1 expression level increased with daylength while AcFT4 was highly expressed in all daylengths. Both genes were expressed in longer days, indicating that AcFT1 is the predominant partner in the negative co-regulation of bulbing by the two genes.
Developmental time-course experiments detailed the gene expression in onion leaf and bulb tissues during the development of a long-day onion cultivar under long-day and short-day conditions. Both AcFT1 and AcFT4 showed significant increasing expression level during plant development, whereas AcFT1 was expressed in long-days with AcFT4 in short-days. The data further support the role of AcFT1 as a promoter and AcFT4 as inhibitor in onion bulb formation. In addition, a number of genes associated with onion carbohydrate metabolism, sulphur metabolism and bulb development were identified as having different tissue-specific expression and provide targets for future studies.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QK Botany | ||||
Library of Congress Subject Headings (LCSH): | Onions -- Growth, Plant photoperiodism, Bulbs (Plants), Plant genetic regulation | ||||
Official Date: | June 2019 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Life Sciences | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Thomas, Brian,1949- | ||||
Extent: | xvi, 194 leaves :illustrations, map | ||||
Language: | eng |
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