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Title: Time for crops : an exploration of circadian variation in model and crop plant species
Author: Rees, Hannah
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2020
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Plants with circadian rhythms which are synchronised to their surrounding environments have a well described fitness advantage. Optimising circadian rhythms to fit local conditions has the potential to affect crop productivity, plant health and resource use efficiency. A rising global population and changing climate mean that these factors are becoming increasingly important. Compared to our understanding of other variables affecting plant growth and yields, circadian variation in crop panels is a relatively untapped source of phenotypic variation. Delayed fluorescence (DF) is an intrinsic property of all photosynthetic material, oscillating with a ~24h period controlled by the circadian clock. It has an advantage over other circadian assays in that it requires no prior genetic modification and works well in monocot species which don’t display robust leaf-movement rhythms. In this project, DF imaging was applied as a tool for circadian phenotyping in wheat, Brassica and Arabidopsis. As part of the process, a high throughput, reliable assay was developed specific to detached leaves of either Brassica or wheat. Several factors which contribute to circadian trait variation were examined and demonstrate species- specific differences in optimum DF imaging settings. DF imaging was used to quantify population level circadian variation for two diverse plant panels; 64 cultivars from a Brassica cultivar set and 191 Arabidopsis accessions from across a broad latitudinal range in Sweden. Putative loci associated with this variation were identified using genome wide association mapping. For the Swedish Arabidopsis population, factors contributing to variation in period length in this region were examined, including geography and population sub-structure. This work lends support to the idea that circadian variation exists in wild populations and is likely to provide a competitive advantage in nature. With the robust DF imaging method, circadian phenotypic diversity in domesticated crops can now be examined. It is my hope that this work will facilitate future research into why this diversity has been selected and whether accurate and robust circadian rhythmicity is an important agricultural trait.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral