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Functional genomic characterization of the Arabidopsis circadian circuit in the plant osmoregulatory and nutrient stress responses
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- Author / Creator
- Khodabocus, Ibrahim
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Plants require periods of light and darkness to grow and develop properly. In plants, the timing of daily events is facilitated by the circadian clock. Most eukaryotes possess a circadian circuit that is entrained by different inputs such as light and temperature. Here, I show that the only elucidated activator of the circadian clock, RVE8, and its two homologs, RVE4 and RVE6 are required for plants to confer osmotolerance. I show that wild-type (WT) plants perform better than rve 4 6 8 plants by examining primary roots under osmotic and salt stress. Subsequent total proteome analyses between WT and rve 4 6 8 whole seedlings at zeitgeber (ZT)11 and ZT23 illustrate that WT plants have differentially abundant proteins which aid in osmoprotection. Next, I surveyed the circadian clock for its role in regulating nutrient acquisition by utilizing a series of plant lines deficient in different core circadian clock transcription factors. Here, I show that the circadian clock has disparate roles in the regulation of nitrogen (N), phosphorus (P), and sulfur (S) nutrition, through the observation of nutrient-dependent primary root and hypocotyl etiolation phenotypes. After screening a compendium of circadian clock deficient mutants, I undertook a focused characterization of the prr5-11 prr7-11, prr5-11, and prr7-11 mutant plants at zeitgebers ZT0, ZT4, ZT8, and ZT12, under control (CTL), -N, -P, and -S conditions, as these mutant lines exhibited the greatest phenotypic differences under nutrient starvation. Using gas chromatography mass spectrometry (GC-MS), I found that the metabolite pool largely differs within each genotype and across different nutrient regiments, implicating both PRR5 and PRR7 proteins in the regulation of nutrient-mediated outputs in Arabidopsis thaliana. Research conducted throughout my thesis finds that the circadian clock has wide-ranging roles in regulating the osmoregulatory and nutrient stress responses, laying a foundation for future experimentation aimed at further exploring the interplay between the circadian clock and drought or plant nutrition.
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- Subjects / Keywords
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- Graduation date
- Spring 2023
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.