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The Interplay Between Flavonols and ROS in Modulating Root Development and ROS Signaling

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title
The Interplay Between Flavonols and ROS in Modulating Root Development and ROS Signaling
author
Chapman, Jordan Marie
abstract
Reactive oxygen species (ROS) are signaling molecules that modulate environmental responses and plant development, including initiation and emergence of root hairs (RH) and lateral roots (LR). Plants produce antioxidant metabolites, including flavonols, to maintain ROS homeostasis. In Arabidopsis, mutants at each step in the flavonol biosynthetic pathway were utilized to manipulate the flavonol profile and examine LR development. A mutant in the first biosynthetic step of the flavonol pathway, tt4, does not produce flavonols and has increased RH and LR number. tt7 makes only one flavonol, kaempferol, which accumulates in the LR primordia (LRP) at levels above wild-type leading to a reduced number of LRs. Superoxide concentration was decreased in tt7 LRP consistent with scavenging by kaempferol to regulate LR emergence. To identify the protein targets of ROS in roots, we used proteomics to identify proteins with cysteine sulfenic acid modifications, which can alter protein activity. We used a dimedone probe linked to biotin to identify 1057 oxidized proteins. Our dataset had 78 overlapping proteins with two previously published datasets that used different methods and Arabidopsis tissue types. Our dataset is enriched in proteins with redox-related activity, such as oxido-reductases, and developmental function, including RH elongation. We used insertion mutants encoding two oxidized proteins linked to RH elongation and observed altered root hair formation consistent with protein oxidation regulating RHs. We completed a redox-proteomic analysis of tt4 and, contrary to our hypothesis, found fewer oxidized proteins than wild-type. We also used flavonoid biosynthetic mutants in a plant genetics educational outreach project that examined the impact of teaching on student learning. We designed a high-school curriculum illustrating how root branching protects plants from drought stress and the impact of genetic modification on plant health. We trained undergraduates to teach this curriculum to high school students. The undergraduate’s knowledge of genetics and appreciation of the potential of GMO crops increased after teaching. This dissertation integrates the use of flavonol mutants with altered ROS in the understanding of root development, ROS biochemical targets, and the importance of plant architecture in combating food shortage as a result of climate change.
subject
Flavonol
lateral root
peer teaching
protein oxidation
proteomics
ROS
contributor
Muday, Gloria K (committee chair)
Alexander, Rebecca W (committee member)
Furdui, Cristina M (committee member)
Zhang, Ke (committee member)
Pease, James B (committee member)
date
2021-06-03T08:36:12Z (accessioned)
2021 (issued)
degree
Biology (discipline)
embargo
2026-06-01 (terms)
2026-06-01 (liftdate)
identifier
http://hdl.handle.net/10339/98817 (uri)
language
en (iso)
publisher
Wake Forest University
type
Dissertation

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