The role of UV-B in regulating flowering initiation in the model plant Arabidopsis thaliana

Zioutopoulou, Anna (2019) The role of UV-B in regulating flowering initiation in the model plant Arabidopsis thaliana. MSc(R) thesis, University of Glasgow.

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UV-B irradiation ranges from 280-315 nm and is an important component of sunlight that reaches the earth. Although UV-B can be harmful in most living organisms, it can also control various photomorphogenic responses in plants. Plants perceive UV-B light through the action of UVR8, the only photoreceptor that has been discovered so far to be capable of absorbing and mediating responses to UV-B light. Additionally, UV-B has a role in modulating plant adaptive reposes, such as the inhibition of the Shade Avoidance Response, which is a number of physiological and molecular features that plants develop in order to cope with vegetative shade.
Very little is known about the role of UV-B or UVR8 in regulating the time of flowering in plants. This thesis investigates the role of UV-B and UVR8 in the initiation of photoperiodic and vegetative shade flowering in the model plant species Arabidopsis thaliana. For that purpose, multiple flowering experiments were conducted, under WL and WL supplemented with UV-B, as well as under low R:FR (shade) or low R:FR that was supplemented with UV-B. For the aforementioned experiments the flowering time was monitored. Moreover, gene expression analysis of key flowering regulators (FT, CO, FLC, SOC1), was performed on various Arabidopsis accessions and uvr8 mutant alleles and over-expressing lines, as well as mutants involved in UV-B signalling and flowering.
Our results indicate that UV-B controls photoperiodic flowering in an ecotype-specific manner, since the effect of UV-B on flowering initiation varied in Col-0, Ler and Cvi ecotypes. Overall, UV-B promoted flowering under Long Day photoperiodic conditions. UVR8 was shown to act as a negative regulator of UV-B induced early flowering, since uvr8 mutants exhibited early flowering phenotypes, while over-expression of UVR8 led to a delay in flowering under white light supplemented with UV-B. Additionally, UV-B was found to induce early flowering in most of the UV-B signalling, light signalling and flowering mutants tested.
Overall, this thesis has uncovered that UV-B can modulate flowering initiation through the action of UVR8 at the transcriptional level. Further research would be essential for further examining the role of UVR8 in mediating UV-B cross-talk with other light and temperature signalling pathways.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Keywords: UV-B, flowering, Arabidopsis thaliana, UVR8.
Subjects: Q Science > QH Natural history > QH301 Biology
Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
Supervisor's Name: Kaiserli, Dr. Eirini
Date of Award: 2019
Depositing User: Miss Anna Zioutopoulou
Unique ID: glathesis:2019-41162
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 Apr 2019 15:12
Last Modified: 26 Apr 2022 08:54
Thesis DOI: 10.5525/gla.thesis.41162

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