Identification & Characterisation of Transcription Factors Affecting the Circadian System of Arabidopsis thaliana.

Tindall, AJ (2016) Identification & Characterisation of Transcription Factors Affecting the Circadian System of Arabidopsis thaliana. PhD thesis, University of Liverpool.

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Abstract

Circadian clocks are endogenous, persistent, temperature-compensating timekeepers which provide temporal organization of biological processes from cyanobacteria to man. Within plants, the circadian clock plays an important role in controlling desirable agronomic traits, integrating a number of abiotic stress signalling pathways. Much of our current understanding of the plant clock has come from the model organism Arabidopsis thaliana, with the vast majority of studies using null mutants and transgenic luciferase reporters. However, whilst our models of the transcriptional-translational feedback loops underlying the clock have become increasingly complex in the last 20 years, the regulation of several key components of the clock on the transcriptional level remains unknown. There is a need for new components in the model to fill in these gaps. Many known components of the plant clock are transcription factors. It was hypothesised therefore that the systematic screening and analysis of putative transcription factors would reveal novel circadian phenotypes. To this effect, a library of 338 hormone inducible transcription factor over-expression lines was screened with the novel delayed fluorescence assay to identify transcription factors giving circadian period phenotypes. Over-expression allows the investigation of partially redundant genes, and of those normally expressed within a hard-to-assay tissue. Twenty-one such genes were identified. Through the use of in silico tools to identify circadian expression patterns and promoter motifs, this shortlist was analysed for predicted interactions and modes of regulation. Traditional pCAB2:LUC+ luciferase markers were used to further phenotype the TF lines, providing a deeper understanding of the effect of the gene on the circadian clock, whilst knock out libraries and hypocotyl elongation assays under monochromatic light were employed to further characterise the genes in question. In this way, the longlist was reduced to three putative transcription factors which gave a circadian phenotypes of interest: INDOLE-3-ACETIC ACID INDUCIBLE 11, the freezing-response regulator MYBC1, and B-BOX DOMAIN PROTEIN/ CONSTANS-LIKE 15 (BBX13/COL15)

Item Type:	Thesis (PhD)
Divisions:	Faculty of Health and Life Sciences > Faculty of Health and Life Sciences
Depositing User:	Symplectic Admin
Date Deposited:	26 Jul 2016 09:13
Last Modified:	16 Jan 2024 17:21
DOI:	10.17638/03001669
Supervisors:	Hall, A hartwell, J ORCID: 0000-0001-5000-223X
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3001669