Universität zu Köln

Piofczyk, Thomas Przemyslaw (2014). Molecular responses to UV-B in Arabidopsis thaliana. PhD thesis, Universität zu Köln.

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Abstract

As an unavoidable consequence of the requirement for light, higher plants are exposed to UV-B radiation. While several key factors of UV-B signalling, damage prevention and repair are known, their interplay, regulation and variation across natural populations remain to a large extent undiscovered. Although it has been proposed that UV-B radiation can cause mutations, realistic estimations of the mutagenic potential of natural UV-B on a genome-wide level in plants are missing. In order to explore natural variation in response to UV-B, growth related phenotypes of 345 Arabidopsis thaliana accessions in response to UV-B irradiation were analysed by genome-wide association studies and complemented by QTL mapping. A complex genetic basis underlying these traits was revealed and identified the RECEPTOR-LIKE PROTEIN 7 as a putative candidate gene partially responsible for this variation. In addition, RNA sequencing of UV-B sensitive and resistant accessions followed by mutant analysis revealed several novel candidate genes involved in the response to UV-B irradiation in Arabidopsis. The mutagenic effects of natural-like UV-B radiation were analysed by whole genome sequencing of over 120 A. thaliana genomes from plants grown for up to three full generations under UV-B conditions corresponding to different sites within the natural distribution range. This revealed unaffected mutation rates in Col-0 wild-type plants, irrespective of the UV-B dosage applied. Similarly, the lack of flavonoid biosynthesis, UV-B photoreception and photolyase UVR3 had no influence on the accumulation of UV-B induced mutations. In contrast, UV-B induced many mutations in plants deficient in the UVR2 photolyase, suggesting the importance of this factor in maintaining genome stability in Arabidopsis. The majority of mutations were transitions, which were specifically enriched by UV-B irradiation. Furthermore, UV-B induced mutations were non-randomly distributed. Mutations occurred preferentially in methylated cytosines of transposable elements in pericentromeric regions. In summary these findings revealed natural variation in A. thaliana in response to UV-B and identified several novel genes associated with the response to UV-B that will be further analysed. Moreover, the mutagenic potential of natural-like UV-B irradiation was estimated and gave insight into the mutational spectrum of UV-B induced mutations and the importance of certain genetic factors to prevent the accumulation of mutations.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Piofczyk, Thomas Przemyslaw piofczyk@mpipz.mpg.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-59783
Date:	2014
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Außeruniversitäre Forschungseinrichtungen > MPI for Plant Breeding Research
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language Molecular biology, UV-B, Arabidopsis thaliana English
Date of oral exam:	20 October 2014
Referee:	Name Academic Title Koornneef, Maarten Prof. Dr. Höcker, Ute Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/5978