Universität zu Köln

Artz, Oliver (2018). On the evolution of light signaling: The COP1/SPA complex in Physcomitrella patens. PhD thesis, Universität zu Köln.

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Abstract

Plants rely on light as an environmental signal and primary source of energy. In the course of evolution plants have developed a sophisticated signaling network enabling them to fine-tune their growth and development according to the ambient light conditions and ensure sustained reproductive success. A major regulator of light signaling is the COP1/SPA complex which targets positively acting light-signaling intermediates such as HY5 for proteolytic degradation. So far, only very few studies have investigated the evolutionary conservation of light signal transduction and our understanding of the COP1/SPA complex beyond Arabidopsis thaliana is very limited. Here, I genetically and biochemically characterized the COP1/SPA complex in the early diverged land plant Physcomitrella patens. PpspaAB double knock-out plants were generated using the CRISPR/Cas9 technology. Other than full spa knock-out lines in Arabidopsis, PpspaAB double knock-out lines exhibited rather mild phenotypic aberrations from wild-type plants in that they developed shorter gametophores but a larger colony diameter when grown in white light. Mutating the spa genes did not lead to strong constitutive photomorphogenesis in darkness. Light-regulation of endogenous protein levels of PpHY5b, a putative target of the COP1/SPA complex in Physcomitrella, was not mediated by PpSPA proteins. These results suggest that either PpCOP1 activity might be more independent of PpSPA proteins than in Arabidopsis or that the light signaling cascade plays a smaller role in Physcomitrella development. In vivo PpCOP1a interacted with PpSPAb and PpHY5b, indicating an evolutionary conservation of a functional PpCOP1/PpSPA complex. More studies investigating the role of not only PpSPA but also PpCOP1 genes are necessary to further elucidate the function of the complex in Physcomitrella.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Artz, Oliver oartz@smail.uni-koeln.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-94963
Date:	17 December 2018
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language plant biology, light signaling, COP1, SPA, HY5, Physcomitrella patens, evolution English
Date of oral exam:	25 February 2019
Referee:	Name Academic Title Hoecker, Ute Prof. Dr. Huelskamp, Martin Prof. Dr. Werr, Wolfgang Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/9496