Universität zu Köln

Kouklas, Evangelos (2017). Functional characterization of the extra petals mutant in Cardamine hirsuta. PhD thesis, Universität zu Köln.

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Abstract

A fixed number of petals characterizes the flowers of different plant families. For example, species in the Brassicaceae have four petals, such as the model plant Arabidopsis thaliana. An exception to this is the A. thaliana relative Cardamine hirsuta, which has a variable number of petals between zero and four. To understand which genes control petal number in C. hirsuta, a genetic screen was performed for mutants with altered petal number. The extra petals (exp) mutant was identified as a recessive allele that caused an increase in petal number above four. In addition, exp flowers exhibited chimeric floral organs and unfused carpel tips. I found that all petals and petal/sepal chimeras arose from whorl 2 in exp flowers. Also, I showed that a mutation in the C. hirsuta orthologue of SPLAYED (SYD) caused the exp mutant phenotype. Most importantly, I showed that an artificial microRNA that silenced SYD gene expression caused an exp phenotype, whereas reintroducing the wild-type SYD locus into exp mutants rescued the phenotype. SYD encodes an ATP-dependent chromatin remodeling factor that activates different pathways during floral development in A. thaliana. Similarities between the phenotypes of syd mutants in A. thaliana and exp, suggest that SYD function may be conserved between these two species. In summary, I identified a function for SYD chromatin remodeling complexes in petal number control in C. hirsuta, and suggest that this type of regulation is a common component of floral development pathways in the Brassicaceae family.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Kouklas, Evangelos vkouklas@gmail.com UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-82498
Date:	1 July 2017
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Außeruniversitäre Forschungseinrichtungen > MPI for Plant Breeding Research
Subjects:	Natural sciences and mathematics Life sciences
Uncontrolled Keywords:	Keywords Language Cardamine hirsuta English SPLAYED English Flowers English Petal English UNSPECIFIED English
Date of oral exam:	26 June 2017
Referee:	Name Academic Title Tsiantis, Miltos Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/8249