Universität zu Köln

Mahlandt, Alexander ORCID: 0000-0002-6553-5829 (2025). Investigation of sister kinetochore orientation during meiosis I and implications in engineered apomixis. PhD thesis, Universität zu Köln.

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Abstract

Despite tremendous strides in our understanding of the specialized cell division that occurs in developing sex cells, the rules that govern step-wise chromosome segregation in the course of meiosis remain incomplete. Protein complexes known as kinetochores position themselves at defined regions of chromosomes to direct their segregation during cell division. During meiosis, kinetochores of replicated chromosomes work in tandem to ensure co-segregation only at the first division and not at the second. While comprehensive studies in a variety of model systems have helped to clarify its actors and mechanism, differing models persist that explain how sister kinetochores mono-orient prior to the first division. Here we present the results of a screening method that uncover novel factors that direct sister co-orientation, and functional study that aims to define their role. The findings provide strong support for a cohesion-based mechanism of sister kinetochore co-orientation. Functional understanding of chromosome segregation is further applied in the pursuit of clonal seed production in cultivated barley. Apomixis is a reproduction strategy that yields clonal progeny through seeds, achieved by skipping meiosis and fertilization. The implementation of apomixis in modern agriculture holds promise for reducing breeding cycles and fixing hybrids. Identification and functional characterization of the genes governing recombination, monopolar orientation, and the second meiotic division during barley meiosis are presented as a means to engineer apomeiosis in a new crop species. Further, we show that misexpression of a dominant embryogenesis factor can trigger parthenogenesis and induce haploids in barley. Together, we show that apomeiosis and parthenogenesis can be engineered in a close relative of wheat, showing promise for a broad application of synthetic apomixis.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Mahlandt, Alexander UNSPECIFIED orcid.org/0000-0002-6553-5829 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-788427
Date:	1 September 2025
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Außeruniversitäre Forschungseinrichtungen > MPI for Plant Breeding Research
Subjects:	Natural sciences and mathematics
Uncontrolled Keywords:	Keywords Language Meiosis English Chromosome biology English Apomixis English
Date of oral exam:	17 September 2024
Referee:	Name Academic Title Mercier, Raphael Professor
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/78842