Control of genetic crossover formation during meiosis

Meiosis is a specialized form of cell-division during which a single round of DNA replication is followed by two cell-divisions thereby reducing the chromosome content from diploid to produce haploid gametes. Accurate segregation of homologous chromosomes at the first meiotic division is dependent on the formation of physical connections, known as chiasmata, between homologous chromosome pairs (homologues). Chiasmata arise from homologous recombination during prophase I of meiosis and are the physical manifestation of genetic crossovers.

In their absence the homologues segregate at random leading to the formation of aneuploid gametes following the separation of the sister chromatids at the second meiotic division. Understanding the factors that control meiotic recombination is of great significance for the improvement of crop-breeding since it is now clear that many species notably cereals, possess large regions on their chromosomes that rarely recombine. This presents a significant barrier for the introgression of new genetic traits. Hence, to overcome this problem we need to know how the frequency and distribution of chiasmata/crossovers are controlled. This needs to be established in an experimentally tractable system before we can transfer this information to crops. Arabidopsis is a model plant system that is ideally suited for the analysis of meiosis as it allows the process to be investigated using a combination of molecular methods and advanced microscopical methods.

The specific aim of this project is to investigate how proteins that contribute to the dynamic organization of the chromosomes during meiotic prophase I interface with the recombination machinery to control the formation of chiasmata. We will study the temporal coordination between the formation of DNA double-strand breaks that initiate recombination and the maturation of the proteinaceous axes of the chromosomes. We will investigate how the functions of key axis components such as ASY1, ASY3, TOPOII are regulated. Recently we have discovered that ASY1 is modified by phosphorylation following the initiation of recombination. As phosphorylation commonly modulates the activity of proteins, we aim to establish how this affects the activity of the axis proteins in relation to chromosome pairing, synapsis and recombination. We anticipate that these studies will provide new insights into the control of meiotic crossover formation in higher plants and other species. The results of these studies will directly inform on-going work aimed modulating the formation of meiotic crossovers in crop species.

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Please find additional funding text below. For further funding details, please see the ‘Funding’ section.

The School of Biosciences offers a number of UK Research Council (e.g. BBSRC, NERC) PhD studentships each year. Fully funded research council studentships are normally only available to UK nationals (or EU nationals resident in the UK) but part-funded studentships may be available to EU applicants resident outside of the UK. The deadline for applications for research council studentships is in January each year.

Each year we also have a number of fully funded Darwin Trust Scholarships. These are provided by the Darwin Trust of Edinburgh and are for non-UK students wishing to undertake a PhD in the general area of Molecular Microbiology. The deadline for this scheme is also in January each year.

Please note the only funding available for our PhD is via the Scholarships mentioned. All applicants should indicate in their applications how they intend to fund their studies. Any academically suitable applicant that does not indicate how they intend to fund their studies will be considered for the Darwin and/or the Elite Scholarships if not already indicated. We can only consider applicants who have their own funding or wish to apply for their own funding or are successful in gaining a Scholarship.