Chromatin and recombination landscapes in the hexaploid wheat genome.

Meiotic recombination creates genetic diversity in the progeny of sexually reproducing species.
For example, reciprocal exchange between homologous chromosomes (known as crossover)
creates novel combinations of genetic variation. The variation-generating processes acting
during meiosis remain a major tool for crop improvement, whereby useful characteristics from
different backgrounds can be combined.
Bread wheat is a major crop in the UK and globally, where meiotic recombination during
breeding remains an essential tool for variety improvement. However, the wheat genome is
extremely large (17 gigabases) and shows highly skewed recombination distributions, with most
crossovers occurring in the distal regions of the chromosomes. This severely limits the ability of
breeders to utilise variation located in the central regions of the chromosomes. Therefore,
developing tools and technologies to control recombination in wheat has direct relevance for
food security.
In this project the student will use chromatin immunoprecipitation (ChIP) followed by high
throughput sequencing to profile the distribution of euchromatic and heterochromatic chromatin
modifications throughout the wheat genome. These distributions will be related to highresolution
genetic maps generated by KWS and genotypes that differ in their genetic map
lengths. These experiments will be conducted in backgrounds of interest to KWS and the
student will identify chromatin patterns that correlate with altered frequencies and patterns of
recombination. The recent public release of a high quality reference genome assembly for wheat
makes this project feasible and timely.
New reverse genetic resources (e.g. TILLING, CRISPR-Cas9) are available that allow genes of
interest to be disrupted in bread wheat. To functionally investigate the role of chromatin on
recombination the student will isolate mutations in epigenetic regulators. These mutants will be
profiled using ChIP-seq in order to characterise how chromatin is altered genome-wide. Finally,
these mutants will be used to measure effects on number and distribution of recombination
events during meiosis.
This project will provide the student with advanced training in wheat genetics and genomics.
They will generate data of basic importance for understanding wheat genome function and
evolution. They will gain experience in wheat genetics relevant to both academic and industrial
scientific contexts.