Recipient organisationJohn Innes CentreSource-published name: John Innes Centre
Funding£924K
PeriodAug 2025 — Aug 2028
In plain English
AI plain-English summary
Every time a wheat or barley plant makes a grain of pollen, its chromosomes swap segments of DNA in a process called crossover—but the plant controls where and how often those swaps happen, and breeders have been stuck with the consequences for a century. This project tackles a fundamental gap in biology: why crossover events are so few and so unevenly distributed along chromosomes. In crops like wheat, that bottleneck limits how quickly breeders can combine desirable traits. The researchers have proposed a new “coarsening” model, in which a protein called HEI10 gradually clusters into larger, more widely spaced spots on chromosomes during cell division. They now need to test whether that model holds across different plants, from the small genome of *Arabidopsis* to the enormous, 120-times-larger genome of wheat, and in polyploids—plants with multiple chromosome sets, which often suffer fertility problems when crossovers go wrong. This is fundamental science, not applied breeding. But understanding the universal rules of crossover placement could eventually let breeders predict—or even manipulate—where DNA swaps occur, accelerating crop improvement for food security.
View original technical description
Eukaryotic sex cells (e.g., sperm and eggs in humans) are produced by a specialised cell division called meiosis, where chromosomes exchange large DNA segments. These DNA exchanges, or crossovers, are essential for generating genetic diversity, and are a driving force for evolution and selective breeding. Crucially, crossover frequency and position along chromosomes are tightly controlled, introducing a bottleneck for plant and animal breeders due to low crossover numbers and their skewed distribution. However, despite a century of research, the cellular mechanisms that determine where, how quickly and how many, crossovers form has remained mostly mysterious. Chromosome size, ploidy and the dynamics of chromosome pairing during early meiosis are all known to have profound effects on crossover patterning, yet how these features interact to influence crossover site designation is unknown. We recently proposed a ‘coarsening’ model for crossover patterning that creates a unique framework to mechanistically dissect the influence of these key features on the crossover landscape. Our coarsening model captures the dynamics of a conserved protein involved in promoting crossovers called HEI10, including its ability to associate into increasingly large, distantly-spaced foci on the chromosomes as meiosis progresses. The dynamics of HEI10 orthologs are very similar in organisms as diverse as plants, fungi and animals, making our model of wide applicability. However, HEI10 is unlikely to be acting alone during the coarsening process, making it critical to also investigate the roles played by the many other recombination proteins. In this proposal, we will address these key issues by performing live-imaging and super-resolution cytogenetics of HEI10 and other recombination proteins in diploid and polyploid plant species, closely coupled with computational modelling. Our goal is to comprehensively understand the processes that determine meiotic crossover site selection. Generating mechanistic insight into this highly conserved aspect of eukaryotic genetics could drive future innovation in plant and animal breeding. Our specific objectives are: 1) Unravel how chromosome pairing, as well as the coarsening dynamics of HEI10 and other recombination proteins, control crossover patterning in Arabidopsis thaliana, a plant with a compact genome commonly used in research. We will use predictive modelling, live-imaging and genetic dissection to understand how these factors interact in time and space to shape the plant recombination landscape. 2) Dissect crossover positioning in polyploids, which are common among major crop species. The presence of multiple homologous chromosomes in polyploids poses a unique challenge for homologue pairing and crossover site selection, causing dramatic reductions in fertility in newly formed polyploid species due to misplaced crossovers. Using modelling and experiments, we will therefore investigate how crossover patterning dynamics are altered to drive the evolutionary stabilisation of meiosis in newly-formed and established polyploids of the Arabidopsis genus. 3) Dissect crossover positioning in a giant polyploid genome, wheat, that is ~120 times bigger than the Arabidopsis genome. Using modelling and experiments, and our insights from Objectives 1 and 2, we will examine whether we can predict how coarsening and pairing contribute to the low numbers and skewed distribution of crossovers along wheat chromosomes. These objectives will enable our team to comprehensively investigate universal mechanisms that drive crossover positions in eukaryotes, including crop species such as wheat, that are economically critical. Our project goals closely align with the BBSRC’s ‘Understanding the rules of life’ and ‘Sustainable agriculture and food’ strategic objectives.
Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.
Is something wrong? Let us know