Accelerating Plant Breeding by Modulating Recombination - Renewal (MODREC2)

To meet expected demand, the world will need to produce 50 percent more food in 2050 than it did in 2012. While similar growth rates have been achieved in the past, future growth faces the additional pressure of a changing climate and the need for reduced chemical inputs. Sustainably enhancing agricultural production is therefore a major challenge facing the sector. A valuable source of traits for disease resistance and abiotic stress tolerance resides in thousands of living wild crop relatives, many of which have been collected and safeguarded in seed banks across the globe. Accessing these “wild” traits for plant breeding, however, is limited by "genetic drag", where low levels of genetic exchange (recombination) means that both desirable and undesirable traits are introduced and can be difficult to separate. Boosting recombination can overcomes genetic drag resulting in great potential to increase the efficiency of traditional breeding programs, helping generate the new combinations of traits required for crop improvement in fewer generations. There are established methods to enhance recombination, however these rely on genetic knockouts which are impractical for many crop varieties and can lead to yield losses due to fertility defects. Our project aims to develop innovative methods to transiently boost recombination without modification of the underlying recombination machinery, overcoming these problems. In the first phase of this programme of research we undertook a small molecule screen to identify inhibitors of key recombination suppressing proteins and have so far identified five lead compounds with recombination boosting potential. We have also gained key insights into interactions between the key pathways limiting meiotic crossovers, enhancing our fundamental understanding of recombination and DNA repair and identifying new targets for recombination boosting compounds. The second phase will focus on optimising the structure and delivery of small-molecule inhibitors to the developing flowers of plants, following this with proof-of-principle demonstration of the technology and developing a route to commercialisation. We will also work with plant breeding companies to develop the tools needed to maximise impact generated from our recombination boosting technology, including developing computational pipelines and associated software to identify and characterise regions of wild-genomes introgressed into cultivated varieties. Another route for crop development is to incorporate the traits and diversity of two genomes into a single individual in inter-specific hybrids and/or allopolyploids. Allopolyploid plants are common in agriculture (e.g. wheat and cotton) as their fixed hybrid nature usually results in improved agricultural traits. Despite their potential, previous attempts to generate new allopolyploid crops have failed as they tend to have genomic instability and low fertility due to recombination between the two sub-genomes. In the first phase of this research, we have gained fundamental insights into polyploid meiosis, developed new tools to track chromosome interactions during meiosis, and identified strategies to engineer a stable meiosis in new allopolyploids by reducing the copy number of key genes in the major crossover pathway. In phase two of the project, we will implement these strategies to develop new meiotically stable Brassica and pasture grasses. This multi-disciplinary project, draws on expertise of the Fellow and collaborators in molecular plant science, phenomics, plant breeding, polyploidy, medicinal chemistry and biochemistry to modify recombination in plants for accelerated plant breeding, helping to develop the high nutrition, climate ready and disease resistant crops needed to meet future food needs.