Accelerating plant breeding by modulating recombination.

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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 climate change 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. Accessing these traits for plant breeding, however, is limited by "genetic drag", where low levels of genetic exchange (recombination) means that both desirable and undesirable "wild traits" are introduced and can be difficult to separate. Boosting recombination overcomes genetic drag allowing access to diverse germplasm, as well as increasing the efficiency of traditional breeding programs, helping generate the new combinations of traits required for crop improvement in fewer generations.Recombination can be increased in plants 8-fold by knocking out anti-recombinase genes. However, establishing multigene knockouts in every breeding program is not practical, approaches used to generate mutants may preclude cultivation in tightly (GMO) regulated environments and the mutations introduced can reduce fertility, so wild type alleles must be restored prior to cultivation. Transiently increasing recombination without modification of the recombination machinery itself would solve these problems.To achieve this goal, we will use high-throughput screening assays to identify small molecule inhibitors of key recombination suppressing proteins that can be used to transiently boost recombination in a wide variety of crop species. To identify inhibitors, we will design targeted compound libraries for screening based on molecules identified in large biomedical drug screens that inhibit human orthologs of our target proteins. In addition, virtual screening of large compound libraries will be used to identify further compounds of interest for testing. We will also identify and/or develop plant versions of peptides known to boost recombination in mammalian systems. Once identified, delivery of recombination boosting small-molecules will be optimised for use in crops. This will be initially be undertaken in Brassica and barley, covering a dicot crop closely related to the model plant Arabidopsis, and a key grain crop, both with well-developed cytological tools. Another route for crop development is to incorporate the traits and diversity of two genomes into a single individual - known as allopolyploidy. 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. Two interacting genes have recently been implicated in suppressing this inter-genomic recombination and we will assess the potential to use/modify these genes, and others in the same pathway, to engineer a stable meiosis in new allopolyploids. If successful we will use this approach to generate new genetically stable allopolyploid Brassica and pasture grasses.This multi-disciplinary project, draws on expertise of the Fellow and Project Partners 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. The final three years of the project will involve product development in collaboration with breeding companies to optimise delivery and effectiveness during plant breeding and establishment of a start-up company to commercialise the product(s) developed.