13 ERA-CAPS. Delineating the crossover control networks in plants (DeCOP)

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Meiosis is a specialized type of cell division required for sexual reproduction. It ensures the reductionof the genome and the recombination of maternal and paternal chromosomal segments prior to theformation of generative cells. The process of meiotic recombination is initiated by programmed DNAdouble-strand breaks (DSBs), introduced by the conserved Spo11 protein. Ultimately, the positions ofthe DSBs define loci of mutual genetic exchange. However, in a single meiotic cell only a small subsetof DSBs are destined to form genetic crossovers (COs), while the remainder are repaired via non-CO pathways. CO formation itself is subject to stringent control, which ensures that each homologuepair receives at least one obligate CO. A phenomenon known as CO interference then ensures thatmost (~85%) additional COs do not occur in an adjacent chromosomal region. As a result multipleCOs are spaced well apart along the homologues. Understanding the factors that control DSBformation and processing to form COs is of fundamental scientific interest, moreover this knowledgewill have important implications for manipulating meiotic recombination in crop plants.In recent years meiosis research in plants has largely focussed on the identification of meioticgenes/proteins involved in recombination pathways or the organization of the chromosome axes andsynaptonemal complex. Although these studies clearly demonstrate the importance of these proteins, itremained mostly enigmatic how their activities are coordinated to ensure the controlled formation ofCOs. Hence this collaborative project (DeCOP) seeks to shift emphasis to focus on howrecombination, chromosome organisation and remodelling are orchestrated to control the frequencyand distribution of COs. Specifically, we seek to identify the protein networks that determine the fateof individual DSBs and establish when CO interference is established. We propose to 1) perform aninnovative screen to identify novel factors that modulate CO formation and interference, 2) investigatethe role of chromosome axis-associated proteins in CO maturation and interference, 3) determine therole of (ATM/ATR mediated) phosphorylation in coordinating meiotic DNA repair and CO formationand 4) to identify proteins involved in the final step of CO formation.The factors and processes studied in the DeCOP project will significantly enhance ourunderstanding of the networks that govern crossover formation in plants. We therefore anticipate thatour findings will strongly stimulate future crop breeding programmes.