Role of DNA mismatch repair genes in meiotic recombination and gamete function

点击翻译按钮获取中文摘要

In recent work we have investigated the biological roles of three key DNA repair genes in the model plant Arabidopsis. This work has allowed us to extend to plants some conclusions that had been drawn from work in yeast and mice, but more importantly, it has allowed us to uncover features that seem to be unique to plants. In the proposed work, we will first examine whether the genes under study exert a similar effect on meiotic recombination as we have shown on mitotic recombination. This is crucial as meiotic recombination is the key player in applied genetics (breeding better varieties for example). Secondly, we propose to perform a mutant screen in order to uncover additional genes limiting recombination between similar but non-identical sequences in plants. These novel mutants will be tested against each other to determine how many distinct mutations these represent. Furthermore, these mutations will be mapped to allow the eventual cloning of these genes. Lastly, we will explore a distinctive feature of the plant MutL homologues we have studied (AtMLH1 and AtPMS1). Mutants in both of these genes exhibit a marked segregation bias against the mutant allele when it is segregating alongside a wild-type allele. Such a phenomenon is not seen with a MutS homologue (AtMSH2) indicating that it does not simply result from the lack of MMR activity. To investigate this phenotype, we will try to determine when this bias arose. In addition, pollen germination and pollen tube growth will be tested. To begin to understand the role played by AtMLH1 in pollen development or function, we will use a functional complementation approach. Cell- and stage-specific promoters will be used to determine the cell type or developmental stage in or at which the AtMLH1 protein is required.