Intellectual Merit: Meiosis, the reductive division of the genome in preparation for fertilization, is a critical biological process. During meiosis, homologous chromosomes interact resulting in the heritable rearrangement of DNA through reciprocal exchange between homologous chromosomes by processes referred-to as crossing over and gene conversion. In most eukaryotes, these events ensure proper chromosome segregation, facilitate DNA repair, and provide a basis for genetic diversity. Molecular geneticists have made substantial progress in understanding the basal recombination machinery, much of which is conserved in organisms as diverse as yeast, plants and mammals. As a result, detailed models describing recombination mechanisms have been proposed. In most organisms, a key protein in these mechanisms is DMC1, which mediates the establishment of physical linkages between homologous chromosomes during recombination. Intense focus on DMC1 in several model organisms has revealed that its activity is closely regulated by a host of mediator proteins. While DMC1 or similar proteins (RecA homologs) are found in organisms as diverse as bacteria, fungi, plants and animals, their mediators are not as well conserved. Indeed, the model plant Arabidopsis thaliana shares only four of the ten proteins proposed to regulated DMC1 in the budding yeast Saccharomyces cerevisiae. As a prelude to this project, ten mutants (suppressors) have been identified that may interact with Arabidopsis DMC1. Understanding the proteins that interact with DMC1 (identified as suppressors of dmc1 mutants) will enable the description of the mechanisms that plants use to mediate meiotic recombination. In addition, expanding our understanding of plant meiotic recombination has the potential for advancing plant biotechnology including our ability to engineer plant genomes by harnessing recombination.
Broader Impacts: The project will create opportunities for participation in cutting-edge research by young scientists from under-served communities. In addition, the PI will continue to participate in and develop a class for advanced undergraduates, graduates, and postdocs that focuses specifically on meiosis and recombination - this class was initiated as part of the broader impact efforts from a prior NSF award.