New insights into the role of DNA synthesis in meiotic recombination

Meiosis comprises two rounds of nuclear division following a single phase of DNA replication, leading to the production of haploid gametes and is essential for sexual reproduction in eukaryotes. Unlike mitosis, meiosis involves homologous chromosome pairing, synapsis, and recombination during prophase I. Meiotic recombination not only ensures the accurate segregation of homologs, but also redistributes alleles among offspring. DNA synthesis is a critical process during meiotic recombination, but our understanding of the proteins that execute and regulate it is limited. This review summarizes the recent advances in defining the role of DNA synthesis in meiotic recombination through analyses of DNA synthesis genes, with specific emphasis on DNA polymerases (e.g., Pol epsilon and Pol delta), replication processivity factor RFC1 and translesion polymerases (e.g., Pol zeta). We also present a new double strand break repair model for meiotic recombination, which includes lagging strand DNA synthesis and leading strand elongation. Finally, we propose that DNA synthesis is one of critical factors for discriminating meiotic recombination pathways and that this differentiation may be conserved among eukaryotes.