title: The DNA replication factor RFC1 is required for interference-sensitive meiotic crossovers in Arabidopsis thaliana.
abstract: During meiotic recombination, induced double-strand breaks (DSBs) are processed into crossovers (COs) and non-COs (NCO); the former are required for proper chromosome segregation and fertility. DNA synthesis is essential in current models of meiotic recombination pathways and includes only leading strand DNA synthesis, but few genes crucial for DNA synthesis have been tested genetically for their functions in meiosis. Furthermore, lagging strand synthesis has been assumed to be unnecessary. Here we show that the Arabidopsis thaliana DNA replication factor C1 (RFC1) important for lagging strand synthesis is necessary for fertility, meiotic bivalent formation, and homolog segregation. Loss of meiotic RFC1 function caused abnormal meiotic chromosome association and other cytological defects; genetic analyses with other meiotic mutations indicate that RFC1 acts in the MSH4-dependent interference-sensitive pathway for CO formation. In a rfc1 mutant, residual pollen viability is MUS81-dependent and COs exhibit essentially no interference, indicating that these COs form via the MUS81-dependent interference-insensitive pathway. We hypothesize that lagging strand DNA synthesis is important for the formation of double Holliday junctions, but not alternative recombination intermediates. That RFC1 is found in divergent eukaryotes suggests a previously unrecognized and highly conserved role for DNA synthesis in discriminating between recombination pathways.
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Yingxiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Cheng
authors.forename: Jiyue
authors.initials: J
authors.lastname: Huang
authors.forename: Qian
authors.initials: Q
authors.lastname: Shi
authors.forename: Yue
authors.initials: Y
authors.lastname: Hong
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Copenhaver
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Gong
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D020090:Chromosome Segregation / Q000235:genetics*; D032461:Chromosomes, Plant / Q000235:genetics; D003434:Crossing Over, Genetic / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics; D059765:Homologous Recombination / Q000235:genetics; D008540:Meiosis / Q000235:genetics; D009154:Mutation; D051818:Replication Protein C / Q000235:genetics*
chemical_list: D004265:DNA Helicases; D051818:Replication Protein C