title: Functional analysis of maize RAD51 in meiosis and double-strand break repair.
abstract: In Saccharomyces cerevisiae, Rad51p plays a central role in homologous recombination and the repair of double-strand breaks (DSBs). Double mutants of the two Zea mays L. (maize) rad51 homologs are viable and develop well under normal conditions, but are male sterile and have substantially reduced seed set. Light microscopic analyses of male meiosis in these plants reveal reduced homologous pairing, synapsis of nonhomologous chromosomes, reduced bivalents at diakinesis, numerous chromosome breaks at anaphase I, and that >33% of quartets carry cells that either lack an organized nucleolus or have two nucleoli. This indicates that RAD51 is required for efficient chromosome pairing and its absence results in nonhomologous pairing and synapsis. These phenotypes differ from those of an Arabidopsis rad51 mutant that exhibits completely disrupted chromosome pairing and synapsis during meiosis. Unexpectedly, surviving female gametes produced by maize rad51 double mutants are euploid and exhibit near-normal rates of meiotic crossovers. The finding that maize rad51 double mutant embryos are extremely susceptible to radiation-induced DSBs demonstrates a conserved role for RAD51 in the repair of mitotic DSBs in plants, vertebrates, and yeast.
authors.affiliation: Department of Genetics, Development and Cell Biology, Iowa State Unversity, Ames, Iowa 50011, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Harper
authors.forename: Inna
authors.initials: I
authors.lastname: Golubovskaya
authors.forename: C Rachel
authors.initials: CR
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Weber
authors.forename: Robert B
authors.initials: RB
authors.lastname: Meeley
authors.forename: John
authors.initials: J
authors.lastname: McElver
authors.forename: Ben
authors.initials: B
authors.lastname: Bowen
authors.forename: W Zacheus
authors.initials: WZ
authors.lastname: Cande
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Schnable
mesh_terms: D000705:Anaphase; D023902:Chromosome Pairing; D004260:DNA Repair; D017343:Genes, Plant; D005854:Germ Cells; D008540:Meiosis; D049469:Meiotic Prophase I; D008969:Molecular Sequence Data; D051135:Rad51 Recombinase / Q000502:physiology*; D012639:Seeds / Q000235:genetics / Q000528:radiation effects; D003313:Zea mays
chemical_list: D051135:Rad51 Recombinase