title: Arabidopsis SPO11-2 functions with SPO11-1 in meiotic recombination.
abstract: The Spo11 protein is a eukaryotic homologue of the archaeal DNA topoisomerase VIA subunit (topo VIA). In archaea it is involved, together with its B subunit (topo VIB), in DNA replication. However, most eukaryotes, including yeasts, insects and vertebrates, instead have a single gene for Spo11/topo VIA and no homologues for topo VIB. In these organisms, Spo11 mediates DNA double-strand breaks that initiate meiotic recombination. Many plant species, in contrast to other eukaryotes, have three homologues for Spo11/topo VIA and one for topo VIB. The homologues in Arabidopsis, AtSPO11-1, AtSPO11-2 and AtSPO11-3, all share 20-30% sequence similarity with other Spo11/topo VIA proteins, but their functional relationship during meiosis or other processes is not well understood. Previous genetic evidence suggests that AtSPO11-1 is a true orthologue of Spo11 in other eukaryotes and is required for meiotic recombination, whereas AtSPO11-3 is involved in DNA endo-reduplication as a part of the topo VI complex. In this study, we show that plants homozygous for atspo11-2 exhibit a severe sterility phenotype. Both male and female meiosis are severely disrupted in the atspo11-2 mutant, and this is associated with severe defects in synapsis during the first meiotic division and reduced meiotic recombination. Further genetic analysis revealed that AtSPO11-1 and AtSPO11-2 genetically interact, i.e. plants heterozygous for both atspo11-1 and atspo11-2 are also sterile, suggesting that AtSPO11-1 and AtSPO11-2 have largely overlapping functions. Thus, the three Arabidopsis Spo11 homologues appear to function in two discrete processes, i.e. AtSPO11-1 and AtSPO11-2 in meiotic recombination and AtSPO11-3 in DNA replication.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Colney, Norwich, NR4 7UH, UK.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Stacey
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuromori
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Azumi
authors.forename: Gethin
authors.initials: G
authors.lastname: Roberts
authors.forename: Christian
authors.initials: C
authors.lastname: Breuer
authors.forename: Takuji
authors.initials: T
authors.lastname: Wada
authors.forename: Anthony
authors.initials: A
authors.lastname: Maxwell
authors.forename: Keith
authors.initials: K
authors.lastname: Roberts
authors.forename: Keiko
authors.initials: K
authors.lastname: Sugimoto-Shirasu
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020090:Chromosome Segregation / Q000502:physiology; D026942:DNA Topoisomerases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008540:Meiosis / Q000502:physiology*; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D051479:Plant Infertility / Q000235:genetics; D011995:Recombination, Genetic; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D014466:Ultraviolet Rays; D000099257:Meiotic Recombination Protein SPO11
chemical_list: D029681:Arabidopsis Proteins; D026942:DNA Topoisomerases; D008741:Methyl Methanesulfonate; C477460:Spo11-1 protein, Arabidopsis; D000099257:Meiotic Recombination Protein SPO11; C515046:SPO11-2 protein, Arabidopsis; C515047:SPO11-3 protein, Arabidopsis