title: The kinesin AtPSS1 promotes synapsis and is required for proper crossover distribution in meiosis.
abstract: Meiotic crossovers (COs) shape genetic diversity by mixing homologous chromosomes at each generation. CO distribution is a highly regulated process. CO assurance forces the occurrence of at least one obligatory CO per chromosome pair, CO homeostasis smoothes out the number of COs when faced with variation in precursor number and CO interference keeps multiple COs away from each other along a chromosome. In several organisms, it has been shown that cytoskeleton forces are transduced to the meiotic nucleus via KASH- and SUN-domain proteins, to promote chromosome synapsis and recombination. Here we show that the Arabidopsis kinesin AtPSS1 plays a major role in chromosome synapsis and regulation of CO distribution. In Atpss1 meiotic cells, chromosome axes and DNA double strand breaks (DSBs) appear to form normally but only a variable portion of the genome synapses and is competent for CO formation. Some chromosomes fail to form the obligatory CO, while there is an increased CO density in competent regions. However, the total number of COs per cell is unaffected. We further show that the kinesin motor domain of AtPSS1 is required for its meiotic function, and that AtPSS1 interacts directly with WIP1 and WIP2, two KASH-domain proteins. Finally, meiocytes missing AtPSS1 and/or SUN proteins show similar meiotic defects suggesting that AtPSS1 and SUNs act in the same pathway. This suggests that forces produced by the AtPSS1 kinesin and transduced by WIPs/SUNs, are required to authorize complete synapsis and regulate maturation of recombination intermediates into COs. We suggest that a form of homeostasis applies, which maintains the total number of COs per cell even if only a part of the genome is competent for CO formation.
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Duroc
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Afef
authors.initials: A
authors.lastname: Lemhemdi
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Larchevêque
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Hurel
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Maria
authors.initials: M
authors.lastname: Cuacos
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Cromer
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Horlow
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Armstrong
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Liudmila
authors.initials: L
authors.lastname: Chelysheva
authors.affiliation: The French National Institute for Agricultural Research (INRA), Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, France.
authors.forename: Raphael
authors.initials: R
authors.lastname: Mercier
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D023902:Chromosome Pairing; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis; D008870:Microtubules / Q000378:metabolism; D009154:Mutation
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C507256:REC8 protein, Arabidopsis; C505574:ZYP1a protein, Arabidopsis; D004720:Endonucleases; C514438:MUS81 protein, Arabidopsis; C000607004:AtPSS1 protein, Arabidopsis; D016547:Kinesins