title: Zip4/Spo22 is required for class I CO formation but not for synapsis completion in Arabidopsis thaliana.
abstract: In budding yeast meiosis, the formation of class I interference-sensitive crossovers requires the ZMM proteins. These ZMM proteins are essential in forming a mature synaptonemal complex, and a subset of these (Zip2, Zip3, and Zip4) has been proposed to compose the core of synapsis initiation complexes (SICs). Zip4/Spo22 functions with Zip2 to promote polymerization of Zip1 along chromosomes, making it a crucial SIC component. In higher eukaryotes, synapsis and recombination have often been correlated, but it is totally unknown how these two processes are linked. In this study, we present the characterization of a higher eukaryote SIC component homologue: Arabidopsis AtZIP4. We show that mutations in AtZIP4 belong to the same epistasis group as Atmsh4 and eliminate approximately 85% of crossovers (COs). Furthermore, genetic analyses on two adjacent intervals of Chromosome I established that the remaining COs in Atzip4 do not show interference. Lastly, immunolocalization studies showed that polymerization of the central element of the synaptonemal complex is not affected in Atzip4 background, even if it may proceed from fewer sites compared to wild type. These results reveal that Zip4 function in class I CO formation is conserved from budding yeast to Arabidopsis. On the other hand, and contrary to the situation in yeast, mutation in AtZIP4 does not prevent synapsis, showing that both aspects of the Zip4 function (i.e., class I CO maturation and synapsis) can be uncoupled.
authors.affiliation: Institut Jean-Pierre Bourgin, INRA de Versailles, Station de Génétique et d'Amélioration des Plantes UR-254, France.
authors.forename: Liudmila
authors.initials: L
authors.lastname: Chelysheva
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Gendrot
authors.forename: Daniel
authors.initials: D
authors.lastname: Vezon
authors.forename: Marie-Pascale
authors.initials: MP
authors.lastname: Doutriaux
authors.forename: Raphaël
authors.initials: R
authors.lastname: Mercier
authors.forename: Mathilde
authors.initials: M
authors.lastname: Grelon
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D023902:Chromosome Pairing / Q000235:genetics / Q000502:physiology*; D032461:Chromosomes, Plant / Q000235:genetics; D003434:Crossing Over, Genetic; D004268:DNA-Binding Proteins / Q000378:metabolism; D005091:Exons / Q000235:genetics; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000302:isolation & purification; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011058:Pollen / Q000166:cytology / Q000378:metabolism; D021381:Protein Transport
chemical_list: C411742:ASY1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D050505:Mutant Proteins; C520833:Zip4 protein, Arabidopsis