XVI International Botanical Congess

Little is known about association and separation of homologous chromosomes during meiosis I, partly due to the absence of mutants that display stabilized homologue association. Here we report the isolation and characterization of such an Arabidopsis mutant. In the mutant during anaphase I of male meiosis chromosomal materials are abnormally extended, and the rDNA in the mutant is always distributed to only one of the microspores. These results strongly suggest that the mutant homologues remain associated following metaphase I, possibly involving the rDNA genes. We found that the disrupted gene is highly homologous to the human and yeast SKP1 genes. The function of yeast Skp1p includes targeting specific proteins for degradation by the ubiquitin-mediated proteolysis. We propose that the Arabidopsis gene controls homologue separation by degrading or otherwise removing a protein complex that holds homologues together prior to anaphase I.