Recent studies of meiotic recombination in the budding yeast and the model plant Arabidopsis thaliana indicate that meiotic crossovers (COs) occur through two genetic pathways: the interference-sensitive pathway and the interference-insensitive pathway. However, few genes have been identified in either pathway. Here, we describe the identification of the PARTING DANCERS (PTD) gene, as a gene with an elevated expression level in meiocytes. Analysis of two independently generated transferred DNA insertional lines in PTD showed that the mutants had reduced fertility. Further cytological analysis of male meiosis in the ptd mutants revealed defects in meiosis, including reduced formation of chiasmata, the cytological appearance of COs. The residual chiasmata in the mutants were distributed randomly, indicating that the ptd mutants are defective for CO formation in the interference-sensitive pathway. In addition, transmission electron microscopic analysis of the mutants detected no obvious abnormality of synaptonemal complexes and apparently normal late recombination nodules at the pachytene stage, suggesting that the mutant's defects in bivalent formation were postsynaptic. Comparison to other genes with limited sequence similarity raises the possibility that PTD may present a previously unknown function conserved in divergent eukaryotic organisms.
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