Global analysis of the meiotic crossover landscape.

Tight control of the number and distribution of crossovers is of great importance for meiosis. Crossovers establish chiasmata, which are physical connections between homologous chromosomes that provide the tension necessary to align chromosomes on the meiotic spindle. Understanding the mechanisms underlying crossover control has been hampered by the difficulty in determining crossover distributions. Here, we present a microarray-based method to analyze multiple aspects of crossover control simultaneously and rapidly, at high resolution, genome-wide, and on a cell-by-cell basis. Using this approach, we show that loss of interference in zip2 and zip4/spo22 mutants is accompanied by a reduction in crossover homeostasis, thus connecting these two levels of crossover control. We also provide evidence to suggest that repression of crossing over at telomeres and centromeres arises from different mechanisms. Lastly, we uncover a surprising role for the synaptonemal complex component Zip1 in repressing crossing over at the centromere.