Direct coupling between meiotic DNA replication and recombination initiation.

During meiosis in Saccharomyces cerevisiae, DNA replication occurs 1. 5 to 2 hours before recombination initiates by DNA double-strand break formation. We show that replication and recombination initiation are directly linked. Blocking meiotic replication prevented double-strand break formation in a replication-checkpoint-independent manner, and delaying replication of a chromosome segment specifically delayed break formation in that segment. Consequently, the time between replication and break formation was held constant in all regions. We suggest that double-strand break formation occurs as part of a process initiated by DNA replication, which thus determines when meiotic recombination initiates on a regional rather than a cell-wide basis.