Characterization of meiotic crossovers in pollen from Arabidopsis thaliana.

Homologous recombination processes, which occur during the prophase of the first meiotic division, while generating new allelic combinations, are mechanistically important for the regular segregation of homologous chromosomes. They generate either crossovers, which are reciprocal exchanges between chromosome segments, or gene conversions. Both kinds of events occur in narrow regions (less than 10 kb) called hotspots, which are distributed along chromosomes. Classical genetic methods for CO characterization, which rely on the building of large populations and require appropriately located markers, are not well suited to the study of meiotic recombination hotspots. Here, we present a method based on allele-specific PCR amplification of single molecules from pollen genomic DNA. It allows detection, quantification and characterization of CO events arising at low frequencies in recombination hotspots.