HCRs, anti-crossover proteins restrict crossover number in Arabidopsis

Abstract

Meiotic crossover recombination affects genetic diversity in population and is a critical tool for breeding. During meiosis, meiotic DSBs are repaired to reciprocal crossovers through class I and class II pathways. Anti-crossover factors such as FANCM, RECQ4 and FIGL1 were known to restrict crossovers in class II pathway dependent manner. However, the mechanism underlining how crossover number is limited to one to three along chromosome remains unexplored. We performed a high throughput genetic screening of higher crossover rate (hcr) mutants by using fluorescent seed-based system, enabling the measurement of crossover frequency in individual plants. We found that hcr mutants (hcr1, hcr2, hcr3) were new anti-crossover mutants by genetic analysis and deep-sequencing. We present characterization of hcr2 and hcr3 mutants, including mapping of them and their effects on crossover frequency in defined intervals along chromosomes.