Isolation of higher crossover rate mutants in Arabidopsis

Abstract

Meiotic recombination produces crossovers from SPO11-mediated DSBs by diverse interhomolog repair pathways. The crossovers affect genetic diversity in population and breeding. Crossover is limited to ~1-3 along chromosomes by three distinct anti-crossover pathways that include FANCM, RECQ4 and FIGL1 factors in Arabidopsis. However, the mechanism underlying crossover suppression in which the DSBs (~40-50 per chromosome) are repaired to 1-3 crossovers remains explored clearly. We have performed high throughput genetic screenings of higher crossover rate (hcr) mutants by using fluorescent seed-based system, enabling the measurement of crossover frequency in individual plants of various mutant pools. Three hcr mutants (hcr1, hcr2, hcr3) were isolated and confirmed to be new anti-crossover mutants by genetic analyses and crossover measurements. The isolation and characterization of hcr mutants reveal new anti-crossover pathways, providing an insight into the crossover suppression mechanism in plants