Crossover control: A key to unlocking genetic diversity in plant breeding.

During meiosis, crossovers between homologous chromosomes generate genetic diversity but are limited in number, widely spaced by interference, and biased toward gene-rich euchromatin while suppressed in pericentromeric heterochromatin. This constrained crossover patterning restricts the genetic variation available for plant breeding. Recent studies have identified key crossover regulators-including the anti-crossover helicases FANCM and RECQ4, the pro-crossover factor HEI10, and heterochromatin-organizing proteins-that can modulate crossover frequency and positioning, although the effects on fertility are species- and context-dependent. Manipulating these pathways offers a strategy to increase crossovers along chromosomes, including recombination-suppressed regions, thereby unlocking hidden genetic variation. Genetic and epigenetic control of crossover formation is emerging as a powerful tool to accelerate crop improvement and enhance genetic gain.