Interconnections between meiotic recombination and sequence polymorphism in plant genomes

Meiosis is fundamental to sexual reproduction and creates genetic variation in progeny. During meiosis paired homologous chromosomes undergo recombination, which can result in reciprocal crossovers. This process can recombine independently arising mutations onto the same chromosome. Recombination locations are highly variable between meioses, although total crossover numbers are tightly regulated. In addition to the effect of meiosis on genetic variation, sequence polymorphisms between homologous chromosomes can feedback onto the recombination pathways. Here we review the major crossover pathways in plants and some of the known homeostatic mechanisms that act during meiotic recombination. We then examine how sequence polymorphisms between homologous chromosomes, that is, heterozygosity, can influence meiotic recombination pathways in cis and trans. Finally, we provide a brief perspective on the relevance of these interconnections for natural selection and adaptation in plants.