Modulation of Meiotic Recombination

Meiotic recombination is one of the principal forces creating the genetic diversity that drives evolution and is the fundamental instrument underlying most crop breeding programmes. A greater understanding of the control of recombination in crop plants would enable manipulation of this process to improve the speed and accuracy of plant breeding. This would be particularly useful for many of the temperate grass species (e.g. wheat, barley, oats and forage grasses such as Lolium and Festuca) where the highly skewed distribution of meiotic crossover (CO) events means that a large proportion of genes rarely, if ever, recombine. These species are all members of the grass subfamily Pooideae, with large genomes and very close syntenic relationships, and all exhibit a non-random pattern of recombination relative to the gene distribution in their genomes whereby chiasmata appear to be preferentially targeted to the ends of the chromosomes. This means that large areas of the chromosome around the centromeric region rarely recombine, even though they represent substantial proportions of the physical maps of the chromosomes. Even small changes in the crossover frequency and distribution, particularly those that promote recombination in centromeric regions, could therefore have a significant effect on the efficiency of breeding in these crops by breaking up some of the extensive linkage blocks. The authors summarise current knowledge on the process of meiosis in barley and highlight strategies which could allow the modulation of meiotic recombination in future.