The RAD51 paralogue HvXRCC2 regulates meiosis and recombination in barley

Abstract

Using a positional candidate-gene approach we show that semi-sterile desynaptic8 mutants are associated with deletions in or of the barley homolog of XRCC2 (X-Ray Repair Cross Complementing 2). In barley XRCC2 mutants, the initial meiotic progression is normal, albeit with a small delay in initiation, with completion of synapsis. Subsequently, however, the absence of HvXRCC2 leads to a dramatic reduction in the number of crossovers, chromosome mis-segregation and infertility, suggesting that HvXRCC2 plays a major role in recombination. This mutant phenotype is congruent with that reported in mammalian studies but contrasts with the XRCC2 mutant in Arabidopsis which is fertile, exhibits normal chromosome pairing and correct chromosome segregation and is associated with an increased rate of crossovers. This study in barley indicates that the XRCC2 mutant phenotype in Arabidopsis is thus not representative of all plants and that XRCC2 is not a good candidate for the modulation of recombination in barley.