Chromosome pairing and fertility of interspecific hybrids between Trifolium repens L. and T. occidentale Coombe

T. occidentale is a diploid wild relative with the potential to improve the drought and salt tolerances of white clover (T. repens). Previous work has shown that it is possible to efficiently produce large T. repens x T. occidentale breeding populations using colchicine doubled (4x) T. occidentale. For effective introgression (backcross) breeding it is also essential that interspecific chromosome pairing and recombination occur. In this study, it was apparent that chromosome pairing was occurring not only between T. occidentale and T. repens sub-genomes, but also between the ancestral sub-genomes of T. repens. Thus interspecific hybridisation has the potential for major genome recombination and opens the way for introgression of traits from T. occidentale into white clover.