Development of breeding populations from interspecific hybrids between Trifolium repens L. and T. occidentale Coombe

Trifolium occidentale is a diploid wild relative of T. repens (white clover) with adaptation to dry, saline coastal habitats. Transfer of drought and salt-tolerant adaptive traits to white clover could be potentially valuable if interspecific hybridization can be achieved efficiently and leads to fertile hybrid populations. To achieve hybridization, 4x plants of T. occidentale were generated. Efficient techniques for generation of 4x plants and their identification using dry pollen shape are described. Interspecific 4x F1 plants were achieved without embryo rescue. F2 populations and first backcross hybrids to white clover were also efficiently achieved. Although male and female fertility were lower than in white clover, they were adequate to produce large amounts of seed from small numbers of inflorescences. Thus, early generation interspecific hybrid prebreeding populations can be readily developed, opening the way for transfer of traits from T. occidentale to white clover.