Track 1-03

Description

Trifolium occidentale Coombe is a stoloniferous, diploid (2n=2x=16) perennial clover indigenous to Portugal, Spain, France, and the British Isles. It grows in relatively dry coastal habitats, in sand dunes and on shallow pocket of soil (Coombe 1961; Coombe and Morisset 1967). As the species grows naturally in saline, dry habitats, it is potentially a source of drought tolerance genes that could be used for the improvement of white clover (Trifolium repens L.) cultivars. Although T. occidentale is reported to be one of the progenitors of white clover (Williams et al. 2012), the 2x forms of T. occidentale cross with difficulty with white clover, resulting in near-sterile triploid hybrids. The two species were first crossed by Chou and Gibson (1968) and subsequently by Gibson and Beinhart (1969), and Chen and Gibson (1974). The relative success of producing F1 hybrids was increased by use of colchicine doubled (4x) T. occidentale. Based on these reports, our objectives were: (1) to artificially double the chromosomes of T. occidentale using colchicine; (2) to use tetraploid (4x) T. occidentale as the pollen parent in crosses with white clover to produce large numbers of F1 hybrids; (3) to evaluate hybrids both cytologically and morphologically; and (4) to develop ad-vanced backcross and intercross progeny for future breeding and selection using white clover as the recurrent parent.

Share

COinS
 

Trifolium occidentale: A Valuable Genetic Resource for White Clover Improvement

Trifolium occidentale Coombe is a stoloniferous, diploid (2n=2x=16) perennial clover indigenous to Portugal, Spain, France, and the British Isles. It grows in relatively dry coastal habitats, in sand dunes and on shallow pocket of soil (Coombe 1961; Coombe and Morisset 1967). As the species grows naturally in saline, dry habitats, it is potentially a source of drought tolerance genes that could be used for the improvement of white clover (Trifolium repens L.) cultivars. Although T. occidentale is reported to be one of the progenitors of white clover (Williams et al. 2012), the 2x forms of T. occidentale cross with difficulty with white clover, resulting in near-sterile triploid hybrids. The two species were first crossed by Chou and Gibson (1968) and subsequently by Gibson and Beinhart (1969), and Chen and Gibson (1974). The relative success of producing F1 hybrids was increased by use of colchicine doubled (4x) T. occidentale. Based on these reports, our objectives were: (1) to artificially double the chromosomes of T. occidentale using colchicine; (2) to use tetraploid (4x) T. occidentale as the pollen parent in crosses with white clover to produce large numbers of F1 hybrids; (3) to evaluate hybrids both cytologically and morphologically; and (4) to develop ad-vanced backcross and intercross progeny for future breeding and selection using white clover as the recurrent parent.