Production of Interspecific Hybrids between Trifolium ambiguum M.BIEB and T.repens L. by Ovule Culture

An ovule culture method was used to produce interspecific hybrids between kura clover (Trifolium ambiguum M. BIEB.) and white clover (Trifolium repens L.). Culture of fertilized ovules from the cross hexaploid T.ammguum (2n=6X=48)×diploid T.repens (2n=32) began 5 days after pollination. After 15∼20 days in culture, hybrid ovules were transferred to a fresh medium, where development into plants occurred. Four interspecific hybrid plants were established in soil. One of these plants has produced flowers. The morphology of the plant was generally intermediate. Root tip cells of the plant possessed the expected somatic chromosome number of 40. The plant possessed the major bands of leaf peroxidase and esterase isozymes derived from the staminate parent as well as from the pistillate parent. A virus assay on Chenopodium amaranticolor indicated that the plant was virus-free. However, it was highly sterile with the absence of viable pollen. The ovule culture method represents the successful production of Trifolium interspecific hybrids via some form of embryo rescue. It appears that this technique can be applied to other interspecific hybrid combinations in the Trifoliutn species.