Selection of a highly-regenerative genotype of white clover (Trifolium repens L.) and plant regeneration from protoplasts derived from this genotype

Summary Callus cultures were induced from hypocotyl sections of 24 varieties of white clover (Trifolium repens L.). The calli did not show any significant difference of growth among the varieties. After the calli has been transferred to three regeneration media, green-spot formation was observed on calli derived from some seedlings. Remarkable intra- and intervarietal variations in the emergence of green spots and some trends between the origin of varieties and the frequency of green spots were observed. In most cases, the green spots turned brown without showing further differentiation, and only two genotypes formed shoots. A callus from a seedling of the Swedish variety Undrom has sustained high levels of plant regeneration throughout 24 months of culture. Protoplasts derived from this selected genotype were divided into cell colonies. 8P (Kao, 1977) medium containing 0.5 mg/1 2,4-D and 0.5 mg/1 kinetin was the most suitable medium for inducing divisions in protoplasts. When subcultured into solid B5 medium, the colonies produced calli, which when transferred to a regeneration medium, formed shoots. This genotype is expected to a useful subject for genetic engineering of white clover.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - 2ip 6-, -dimethylallylamino purine - NAA -naphthaleneacetic acid