Characterization of factors affecting plant regeneration frequency of Medicago lupulina L.

Summary

Different hormones, length of hormone pretreatment, and developmental status of plants were found to influence the shoot and root differentiation frequencies from immature inflorescence explants of Medicago lupulina L., a diploid autogamous species. Explants of immature inflorescence pretreated with phytohormones for a short period (10 min −6 h) were placed on hormone-free medium for shoot differentiation. Cytokinins, such as BA, were found to be essential for shoot differentiation, whereas treatment with 2,4-D could only induce root differentiation. Explants with hormone pretreatment for 30 min to 1 h produced the highest shoot regeneration rate. Plants at the beginning of flowering were found to have a better regeneration ability than those at fruiting or maturation. After a 10 mg/l BA pretreatment, respective shoot differentiation frequencies of 39%, 36% and 23% were observed for explants of self-progeny plants, regenerated plants, and plants propagated by cuttings, although the three categories of plants were originally derived from the same plants.