Tissue Culture and Regeneration of the Southern Type Medicago sativa L .CV. Millennium

Cotyledon and hypocotyl of 5～7 d germinated seedlings were used to study callus induction and plant regeneration in Medicago sativa L.CV.Millennium.The results showed that hypocotyl was the optimal explant material in callus induction,callus induction rate was evidently enhanced with the increased concentration of 2,4-D.The effective medium for inducing callus was 2,4-D 2 mg/L+6-BA 0.5 mg/L,the inducing rate was 100%.The selected optimum medium was MS+KT1.0 mg/L+NAA 0.05 mg/L,the differentiate ratio from cotyledon and hypocotyl of Millennium alfalfa was 40% and 50%,respectively.When the young plants were cut and transferred to the 1/2MS+20 g/L sucrose medium,roots could be induced after 6 d,root inducing rate was 100%.The period of regeneration was only 60~70 days.These results indicated that the plant cotyledon and hypocotyl regeneration systems of southern type alfalfa have been successfully established and the regenerated plant was obtained.