Foundation Of Regeneration System On Dioscorea Nipponica Makino And Genetic Analysis Of Tissue Culture Seedlings

Two regeneration systems were established respectively on Dioscorea nipponica Makino through two approachs: one was inducement and differentiation of callus with seed as explant and the other was inducement of clustered shoot with axillary bud as explant. Meanwhile, rapid propagation of tissue culture seedlings'root was studied and tissue culture seedlings were put up genetic analysis based on their differences of rooting. The main results could be summarized as follows:1. Inducement of callus: Callus could be induced by different explants including seed, radicle, stem , laminae and footstalk, but differences of induce ratio and growth form of callus were obvious. It proved seed was the best explant for inducing callus. The best culture medium was MS+6-BA3.0 mg/L+NAA2.0 mg/L+2,4-D3.0 mg/L, and the highest induce ratio was 80.8%.2. Differentiation of callus: The gemma can be induced when the callus was transferred into the culture medium with MS+6-BA2.0mg/L+NAA 2.0 mg/L and the highest inducement frequency can be reach 75.47%. The best culture medium of rooting was MS+6-BA0.5 mg/L+NAA0.5 mg/L, and the highest induce ratio was 86.2%.3. Inducement of clustered shoot and regeneration system was established: Shoot could induce with axilla bud as explant, the best culture medium was MS+6-BA2.0mg/L+NAA0.5mg/L, and the highest induce ratio was 55.6%. The best culture medium for subculture was MS+6-BA3.0 mg/L +NAA 1.0-1.5 mg/L with the highest induce ratio was 80.8% and 1/2 MS medium with no hormones was furthest suitable for root'induction.4. Rapid propagation and morphological differentiation of tissue culture seedlings'root: The best medium for root'propagation was MS+0.2 mg/LNAA+0.5 mg/LIBA+0.2-0.5 mg/LPP333, and the proliferation time was more than 93.12. Root'growth form changed during the course of rapid propagation, and the form could divided into three kinds. First kind of root was tall and slender, soft, did not have the root hair, the color assumed brown or black, its growth took on geotropism, meanwhile, its proliferation time was small and it was only 10.47 on average. Second kind of root was sturdy, harder, the color assumed faint yellow, there was some root hair on it, its growth didn't take on geotropism, its proliferation time was big and it was 67.48 on average.The third kind root was admixture of the first and second kind and two kinds root grew together. Different hormones'combination could influence the root'form but could not change diosgenin'content in root, NAA was the key factor for changing the form.5. Differences of rooting and genetic analysis of tissue culture seedlings: Root number, root length, root weight and diosgenin'content of different tissue culture seedlings were compared and tissue culture seedlings were analyzed by RAPD and clustering analysis. It proved that one seedling(number 13) was better than others obviously, and the inheritance distance between it and others was big. The results showed number 13 was one variation. At the same time there were correlations between diosgenin'contents and root'growth form and genetic difference.