| Somatic embryogenesis, direct organogenesis and plantlet clone for Taxodium mucronatum were conducted in this research.. The main results as follows:1. Hypocotyl and cotyledon developed from the seeds of Taxodium mucronatum were cultured as the initiation explants for direct inducement of somatic embryos. Comparing with cotyledon, hypocotyl was better for us to induce somatic embryos, and the hypocotyl culture times directly effect on inducement frequency of somatic embryos also. The hypocotyl direct inducement frequency was 24.5% on the DCR medium with 2.0mg/l BA+0.1mg/lIBA. It is necessary for the development of somatic embryos by transferring the culture materials on hormone-free DCR medium.2. Hypocotyl and cotyledon developed from the seeds of Taxodium mucronatum were also cultured as the initiation explants for direct organogenesis. It was not able to induce adventitious buds by the explant of cotyledon. With hypocotyl explants, the highest inducement frequency of adventitious buds was 58.5% on the DCR medium with 2.0mg/l BA, 0.1mg/1 IBA and 0.01mg/1 TDZ. The medium with low concentration of TDZ and BA was good to inducement and differentiation of adventitious buds of hypocotyl. Adventitious buds cultured on hormone-free DCR medium for elongation, subculture every four or five weeks, and cut the buds for rooting inducement after subculture two or three times. On hormone-free 1/2DCR medium the rooting frequency could be above 70%.3. There are two kinds of explants to be used for plantlet clone of Taxodium mucronatum. The first one was the young seedling developed from the seeds. The results were shown that: dormant buds induced are sensitive to the different hormone concentration. Cultured young seedlings on DCR medium supplemented with 0.5 mg/1 BA and 0.2mg/l IBA was the best way of inducement, and with inducement frequency higher than 80%, mean number of dormant buds was around 2-5. The medium should be wiped off hormone when dormant buds induced. For elongation of the dormant buds, the suitable culture medium was DCR+Gln500mg/l. It can advance elongation of dormant buds when DCR basal medium supplemented with 500mg/lGln. The medium of 3/4DCR+0.05%AC is used for rooting, and the highest rooting rate is 78%. Using hormone to induce roots could produce mass of callus on the end top of cuttings and it was not benefit to the plantlets survive after transplant. In addition, it was easily for the plantlets with long internode and vigorous stem to induce root system. When the roots developed to 2-4cm long, the plant could be transplanted after 3-7 days acclimation4. The second kinds of explants for plantlet clone was axillary buds developed from stem. The best inducement and elongation medium for axillary buds was DCR medium supplemented with 0.05mg/l IBA and 0.025mg/l BA, and inducement frequency up to 100%. Cutting down longer axillary buds from stem was good to other smaller axillary buds developed, and more new axillary buds produced from stem. The proper medium for inducing dormant buds from axillary buds was DCR medium supplemented with 0.3mg/l BA, 0.1 mg/1 NAA and 500mg/l Gln. The frequency of inducement was significant increased by adding Gin. TDZ was not suitable for dormant buds inducing from axillary buds. The best medium for elongating induced dormant buds was DCR+0.1%AC, subculturing 2-3 times, cutting down for rooting. The best medium for rooting in this research is 3/4DCR medium supplemented with 0.1 mg/1 IBA and 0.05mg/l NAA, however, the rooting rate was only 25%.The frameworks for somatic embryogenesis, organogenesis, and micropropagation as mentioned above were established, and then the genie transformation of Taxodium mucronatum can be conducted on this system also.
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