| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 93 === Explants taken from 1 cm young leaves of Phalaenopsis amabilis and Phalaenopsis Nebula formed somatic embryos directly from wound surfaces, leaf tips, adaxial sides and edges of leaf explants without an intervening callus after one month of culture on 1/2 MS medium supplemented with 3 mg/l TDZ in darkness. Average of number somatic embryos per explant was promoted when subculture in 45 days of culture and produced large number of somatic embryos after 60 days of culture. The results show that enhanced the percentage of somatic embryos survival and develop into plantlets from two-month old embryos when cultured on a medium supplemented with 0.5-1 mg/l BA. The directly somatic embryogenesis of leaf explants in Phalaenopsis is successful for plant regeneration and this protocol could be useful for further genetic transformation in this orchid.
Young leaf explants of Phalaenopsis amabilis and Phalaenopsis Nebula directly formed somatic embryos from both side of leaf explants. In addition, explants placed adaxial-side-up orientation on culture medium had significant higher percentage of embryogenesis than the abaxial-side-up orientation. Light regime inhibited direct embryo formation from leaf explants, and had higher percentage of browning than in darkness. In conclusion, adaxial-side-up orientation and culturing under darkness were more suitable for embryo induction from Phalaenopsis leaf explants.
Explants taken from 1 cm leaves of Phalaenopsis amabilis and Phalaenopsis Nebula promoted the direct somatic embryogenesis from the wound surfaces and adaxial side of leaf explants on 1/2 MS medium supplemented with all five cytokinins (2iP, kinetin, BA, TDZ and zeatin). There was no any embryos formed on a hormone-free medium for leaf explants. The best response of Phalaenopsis amabilis was 80% and 65% of embryogenesis on medium supplemented with 3 mg/l BA and 3 mg/l TDZ respectively. However, 3 mg/l TDZ became the embryo higher in numbers. The highest percentage of embryogenesis in Phalaenopsis Nebula was 65% with 3 mg/l TDZ. In addition, the percentage of embryo formation was 35% on medium supplemented with 20 μM ACC. The presence of auxin, GA3, ancymidol, polyamines, AgNO3 and CoCl2 had no inductive effect on embryo formation.
Both of the percentage of embryogenesis explants and the number of embryos per explant from young leaf explants of Phalaenopsis amabilis were affected by medium composition. Leaf explants was more suitable on 1/2 MS basal medium. There was no embryogenic response and explants necrosed on medium without sucrose, and should be supplement 20 g/l sucrose for the requirement on embryogenesis. The presence of 170 mg/l NaH2PO4 and 0.25 g/l PVP promoted the somatic embryogenesis on leaf explants. Besides, active charcoal inhibited the embryo formation on leaf explants.
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