| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 88 === The embryogenic suspension cells of fringe tree (Chionanthus retusus Lindl.) was amprised of heterogenous population. According predominant cell population, which could be discriminated into eight developmental stages, including free cells and cell cluster, cell mass, pro-globular body, globular body, enlarged body, deformed body reorganization body and releasing propagale stages. The eight developmental stages could be epitomized as three develop mental phases, including the proliferation phase was vigorous cell division and developed into polar or apolar cell musses, the globularization phase was characterized with dermal structure, and the reproduction phase was directly or indirectly releasing propagules. Measuring cell packing volume (CPV) in-dicated that the pro-globular body stage and globularization phase was higher growth rate with 10 days time increase in each subculture generation.
There are two models or three pathways for maintenance and recyclic growth of embryogenic cell culture. The duration of cyclic growth varied in the range 2 ~ 5 months dependent growth phases, refresh medium ratio and sub-culture duration. While the conditional medium：fresh medium of 1:1 ~ 1:4 ratio, and 10 days interval of subculture, would maintain embryogenic cell growth vigorously. The growth type and cyclic pathway were affected by cells exogenous auxin.
The assay of embryogenic potentiality of suspension cells was conducted on SH median supplemented with 0.4 mg/l NAA, 45 g/l sucrose and 2.5 g/l gelrite. If was demonstrated that the cell population of pro-globular body stage and globular body stage showed higher competence of somatic embryogenesis and regenerated an amount of somatic embryos quickly.
The extracellular pH value associated of the three growth phases was measured at the end of subculture generation. The proliferation phase showed pH 5.3±0.3, the globulization phase indicated pH 5.6±0.3 and the reproduction phase was pH 5.35±0.3. The normal cell line''s pH values arose above 5.0 under long-term subculture. The abnormal cell population downgraded to 4.2. It is suggested that the extracellular pH level may serried as indexing of cell growth vigor.
In the subculture generation, the extracellular pH change could be distinguished as rapid change and auto-regulated phases. The rapid rising occurred 1 ~ 2 hours after subculture, then drop to lower pH level by 30 hours. Thereafter, gradually auto-regulated to a higher level until the end of subculture generation, which was associated with growth phase.
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