| Summary: | 碩士 === 國立成功大學 === 生物學系 === 88 === Abstract
In Phalaenopsis (Orchidaceae) including the fragrant taxa, P. violacea, P. amboinenesis, P. Orhcid World and HO-934, and non-fragrant taxa, P. amabilis, the morphology and fine structures of floral osmorphores were studied by light microscopy, scanning electron microscopy and transmission electron microscopy. Meanwhile, the localization of the cells and tissues related to accumulation and transportation of scent substances were examinated by histochemistry.
The glandular hairs of sepal and petal are presented in both fragrant taxa and non-fragrant taxa. The normal secretion or emission of fragrances in these taxa is taken by epidermis instead of a special osmophore. In addition, there are large amount of plastid, endoplasmic reticulum and vesicles along the margin of cell membrane, and the amount of plastid number, starch grains in plastid and plastoglobuli are positively correlated to the presence and strength of fragrances. We suggested that the scent substances be synthesized at sub-epidermal cells in the plastid and accumulated in ER, then transported to the cell membrane in the form of multilamellate bodies or vesicles. At last, these scent substances are passed to epidermis via plasmodesmata or intercellular space, then across the cell membrane and wall to secreted out.
Comparative studies of both fragrant clones, W9-70, and non-fragrant clone, S82-159, in P. equestris were also taken. The results are similar to the above-mentioned taxa, no definite structures or osmophore present in both clones. The adaxial epidermis cells of sepal and petal are the major location for secretion of these substances. The strength of scent are strongly influenced by the amount of plastid, lipids and multilamellate bodies. The scent substances are synthesized before anthesis. They accumulated in the membranous system and then transported to the cuticular layers of epidermal wall. At the second days after anthesis, the scent products are increasingly emitted under the photo stimulus. The fragrance lasted approximately 10 days long, hence the amount of scent are gradually turndown and nearly undetectable when the flower is wilted. Meanwhile, the organelles in the epidermal cells are also disintegrated at this time.
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