Embryology of the Lady's Slipper Orchid, Paphiopedilum Delenatii: Ovule Development

仙履蘭之胚胎學研究：胚囊發育

李勇毅(Yung-I Lee) ； Edward C. Yeung

《Botanical Studies》 53卷1期 (2012/01) Pp. 97-104

摘要

仙履蘭（Paphiopedilum delenatii）為原生於越南的瀕危蘭花物種，具有極高的觀賞價值。深入研究瀕危物種的生殖生物學將有助於推展繁殖與保育工作之規劃。仙履蘭之胚囊發育為雙孢型，成熟的胚囊具有六細胞。在授粉前，珠心絲構造已存於子房內。授粉後15 天，位於珠心絲頂端的孢原細胞分化成大孢子母細胞。當大孢子母細胞成熟時，其細胞核坐落於近珠孔端；如此使得大孢子母細胞的細胞質呈不均勻分布，富含澱粉粒的細胞質則較集中於合點端。第一次減數分裂後，明顯的胼胝質層將二分子隔開：一個近珠孔，另一個近合點。接著，靠近合點而具有功能的二分子被胼胝質完全包圍。當具有功能的二分子擴張，胼胝質此時累積於二分子之共同細胞壁，以及近合點端之細胞壁。本研究另一值得注意的觀察結果：仙履蘭成熟胚囊之兩側細胞壁具有角質之累積。由於仙履蘭胚囊的體積相當大，累積角質可能提供胚囊細胞壁支撐，並且在受精後保持胚囊內之水分以助後續之胚胎發育。

關鍵字

胼胝質 ； 胚胎學 ； 仙履蘭 ； 尼羅紅 ； 胚珠

並列摘要

Paphiopedilum delenatii is an endangered slipper orchid with delicate flowers that is native to Vietnam. An understanding of this plant species' reproductive biology is required for its effective propagation and conservation. P. delenatii has a bisporic pattern of embryo sac development with a six-celled number in a mature embryo sac. Prior to pollination, the nucellar filaments are present within the ovary. The archesporial cell at the tip of the nucellar filament differentiates into a megasporocyte fifteen days after pollination. As the megasporocyte matures, the nucleus becomes located at the micropylar end of the cell, resulting in an uneven distribution of the cytoplasm with the starch granules becoming more abundant at the chalazal end. After the first meiotic division, a distinct callose layer separates the micropylar dyad from the chalazal one. Soon after, a callose wall completely encloses the functional dyad at the chalazal end. As the functional dyad increases its size, the callose remains in the common wall separating the two dyads as well as in the chalazal end wall of the functional dyad. One notable finding of this study is the presence of cuticular material in the lateral walls of the mature embryo sac. The deposition of the cuticular material may serve to strengthen the fairly large embryo sac and helps to conserve water for the developing embryo after fertilization.

並列關鍵字

Callose ； Embryology ； Lady's slipper orchid ； Nile red ； Ovule