小叶兜兰的果实生长和雌配子体发育

为了解濒危兰科植物小叶兜兰(Paphiopedilum barbigerum Tang et Wang)胚珠和雌配子体的发育过程,采用常规石蜡切片技术对其果实的生长动态进行了研究。结果表明,授粉后60~75 d的蒴果内种子数量迅速增加,到授粉后120 d时种子充满整个蒴果。授粉后40 d的胎座上分化形成多数由1层表皮细胞包被1列细胞的胚珠原基;授粉后60 d时位于胎座指状结构末端处紧靠表皮细胞下方的孢原细胞分化为大孢子母细胞。之后,大孢子母细胞经过减数分裂和有丝分裂最终形成成熟胚囊;授粉后135 d胚囊发育成熟,附着在胎座上的种子个体分化明显。小叶兜兰胚囊的发育类型为双孢子葱型,胚珠为倒生胚珠,薄珠心,单珠被,成熟胚囊为8核。这为小叶兜兰的生殖生物学及繁殖体系的建立提供理论依据。

Fruit Growth and Female Gametophyte Development in Paphiopedilum barbigerum Tang et Wang

In order to understand the development of ovule and female gametophyte in Paphiopedilum barbigerum Tang et Wang, an endangered species in Orchidaceae, the growth dynamic of its capsule was studied by conventional paraffin section method. The results showed that the number of seeds in capsule increased rapidly during 60-75 days after pollination, and its capsule would be full of seeds at 120 days after pollination. The ovule primordium, a row of cells surrounded by a layer of epidermal cell, began to differentiate at 40 days after pollination. The archesporial cell under the epidermal cells at the end of placenta finger structure differentiated into megaspore mother cell at 60 days after pollination. The megaspore mother cell eventually formed the mature embryo sac after meiosis and mitosis. It took about 135 days from pollination to maturation of embryo sac, and seeds attached to placenta had differentiated obviously. The development of embryo sac was Allium type. The mature ovule was anatropous with thin nucellus and single integument. The mature embryo sac had 8 nuclei. These would provide theoretical basis for studying in reproductive biology and establishment of reproductive system.