香果树花及胚胎发育的细胞学研究

Cytology Research on the Flower and Embryo Development of Emmenopterys henryi Oliv

香果树为茜草科香果树属单种属植物,是我国特种古老珍稀濒危树种。对香果树大小孢子发生及胚胎发育过程进行了细胞学观察,观察结果表明:香果树子房两室,中轴胎座,胚珠多数,倒生,单珠被,厚珠心。大孢子四分体排列成线性,靠近合点端的大孢子发育成功能大孢子,珠孔端的3个退化,胚囊发育为蓼型,典型的七胞八核胚囊。雄蕊浅黄色,蝶形花粉囊,小孢子四分体成四面体型,成熟的花粉为二胞花粉。胚胎发育过程经历了合子、原胚、球形胚、心形胚、鱼雷胚5个阶段,种子成熟时,胚发育未完全成熟。本文在香果树大小孢子发生发育切片的观察中未发现异常现象,胚胎发育停留在鱼雷胚时期。

Emmenopterys henryi Oliv, one of the China＇ s unique species, belongs to Rubiaceae. It is an endan- gered endemic single species genus plant. A detailed morphological description of megasporogenesis, microsporo- genesis, and the development of the embryo in the rare endangered plant E. henryi is presented. The ovule is a- natropous, single-integument, and crassinucellate. The megaspore mother cells undergo miosis and develop into 〉 a linear tetrad. The large one at chal,azal end is functional megaspore and developed into a polygonum type of em- bryo sac after the third mitotic division. Each anther of E. henryi is with four sacs. The meioses of microspore mother cell is normal and cytokinesis is modified simultaneous type, and tetrads are tetrahedral. The pollen grains are monocolpate and two celled at shedding. The embryogeny passed through zygote, proembryo, globular embryo, heart and torpedo stages. When the seeds are ripe, embryo is not completely mature. Through the study we found that there is no abnormal phenomenon in the megasporogenesis, microsporogenesis process and the em- bryo stays in torpedo stage.