凹叶厚朴大、小孢子发生和雌、雄配子体发育的研究

STUDIES ON THE MEGASPOROGENESIS AND MICROSPOROGENESIS AND THE DEVELOPMENT OF THEIR FEMALE AND MALE GAMETOPHYTE IN MAGNOLIA BILOBA

凹叶厚朴花药四囊型,腺质绒毡层有1-2层细胞,小孢子形成时胞质分裂方式为修饰性同时型．小孢子四分体排列方式为左右对称型,成熟花粉粒为二细胞型。四分体和小孢子在发生时有不规则变形。子房单心皮。心皮腹面壁上着生2个胚珠,胚珠倒生型,厚珠心,双珠被;抱原细胞一个,并且自表皮下第2层细胞处分化。胚囊发育为单孢蓼型。凹叶厚朴的胚胎学特征与木兰科其它植物的胚胎学特征基本相同,属于较原始的被子植物胚胎类型。在凹叶厚朴大、小孢子发生和雌、雄配子体发育过程中存在部分败育现象。本文初步探讨了凹叶厚朴濒危的生殖生物学原因。

The anther of Magnolia biloba is tetrasporangiate with glandular tapetum, which consists of one or two layers of cells. Cytokinesis during meiosis of its microspore mother cell is modified simultaneous type, and the microspore tetrads are isobilateral. Mature pollen grains are two-celled. Tetrad cells and microspores are irregularly shaped during the microsporogenesis. There were two ovules on the ventral surface of unicarpellate ovary wall. Ovules were anatropous, bitegmnous and crassinucellar. Archesporial cell was one cell and differentiated from cell in the second layer beneath epidermis. The development of the embryo sac conformed to the polygonum type. The embryological characteristics of Magnolia biloba are very similar to those of other species in Magnoliaceae. The megasporogenesis and microsporogenesis and the development of their female and male gametophyte are partially abnormal. Abnormal phenomena in the process of reproduction of Magnolia biloba causing this species to be endangered was discussed.