摘要
刺五加Ｅｌｅｕｔｈｅｒｏｃｏｃｕｓｓｅｎｔｉｃｏｓｕｓ（Ｒｕｐｒ．ｅｔＭａｘｉｍ．）Ｍａｘｉｍ．雄株的小孢子发生和雄配子体发育过程正常，大孢子发生和雌配子体发育过程多不正常。雄花具５个花药，花药４室，药壁发育属双子叶型，腺质绒毡层，绒毡层细胞多具２核。小孢子母细胞经减数分裂形成四面体形四分体，其胞质分裂为同时型。成熟花粉为３细胞型。子房下位，５室；每室有上胚珠和下胚珠，上胚珠退化，下胚珠倒生、具单珠被、厚珠心；大孢子母细胞经减数分裂形成线形或“Ｔ”形四分体，偶尔有２个并列或串联的四分体或在四分体之上又出现孢原细胞。其功能大孢子位置不确定。雌配子体发育中异常现象较多。开花时，雌配子体主要为反足细胞退化后的四细胞胚囊。刺五加雌株的小孢子母细胞不能进行减数分裂或减数分裂不正常，不能形成四分体。开花时，药室空瘪，无花粉形成。其大孢子发生和雌配子体发育过程正常，大孢子母细胞减数分裂形成线形或“Ｔ”形四分体，合点端大孢子为功能大孢子，胚囊发育属蓼型。开花时，雌配子体主要为七细胞八核或七细胞七核胚囊，其卵器尚未发育成熟。刺五加两性株的小孢子发生过程无异常，但雄配子体发育过程有部分异常；开花时，药室内有或多或少的空花粉，且?
This paper describes megasporogenesis, microsporogenesis, and development of female and male gametophytes in Eleutherococcus senticosus. The main results are as follows: Flowers of E. senticosus are epigynous, pentamerous. Anthers are 4 microsporangiate. An ovary has 5 loculi. Each ovary loculus has 2 ovules: the upper ovule and the lower ovule. The upper one is orthotropous and degenerates after the formation of archesporial cell, while the lower one is anatropous, unitegmic and crassinucellar, and able to continue developing. In male plants,microsporogenesis and development of male gametophytes took place in regular way, but a series of abnormal phenomena were found in megasporogenesis and development of female gametophytes. The microspore mother cells gave rise to tetrahedral tetrads by meiosis. Cytokinesis was of the simultaneous type. The mature pollen was 3 celled and shed singly. The anther wall formation belonged to the dicotyledonous type. At the stage of microspore mother cell, the anther wall consisted of four layers, i.e. epidermis, endothecium, middle layer, and tapetum. The tapetum was of glandular type and its most cells were binucleate. When microspores were at the uninucleate stage, the tapetum began to degenerate in situ. When microspores developed into 3 celled pollen grains, the tapetum had fully degenerates. In the lower ovule of male flower, the megaspore mother cell gave rise to a linear or“T” shaped tetrad. In some cases, a new archesporial cell over the tetrad or two tetrads parallel or in a series were observed. Furthermore, the position of functional megaspore was variable; any one or two megaspores might be functional, or one megaspore gave rise to a uninucleate embryo sac, but two other megaspores also had a potentiality of developing into the embryo sac. In generally, on the day when flowers opened, female gametophytes contained only 4 cells: a central cell,two irregular synergids and one unusual egg cell. In female plants, microspore mother cells and secondary sporogenous cells were observed. But at the stage of secondary sporogenous cell, the newly differentiated tapetum took the appearance of degeneration. Later, during the whole stage of meiosis, the trace of degenerative tapetum could be seen. At last, the microsporangium degenerated and no tetrad formed. On the blossom day,all anthers shriveled without pollen grains. In female flowers,megasporogenesis and development of female gametophytes were normal: the tetrad of megaspores was linear or “T” shaped; the chalazal megaspore was usually functional; the development of embryo sac was of the Polygonum type. On the blossom day, most embryo sacs consisted of 7 cells with 8 nuclei or 7 cells with 7 nuclei; but the egg apparatus was not fully developed. In hermaphroditic plants, microsporogenesis was normal but the development of male gametophytes was partially abnormal. When the hermaphroditic flowers blossomed,there were more or less empty pollen grains in the microsporangium and these pollen grains were quite different in size. The development of most gynoecia was normal but numerous abnormal embryo sacs could be seen. On the blossom day,female gametophytes were mainly 7 celled with 8 nuclei or with 7 nuclei or 4 celled with antipodal cells degenerated; the egg apparatus was not fully developed either.
出处
《植物分类学报》
CSCD
1998年第4期289-297,共9页
Acta Phytotaxonomica Sinica
基金
国家自然科学基金
关键词
枣五加
孢子
发生
配子体
发育
Eleutherococcus senticosus
Megasporogenesis
Microsporogenesis
Male and female gametophytes
Gametophyte development
