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作 者 ：王亚玲;张寿洲

期 刊 ：武汉植物学研究 2008年 26卷 6期 页码：547-553

关键词：香港木兰；小孢子发生；雄配子体发育；败育现象；

Keywords:Magnolia championii Benth., Microsporogenesis, Male gametophyte, Abortion,

摘 要 ：采用常规胚胎学方法,对香港木兰(Magnolia championii Benth.)小孢子形成及雄配子体发育过程进行了研究。结果显示,香港木兰花药具4个小孢子囊,小孢子囊壁5~6层,其中腺质绒毡层1~2层;小孢子减数分裂时胞质分裂方式为修饰性同时型,四分体排列方式为四面体型或左右对称型,偶为交叉型,成熟花粉粒为二细胞型。在次生造孢细胞、小孢子母细胞、四分体时期都会出现败育,且在很多成熟花药中全部是败育的单核花粉。PAS染色后发现,相对正常发育的小孢子囊,在这种小孢子囊壁中仍有大量淀粉粒残留,可能是药隔中的营养物质不能及时从药隔组织转移到小孢子囊壁以供给小孢子发育所需的营养,使整个药室内的小孢子发育都停滞在单核期。通过不同生境植株花粉萌发率的对比,推断空气湿度是影响香港木兰小孢子正常发育的一个重要因素。

Abstract:The microsporogenesis and the male gametophyte development of Magnolia championii Benth.were investigated.The general course of the pollen formation in Magnolia championii agrees with that in other plants of Magnoliaceae.Its anther is four sporangia.The archesporial cell is hypodermal in origin.The wall of an anther consists of the epidermis,two endotheciums,two ephemeral middle layers,and one or two tapetum layers.The tapetum is glandular and is of one to three nucleates.The division of the microsporocyte is of the modified simultaneous type.The microspore tetrads are tetrahedral or isobilateral,rarely decussate.The pollen grains are 1-sulcate and shed at the 2-celled stage.The low pollen germination rate results from various abortions at different stages in development,such as secondary sporogenous cell,microspore mother cell and tetrads.Of all the abortions observed the most common is that the microspores stopped developing and were sheded off from the anthers in a uninucleate condition.For this occurrence the failure of timely transfer of nutrition from the connection to the anther wall is believed to be responsible.As the environment seems to affect pollen germination rates,it can be speculated that the appropriate air humidity is one of the most important conditions for the regular development of pollen.The sharply changing weather becomes,as it seems,the main reason for the declining population reproduction.

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