连香树科（Cercidiphyllaceae）的胚胎学与相关科的比较研究

【作者】 段雪妮；

【导师】 任毅；

【作者基本信息】 陕西师范大学 ， 植物学， 2009， 硕士

【摘要】 连香树科及相关科:领春木科和昆栏树科是东亚植物区系成分的特征科,系第三纪孑遗植物,在被子植物系统演化研究中有重要价值。本文采用石蜡切片和半薄切片法对连香树科胚胎学进行了研究,包括大、小孢子发生,雌、雄配子体形成等内容,同时在补充了领春木科和昆栏树科的一些胚胎学特征的基础上,结合前人对其它科的研究资料,分析比较了连香树科的系统位置及其与邻近类群的亲缘关系。主要结果如下:1.连香树科的胚胎学特征单性花,雄花花药4室,花药壁的发育为基本型,腺质绒毡层,其细胞多具2核。小孢子母细胞经减数分裂形成的四分体多为四面体型,也有十字交叉型,其胞质分裂为同时型。在四分体后期,一部分小孢子败育。成熟花粉为2细胞型。胚珠具双珠被,厚珠心,珠心组织由珠心表皮细胞和周缘细胞分裂共同形成。大孢子母细胞减数分裂形成三分体,合点端大孢子为功能大孢子,胚囊发育属蓼型。胚囊发育成熟后,反足细胞很快退化。2.领春木科的胚胎学特征花两性,花药4室,花药壁的发育为基本型,腺质绒毡层,其细胞多具2核。小孢子母细胞经减数分裂形成的四分体多为四面体型,也有十字交叉型。四分体和小孢子在发育的过程中,出现败育现象,成熟花粉为2细胞型。领春木的心皮常具2～3颗胚珠,很少为单胚珠。胚珠倒生,双珠被,外珠被由3～4层细胞组成,内珠被由2层细胞组成,外珠被在珠孔端分别形成增厚为7层细胞厚,珠孔由内外珠被共同形成。7～8层发达的珠心组织包着大孢子母细胞。3.昆栏树科的胚胎学特征花两性,花药4室,腺质绒毡层,其细胞多具2核,在其后的发育过程中形成乌氏体。小孢子母细胞经减数分裂形成的四分体为四面体型。成熟花粉为2细胞型。在小孢子四分体后期,同一侧的两个小孢子囊互相侵入生长而使两个小孢子囊相通而开裂。昆栏树的每个心皮具胚珠多数,内珠被首先发生,紧接着是外珠被。随着孢原细胞分裂形成周缘细胞和大孢子母细胞,内珠被下方,珠心基部表皮向外突起,分裂,形成兜状外珠被。比较和分析表明:1.连香树科、领春木科、昆栏树科的胚胎学特征差别较大,反映出这三个科在系统演化关系上有一定的距离。2.胚胎学特征支持连香树科和虎耳草目中的交让木科有较近的亲缘关系,而且连香树科的胚胎学特征表明其系统与发育上的独特性。更多还原

【Abstract】 The eastern endemic families:Cercidiphyllaceae and its related families:Eupteleaceae and Trochodendraceae share great importance in the research of angiosperm systematic evolution.We perform investigations by using the technologies of paraffin sections and hemi-thin slices,including microsporogenesis,megasporogenesis,male and female gametogenesis of Cercidiphyllaceae,and also do some embryological research of Eupteleaceae and Trochodendraceae in addition,to discuss the Cercidiphyllaceae’s systematic position based on comparing the embryological characters with their related families.The main results are as follows:1.The embryological characters of Cercidiphyllaceae:Unisexual flowers.The anthers are tetrasporangiate.The formation of the anther wall belongs to the Basic Type.The tapetum is glandular and most of its cells are binucleate.The microspore mother cells give rise to more tetrahedral tetrads than decussate tetrads by meiosis and the cytokinesis follows the simultaneous type.Degeneration takes place in some tetrads.When the anther wall dehisces,the mature pollens are 2-celled.Ovules are bitegmic and crassinucellate which originates from both of the primary parietal cell and the epidermal cells of the nucellus.No hypostase is formed.The megaspore mother cell gives rise to a triad.The chalazal megaspore functions and the development of embryo sac conforms to the Polygonum type.Three antipodal cells are ephemeral.2.The embryological characters of Eupteleaceae:Bisexual flowers.The anthers are tetrasporangiate.The formation of the anther wall belongs to the Basic Type.The tapetum is glandular and most of its cells are binucleate.The microspore mother cells give rise to more tetrahedrai tetrads than decussate tetrads by meiosis.Degeneration takes place in some tetrads and uninucleate pollens.When the anther wall dehisces,the mature pollens are 2-celled.The ovules are anatropous,bitegmic and crassinucellate,2-3 ovules exsits in the carples mostly.The outer integument is composed of 3-4 layers of cells,the inner integument is composed of 2 layers of cells,the outer integument thickens to 7 layers of cells in the micropyle end,the micropyle are formed by both the inner and outer integuments.Nucellar tissue is well developed,7-8 layers of nucellar cells densely arranged.3.The embryological characters of Troehodendraeeae: Bisexual flowers.The anthers are tetrasporangiate.The tapetum is glandular,in the subsequent development,the cells of the tapetum produce Ubisch body.The microspore mother cells give rise to tetrahedral tetrads.The stomium between the two pollen sacs grows invasively to each other,and finally leads to the dehiscence of the anther wall.The mature pollens are 2-celled.The ovules are anatropous,bitegmic and crassinucellate,the inner integument initiates first,followed by the outer one. As the development of the megasporal mother cell,the epidermal cell at the base of the nuceilus protrudes outward and then divides,finally the hood-shaped outer integument initiates.Systematies relationship based on embryological embryological features:1.Comparisons on the basis of embryological data indicate that Cercidiphyllaceae, Eupteleaceae,Trochodendraceae are unlikely to have close affinities with each other.There is considerable phylogenetic distance between them.2.The embryological characters support close relationship between Cercidiphyllaceae and Daphniphyllaceae in Saxifragales.Embryological features demonstrate Cercidiphyllaceae’s highly unique.更多还原