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题名: 牛筋条属的系统学研究-兼论栒子属的系统学问题
作者: 周丽华
学位类别: 博士
答辩日期: 1999
授予单位: 中国科学院昆明植物研究所
授予地点: 中国科学院昆明植物研究所
导师: 吴征镒
关键词: 蔷薇科 ; 牛筋条属 ; 枸子属 ; 系统学
学位专业: 植物学
中文摘要: 本文采用形态学、解剖学、胚胎学、花器官发生学、孢粉学、细胞学和分支系统学等多学科的研究手段和方法进行了牛筋条属的系统学研究,目的是为解决该属一百多年来悬而未决的系统位置争议提供有说服力的证据。结果首次报道了牛筋条属的解剖学、胚胎学、花器官发生学研究资料,补充了该属的孢粉学和细胞学资料。并对蔷薇科四个亚科的多个外类群开展了有关学科的研究工作,获得了大量的第一手资料。据源自本研究的多学科证据,同时综合已往的相关资料,作者对牛筋条属的系统位置进行了探讨。主要研究结果及结论如下:1.形态解剖学 研究首次报道了牛筋条属的系统解剖学资料、澄清了前人在该属形态解剖方面的一些观察错误和遗漏,并且显示:花果的特征,尤其萼片宿存、萼筒三肉质膨大、雄蕊数目和排列、果实的类型等表现出牛筋条属与苹果亚科成员的自然亲缘关系。因此,形态学和解剖学结果支持将该属置于苹果亚科之下,而不主张将其归属于李亚科或另立牛筋条亚科。2.胚胎学:首次报道牛筋条属具有如下胚胎学特征:四囊型花药,腺质绒毡层,小孢子形成方式为同时型,小孢子四分体四面体型和左右对称型,成熟花粉粒二细胞型;倒生胚珠,双层珠被,内珠孔,具厚珠心,珠心细胞5-6层,具有来源于胎座的珠孔塞;大孢子母细胞减数分裂的结果形成大孢子三分体,大孢子排列为线形,功能大孢子位于合点端,以单孢子为主,偶见双孢子。胚囊为蓼型。胚的发育类型为石竹型。胚乳为核型。研究结果同时显示:牛筋条属的胚胎发育过程存在功能大孢子和雌配子体的退化现象、多孢子和多胚现象,以及正常有性生殖与无融合生殖并存的现象。故认为牛筋条属可在苹果亚科中找到其合适的系统位置,并为其中较为原始的成员。3.花器官发生学:牛筋条属的花器官发生特点为:花萼以2/5叶序沿逆时针方向发生;花瓣原基近同时成轮状发生于花萼原基的向心相间处;雄蕊20枚,分三轮发生(10+5+5)。最先出现5枚位于花瓣原基向心相间处的雄蕊共同原基,它进一步发育为10枚,分列于花冠原基两侧的向心位置。第二轮雄蕊5枚出现于与花冠原基相对的向心位置。第三轮雄蕊原基5枚出现于第二次发生的两枚雄蕊间,第二第三轮发生的雄蕊原基排成一环。雄蕊在发育的早期排成两环,但在成熟花中仅成一环。心皮原基的膨大始于第一次发生的雄蕊原基出现之后,数目为1,但早期有2的迹象。雌蕊发育初期腹缝线较长时间未闭合,发育至后期闭合且出现柱头、花柱和子房的分化。将牛筋条属的花器官发生特点同本科四个亚科相比较,尤其是在花萼的发生顺序,雄雌蕊的数目、发生和排列等亚科间有差别的特征上,该属与苹果亚科几完全类似,而与李亚科等差异较大。故花器官发生学证据支持将牛筋条属置于苹果亚科下,而不支持将其归属李亚科或另立亚科的系统学方案。4.孢粉学:牛筋条属的花粉为典型的三孔沟类型,外壁纹饰为条纹-穴状,与李亚科单纯的条纹状比较相去甚远,而与苹果亚科的花粉从外壁纹饰到形状和体积等都很接近。这表明有关的证据支持牛筋条属与苹果亚科有较近缘的关系而不支持将该属归人李亚科或将该属另立为牛筋条亚科的系统学处理。5.细胞学:牛筋条属的体细胞染色体数目为34,基数为17。中期细胞染色体长度介于1.66μm至0.87μm之间,平均长度为1.24μm,为小染色体至微小染色体。核型公式为 2n=34=28m+6sm。核型分类为1A型。这些特征与苹果亚科的成员极为相似,从而说明该属可在苹果亚科中找到其合适的系统位置,同时由于前者的染色体对称性更强,按照Stebbins(1971)的核型进化理论,它可能是苹果亚科中较原始的类群。牛筋条属的小孢子母细胞减数分裂过程中,中期I的价体构型特征为:染色体配对形成12个二价体,10个单价体。这一特征不仅从染色体数目上进一步表明了该属和苹果亚科之间的亲缘关系,也为苹果亚科的异缘多倍体起源观点提供了可贵的支持证据。6.分支系统学:综合多学科的证据,尤其是根据生殖器官的形态结构、胚胎学、细胞学、木材解剖学和植物化学等方面的质量性状进行的分支系统学研究结果表明:牛筋条属与苹果亚科的成员枸子属,山楂属和苹果属构成了一个单系群,且牛筋条属位于其基干部位。这表明分支分类学结果支持苹果亚科为单系类群的观点,并支持将牛筋条属作为苹果亚科的成分,并且是其中最原始的成员。分支分析结果同时表明,有11个共近裔性状支持将牛筋条属和苹果亚科聚在同一分枝上,而只有一个性状将其分开,这明确显示牛筋条属应为苹果亚科的下属成员,,而不支持其独立为亚科等级的系统学处理。同时因牛筋条属和李亚科存在较大分异。分支分析的结果对将牛筋条属归于李亚科之下的系统学观点不提供支持证据。7.结论:多学科的研究结果一致表明,牛筋条属能在苹果亚科中找到其合适的系统位置,并有可能是其中较为原始的成员。分支分类学研究的结果进一步明确了各个分支学科孤立的系统学结论。支持将该属置苹果亚科,并且显示它与心皮多数分离,子房半下位,叶全缘的枸子属最为近缘。其次,在论文的第二部分中,作者对枸子属系统分类学的一些重要问题,如性状的评价、系统的划分等进行了初步讨论,提出了枸子属5组8系的属下系统划分纲要。同时,在前人研究的基础上,观察了大部分有关名称的模式材料和现存于KUN和PE的有关标本,结合部分种的野外调查、细胞学、孢粉学和叶表皮微形态特征对枸子属的高山组和匍匐组,即中国植物志概念下的单花组(Sect. Uniflos Yu),进行了初步的分类修订。结果将该类群在目前西方现行系统中分属2亚属、4组、16系的80个种归并为2组,4系,24种。最后从该属下各分类单位的分布规律,对该属的区系起源和发生进行了初步的讨论。
英文摘要: Dichotomanthes is a monotypic genus endemic to southwestern China's Yunnan and Sichuan provinces, the only species being D. tristaniaecarpa Kurz. As one of the key groups in the phylogenetic study of the Rosaceae, its systematic position has drawn much attention and has long been a controversial matter. It was wrongly referred to the family Lythraceae when Kurz (1873) established it. Later, Hemsley (1886) treated it as a genus in the Rosaceae, close to Pygeum of the subfamily Prunoideae, on the ground that Dichotomanthes has the characters of epi-perigynous flowers, dry single carpel and superior 1-locular ovary, this view was supported by Rehder (1916). In fruit, however, the hard and dry carpel of Dichotornanthes, which surrounded by red and thick hypanthium and thus make the fruit appear similar to a pome. Therefore this genus was thought to have close relationship to the members of Maloideae (or Pomeae) (Hutchinson, 1964; Yu et al., 1974; Challice, 1981; Zhang, 1992). Most interestingly, it is considered to be an isolated genus in the Rosaceae and should be established as an independent subfamily Dichotomanthoideae (Gladkova, 1969; Takhtajan, 1997). Until now, the disputation about the systematic position of this genus has not been documented, so solution is needed urgently by synthesizing the relevant data from different branch sciences. For the above reason, this research carried out the phylogenetic study of the genus Dichotomanthes by means of plant morphology, anatomy, embryology, floral development morphology, palynology, cytology and cladistics. The data of anatomy, embryology, floral development morphology of this genus are reported for the first time, and the data of palynology, cytology are supplementary reported. At the same time, different genera from the four subfamilies of Rosaceae axe also studied through the above branch sciences and a number of first-hand data were also obtained. On the basis of results of this study, and together with concerned references, the systematic position of Dichotomanthes is discussed. The essential points were summarized as follows: 1. Morphology and anatomy The morphological and anatomical data of Dichotomanthes are reported as follows: The habit of Dichotomanthes is a large evergreen tree not as earlier documented as a shrub to small tree. The primary xylem is tetrarch in protoxylem of the root. The cells of endodermis have casparian strip structure in its radial wall and cross wall and the vascular bundle is a collateral type in the stem. The wood structure pattern is diffuse-porous. It has dorsi-ventral leaves, and the stomatal type is cyclocytic. The structure of inflorescence is a compound cyme but not corymb that belongs to an indefinite inflorescence. Both calyx and corolla numbers are five, and arranging is imbricate. The calyx is persistent which is covered with tomentum in both sides, and the hypanthium begins to accrescent in flowering and becomes fleshy surrounding the nut during fruiting. The number of stamens is very stable at 20 not 15-20 as former literature described, and the filaments were coherent to each other at their base and cofinate with the calyx tube. There is one carpel in its pistil that has differentiation of stigma, style and ovary. The style represents changes of position from terminal to lateral then to terminal again. The fruit type is pome like. Besides the typical representation of the nut exposed outside from the hypanthium, there is another form of fruit which the nut is surrounded by the hypanthium completely. All the data from the Morphology and Anatomy, especially the calyx persistent, hypanthium accrescenting, the anther number and arrangement and the pome like fruit etc., support placing Dichotomanthes in Maloideae but reject placing it under Pmnoideae or isolating it as a subfamily. 2. Embryology The principal embryological features of Dichotomanthes are shown as below: The anther is tetrasporangiate, and the anther wall comprises the epidermis, fibrous endothecium, two to three ephemeral middle layers, and secretory tapetum of multinucleate cells. Simultaneous cytokinesis follows meiotic divisions in microspore mother cells, resulting in tetrahedral and decussate tetrads. The pollen grains are tricolporate, and two-celled at the dispersal stage. The ovule is anatropous, bitegmic and crassinullate with five to six layers of cells. In the bitegmic ovule, only the inner integument takes part in the formation of micropyle. The development of obturator is observed. The megaspore mother cells undergo meiotic divisions, and develop into linear triads. The chalazal functional megaspore develops into a Polygonum type of the embryo sac. Generally, only one megaspore mother cell is observed in one ovule, but two megaspore mother cells in one ovule are occasionally observed. The embryogeny conforms to Caryophyllad type. The development of endosperm is of the Nuclear type. In the development of embryology, the degenerations of functional megaspore and a number of eight nucleate embryo sacs are happened. The appearances of polyembryony and polyspory are also observed. There are secondary functional megaspores that come from somatic cells, so a tendency to apospory exists. This character shows that, in the genus of Dichotomanthes, though the formal Polygonym type of embryo sac is occupying the leading line, the appearance of apomixis still exists. In the members of Maloideae, apomixis is predominant in its development of embryology. But for the Dichotomanthes, it contains both the formal Polygonym type of embryo sac and apomixis, and the former type is more primitive than the later one. So we can conclude that Dichotomanthes has more primitive data in the embryological development. Therefore, Dichotomanthes may find a reasonable systematic position in Maloideae and to be the comparative primitive member in the subfamily. 3. Floral development morphology The characters of floral development morphology of Dichotornanthes and some members of the four subfamilies in the Rosaceae are as below: Spiraeoideae: The inflorescence is a definite inflorescence. Floral Pentamerous. The five sepal primordia are subsequently initiated in 1/5 phyllotactic pattern following clockwise direction. And the five petal primordia initiate in an alternate position with respect to sepals and inside the cup at the edge of the floral meristem simultaneously. Stamen initiats as 10 primordia form slightly below and adjacent to the petals, these primordia appear to initiate simultaneously and are also evenly distributed in at least two whorls. The initiation of carpel primordia occurs slightly after the initiation of the first 10 stamen primordia, but a little overstep to the second stamen primordia. There are five carpels, which are separate to each other in all its life. The ovules are numerous in each carpel and initiate on the ventral suture. Rosoideae: The five sepal primordia are subsequently initiated in a 2/5 phyllotactic pattern following an anti-clockwise direction. The five petal primordia initiate in an alternate position with respect to sepals and inside the cup at the edge of the floral meristem simultaneously. Stamens initiate as 10 primordia forming slightly below and adjacent to the petals, these primordia appear to initiate simultaneously and also evenly distributed, the stamen primordia occur in five whorls (10+10+10+10+10), when mature its arrangment is the same. The initiation of carpel primordia occurs slightly after the initiation of the first 10 stamen primordia, but a little overstep to the second stamen primordia. The carpels are numerous, and separate to each other in all its life. There is one ovule in each carpel. Prunoideae: The sepal primordia are subsequently initiated in a 2/5 phyllotactic pattern following anti-clockwise direction. The five petal primordia initiate in an alternate position with respect to sepals and inside the cup at the edge of the floral meristem. Stamen initiation as 10 primordia, form slightly below and adjacent to the petals, these primordia appears to initiate simultaneously, the stamen primordia happen in three whorls (10+10+10), but they arrange as two whorls in a mature flower. The initiation of the single carpel primordia occurs slightly after that of the first 10 stamen primordia, but a little overstep to the second stamen primordia. The single carpel forms a locule and contains two ovules in it. Maloideae: The sepal primordia are subsequently initiated in a 2/5 phyllotactic pattern following an anti-clockwise direction. The five petal primordia initiate in an alternate position with respect to sepals and inside the cup at the edge of the floral meristem simultaneously. Stamens initiate as 5 common stamen primordia forming slightly below and opposite to the petals, each common primordia then divide to 2 and arrange in both sides of petal primordia. The stamen 20, occur in three whorls (10+ 5+5), but its arrange in one whorl at maturity. The initiation of carpel primordia occurs slightly after the initiation of the first 10 stamen primordia, with a little overstep to the second whorl of stamen primordia. The number of carpels is one to five. The suture of ventral opened for a long time in its development.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/500
Appears in Collections:昆明植物所硕博研究生毕业学位论文_学位论文

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