【作者】 蒲吉霞；

【导师】 何兴金；

【作者基本信息】 四川大学 ， 植物学， 2007， 硕士

【摘要】 棱子芹属(Pleurospermum Hoffmann)隶属于伞形科(Apiaceae)芹亚科(Apioideae)美味芹族(Smyrnieae)，约80种，主要分布于亚洲北部和欧洲东部，集中分布于喜马拉雅山区高山地带。《中国植物志》记载我国有32种，2变种，产西南、西北至东北各省，其中25种产于我国西南部的横断山区。四川有13种，主要分布于四川西部的高海拔地区。本属植物中大部分为我国传统中药或民间常用的药用植物，具有重要的经济价值和研究意义。已有的研究大部分都集中在药用化学成分上，并可见有关本属的形态分类和细胞及分子系统学的零星报道，而有关系统地研究本属植物的系统分类与进化方面的报道较少。本研究从叶表皮形态、花粉形态学、细胞分类学、分子系统学、分支分类等方面讨论该属的系统分类和进化机制等问题，并试图解释该属植物的起源与进化，为该属植物的系统学和物种生物学研究提供资料。对横断山区棱子芹属5种6个居群植物的叶表皮形态，进行光学显微镜观察，发现5种植物的叶上表皮均未见表皮毛分布，表皮细胞表面观为不规则多边形和不规则形两种，但以不规则形居多；在棱子芹属内，除了西藏棱子芹(P．hookeri)和松潘棱子芹(P．franehetianum)上下表皮都有气孔器分布，其他3种植物宝兴棱子芹(P．davidii)、翼叶棱子芹(P．decurrens)和瘤果棱子芹(P．wrightianum)气孔器仅见于叶下表皮。气孔器类型均为无规则型，保卫细胞的轮廓呈椭圆形和近圆形。研究表明叶表皮微形态特征对于棱子芹属的分类和系统学研究具有重要意义。对棱子芹属6个种的花粉，进行了光学显微镜和扫描电镜观察，该6个种的花粉形态特征均为首次报道。该属花粉形态较为原始，极轴与赤道轴之比不超过2，赤道向外突出，沟长，几乎达极，沟缘及孔缘加厚明显。不同种的花粉在赤道面观、极面观、外壁纹饰等方面存在一定差异，但并不显著。花粉形态表明棱子芹属植物在伞形科中处于比较原始的系统位置，属下分化程度较低的类群。综合植物形态、地理分布等相关特征，认为棱子芹属花粉存在由菱形向矩形演化的趋势。对4种棱子芹属植物进行体细胞染色体数目观察和核型比较分析，结果表明，本属内染色体基数存在种间差异，其中西藏棱子芹(P．hookeri)2n=2x=22，其余三个种松潘棱子芹(P．franehetianum)、翼叶棱子芹(P．decurrens)、宝兴棱子芹(P．davidii)2n=2x=18。从染色体基数上看，棱子芹属应存在至少两个不同的起源，并分别沿不同的路径分别进化。4个种的染色体数目和核型均为首次报道。选取棱子芹属4种植物，进行了分子系统学研究，选择核糖体nrDNA中的非编码区ITS基因及其中的5.8S编码区序列，进行其序列测定。结合GenBank已有的本属各种和邻近属种的ITS序列资料18种，用PAUP4.0b10软件中的最大简约法、邻接法和最大似然法分别对棱子芹属及其近缘属进行了系统发育重建。分析结果显示，棱子芹属为一复系群，参与建树的6个种分别聚合为两支，其中西藏棱子芹和云南棱子芹(P．yunnanense)互为姊妹群，与针果芹(Chaerophyllum)+香根芹(Osmorhiza)+山茉莉芹(Oreomyrrhis)的复合群关系更为紧密；而松潘棱子芹、丽江棱子芹(P．foetens)、翼叶棱子芹和棱子芹(P．uralense)很好地组成了。一个单系群。ITS证据表明棱子芹存在明确的属下分化，结合细胞学证据，认为棱子芹属植物应存在至少两个不同的起源，其中以西藏棱子芹为代表的一支2n=2x=22，而以松潘棱子芹为代表的另一支2n=2x=18。根据吴征镒(1979)将中国植被区系分为两个植物区，七个亚区和二十二个地区，我们以此为依据讨论中国棱子芹属的分区问题。结果表明中国棱子芹属植物主要分布于横断山区及其向四周衍生的高海拔地区，水平分布的区域交叉重叠，几乎均以横断山区和四川为分布中心。从该属生态分布看出，它们无论是水平分布还是垂直分布，都体现出其旧世界温带的分布特征。本研究综合各实验结果，以形态特征为主，参考细胞学和分子系统学的结论，将四川棱子芹属分成2个组，即狭翅组(Sect．Angustialae)和阔翅组(Sect．Latialae)。从已有的资料，我们认为应该对棱子芹属属的范围做出调整，细胞和分子证据显示并非单系群；我们考虑重新界定棱子芹属的属的范围。更多还原

【Abstract】 Pleurospermum Hoffmann belongs to tribe Smyrnieae of subfamily Apioideae, Apiaceae. It comprises about 80 species, mainly distributed in Northern Asia and Western Europe with a high concentration in the alpine areas of Mts. Himalayas. 32 species together with 2 varieties were recorded in Flora of China, found in the southwest, northwest and northeast provinces of China. 25 species among them are endemic to Hengduan Mountains in Southwest China. Many plants of this genus have been utilized as traditional medicine in China and thus are economically valuable. Existing researches mainly focus on the chemical constituents of Pleurospermum plants, and few taxonomic and systematic researches were reported. Taxonomy of this genus has always been problematic both at the intrageneric and infrageneric levels, and study on evolution of this genus is absent. In this thesis, leaf epidermis, pollen morphology, karyology and molecular phylogeny of Pleurospermum were investigated in order to discuss the taxonomy and systematics of this genus as well as to explore the origin and evolution of it.Micromorphological characters of leaf epidermis in 5 species (6 populations) from Hengduan Mts. were examined using light microscopy (LM). Foliar trichome are absent in all the 5 species. Leaf epidermal cells are irregular or polygonal in shape, usually irregular. Stomatal apparatus are found on both adaxial and abaxial epidermis of P. hookeri and P. franehetianum, and are only observed in the abaxial epidermis of P.davidii, P. decurrens and P. wrightianum. The stomatal apparatuses are all anomocytic in the 5 species.Pollen morphology of 6 species of Pleurospermum under light microscopy (LM) and scanning electron microscopy (SEM) were examined and first reported in this thesis. It is shown that pollen characteristics of Pleurospermum are primitive compared to other species in Apiaceae, e.g. the ratio of polar axie to equator axle (P/E) no more than 2, equator protrusive, germinal furrows extending almost to pole, exine thickened at furrow edges and pore edges. Interspecific variations exhibit in terms of equator view, polar view and exine exolamelle. Pollen morphological characteristics indicate that Pleurospermum is a relatively primitive genus in Apiaceae and the infrageneric diversification is not prominent. It is concluded that there is an evolutionary trend of pollen morphology from rhomboidal type to retangular type in Pleurospermum considering the plant morphology and their distribution.Chorosomal numbers of 4 Pleurospermum species were counted and their karyotypes were observed. There are two different chromosomal base numbers within the 4 species, i.e. P. hookeri 2n=2x=22, P. franehetianum, P. decurrens and P. davidii 2n=2x=18. The difference of chromosomal base number indicates that plants of Pleurospermum have at least two different origins and their evolutionary paths are different accordingly. All the chromosomal numbers and karyotypes were first reported here.Internal transcribed sequences (ITS) of ribosomal DNA were analyzed to reconstruct the phologeny of Pleurospermum and its related genera using the maximum parsimony, neighboring-joint and maximum likelihood methods in PAUP4.0b10, respectively. All the results show that Pleurospermum is polyphyletic. The 6 species of Pleurospermum involved in this research cluster into two clades. One clade is made up of P. hookeri and P. yunnanense which are sister groups to each other, and this clade is shown close to the clade of Chaerophyllum+Osmorhiza+Oreomyrrhis. The other clade is the monophyletic group comprising P. franehetianum, P. foetens, P. decurrens and P. uralense with high bootstrap support. Evidences from ITS show that infrageneric divergence exists within Pleurospermum. It is concluded together with the karyological evidences that there are at least two origins in Pleurospermum. P. hookeri represents the clade with chromosomal number 2n=2x=22, while P. franehetianum represents the other clade with chromosomal number 2n=2x=18.In this article, we study the distribution of Pleurospermum Hoffmann in China, according the partition vegetation flora from Wu Zhengyi.The results indicated that most of the Pleurospermum Hoffmann in China distribute in the Hengduan mountains and the circumference of high altitude. In this region, we think that Sichuan is one of the diversity centers.Finally in the present paper, based mainly on morphological characteristics, especially the karyology and molecular systematics, combined with reference to cladistic analysis results and the results of experiments, a conclusion is that Pleurospermum H. in Sichuan can be divided into the following 2sections—Sect. Angustialae and Sect. Latialae. Sect. Angustialae is the most advanced one.The taxonomic arrangement is reviewed; The genus of Pleurospermum Hoffmann and the nearly relationship genus are closing to each other in their morphous. The taxonomy is complicated.It is not monophyly according the research of cytology and molecule. In this region, we think that the circumscription of this genus can be abbreviated.更多还原