【作者】 陈薇薇；

【导师】 何兴金；

【作者基本信息】 四川大学 ， 植物学， 2007， 硕士

【摘要】 中国是世界当归属的分布中心之一，而中国的西南地区又是中国当归属植物分布种类最多的地区，因此西南地区当归属植物的系统分类研究对世界当归属植物的研究具有重要意义。本文在形态分类的基础上，对当归属植物进行了较为全面的综述及实验研究，包括比较解剖学、细胞分类学、花粉形态学、分子系统学等，并对中国当归属植物的地理分布特征进行了分析。对10种当归属植物的果实进行比较解剖学研究，其结果表明：当归属果实均背腹压扁，背棱槽内油管多为1，偶2，合生面油管多为2，偶3-6；侧棱翅状，或阔或狭。胚乳特征在种间也有差异，在分生果腹面微凹、平直至微凸。总结前人及本实验中对本属植物果实解剖的研究结果，推断其进化方向为：果体由背腹不甚压扁到比较压扁：背棱翅由指状隆起向三角状隆起至波状隆起直至无翅方向发展；侧棱翅由宽短向薄、细长方向演化；中果皮由多列细胞至1-2列细胞，最特化的是中果皮中空；内果皮由较明显的或微木化的细胞演化为扁平、细小的薄壁细胞。且种内果实特征具有进化的不同步性，这是当归属植物处于不断分化中的一种表现。对16种当归属植物的花粉形态进行了光学显微镜和扫描电镜观察，其中7种的植物的花粉形态为首次报道。研究结果表明当归属的花粉粒较大，且分化明显，包含了伞形科花粉的原始、中等进化和进化的所有类型，以菱形、椭圆形、近长方形、赤道收缩形为主，萌发孔为角孔或边孔，从花粉的这种多类型证明该地区的当归属植物既起源古老同时又在不断分化着。结合试验结果与已有资料，推断当归属植物花粉特征的主要进化趋势表现在花粉形状上为：菱形→椭圆型→矩形→赤道收缩；花粉大小、体积上的演化趋势为：大→中等→小；萌发沟：长→短，宽→细；内孔：方形→椭圆→横长；单孔→复孔；外壁纹饰：近光滑→疣状→短条—网状→条网状→细网状；外壁层次：2层，外层逐渐增厚，内层逐渐变薄。对4种6个居群当归属植物的细胞核型进行研究，结合前人及本实验结果得出以下结论：西南地区当归属染色体数目多数为2n=2x=22，多为中部和近中部着丝粒染色体，核型多为2A型，少数为1A型。首次报道两个基数x=12的当归居群，认为该种在二倍体水平上染色体数目发生了畸变的非整倍性上升。通过野外调查和查阅各大标本馆的记录，首次较为全面的对中国当归属植物的地理分布进行了研究。探讨了当归属的物种分布和演化关系。结果认为：横断山脉地区(广义)地区是我国当归属植物的分布及分化中心之一，东北地区是一个次生现代分布中心。初步确定当归属植物迁移路线：一是横断山脉自川西高原向北经甘肃传入华北地区；二是由重庆西北(沿秦岭直到川东-鄂西)，经湖北进入华中、华东地区；三是由东北地区向南经蒙古草原进入华北地区。但是在局部区域内也存在着特化类群。选取当归属3种植物，测定其核rDNA中的ITS基因序列，结合GenBank已有的本属21种的ITS序列资料，用PAUP4.0b10软件中的最大简约法和最大似然法以及MrBayes软件对系统发育的贝叶斯推测分别对当归属进行了系统发育重建，并分析了种间的亲缘及进化关系。综合当归属植物的形态特征，采用PAUP4.0中的最大简约法对其进行分支分析，对当归属的原始性状进行了推论，并结合分子分类的结果进一步分析了属下种间的亲缘关系。最后，综合各实验结果，以形态特征为主，参考分子和分支分析的结论，建立了当归属的属下系统，并首次对中国当归属进行分组，将其分为5个组，即少叶组、狭翅组、阔翅组、多管组和当归组。其进化方向为少叶组→狭翅组→阔翅组→多管组→当归组。当归组代表了本属最进化的类群。对于阿坝当归，其花瓣、果实、花粉、叶表皮等性状与当归属其它种有较大相似性，但各性状的演化具有不同步性，所以阿坝当归应该是当归属与独活属之间的过渡种，但其大多数形态解剖学、孢粉、细胞学证据还是与当归属植物更为接近，支持将阿坝当归并入当归属。更多还原

【Abstract】 Southwest China is one of the distribution centers of Angelica L., so thesystematic and taxonomic study on Southwest China’s Angelica species has a greatsignificance. Previous studies were reviewed and lab work was carried out in thisresearch in terms of anatomical characteristics, pollen morphology, karyotype andmolecular systematics. Geographic distribution of Angelica in Southwest China wasalso analyzed.All the Angelica fruits are dorsal compressed, in most cases the valleculae ofdorsal rib each has only 1 vittae (occasionally 2) and the concrescence has two(occasionally 3-6). Their aliform lateral ribs may be equal to or wider than the fruititself but in some cases narrower. Different species show different endospermcharacteristics. Thus, the anatomical characteristics of fruits might serve asreferences in revealing the interspecific relationship within Angelica.Chromosome number of Southwest China’s Angelica species is invariably2n=2x=22, with most chromosomes median and submedian centromeric, andsubterminal centromeric chromosomes were observed in A. omeiensis. The majorityof karyotypes belong to 2A, and some populations of A. laxrfoliata have 1A type.These distinct interspecific differences of chromosomal morphology provideimportant evidences for classification of Angelica.Pollen grains of Southwest China’s Angelica plants are big and distinctlydifferentiated, with diverse types ranging from primitive ones to medium andadvanced ones. Pollen shapes are mainly sub-rhombus, oval, sub-rectangle and equator-constricted, aperture angulaperturate or lateral aperture. The diversity ofpollen type indicates that Angelica in Southwest China has an early origin and hasbeen evolving all the while. Therefore, pollen characters are also importantevidences for the classification of this genus.ITS gene of 3 Angelica species were sequenced and analyzed together with theexisting molecular data in NCBI GenBank. Phylogeny of this genus wasreconstructed with maximum parsimony and maximum likelihood methods inPAUP4.0 respectively.As a genus belongs to temperate zone, Angelica L. mostly distributes inNorth America and East of Asia. China is the first in Asia in terms of abundance andthere are two richness centers in this country, i.e. Besides Sino-Japan forestsubkingdom, the most dominantfloristic composition of Angelica L. isSino-Himalaya forest subkingdom. Because ofthe diversification in morphology,pollen characteristics, karyotype, and so on, as wellas the abundance of Angelica L.in this region, we think that East Asia is one of the richness centers, origin centersand diversity centers.A comprehensive analysis of morphological characters was made with cladisticmethod using PAUP4.0. Primitive characters of China’s Angelica were concluded, and the interspecific relationship within the genus was further discussed with theresult of molecular phylogeny combined.Based on above analyses, Angelica L. is devided into 5 sections: Sect.Paucifoliata, Sect. Plurivittata, Sect. Angustialae, Sect. Latialae and Sect. Angelica.Sect. Angelica is the most advanced group of the genus. As for A. apaensis, itdistinctly differs from the other species of Angelica L. in the characteristics of petalsand fruits, pollen morphological features as well as characteristics of leaf epidermis.Futhermore, evolution of these features is not simultaneous, so it’s rather difficult tomake certain treatment of its taxonomical status and further researth work isexpected.更多还原