裂叶沙参与泡沙参剖解生态学的比较研究

借助于光镜和扫描电镜,系统观察了濒危植物裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏ－ｐｈｙｌｌａ Ｈｏｎｇ）的根、芦头、茎和叶的解剖特性及茎、叶、种子的表面形态特征,并将有关性状与广布沙参（Ａ．ｐｏｔａｎｉｎｉｉ Ｋｏｒｓｈ．）作了对比研究。结果表明,两种沙参在叶表皮细胞形态,垂周壁式样,角质层初级雕纹及次级雕纹;叶片气孔形状及外拱盖外缘纹饰及内缘形状,保卫细胞上角质层薄厚及蜡质纹饰;叶表毛状体形状     

不同海拔高度泡沙参叶片形态研究

对不同海拔高度的泡沙参叶表形态、气孔特征进行了观察,比较了不同海拔高度对泡沙参叶片生态适应的影响。结果表明：泡沙参叶表皮角质层较厚,被有大量表皮毛和蜡质颗粒,海拔越高越明显;泡沙参气孔复体类型均为不规则型,气孔保卫细胞角质层较厚,气孔口较小,气孔密度与气孔大小成反比,并且气孔大小随海拔升高而减小,气孔密度随海拔升高而增大,是一种抗旱适应的表现。     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参(Adenophora lobophylla)和泡沙参(A. potaninii)叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明:裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的气孔开度逐渐减小和部分气孔关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合作用的气孔限制较明显。     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）和泡沙参（Ａ．ｐｏｔａｎｉｎｉｉ）叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明：裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的孔开度逐渐减小和部分气关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合     

裂叶沙参和泡沙参气孔行为与蒸腾特性的关系

采用LI-6400便携式光合分析系统对裂叶沙参和泡沙参进行了不同遮光水平蒸腾速率的测定,并同步测定了叶片气孔大小、气孔密度、气孔开度和气孔导度等气孔行为.采用相关系数和通径系数分析方法分析了不同遮光水平裂叶沙参和泡沙参气孔行为与蒸腾特性的关系.结果表明:不同遮光水平测定的气孔行为对裂叶沙参和泡沙参蒸腾作用的直接影响大致相同,其中,两种沙参的气孔密度对蒸腾速率的直接影响较大.但泡沙参的气孔导度与蒸腾作用具有极显著的相关关系.     

裂叶沙参和泡沙参种群有性生殖和无性繁殖的比较

通过对裂叶沙参(Adenophora lobophylla Hong)和泡沙参(A.potaninii Korsh.)种群有性生殖和无性繁殖特性的对比,揭示濒危植物裂叶沙参的种群内部致濒机制。结果表明:裂叶沙参种群幼苗抢占草本层上层空间能力弱于泡沙参种群;裂叶沙参种群是以相对长的生殖期和高产籽量来适应环境;裂叶沙参种群开花结实量虽高于泡沙参种群,但其中成熟种子少,种子质量差,致使其种群由种子到一年生幼苗的转化率极低,并且幼苗生活力弱,是导致其种群濒危的重要内部原因。裂叶沙参种群除有性生殖外还兼有较弱的无性繁殖,是对其有性生殖的一个重要补充。     

濒危物种裂叶沙参及其近缘广布种泡沙参的遗传多样性研究

根据对１２个形态性状的统计分析和１０个基因位点的等位酶检测,探讨了濒危植物裂叶沙参及其近缘广布种泡沙参的遗传多样性水平,对３个裂叶沙参和６个泡沙参天然群体的遗传分析表明,两种沙参属植物均具有很高的遗传变异水平,这种变异性既体现在形态学水平上,也体现在酶位点水平上,在２个茎叶形状以及１０个花果和种子形状上,濒危种裂叶沙参的变异性均与广布种相当,同样,根据７个酶系统１０个等位酶位点的度量,裂叶沙参群体     

安徽黄精属(Polygonatum)植物叶表皮研究

利用光学显微镜及扫描电子显微镜观察了安徽省黄精属９种植物的叶表皮;统计并测量了气孔类型、气孔大小、气孔密度及气孔指数等;描述了表皮角质膜、蜡质纹饰、气孔的形状及气孔外拱盖等有关特征。结果表明：黄精属植物叶表皮气孔器类型属只有２个保卫细胞而无任何副卫细胞的单子叶植物气孔器类型。气孔的某些特征,如气孔器类型、气孔器分布特征、表皮细胞形状及垂周壁式样、角质层及蜡质纹饰等在种间差异不大,可作种间区别的次级特征用。     

裂叶沙参与泡沙参种群分布格局分形特征的分析

 裂叶沙参与泡沙参种群在不同海拔区域分布格局的计盒维数与其在群落中占据空间的能力成正比,并且与环境因素密切相关。在裂叶沙参与泡沙参种群较为适生的区域,海拔2700～3100m,两者在群落中占据空间的能力最强,他们的计盒维数达到最高。在低于海拔2700m或高于海拔3100m,环境条件严酷的区域,裂叶沙参种群与泡沙参种群占据空间的能力不同程度的下降。在不同的海拔区域,广布种泡沙参种群占据空间的能力均比裂叶沙参种群高,而其受环境因素影响较弱。在海拔2700m以下地区,泡沙参种群水平分布格局的计盒维数比裂叶沙参种群高4.5倍;在两种群较为适生的区域,海拔2700～3100m,泡沙参计盒维数比裂叶沙参种群高1.5倍,差异最小;在泡沙参与裂叶沙参种群分布的上限,海拔3100m以上地区,两者计盒维数差异又增加,泡沙参计盒维数比裂叶沙参种群高1.8倍。这说明裂叶沙参种群的内在适应力、竞争力比泡沙参种群相对较弱。     

濒危种裂叶沙参种群生命表和存活曲线的研究及其与广布种泡沙参的对照

以近缘广布种泡沙参为对照,本文编制了濒危种裂叶沙参种群的标准生命表、存活曲线以及海拔２３００～２４００ｍ、２７００～２９００ｍ、２９００～３１００ｍ和３１００～３４００ｍ区域４个种群的生命表,存活曲线。根据其生活史,讨论了裂叶沙参各种群特定年龄的存活量、死亡量和死亡率等重要参数。裂叶沙参种群存活曲线属ＤｅｖｅｙＣ型,１～５年生死亡率最高,个体最长寿命２５年。而泡沙参种群的死亡高峰期是１～３年,个体最长寿命２１年。导致裂叶沙参种群幼龄个体死亡的内在原因是其较弱的抗逆性和适应能力;外在原因是严重的干旱、外界干扰和群落内的光照不足。裂叶沙参种群适应不良环境的能力较泡沙参弱：在海拔２７００ｍ以下地区,由于外界干扰和环境干旱,除水份条件较好的特殊生境,大多种群呈严重衰退趋势,不能满足编表条件,只有海拔２７００ｍ以上区域的种群呈稳定或扩展趋势;而泡沙参各种群在不同海拔区域均呈稳定或扩展趋势,满足编表条件。从海拔２３００ｍ到３４００ｍ,不同裂叶沙参种群个体寿命呈：短长短的格式,与外界严酷较好严酷的环境相对应。这表明裂叶沙参种群在严酷环境条件下改变了其生存对策,缩短了个体寿命。     

Biosystematic studies on Adenophora potaninii Korsh.complex (Campanulaceae) V.A taxonomic treatment

Adenophora is an extremely variable genus,and its taxonomy is very controversial.Of the genus,Adenophora potaninii complex,including A.potaninii,A.bockiana,A.wawreana,A.lobophylla,A.biformifolia,A,polydentata,and A.wawreana var.lanceifolia,is a typical group with different taxonomical treatments due to high level of morphological diversity.We carried out extensive biosystematic studies based on population sampling,transplantation experiments and offspring tests,cluster analysis,and a crossing experiment.The results reveal four main findings.(i) Leaf forms of the A.potaninii complex were extremely polymorphic; the leaf form of A.potaninii and A.bockiana,and that ofA.wawreana and A.biformifolia could be found,respectively,on a single population or among the offsprings of a single plant.(ii) Cluster analysis and a crossing experiment indicated that A.bockiana and A.polydentata could not be separated from A.potaninii,nor d.biformifolia from A.wawreana.(iii) Adenophora potaninii and A.wawreana were gradational in morphology and their compatibility value was slightly reduced compared to that within each entity.(iv) Adenophora lobophylla was distinct from the other members of the complex in shape and size of corolla,relative length of style,and shape of capsule.This species was incompatible reproductively with the other members of the complex,but partly compatible with A.stenanthina,a species in another section.Therefore,we recognized only one species with two subspecies in the complex,A.potaninii subsp.potaninii and subsp,wawreana,moved A.lobophylla out of the complex,and reduced all the other names as new synonyms.     

Comparative Studies of Sexual Reproduction and Asexual Propagation Between Populations of Adenophora lobophylla and A. potaninii

To reveal the internal mechanism which lead to the endangerment of the AdenophoUa lobophylla Hong population, comparative studies of sexual reproduction and asexual propagation between the populations of A. lobophylla and A. potaninii Korsh were carried out. Young seedlings of A. lobophylla had less ability to occupy the uper space of the herbaceous layer than those of A. potaninii. The A. lobophylla population produced much more seeds and lived a long reproductive life to adapt the ambient environment. Though the number of flowers and fruits of A. lobophylla population was more than those of A.potaninii population, the number of its ripe seeds as well as the quality was less. Thus, the development rate from its seeds to one-year old seedlings was very low, and viability of its young seedlings was very poor. This could be the important factor causing the imminent population endangerment of A. lobophylla. Besides the sexual reproduction, the A. lobophylla population also had a comparatively tiny ability of asexual propagation, which was advantageously complementary to its sexual reproduction.     

A Reevaluation of the Status of A. lobophylla Based on ITS Sequence,with Reference to the Utility of ITS Sequence in Adenophora

Adenophora Fisch. (Campanulaceae)is a medium-sized and diverse genus, which occurs mainly in eastern Asia, particularly in China. Although several taxonomic systems have been proposed, there is still much debate on the delimitation and systematic arrangement of the species within the genus, due mainly to high variation in morphology, habitats, phenotypic plasticity, and potential hybridization. A. lobophylla Hong is a rare perennial endemic to several counties of Sichuan, China. Since this species was recognized, much work has been done on its taxonomic status, including morphology, crossing experiment and allozymes. However, evidence available is not concordance so far, and its relationship with other species within the genus remains largely uncertain. In the present paper, the internal transcribed spacer(ITS) region of 18s～26s nuclear ribosomal DNA was sequenced in 10 representatives of Adenophora and two outgroup species of Campanula to assess its utility for phylogenetic reconstruction in Adenophora, in addition to reevaluation of the taxonomic status of A. lobophylla. The results indicate that there exist high sequence alignability and length conservation among ITS sequences, with informative sites being 3.9% and length ranging from 539 to 541 bp and G + C content varying from 57% to 60%. Phylogenetic　analyses using Fitch parsimony show that A. lobophylla is closely related to A. himalayana instead of A. potaninii or A. stenanthina as revealed by previous morphological work and crossing experiment. The ITS phylogeny is generally congruent with other evidence in that A. lobophylla should be removed from the A. potaninii complex or even subsect. Microdiscus. Its appropriate placement, however, should be further explored. In pairwise comparisons at unambiguously aligned sites, sequence divergence was relatively low among Adenophora species with the values ranging from 0.0 to 3.9% in spite of the fact that the species surveyed covered all of the sections and subsections of the genus. In contrast, high sequence divergence is found among Adenophora and Campanula species with the values from 17.8 % to 19.2 %. The low divergence among Adenophora species is justified considering its recent origin, and also suggests that ITS sequence would provide a promising source of nuclear phylogenetic markers to reconstruct the phylogeny within Campanulaceae on the tribe and family levels.     

用核糖体DNA的ITS序列探讨裂叶沙参的系统位置——兼论ITS片段在沙参属系统学研究中的价值

本文采用PCR直接测序方法,对来自沙参属全部2组7亚组的10个种和作为外类群的风铃草属2个种的核糖体DNA　ITS片段进行了序列分析。在重点探讨裂叶沙参分类地位的同时,分析了ITS片段序列在沙参属系统发育重建中的价值。结果表明,在沙参属中,ITS片段在长度、GC含量和位点变异量上均比较一致;长度539bp～541 bp,GC含量57％～60％,信息位点只占总位点的3．9～6％。采用PAUP软件进行的系统发育分析表明,裂叶沙参A．lobophylla与大花盘亚组的A．himalayana组成一支,而不是象以往形态学和杂交试验所推断的与泡沙参A．potaninii或A．stenanthina近缘。可见,ITS序列进一步支持将裂叶沙参移出泡沙参复合体甚至移出有齿亚组的推论,但同时也表明将其作为A．stenanthina的近缘种是不适宜的。尽管本研究所测定的类群已涵盖了整个沙参属,但种间序列的两两比较表明,沙参属种间在ITS片段上的分化很小(0.0～3.9％),相比之下,沙参属类群与风铃草属类群间的分化却很高(17.8％～19.2％)。这大概和沙参属起源较晚、遗传分化较小有关。本文还就ITS片段在沙参属和桔梗科系统学研究中的价值进行了讨论。