【作者】 李珊；

【导师】 赵桂仿；

【作者基本信息】 西北大学 ， 植物学， 2004， 博士

【摘要】 金钱槭属（Dipteronia Oliv.）隶属于槭树科（Aceraceae），是我国特有少种属。属下仅包括云南金钱槭（D.dyeriana Henry）、金钱槭（D.sinensis Oliv.）两个种，分别被列为国家二级、三级珍稀濒危保护植物。为了更好地保护我国特有种质资源，本文在广泛收集金钱槭属植物材料的基础上，首次对该属植物进行了保护遗传学和分子亲缘地理学研究。 首先，通过查阅标本、翻阅资料、走访有关专家及对云南、湖北、重庆等9个省市33个代表性地点的野外实地调查，较为全面、系统地报道了金钱槭属植物的生长状况、生存环境、人为干扰等情况，为对该属植物进行全面研究补充了基本资料。 其次，应用RAPD标记技术对金钱槭、云南金钱槭居群的遗传多样性和遗传分化进行了比较研究。利用18条随机引物对17个金钱槭居群的226个个体进行扩增，共检测到128个位点，其中多态位点119个。总多态位点比率（PPB）为92.97％，显示金钱槭具有较高水平的遗传多样性。Shannon多样性指数（0.5563）、Nei基因多样性指数（0.3864）和基因分化系数值(G_ST=0.4470)说明，尽管大多数遗传变异仍然存在于居群内，但居群间已产生较高水平的遗传分化。AMOVA分析结果显示，金钱槭居群内遗传变异占总遗传变异量的56.89％，居群间遗传变异占总变异量的43.11％，进一步支持了上述结果。金钱槭居群间的基因流Nm=0.6685，Nm＜1，居群间基因交流匮乏。居群间地理距离与遗传距离（经、纬度，海拔）的相关性分析结果显示，遗传距离与经度差异间具有极显著水平的正相关性（P＜0.01），聚类分析、主成分分析结果也显示出各聚类群与地理差异存在相关性的趋势。用相同的18条引物对4个云南金钱槭居群的45个个体进行RAPD扩增，共检测到103个位点，其中多态位点84个，云南金钱槭物种水平的多态位点比率为81.55％。AMOVA分析结果揭示，云南金钱槭居群内遗传变异占总变异量的57.86％，居群间遗传变异占总变异量的42.14％，与基因分化系数(G_ST=0.4267)分析结果基本一致。云南金钱槭居群间的基因流Nm=0.6719，Nm＜1，居群间基因交流十分有限。居群间遗传距离与地理隔离的相关性分析结果显示，云南金钱槭居群间遗传距离与地理隔离不存在显著的相关性。对金钱槭、云南金钱械居群遗传多样性及遗传分化进行比较发现:l)金钱械的遗传多样性水平高于云南金钱械，符合广布种的遗传多样性高于狭域种这一规律。2)金钱械、云南金钱械居群间的遗传分化均已达到较高水平，居群间的基因流匾乏。3)在大尺度上（金钱械）遗传距离与地理距离有相关性而在小范围内（云南金钱械）则无上述关系，这可能与位于不同分布区内的物种所承受的生境选择压力不同有关。 第三，通过测量27项果实、种子、枝叶的宏观、微观形态学性状，揭示了云南金钱械的形态变异模式。同时结合遗传变异及生态因子资料，分析了云南金钱械形态变异的产生、维持机制。形态学性状分析结果表明:l)各居群形态性状变异系数平均值从大到小的排列顺序为:文山居群>屏边居群>黑龙潭居群>蒙自居群。2)在27个性状中，有4个性状在居群间的差异达显著性水平（尸<0.05），巧个达极显著水平（尸<0.01）。果实长度在居群间的变异最大，小叶叶长/叶柄长在居群间的变异最小。3)文山居群与屏边、黑龙潭、蒙自居群间已产生显著或极显著水平的形态差异，而后三者间的差异未达显著水平。形态变异与遗传变异、生态因子间的相关分析结果显示:l)形态性状变异系数与多态位点比率、Shann口n多样性指数及Nei基因多样性指数间存在着正相关关系，但相关性均未达显著水平。2)形态变异与生态因子间存在较复杂的相关性，海拔、土壤含水量等6个生态因子与一些形态性状的相关性已达显著或极显著水平。相对于其它生态因子来说，海拔对形态性状变异的影响最大。上述结果说明，云南金钱械的形态变异虽然具有一定的遗传基础，但可塑性及环境压力对形态变异所产生的作用更大一些。基于形态性状和RAPD数据的聚类分析结果进一步说明，云南金钱械的形态变异受到环境因子的强烈影响而与遗传背景的关系不显著。 第四，本文采用PCR一RFLP技术对金钱械属植物进行了分子亲缘地理学研究。选取7对叶绿体DNA通用引物对来自17个金钱械居群、4个云南金钱械居群的63个个体进行PCR扩增，扩增产物用从刁。111、FunDH等四种4碱基内切酶和EeoRI+Rsal、Hindlll+Hin石I两种4、6碱基限制性内切酶组合进行酶切。42种引物/酶组合在云南金钱械中共检测到109个DNA片段，所有片段均为单态，在金钱械中共检测到124个片段，其中多态片段20个，多态片段占总片段数量的16.13%。分析所有酶切片段，发现了6种cPDNA单倍型，其中云南金钱械独享一种单倍型，金钱械具有另外5种单倍型。金钱械的5种单倍型具有叨显的地理分化，根据单倍型的地理分布格局和所属山系，将所研究的金钱械居群划分为4个地理单元:秦岭地理单元、武陵山地理单元、山民山地理单元和大巴山地理单元。通过AMOVA软件计算得到4个地理分布单元间的分化系数（Gs:）值为0.9299，即有92.99%的遗传变异存在于地理分布单元间，7.01%的遗传变异存在于地理单元内，说明金钱械更多还原

【Abstract】 Dipteronia Oliv., an endemic genus to China, belongs to the family Aceraceae. It only includes two species, namely D. dyeriana Henry and D. sinensis Oliv., which are respectively listed among Grade II and Grade III National Protected Rare and Endangered Plants. To better protect this germplasm resource, this paper has for the first time performed conservation genetic and molecular phylogeographical researches on the basis of large-scale collecting of plant materials of Dipteronia Oliv..Firstly, by referring to specimens, looking up related literature and visiting specialists, and through field surveys in 33 representative sites across nine provinces and cities such as Yunnan, Hubei and Chongqing, this paper has for the first time given a relatively comprehensive and timely report about Dipteronia Oliv.’s situation such as its growth status, habitats and artificial disturbances. All these have provided fundamental materials for the performance of related comprehensive researches.Secondly, a comparative study upon the genetic diversity and genetic differentiation of D. sinensis Oliv. and D. dyeriana Henry has been carried out by means of RAPD markers. 128 loci, with 119 of them polymorphic, have been detected in 226 individuals corresponding to 17 D. sinensis Oliv. populations by using 18 random primers. The proportion of polymorphic loci (PPB) is 92.97%, indicating that D. sinensis Oliv. has a relatively high level of genetic diversity. Shannon diversity index (0.5563), Net’s gene diversity index (0.3864) and gene differentiation coefficient (GST=0.4470) together reveal a relatively high level of interpopulational genetic differentiation despite the existence of most genetic variation within populations. Results of AMOVA analysis show that D. sinensis Oliv.’s intrapopulational and interpopulational genetic variations account for 58.89% and 43.11% of the total amount of genetic variation respectively, which further supports the above-mentioned results. A deficiency in gene flow among D’. sinensis Oliv. populations has also been revealed (Nm=0.6685, Nm<1). Results of correlation analysis between interpopulational geographical distances (longitude, latitude and altitude) and interpopulational genetic distances show a remarkably significant positive correlation between genetic distancesand longitude differences (P<0.01). Results of clustering analysis and principal component analysis (PCA) also show a trend of correlation between each cluster group and geographical differences. By applying the same 18 primers to 45 individuals corresponding to 4 D. dyerlana Henry populations, RAPD analysis detects 103 loci, with 84 of them polymorphic, and reveals that its proportion of polymorphic loci (PPE) on the specific level is 81.55%. Results of AMOVA analysis show that D. dyeriana Henry’s intrapopulational and interpopulational genetic variations account for 57.86% and 42.14% of the total amount of genetic variation respectively, which basically complies with the results of gene differentiation coefficient analysis (G.s7=0.4267). A limited gene flow among D. dyeriana Henry populations has also been revealed (Nm=0.6719, Nm<1). Results of correlation analysis show that there exists no significant correlation between interpopulational genetic distances and geographical isolation. By comparing the genetic diversity and genetic differentiation of D. dyeriana Henry and D. sinensis Oliv., it reveals that: (1) D. sinensis Oliv. has a higher level of genetic diversity than D. dyeriana Henry does, which follows the rule that the genetic diversity of cosmopolitan species is higher than that of stenochoric species; (2) both D. dyeriana Henry and D. sinensis Oliv. display a relatively high level of interpopulational genetic differentiation and a deficiency in gene flow among populations; (3) there exists a correlation between genetic and geographical distances on a large scale (D. sinensis Oliv.), but not on a small scale (D. dyeriana Henry), which may has something to do with the selection pressure exerted on species by their habitats更多还原