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题名: 濒危植物三棱栎的的遗传多样性研究
作者: 韩春艳
学位类别: 硕士
答辩日期: 2004
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: 孙卫邦
关键词: 三棱栎 ; 遗传多样性 ; RAPD分析 ; 核型分析 ; 濒危机制 ; 保护措施
学位专业: 植物学
中文摘要: 三棱栎[Trigonobalanus dojchangensis(Camus)Forman]是壳斗科三棱栎属(Trigonobalanus Forman)三个种中唯一分布在中国的种类,是受国家二级重点保护的、具有重要科学研究价值和园林观赏功能的珍稀濒危植物。本研究结合种群生态学、生殖生物学和种子生理学的部分研究结果,采用分子生物学和细胞学的有关原理和研究方法,从分子(DN)和细胞两个层次上对三棱栎的遗传多样性进行综合研究,检测了5个居群的遗传多样性水平和遗传结构,首次报道了三棱栋的染色体数目及4个居群的染色体核型,探讨了三棱栎致濒的内外因素及历史地理因素,提出了如何保护和丰富三棱栎遗传多样性的措施。1.分子水平的遗传多样性研究用随机扩增多态DNA(RAPD)标记对5个三棱栎居群共99个个体进行遗传多样性和居群遗传结构分析。16个引物共检测到157个位点,其中多态位点83个,占52.87%。三棱栎物种水平Shannon多样性指数I=0.2431,Shannon多样性指数平均居群内遗传多样性值为0.1151,在总的遗传变异中,居群间遗传多样性占52.65%,居群内遗传多样性占47.35%;也就是说根据Shannon指数得出的遗传分化值为0.5265。三棱栎物种水平Nei基因多样度h=0.1595,种内总遗传变异量Ht=0.1600,居群内遗传变异量Hs=0.0749,遗传分化系数Gsl=0.5320,说明居群间的遗传变异占53.20%。Shannon指数和Nei指数所得的三棱栎遗传分化值极为接近(分别为0.5265和0.5320),居群间变异量大于居群内变异量,因此三棱栎的遗传变异主要存在于居群之间,居群间已出现强烈的遗传分化。与大多数同科植物相比,三棱栎遗传多样性水平较低,基因流Nm只有0.4398,即居群间每代迁移数Nm远远不足1,三棱栎居群间的基因交流极为有限,低水平的基因流明显不能防止由于遗传漂变引起的居群之间的遗传分化。澜沧居群的遗传多样性水平明显低于其它居群,聚类分析也发现其处于一个独特的分支,澜沧居群是一个比较独特的居群。三棱栋偏低的遗传多样性和强烈的遗传分化,一方面说明在三棱栎演化过程中可能因遭受强烈的地史变化而使其居群数量大规模减少,从而丢失部分遗传多样性;同时也说明人类的强烈干扰造成的三棱栎生境破碎化和居群隔离,导致了三棱栎由于遗传漂变、自交衰退等原因,加速了遗传多样性的进一步丧失。2.三棱栎的细胞生物学研究通过对三棱栎澜沧、沧源、西盟、孟连4个居群染色体的观察,发现三棱栎体细胞染色体数目为2n=14,4个居群的核型公式均为2n=14=10m+2sm+2st,核型类型均为2A。染色体组平均总长为28.42μm,染色体平均长度为2.03μm,最长染色体平均长度为2.78μm,最短染色体平均长度为1.51μm。对三棱栎四个居群的染色体,在常规染色体水平上进行核型分析发现,三棱栎居群间核型变异不显著。各居群仅在染色体相对长度比(最长/最短)、平均臂比、AS.K.(%)值上有小的变化,在染色体臂上分布的次绩痕的数目和分布也比较稳定。综合各项数据来看,三棱栎各居群间核型变异很小,核型分析难以反映三棱栎的遗传变异水平。3.三棱栎的致濒因子分析及其遗传多样性保护策略三棱栎是壳斗科中的原始类群,有着古老的地史,目前仅分布于云南南部和泰国北部的狭小地区。有关研究表明,三棱栎在云南的生境极度破碎化,群体相互孤立,同时由于不合理的薪炭利用使群体数量快速下降,外来入侵物种威胁着群体的扩增和群体的形成;三棱栎结实率低,在自然条件从种子萌发、幼苗生长至成年的转化率低。本研究显示三棱栎的遗传多样性水平比其它壳斗科植物低,且居群间遗传分化强烈、基因流小。因此,三棱栎的致濒因子不是单一的,从现象上看可能更多的是人类活动对生境的破坏、当地人群的直接砍伐利用及生殖障碍,而从本质上讲应是其演化过程中可能的地史灾难、生态、遗传和生理等因素的综合。该物种的解濒和遗传多样性的有效保护是一个复杂的系统工程,应采取综合措施。不但要考虑栖息地的有效保护和适生生境的人工恢复,还应根据遗传多样的研究结果,在进行大量的科学采种育苗的基础上,开展回归引种和种群人工重建。此外,还应通过不同种群后代的薪炭栽培利用和园林应用来实现种质资源可持续利用和迁地保护。
英文摘要: Trigonobalanus doichangensis (Camus) Forman, only one species of Trigonobalanus in Fagaceae which distributed in China, was one rare and endangered plant with important scientific value and ornamental function, and listed as the second-ranked national protection plant of China. This research adopted the relative theory and method of molecular biology and cytology, based on partial researchful results of population ecology, reproductive biology and seed physiology. This thesis synthetically studied the genetic diversity of T. doichangensis in two hierarchies of molecular(DNA) and cell, examined genetic diversity and genetic structure of five populations, and first reported chromosome number of T. doichangensis and karyotype of four populations. This thesis also discussed inherent and extrinsic factor and history geography factor that induced endangerment, and put forward some measures about how to protect and enrich the genetic diversity of T. doichangensis. 1. Genetic diversity research at molecular level The genetic diversity and population genetic structure of five populations with total of 99 T. doichangensis individuals were estimated with random amplified polymorphic DNA (RAPD) markers. One hundred and fifty-seven loci were amplified with 16 oligonucleotide primers, of which 83 loci (52.87%) were polymorphic. Shannon's information index (I) at the species level was 0.2431, the mean genetic diversity within-population was 0.1151; in the total genetic variation, the genetic diversity among-population accounted for 52.65%, the genetic diversity within-population accounted for 47.35%; that is to say, the genetic differration based on Shannon information index was 0.5265. Nei's gene diversity (h) was 0.1595 at the species level. Total genetic diversity (Hi) was 0.1600, and the genetic diversity within populations (Hs) was 0.0749, the coefficient of gene differentiation Gst=0.5320. The genetic variation among different populations accounted for 53.20 % of the total. The gene differentiation of Shannon information index and Nei index were tallied with each other, this indicated that the genetic variation existed mainly among populations rather than within populations, the strong genetic differentiation existed among the populations of T. doichangensis. In comparison with other plants in Fagaceae, the genetic diversity of T. doichangensis is lower and the gene flow among populations is very restricted, Mm=0.4398. The number of migrants per generation Nm
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/730
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濒危植物三棱栎的的遗传多样性研究.韩春艳[d].中国科学院昆明植物研究所,2004.20-25
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