论文标题:蒙古栎天然群体遗传多样性研究
Study on Genetic Diversity of Natural Populations in Quercus Mongolica
论文作者 李文英
论文导师 马钦彦；顾万春,论文学位 博士,论文专业 生态学
论文单位 北京林业大学,点击次数 95,论文页数 117页File Size5494k
2003-05-01论文网 http://www.lw23.com/lunwen_400239227/ 蒙古栎;辽东栎;AFLP标记;同工酶;天然群体;遗传多样性;表型多样性
Quercus mongolica,Quercus liaotungensis,Natural population,Morphology,Allozyme,AFLP marker,Genetic diversity.
根据中国蒙古栎(Quercus mongolica)天然林资源分布和现地调查结果，按照蒙古栎分布区内群体分布及其生态梯度进行(随机)分组取样，从其全分布区的8个天然群体(黑龙江省的大兴安岭、嘉荫和双鸭山群体，吉林省的蛟河、内蒙古自治区通辽市大青沟自然保护区、辽宁省宽甸县、河北省的雾灵山自然保护区以及河北省赞皇县彰石岩乡)采集供试材料，并以其近缘种辽东栎(Quercus liaotungensis)1个群体(北京东灵山)为对照，每个群体选取30株个体采样。测定了共计9个群体的当年生枝的顶芽、叶、坚果、壳斗的表型多样性、9个群体的等位酶多样性、其中4个群体的DNA多样性，并对3个不同层次的遗传多样性研究进行了比较和评价。根据揭示的遗传多样性规律，初步构建了蒙古栎的核心种质，提出了蒙古栎遗传多样性的保护措施。主要结果如下： (1)表型多样性的研究结果：表型性状的方差分析表明蒙古栎种内表型性状在群体间和群体内差异都极显著(α=0.01)。蒙古栎群体平均表型分化系数(V_(ST))为0.5609，群体间变异(56.09％)略大于群体内变异(43.91％)。蒙古栎表型多样性以性状遗传变异为量化特征，揭示了其种内表型梯度变异的规律性：随着经纬度的增加，坚果逐渐增大，坚果形状由近球形向长椭球形变异；叶形由长倒卵形向宽倒卵形变异；随着海拔升高，坚果逐渐变小。蒙古栎表型性状(顶芽、叶、壳斗、坚果)间存在显著或极显著的相关关系。利用群体间欧氏距离进行UPGMA聚类分析表明，蒙古栎群体可以划分为两大类组，4个亚类。 (2)等位酶遗传多样性研究结果：蒙古栎群体间基因位点数、等位基因频率和多态位点存在差异，群体间特异基因、局域基因及广域基因分布不同，群体间遗传参数P、A、Ae、He的差异，揭示了群体间遗传结构的差异，表明蒙古栎群体遗传多样性的明确特征。蒙古栎在种和群体水平的遗传变异水平偏低，多态位点百分率P分别为52.38％、28.976％，期望杂合度He分别为0.099、0.085，观测杂合度Ho分别为0.092、0.088；群体间遗传分化度Gst为0.1077，遗传多样性中的89.23％存在于群体内；群体水平的基因流Nm值为2.071。蒙古栎群体间的平均遗传距离D较小，为0.0121，各群体之间的遗传一致度Ⅰ为0.974～1.00；东灵山群体辽东栎群体的遗传多样性较低，多态位点百分率P为36.36％，期望杂合度He为0.083，观测杂合度Ho分别为0.070；利用群体间遗传距离进行的UPGMA聚类结果表明，蒙古栎自然分布区的东北部的4个群体和西南部的2个群体分别聚为一亚类，这与其地理分布 摘要格局大致吻合，但群体间遗传距离与地理距离无明显相关性。 (3) AFLP分子标记研究结果:利用筛选出的4对荧光引物，对4个群体共计%个个体进行了AFLP标记分析，每对AFLP引物扩增出63一113条带，共得到346条多态带;AFLP标记测定的扩增谱带频率的差异，反映了群体间遗传结构的差异，揭示了基因频率在群体间差异显著，从而在DNA分子水平上揭示了种内群体遗传多样性的差异;群体特异带及群体间共有带的差异与分布揭示了各群体的遗传差异及相似性;蒙古栋遗传多样性在群体间存在真实遗传差异，但遗传多样性分布主要存在于群体内，群体间的遗传分化系数(Gst)为0.077，即遗传多样性的92.3%分布在群体内。蒙古栋在种级水平的遗传多样性参数略高于群体水平，多态条带百分率尸分别为96.8%、67.17%，有效等位基因数A。分别为1.22、1.19，Nei基因多样性指数H分别为0.145、0.125，Shannon多样性指数I分别为0.246、0.2083。东灵山辽东栋群体的遗传多态带百分率为67.63%，Shannon指数I为0.220，Nei基因多样性指数H为0.1 336。UPGMA聚类分析结果表明，蒙古栋自然群体间的遗传距离有随地理距离跨度递增趋势。蒙古栋遗传多样性偏低可能与其在历史上人为干预和破坏较为严重，而且经受繁殖瓶颈效应造成有效群体较小，以及现存林分基本上为次生林等因素有关。 (4)表型、同工酶、DNA分子标记3种方法揭示的遗传多样性水平有差异，表型性状比同工酶具有更大的变异性，是基因表达与生态环境交互作用的结果，对环境更敏感，DNA要比同工酶更稳定些;群体分化以表型的最大，同工酶次之，DNA水平的分化最小;评价了3种方法在遗传多样性研究中的优点与不足;3种方法揭示的群体聚类结果较一致，反映了较一致的群体间关系，说明表型、同工酶、DNA3种方法在评价蒙古栋(同一套试材)遗传多样性中的祸合性较好。(5)根据蒙古栋表型变异及同工酶遗传多样性量化研究结果，初步确定并构建了蒙古栋核心种质保存的样本策略，确定了最优化的抽样保存群体“6+l”方案;基因型保存模式，每群体所需要保存的无亲缘关系基因型平均为25一30个，基本可达到基因资源保护的目的;本研究为蒙古栋及其它栋类植物种质资源保存、评价和利用研究奠定了可信赖的实验依据。
Based on field investigations and analysis of the natural distribution of Quercus mongolica in P. R. China, eight populations of Q. mongolica (Daxinganling, Jiaying, Shuangyashan, Jiaohe, Daqinggou, Kuandian, Wulinshan and Zhanhuang) and one population of Quercus liaotungensis (Xiaolongmen as control) were selected and investigated. Material collections and measurements were made on the nine populations(thirty individual plants each population). Genetic diversities were evaluated and compared at three levels of morphology(i.e., apical bud, leaf, seed and cupule for nine populations), allozyme(nine populations) and DNAs(AFLP analysis on four populations) in order to determine core germplasm of Q. mongolica and put forward effective methods for conservation of the genetic diversity. Main results obtained are as follows:(1) Morphological diversities among/within populations were discussed by analyzing characters such as apical bud, leaf, acorn and cupule. Analysis of variance for all characteristics were significantly different among populations and among individuals within population. The mean phenotypic differentiation coefficient (VST) shows that the variation among populations(56.09%) is slightly higher than that within population. The acorn becomes larger, the shape of the acorn changes from nearly spherical to oblong, and leaf shape of the longitude and latitude, upon increasing of the lonitude and latitude. The acorn gets smaller as the altitude becomes higher. There exists correlations among the morphological characters mentioned above. According to the correlation analysis, the populations of Q. mongolica investigated may be divided into two groups and four sub-groups.(2) A gel electrophoresis method was used to study the genetic diversity of eight Quercus. mongolica populations located at Daxinanling, Jiayin, Shuangyashan, Xiaoxinganling mountain, Heilongjiang Province, Jiaohe, Jilin Province, Kuandian,Liaoning Province, Daqinggou, Inner Mongolia Autonomous Region, Wulingshan, Zanhuang , Hebei Province, and one Quercus liaotungensis (a variety of Q. mongolica) population at Donglingshan, Beijing. Twelve of 22 loci from 13 enzymes assayed were polymorphic. Quercus mongolica maintained low level of genetic variation as compared with the average Quercus species. At species level, the mean number of alleles per locus (A) was 1.905, the percentage of polymorphic loci (P) was 52.38%, and the observed heterozygosity (Ho) was 0.092. At population level, the estimates were A=1.421, P=28.976%, and Ho- 0.088. Genetic differentiation (Gst) was high among populations, Gst was 0.107, and the means of genetic distance 0.0121. The Nei"s genetic identity ranged from 0.974-1.00. The gene flow was 2.0799. In contrast, the estimates for Quercus liaotungensis were almost the same ( A=1.5, P=36.36%, Ho=0.070).According to the UPGMA cluster analysis based on the genetic distance , 4 populations located in northeast and 2 populations in southwest of the geographical distribution are classified into 2 sub-groups in separate, there was no clear relationship between genetic distance and geographic distance among populations.(3) Three Q. mongolica populations located at Jiayin, Xiaoxinganling mountain, Heilongjiang Province, Daqinggouin Inner Mongolia Autonomous Region, and Wulingshan in Hebei Province, and one Q. liaotungensis (a variety of Q. mongolica) population at Donglingshan in Beijing, totally 96 individuals were selected and analyzed by amplifications using 4 pairs of AFLP primers screened, 63-113 bands produced each primer pair and 346 polymorphic locus were obtained. As for Q. mongolica, Shannon"s information index (I) is 0.246 and Nei"s gene diversity index (H) is 0.1453, genetic differentiation coefficient among populations (Gst) is 0.077. As for Q. liaotungensis, Shannon"s information index is I = 0.220 and gene diversity index H = 0.134. Genetic identities among the four populations were high as above 0.978 ,this indicated that the low level of genetic differentiations between Q. liaotungensis and Q. mo
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