大针茅居群遗传分化和RAPD 位点多态性分布的分析

利用RAPD 分子标记技术对5 个居群的90 个大针茅个体间的遗传关系以及RAPD 多态性与所在生境的相关性进行了研究。16 个引物共扩增得到310 个RAPD 位点, 利用几种多元分析方法对所得位点进行分析, 结果显示: 主轴法分析能够在三维坐标下将90 个大针茅个体按居群来源进行分类, 前三个轴虽然只解释了总变异的21 . 91% , 却能将所研究的居群完全分开; 典范判别分析可以将97 .8%的大针茅个体正确地分类到已知居群, 且在二维功能轴下能够清晰地看到个体按居群来源进行了分类; Spearman 秩相关分析和多元逐步回归分析均得出大针茅RAPD 位点的Nei′s 基因多样性与气候因子( 包括年降水量、积温、年均温、一月份均温和七月份均温) 之间存在显著的关联性。基于以上结果我们可以得出: 大针茅地理居群分化显著; 大针茅RAPD 多样性并非随机分布而是与生境气候因子相联系; 气候差异的自然选择, 对大针茅遗传多样性和遗传结构的特点起决定作用。研究结果对大针茅种质资源的保护具有重要的指导意义。

An Analysis of Genetic Differentiation and Distribution of RAPD Polymorphism in Stipa grandis (Gramineae) Populations

The genetic differentiation and RAPD polymorphism of 90 Stipa grandis individuals from five populations were studied using RAPD markers . Sixteen oligonucleotide primers were used to amplify 310 RAPD loci , which were analyzed using several multivariate methods . The Principal Coordinated Analysis (PCoA) clearly clustered 90 Stipa grandis individuals into five groups in 3-dimension plot and the individuals from the same population were clustered into one group, even though the first three coordinates explained only 21.91% of the total variance. The Canonical Discriminant Analysis couldcluster individuals into their corresponding populations, with 97.8% of the correctness. The Spearman Rank Correlation and Multiple Regression Analysis established a strong and significant association between some of the RAPD loci and certain climatic factors ( annual precipitation, ≥10℃ cumulative temperature in a year, annual mean temperature, mean temperature in January and mean temperature in July). All these results indicated that (1) the genetic differentiation of Stipa grandis populations was significant, (2) the RAPD polymorphism was not randomly distributed but associated with the climatic characters of habitats, and (3) the natural selection of climatic divergence played an important role in affecting the genetic diversity and genetic structure of Stipa grandis populations. The results of this study may be useful for guiding the conservation of germplasm of Stipa grandis.