利用RAPD分子标记探讨新疆刚毛柽柳天然居群的遗传多样性

以新疆塔里木盆地大量分布、怪柳属中最耐盐碱的种之一、盐生荒漠的建群 种-刚毛怪柳（Tamarix hispida Wild.）为研究对象，选取其中9个天然居群，运用RAPD（随机扩增多态性DNA）分子标记进行遗传多样性的研究。从60条10碱基组成的随机引物中筛选出10条，对所有个体的基因组DNA 进行PcR扩增，得到基因组DNA片段的长度介于200一250obP之间，共检测到 157个可重复的位点，多态性位点占总位点数的98，7％。Shanaon表型多样性指 数估计居群间的遗传多样性为62 ．45％；Nei基因多样性指数估计居群间的遗传分 化系数为55．30％，对二级谱系的AMOVA分析得到小st为住5450，表明本地区刚毛怪柳的遗传多样性较丰富，居群间遗传分化的水平稍大。所选居群的聚类分析表明，居群内个体首先聚合在一起，遗传距离与直线地 理距离不存在明显的相关性。反映居群间基因流强度的Nm值为0．203，表明居 群间的基因流很少。居群间分化度指数GsT值也反映出居群间的遗传多样性水平 要稍高于居群内，认为虽然环境的选择起到一定的作用，但形成并维持新疆刚毛 怪柳遗传分布格局的主要因素还是基因流的隔离。分子证据表明刚毛怪柳的繁育系统属于一种自交和不完全异交混合的交配 类型。遗传多样性的研究表明，对于盐生荒漠类型脆弱但占有重要地位的刚毛怪柳 群落来说，遗传变异多发生在居群间，遗传资源的保护应以大范围保护为主，保护范围应尽可能的涉及较多的群体，而居群内保护的个体不必太多。Tamarix hispida Wild, is a constructive species in salt desert's ecological environment in Tarim basin. This paper described the genetic diversity and population structure of nine T. hispida nature populations in Xinjiang at DNA level using RAPD to find the genetic diversity of T. hispida, the relationship of the genetic structure, ecological and biological property and also reasonable utilization of germplasm resources. Ten random primers were chosen for PCR analysis and DNA segement lengths applified were between 200 to 2500bp. 157 repeatable loci(average 13-21 loci each primer) appeared and the proportion of polymorphic loci was 98.7%. The genetic structure of populations estimated by Shannon's phenotypic diversity index and Nei's genetic Index separately were 62.45% and 55.30%. 4>st index was 0.5450. It stated that most of the variation of 1 hispida occurred among different populations. The result of cluster analysis (NJTREE) was used to generate dendrograms showing no obvious correlation between genetic distance and geographic distance among the T. hispida populations. Nm was 0.203, far below 1, stated the gene flow of populations is very low. GST also showed the genetic diversity among populations were high, so we consided alought the selection of environment had a certain effert, the isolation of gene flow was the main factor to form and maintain the genetic distribution of T. hispida. The breeding system of T. hispidawas a selfing and outcrossing mixed-mating type by GST index. According to the frangibility and temporary stability of its ecology system and its important function in salt desert, author raised the protect strategy of T.hispida germplasm resources should be in large-scale, namely, the protect area should involve more population and the individual within population need fewer