三峡库区稀有植物裸芸香的遗传多样性和保育策略

采用随机扩增多态性DNA(RAPD)对采自长江三峡库区丰都(FD)、巫溪(WX)、巫山(WS)、巴东(BD)、兴山(XS)、秭归(ZG)6个自然居群的128份裸芸香(Psilopeganum sinense)样品进行了基因组DNA多态性分析。用13条引物，共扩增出85条谱带，其中57条多态带，多态位点占67．06％。6个居群的多态位点比率分别为25．97％(FD)、29．73％(WX)、24．32%(WC)，43．21％(BD)、30．26％(XS)、39．19％(ZG)。用POPGENE 1．31版和NTSYS 2．10版软件对数据进行分析，结果显示：裸芸香具有较高的遗传多样性，居群总的Neis'基因多样性为0．2082，总Shannon信息多样性指数为0．3196；但各个居群内部遗传多样性较低，居群内平均Neis'基因多样性为0．1094，平均Shannon信息多样性指数为0．1641；居群间的基因分化系数Gst=0．5391，基因流Nm=0．4275，居群间基因分化大于居群内基因分化，居群间的基因交流相当少。UPGMA聚类可将6个居群分为两大类：丰都居群和以巴东居群为地理中心呈星散状分布的其他5个居群。居群间的遗传距离与地理距离呈显著正相关(r=0．93094，P=0．9861)。最后我们初步探讨了裸芸香的濒危原因，并提出了有效保护该物种的措施。

Genetic diversity and conservation strategy of Psilopeganum sinense, a rare species in the Three-Gorges Reservoir area

The genetic diversity of 128 individuals from six Psilopeganum sinense populations from the Three-Gorges Reservoir area was analyzed using RAPD. Thirteen primers produced a total of 85 scorable markers, of which 57 (67. 06% ) were polymorphic. The percentage of polymorphic loci of the six populations was 25.97% (FD) , 29.73% (WX) , 24.32% (WS) , 43.21% (BD) , 30.26% (XS) , and 39. 19% (ZG) , respectively. As analyzed by POPGENE 1. 31 and NTSYS 2. 10, the genetic diversity of Psilopeganum sinense was high, with an average Nei's gene diversity of 0.2082 and an average Shannons Information Index of 0.3196. In contrast, the genetic diversity within each population was low, with an average Neis gene diversity of 0. 1094 and an average Shannons Information Index 0. 1641. In addition, Gst was 0. 5391 and Nm was 0. 4275 , indicating more differentiation and less gene exchange between populations than within populations. The UPGMA cluster analysis showed that the six populations were genetically clustered into two groups, of which one was the Fengdu population and the other consisted of the remaining five populations distributed geographically with the Badong population as the center. A positive correlation (r =0. 93094 ,p =0. 9861) existed between geographical distance and genetic distance. Finally we discussed the cause of the endangerment status Psilopeganum sinense and proposed some management strategies for effectively protecting this species.