目的分析不同居群美花石斛种质资源的遗传多样性、濒危现状以及亲缘关系。方法利用RAPD分子标记技术和方法对不同居群美花石斛进行检测;通过计算遗传相似系数建立其聚类分析图。结果从117个随机引物中,共筛选出8个有效引物,对8个美花石斛居群进行RAPD-PCR扩增,共扩增出287个条带,平均每个引物的扩增条带为35.88个;287个条带共占据78个位点,其中11个位点是8个居群的共有位点,67个为多态位点,多态性比率达85.95%;8个居群的相似性系数在0.149~0.517。结论美花石斛遗传多样性水平低于铁皮石斛种内遗传多样性水平;美花石斛的濒危原因与人为过度采收、种子自然萌发力弱和遗传多样性水平较低有一定的关系;美花石斛8个居群比较自然地向3个方向演化发展,并形成3个分支;美花石斛系统演化规律与其地理分布的相关性有待于进一步研究。

Objective To analyse the genetic diversity,endangered situation,and phylogenetic relationship of germplasm resources in different populations of Dendrobium loddigesii by RAPD.MethodsGenetic diversity,phylogenetic relationship,and molecular authentication in different populations of D.loddigesii were investigated by the methods of RAPD markers and dendrogram of cluster analysis was established by calculating the genetic similar coefficient. Results A total of 287 bands with an average of 35.88 per primer were amplified from eight populations by eight effective primers,which selected from 117 primers. The 287 amplified bands took up 78 loci in all gelatin boards, among which 11 loci were monomorphic and 67 were polymorphic,corresponding to 85.95% genetic polymorphism.The similarity coefficients were from 0.149 to 0.517 in these eight populations of D.loddigesii.Conclusion Compared with D. officinale,the level of genetic diversity of D. loddigesii is distinctly lower. The reasons for D.loddigesii being on the brink of extinction are relevent to the artificial destroyed phenomenon, infirmly reproductive ability and lower genetic diversity of this species.The eight populations of D.loddigesii can be developed to three directions naturally according to their cluster dendrogram.It is necessary to further research whether the phylogenetic relationship of D.loddigesii will be related to its geological distribution.

科技部国家科技基础条件平台项目(2004DKA30410);韶关市科技计划项目(韶科2005-10)