极小种群野生植物白花兜兰ISSR遗传多样性分析

Genetic Diversity Analysis by ISSR of Paphiopedilum emersonii,a Plant Species with Extremely Small Populations

关键词:  白花兜兰  濒危植物  ISSR  遗传多样性  聚类分析

Key words:  Paphiopedilum emersonii  endangered plant  ISSR  genetic diversity  cluster analysis

摘要:

为探究极小种群野生植物白花兜兰(Paphiopedilum emersonii)的遗传多样性，为其野生资源保护和优良种质资源筛选提供科学依据，采用ISSR分子标记技术对白花兜兰8个野生种群的122份样品进行遗传多样性分析。结果表明：从100条ISSR通用引物中筛选出6条多态性较高的引物，共扩增出35条谱带，其中多态性条带30条，平均每条引物总扩增条带数为5.83条，多态性比率均值为87.70%。白花兜兰8个野生种群的等位基因数(N_a)均值为1.783 3，有效等位基因数(N_e)均值为1.481 7，Shannon's信息指数(I)均值为0.419 1，Nei's基因多样性指数(H)均值为0.280 8，说明白花兜兰种群的遗传多样性属于中等水平；种群间的遗传分化系数(G_st)均值为0.124 7，种群内遗传变异大于种群间遗传分化，遗传变异主要来自种群内个体间；基因流(N_m)为3.509 3>1，表明白花兜兰种群间交流频繁，从而限制了由遗传漂变导致的遗传分化。采用非加权组平均法(Unweighted Pair-group Method with Arithmetic Means,UPGMA)进行聚类分析，8个白花兜兰野生种群分为两大类，第一大类包括环江木论兰花山(HML)和环江木论峒炼山(HMD)两个种群，第二大类包括荔波永康乡家别组(LYZ)、荔波黎明关干排组(LLG)、罗城怀群乡(LH)、宜州龙头乡独山屯(YLD)、宜州刘三姐乡岩田动湖(YLY)和荔波黎明关关吉洞(LLJ) 6个种群。白花兜兰野生资源具有中等水平的遗传多样性，种群HML和种群HMD遗传多样性水平高于其他种群，在进行遗传育种时可优先选择。

Abstract:

In order to explore the genetic diversity of Paphiopedilum emersonii, which is a small wild plant population,and provide scientific basis for its wild resource protection and excellent germplasm resource screening,the genetic diversity of 122 samples from 8 wild populations of P.emersonii was analyzed by ISSR molecular marker technology. The results showed that 6 primers with high polymorphism were selected from 100 ISSR universal primers. A total of 35 bands were amplified,including 30 polymorphic bands. The average total number of amplified bands per primer was 5.83,and the average rate of polymorphic bands was 87.70%. The average number of alleles (N_a),effective alleles (N_e),Shannon's information index (Ⅰ) and Nei's gene diversity index (H) were 1.783 3,1.481 7,0.419 1 and 0.280 8,respectively.The results indicated that the level of genetic diversity of the P.emersonii populations were medium. The mean genetic differentiation coefficient (G_st) among populations was 0.124 7. The genetic variation within populations was greater than that among populations. The genetic variation mainly came from individuals within populations. The gene flow (N_m) was 3.509 3>1,indicating that the communication between populations were frequent,which limited the genetic differentiation caused by genetic drift. UPGMA cluster analysis showed that the 8 populations of P.emersonii were divided into two categories. The first category included population of HML and HMD,and the second category included population of LYZ,LLG,LH,YLD,YLY and LLJ.The results of this study found than the wild resources of P.emersoniis have a moderate level of genetic diversity. The genetic diversity of population HML and population HMD is higher than that of other populations,which can be preferentially selected in genetic breeding.