基于ISSR和RAPD标记的四个夏蜡梅种群的遗传多样性研究

Genetic diversity of four populations of Calycanthus chinensis based on ISSR and RAPD markers

利用ISSR和RAPD技术对4个夏蜡梅种群25个单株的遗传多样性进行研究。从60条简单重复序列引物中筛选出了10条引物在25个个体中共检测到62个可重复的位点,其中多态位点为41个,总的多态位点百分率为65.60%;从60条寡居核苷酸引物中筛选出了10条引物共扩增出52个位点,其中多态性位点31个,多态性位点的百分率为57.50%。Shannon指数估算的夏蜡梅群体总遗传多样性为0.3737,各群体平均遗传多样性为0.1645。Nei’s指数估算的夏蜡梅群体总遗传多样性为0.2528,各群体平均遗传多样性为0.1117;物种水平的有效等位基因数为1.4473,平均值为1.1972。4个自然群体的基因分化系数Gst=0.5297,即总的变异中有52.97%的变异存在于群体间,而群体内的遗传变异占总变异的47.03%,群体间遗传距离平均值0.2187。也表明了夏蜡梅4个群体间出现了遗传分化。夏蜡梅群体间的基因流较低,Nm=0.4450。聚类分析将4个种群聚为2支,且聚类结果表现出明显的地域性特征。作为狭域分布种,夏蜡梅各群体间存在遗传分化和多样性程度不高,对夏蜡梅种群多样性的就地和迁地保护势在必行。

Genetic diversities of 4 populations 25 individuals of Calycanthus chinensis were studied by ISSR and RAPD marker. 62 loci were identified with 10 simple sequence repeat primers screened from 60 primers,out of which 41 loci were polymorphic and the percentage of polymorphie bands was 65. 60% ;52 loci were identified with 10 oligonueleotide primers screened from 60 primers,out of which 31 loci were polymorphic and the percentage of polymorphic bands was 57. 50%. Shannon＇s indices of diversity （I） were 0. 3737 among the species level with the average of 0. 1645 among pop- ulations. Nei＇s gene diversity（h） was 0. 2528 among the species with the average of 0. 1117 among populations;and the effective number of alleles （ne） was 1.4473 among the species with the average of 1, 1972 among populations. Geneticvariance analysis showed the coefficient of gene differentiation （C-st） was 0. 5297 at species level, and the gene flow （Nm） was 0. 4450. Cluster analysis indicated that 4 populations could be divided into 2 groups and consistent with their geo- graphical distributior~ As a highly restricted geographical distribution species, the genetic diversity level of C. chinensis was not high. It is necessary to take measures to protect in situ or ex situ endangered species.