胡桃楸天然种群遗传多样性的ISSR分析

ISSR analysis of genetic diversity of Juglans mandshurica Maxim populations

为了了解胡桃楸资源的遗传多样性状况,采用ISSR分子标记技术,对胡桃楸集中分布区内6个种群共180个样本的遗传多样性进行研究。从50条引物中筛选出14条用于扩增,共检测到140个位点,其中多态位点120个,多态位点百分率为85.71%。在物种水平上胡桃楸的Shannon信息指数为0.4521,Nei指数为0.3024,表明物种水平的遗传多样性较高;在种群水平上遗传多样性随纬度从南到北呈现单峰型变化规律,老爷岭种群的遗传多样性最高,三合种群的最低。AMOVA分析结果表明,胡桃楸的遗传变异大多数存在于种群内,占总遗传变异的81.83%,18.17%的变异存在于种群间。基于Nei＇s遗传多样性分析得出的种群间遗传分化系数为0.1618,各居群间的Nei＇s遗传距离在0.0470~0.1225之间。UPGMA聚类分析的结果与自然地理分布规律基本相一致,地理上较近的种群,在遗传上聚在一起。鉴于胡桃楸的遗传多样性现状和种群遗传结构,胡桃楸濒危的主要原因不在其遗传变异方面,主要来自于人为干扰和其生境的破坏与退化。

In order to investigate genetic diversity of Juglans mandshurica Maxim resources,genetic diversity of 180 individuals among six J.mandshurica Maxim populations from centralized distribution areas were researched appling Inter-simple sequence repeat（ISSR） molecular technique.Through screening from 50 primers,14 ones were selected out.120 polymorphic loci were detected from total 140 loci,and the total percentage of polymorphic band was 85.71%.At species level Shannon＇s information index and Nei＇s gene diversity index of J.mandshurica Maxim was 0.452 1 and 0.302 4,respectively,and it indicated that the genetic diversity at species level relatively high;while at population level,the genetic diversity was unimodal along the latitude from south to north,that of Laoyeling was the highest and Sanhe was the lowest.Results of AMOVA analysis demonstrated that the within-population component had a high degree which accounted for 81.83% of the total variation,while the among-population component accounted for 18.17%.The coefficient of gene differentiation among populations was 0.161 8 based on Nei＇s genetic diversity index and pairwise genetic distance among populations ranged from 0.047 0 to 0.122 5.In addition,results of UPGMA clustering analysis showed that the populations that clustered together in genetic was near in geographical,according with distribution of physical geography.The mainly reason for preservation of J.mandshurica Maxim was not genetic variations but cutting,habitat destruction and degradation.