基于SSR标记的辽宁蒙古栎天然群体遗传多样性研究

Study on Genetic Diversity of Natural Quercus mongolica Populations in Liaoning Province Revealed by SSR Markers

蒙古栎是东北重要的森林树种之一,具有很高的生态价值和经济价值,其原生种质资源受到严重干扰,一些群体处于渐危或濒危状态。为更好保护和利用辽宁地区现有蒙古栎遗传资源,利用10对新开发的蒙古栎特异的核SSR分子标记,分析辽宁省境内分布蒙古栎天然群体的遗传多样性水平,计算群体间的遗传分化和基因流强度,并利用Mantel检验验证地理隔离与遗传距离的相关性。采用10对SSR引物分析了8个天然群体共111个个体的遗传多样性。结果表明:每个SSR位点的平均等位基因数为7.3,平均有效等位基因数为2.813,平均期望杂合度为0.624,Shannon多样性指数为1.270。不同群体存在多样性差异,8个群体的期望杂合度在0.558~0.612,平均为0.588;群体分化系数(FST)为0.0655,表明遗传变异主要存在群体内,群体之间遗传分化较小;群体之间存在基因流(Nm)达到4.471,遗传距离和地理距离之间具有显著的正相关关系(r=0.631,p<0.05)。辽宁省分布的天然蒙古栎群体具有丰富的SSR多样性,其遗传多样性水平相对较高;群体间有较强的基因流,这导致不同群体间的遗传分化较低,绝大部分遗传变异是发生在群体内的,而且距离越远,遗传分化也越高。揭示了辽宁分布的蒙古栎的遗传多样性水平及遗传分化程度,为今后辽宁省蒙古栎的遗传改良及育种造林提供理论依据。

Q.mongolica as one of the important forest tree species in Northeast China with high ecological and economic value are severely endangered.In order to provide strategies for better protection and utilization of the genetic germplasm resources of Q.mongolica.10 novel specific SSR markers developed in our previous study were used to analyze the genetic diversity,genetic differentiation and gene flow.Correlation between genetic and geographical distance was evaluated by Mantel test.Geneticdiversity of 111 individuals of 8 natural populations was analyzed by using 10 pair of SSR primers,for each locus,average number of alleles,average number of effective number of alleles and mean expected heterozygosity was 7.3,2.813 and 0.624,respectively.The Shannon diversity index was 1.270.The various genetic diversity was detected in eight populations with a mean expected heterozygosity of 0.588(range:0.558 to 0.612).The mean genetic differentiation among population(FST)was 0.0655,which showed that genetic variation distributed within populations.The mean gene low(Nm)was 4.471.There was a significant correlation between genetic distance and geographical distance(r=0.631,p<0.05).The research results showed that rich genetic diversity of Q.mongolica populations distributed in Liaoning Province was detected and the level of genetic diversity was relatively high in species of Quercus genus.The majority of genetic variation was distributed within populations,indicating low level of genetic differentiation among populations.There was a strong gene flow among the populations,which led to a low genetic differentiation among different populations and high diversity.Moreover,the genetic distance among Q.mongolica populations became larger with the increase of geographical distance.Overall,these findings were strongly related to the anemophilous characteristics of mating system of Q.mongolica.This study revealed the level of genetic diversity and genetic differentiation of Q.mongolica and provided a theoretical basis for genetic improvementand breeding forestationstrategies for Q.mongolica germplasm in Liaoning province.