西南地区古杨树遗传多样性的SSR分析

SSR Revealed Genetic Diversity in Large Old Poplars from Southwest China

采用SSR分子标记技术,对采集于中国西南地区的7种15个群体共226株杨树古树的遗传多样性进行分析,以揭示杨树古树的遗传变异水平及其遗传关系,为该区域杨树古树资源的合理保护与利用提供依据。结果显示:(1)7对SSR引物组合共扩增出80个多态性位点;以有效等位基因数为标准,7种杨树之间的遗传多样性水平依次为:西南杨>昌都杨>康定杨>藏川杨>乡城杨>川杨>德钦杨;杨树种内群体间的遗传多样性依次表现为:乡城杨的稻城群体>乡城群体>雅江群体,西南杨的理塘群体>乡城群体>稻城群体,德钦杨的香格里拉群体>德钦群体,昌都杨的芒康群体>贡觉群体>昌都群体,藏川杨的德钦群体>芒康群体。(2)乡城杨和西南杨群体内近交系数(F_(is))分别为-0.024 6和-0.253 5,藏川杨、德钦杨和昌都杨的Fis分别为0.205 4、0.240 1和0.029 2;乡城杨、西南杨、藏川杨、德钦杨和昌都杨群体间的遗传分化系数(F_(st))分别为0.156 1、0.253 5、0.128 8、0.182 0和0.177 3;除西南杨群体间基因流N_m小于1外,乡城杨、藏川杨、德钦杨和昌都杨群体间的基因流N_m均大于1。(3)7种杨树古树的遗传相似系数介于0.089 0~0.691 0,平均为0.402 0;UPGMA及Bayesian聚类结果均显示,7个树种可以分为3个大组,即川杨与康定杨聚为一组,乡城杨与西南杨聚为一组,藏川杨、德钦杨和昌都杨聚为第3组;5种杨树古树的群体UPGMA聚类结果显示,除西南杨的理塘群体与乡城杨聚为一组外,各杨树古树种与群体间的聚类关系较为紧密。研究表明,西南地区杨树古树具有较为丰富的遗传多样性,且其遗传变异主要均存在于群体内不同个体之间,任何个体的丧失均会导致杨树古树遗传多样性的降低或丧失,故需要加强对该区域现存古树资源的保护。

In order to reveal the genetic variation and relationship of large old poplars,we collected 226 samples on 7 Populus species from 15 populations that distributed in southwest China,and molecular marker of the large old poplars was conducted by SSR technology,which will provide the basis for reasonable protection and utilization of large old poplars in this area.The results showed that：（1）80 polymorphic loci were amplified by 7 pairs of primers.According to the values of the number of effective alleles,the genetic diversity among the large old poplars of 7 Populus species was in the order of P.schneideri〉P.qamdoensis〉 P.kangdingensis〉 P.szechuanica var.tibetica P.xiangchengensis〉 P.szechuanica〉 P.haoana,and the genetic diversity among populations within 5 Populus species were Daocheng population 〉Xiangcheng population 〉Yajiang population in P.xiangchengensis,Litang population 〉Xiangcheng population〉 Daocheng population in P.schneideri,Shangri-la population 〉Deqen population in P.haoana,Markam population〉 Gonjo population 〉Qamdo population in P.qamdoensis,and Deqen population Markam population in P.szechuanica var.tibetica,respectively.（2）The inbreeding coefficient（Fis）within population of P.xiangchengensis,P.schneideri,P.szechuanica var.tibetica,P.haoanaand P.qamdoensis was-0.024 6,-0.253 5,0.205 4,0.240 1 and 0.029 2,respectively.The coefficient of genetic differentiation（F_（st））was 0.156 1,0.253 5,0.128 8,0.182 0 and0.177 3,respectively,among the populations of P.xiangchengensis,P.schneideri,P.szechuanicavar.tibetica,P.haoanaand P.qamdoensis.Gene flow（N_m）among populations of P.xiangchengensis,P.szechuanicavar.tibetica,P.haoanaand P.qamdoensis was more than 1,except P.schneideri.（3）The genetic similarity coefficient among the 7 Populus species was ranged from 0.089 0 to 0.691 0,with the average of 0.402 0.The UPGMA clustering and Bayesian analysis both indicated that the 7 Populus species was divided into three groups.P.schneideri and P.kangdingensis comprised the first group,the second group consists of P.xiangchengensis and P.schneideri,while P.szechuanicavar.tibetica,P.haoanaand P.qamdoensis were at the third group.The UPGMA cluster result among populations revealed that the Litang population of P.schneideri was clustered with P.xiangchengensis,while the populations of other species were clustered closely.These results demonstrated that the large old poplars held high level of genetic variation,and the genetic variation mainly existed in different individuals within population,which means that the genetic diversity of large old poplars will decrease or loss results from the loss of individuals.Thus,it is essential to protect the large old poplar resources distributed in these areas.