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林业科学 ›› 2018, Vol. 54 ›› Issue (2): 30-41.doi: 10.11707/j.1001-7488.20180204

• 论文与研究报告 • 上一篇    下一篇

基于SSR标记的西藏光核桃群体遗传多样性和遗传结构分析

包文泉1, 乌云塔娜2, 杜红岩2, 李铁柱2, 刘慧敏2, 王淋2, 白玉娥1   

  1. 1. 内蒙古农业大学林学院 呼和浩特 010018;
    2. 中国林业科学研究院经济林研究开发中心 郑州 450003
  • 收稿日期:2017-10-25 修回日期:2017-11-26 出版日期:2018-02-25 发布日期:2018-03-30
  • 基金资助:
    国家"十二五"科技支撑课题"仁用杏和巴旦杏高效生产研究与示范"(2013BAD14B02)。

Genetic Diversity and Population Structure of Amygdalus mira in the Tibet Plateau in China Based on SSR Markers

Bao Wenquan1, Wuyun Tana2, Du Hongyan2, Li Tiezhu2, Liu Huimin2, Wang Lin2, Bai Yu1   

  1. 1. College of Forestry, Inner Mongolia Agricultural University Hohhot 010018;
    2. Non-Timber Forest Research and Development Center, Chinese Academy of Forestry Zhengzhou 450003
  • Received:2017-10-25 Revised:2017-11-26 Online:2018-02-25 Published:2018-03-30

摘要: [目的]利用SSR标记深入研究西藏光核桃的遗传多样性及遗传结构,揭示其遗传结构与地理分布、海拔梯度等的相关性,为西藏光核桃资源的有效利用与科学保护提供理论依据。[方法]利用25对SSR引物,分析西藏地区21个光核桃天然群体420份个体的遗传多样性和遗传结构。应用GenAlEx 6.501、Arlequin v3.1、NTSYS pc version 2.10、STRUCTURE、STRUCTURE Harvester、CLUMP和Distruct等软件进行遗传参数估算、主坐标分析、遗传变异分析、聚类图构建及遗传结构分析。[结果]基于25个SSR分子标记的遗传多样性分析表明,西藏光核桃群体遗传多样性和近亲繁殖水平适中,其平均等位基因数(Na)、有效等位基因数(Ne)、期望杂合度(He)、观察杂合度(Ho)、Shannon's信息指数(I)和近交系数(F)分别为3.8、2.5、0.52、0.44、0.95和0.17,其中,P17群体遗传多样性最高(Ne=4.7,He=0.63,Ho=0.56,I=1.57),而P18群体遗传多样性最低(Ne=1.7,He=0.30,Ho=0.22,I=0.49)。西藏光核桃的贝叶斯遗传结构分析(STRUCTURE)与遗传距离的主坐标分析(PCoA)、UPGMA聚类分析结果基本一致,均将供试420份光核桃个体划分为3个类群,其分组结果具有明显的地理区域特性。Mantel检测显示遗传距离与地理距离(r=0.50,P < 0.01)、海拔梯度(r=0.61,P < 0.01)呈显著正相关。分子方差分析(AMOVA)显示,16.3%的遗传变异来自群体间,群体间的遗传分化水平为中等,而大部分遗传变异(83.7%)来自群体内。[结论]西藏光核桃遗传多样性适中,群体间存在地理隔离效应和海拔梯度的遗传变异,其遗传分化程度较高,这可能源于西藏光核桃生境片段化、海拔梯度的影响以及山脉阻隔引起的地理隔离效应。西藏光核桃受人为干扰较严重,且个体间的近亲繁殖较频繁,若不及时采取保护措施,其遗传多样性将会逐渐降低。基于遗传结构分析,确定西藏光核桃3个保护单元,并建议限制人为活动对其破坏,实施就地保护的同时,促进不同居群间的基因交流,保护西藏光核桃的遗传多样性。

关键词: 光核桃, 西藏, 遗传多样性, 遗传结构, SSR

Abstract: [Objective] In order to provide a theoretical basis for effective conservation and rational utilization of Amygdalus mira resources in Tibet, genetic diversity and population structure of 21 populations of A. mira were studied using SSR markers, and correlation between genetic structure and geographical distribution, altitudinal gradient were also analyzed.[Method] A total of 420 individuals from 21 populations were assayed by 25 pairs of SSR primers. Genetic diversity parameters, principal coordinates analysis (PCoA), and analysis of molecular variance (AMOVA) were carried out using GenAIEx 6.5 and Arlequin v3.1 software. NTSYS software was used for cluster analysis based on the matrix of Nei's genetic distance. STRUCTURE, STRUCTURE Harvester, CLUMP, and Distruct software were used to analyze genetic structure.[Result] Result showed that both genetic diversity and inbreeding were moderate within A. mira populations. The average number of alleles, effective number of alleles, expected heterozygosity, observed heterozygosity, Shannon's information index, and inbreeding coefficient were 3.8, 2.5, 0.52, 0.44, 0.95, and 0.17, respectively. The highest level of genetic diversity was in the P17 population (Ne=4.7, He=0.63, Ho=0.56, and I=1.57), while the lowest was in the P18 population (Ne=1.7, He=0.30, Ho=0.22, and I=0.49). According to STRUCTURE, Principal coordinates analysis (PCoA) and UPGMA cluster analysis, 420 individuals could be divided into three genetic clusters, which were significantly correlated with geographic altitudes. Mantel test showed that the genetic distance among the populations was significantly correlated with geographic distance (r=0.50, P<0.01) and geographic altitude (r=0.61, P < 0.01). AMOVA analysis showed that 16.3% genetic variation was among the populations, which indicate that the level of genetic differentiation among population is moderate, while, a high genetic variation (83.7%) was within populations.[Conclusion] It was suggested that the genetic diversity of A. mira in Tibet plate was moderate. The impact of geographical isolation and elevation gradients on genetic diversity was shown within populations. The degree of genetic differentiation was high, which could be due to the habitat fragmentation, elevation gradient, and the mountains block that caused by the effect of geographical isolation. The natural resources of A. mira in Tibet was seriously disturbed by human activities, and inbreeding among individuals was frequent. Therefore, the genetic diversity will gradually decrease if protection measures are not taken in time. Based on the genetic structure analysis, three protection units of A. mira in Tibet have been determined, and the human activities should be prevented. We suggest that it be conserved in situ and the exchange of genes between different groups should be promoted to protect the genetic diversity of A. mira in Tibet.

Key words: Amygdalus mira, Tibet, genetic diversity, genetic structure, SSR

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