北沙柳群体遗传多样性和遗传结构分析

以内蒙古北沙柳(Salix psammophila)国家种质资源库内9个群体(P1~P9)288个无性系为实验材料,利用TP-M13-SSR技术,选取22对具有多态性EST-SSR北沙柳引物,采用毛细管电泳对PCR产物进行检测,分析北沙柳遗传多样性、分化程度和群体遗传结构,为北沙柳种质资源库遗传管理、无性系鉴定、品种选育、遗传改良和构建指纹图谱提供理论依据。结果显示:(1)22对EST-SSR引物共检测到222个等位基因,各位点平均等位基因数(A)为10,四倍体基因型丰富度(G)和特异基因型(G1)总和分别为1 460和802个,平均特异基因型比率(P1)和种质鉴别率(P2)分别为45.86%和13.21%。(2)9个群体平均等位基因数(A)为7.475,基因型丰富度(G)为15.586,观察杂合度(Ho)和期望杂合度(He)分别为0.577和0.638。以期望杂合度He为标准,北沙柳群体遗传多样性水平最低的是P1和P9。(3)北沙柳群体遗传分化系数仅为0.02,AMOVA分子变异分析显示,北沙柳群体大部分遗传变异来自群体内(97%),群体间变异仅为3%。(4)三维主成分、聚类和Structure群体遗传结构分析显示,9个群体被划分为2个组,Mantel检验表明北沙柳遗传距离与地理距离极显著相关(r=0.684 P0.001)。研究表明,北沙柳种质资源具有丰富的遗传多样性,这是其具有耐旱、耐寒、耐高温、耐沙埋和抗风蚀等适应性较强的分子基础;北沙柳的遗传变异集中在群体内;分布区群体呈现由中心向边缘群体扩张分化的趋势。

Genetic Diversity and Population Genetic Structure of Salix psammophila

In order to provide scientific and theoretical support for Salix psammophila germplasm management, identify of genets, selective breeding, genetic improvement and fingerprint, we selected 22 pairs of primers with high polymorphism and used capillary electrophoresis to detect PCR products based on TP M13 SSR technique to analysis genetic differentiation and genetic structure of S. psammophila. The results showed that: (1) 22 pairs of EST SSR primers detected a total of 222 alleles, the average number of alleles (A) was 10, the sum of tetraploid genotypic richness(G) and number of unique genotypes (G₁) were 1 460 and 802, the average of rate of unique genotypes (P₁) and rate of identified germplasms (P₂) were 45.86% and 13.21%, respectively. (2) In nine populations, the average number of alleles (A) was 7.475, the genotype richness (G) was 15.586, observed heterozygosity (H_o) and expected heterozygosity (H_e) were 0.577 and 0.638, respectively. Based on the expected heterozygosity (H_e) standard, the highest genetic diversity of populations was P1 and P9. (3) Genetic differentiation coefficient (G_st) was only 0.02. AMOVA molecular variation analysis showed that most of the genetic variation within populations (97%). The variation among populations was only 3%. (4) Three dimensional principal coordinate analysis, cluster and structure analysis showed that 9 populations were divided into 2 groups. Mantel test showed significant correlation of S. psammophila genetic distance and geographic distance (r=0.684 P<0.001). The results showed that the rich of genetic diversity Salix germplasm was the molecular of adaptability, drought resistant, cold resistant, high temperature, strong wind erosion and sand burying; Most of genetic variation were within populations; The distribution population showed a tendency of expansion and differentiation from central to marginal populations.