滇杨种群遗传多样性与遗传结构

滇杨(Populus yunnanensis)是我国西南地区的特有树种, 具有速生、易无性繁殖、适应性强等优良特性, 是典型的南方型杨属树种。研究滇杨遗传多样性及种群结构对其种质资源的收集、保存和利用具有重要的意义。本研究从我国滇杨主要分布区云南和四川共采集了6个种群, 包括云南的昭通(ZT)、会泽(HZ)、嵩明(SM)、洱源(EY)、拉市海(LS)以及四川的美姑(MG), 共64个个体, 利用34对SSR分子标记和3对cpDNA叶绿体标记开展遗传多样性与遗传结构研究。SSR引物共检测到154个等位基因, 平均等位基因数为4.529, 观测杂合度(Ho)与期望杂合度(He)分别为0.552和0.472, 遗传分化系数(Fst)平均值为0.238, 多态性信息含量指数(PIC)平均值为0.421, 基因流(Nm)为0.806。滇杨的遗传结构分析(DAPC)与遗传距离的主坐标分析(PCoA)、UPGMA聚类分析均将6个种群划分为3个亚类: 第?亚类包括昭通种群、会泽种群和嵩明种群的4个个体, 第??亚类包括嵩明种群的6个个体以及洱源种群和拉市海种群, 第III亚类为美姑种群; 嵩明种群包含第?和第??两个亚类的混合遗传成分。3个cpDNA联合序列中共检测到35个变异位点, 分为13个单倍型, 其中单倍型H5在种群中分布最为广泛, 其余的单倍型均为种群特有的单倍型。分子方差分析(AMOVA)表明种群内的遗传变异大于种群间变异。研究表明滇杨不同种群的遗传分化具有地域性, 可选择就地保护; 昭通种群遗传多样性最高, 且包含7种叶绿体单倍型, 单倍型类型最多, 应优先保护。

Genetic diversity and population structure of Populus yunnanensis

Populus yunnanensis is an endemic tree species to Southwestern China. It is a typical southern Populus species that is fast-growing species with easy to clone propagules and is highly adaptable. It is important to research the genetic diversity and population structure of P. yunnanensis for the collection, preservation and utilization of the germplasm resources. In this study, 64 individuals were collected from six populations, spaning the main distribution areas of P. yunnanensis, including Zhaotong (ZT), Huize (HZ), Songming (SM), Eryuan (EY), Lashihai (LS) and Sichuan Meigu (MG). A total of 34 pairs of SSR primers and three pairs of cpDNA primers were used to determine out the genetic diversity and genetic structure. A total of 154 alleles were detected by SSR primers in P. yunnanensis. The average number of alleles was 4.529. The observed heterozygosity (Ho) and expected heterozygosity (He) were 0.552 and 0.472, respectively. And the average genetic differentiation coefficient (Fst) was 0.238. The average polymorphism information content (PIC) was 0.421 and the gene flow (Nm) was 0.806. The results of the DAPC, PCoA and UPGMA analyses showed that the six populations can be divided into three sub-categories: Group ? included ZT, HZ and four individuals of SM. Group II included EY, LS and the six remaining individuals of SM; and group III included MG; SM population include mixed genetic components from ? and ??. A total of 35 variable sites were detected in the three cpDNA combinations, forming 13 haplotypes. Among them, haplotype H5 was the most widely distributed in the population, while the remaining ones were of private haplotypes. Analysis of molecular variance (AMOVA) showed that genetic variation within the population was greater than between populations. The study clarifies that P. yunnanensis has geographical distribution characteristics and is suited to in situ conservation. As ZT population has the highest genetic diversity and contains seven chloroplast haplotypes, it should be given protection priority.