甘草的遗传多样性和谱系地理结构的研究

Genetic diversity and phylogeographic structure of Glycyrrhiza uralensis

关键词:  甘草，ITS序列，cpDNA序列，地理分布格局，谱系地理学

Key words:  Glycyrrhiza uralensis, ITS sequence, cpDNA sequence, geographical distribution pattern, phylogeography

摘要:

为了揭示甘草（Glycyrrhiza uralensis）的遗传多样性和谱系地理结构，该研究基于ITS和3段叶绿体基因（matK、psbA-trnH和trnS-trnG）序列对20个甘草居群100份样本进行扩增后测序，并对数据进行分析。结果表明：（1）ITS序列长度为691 bp，包含63个变异位点，单倍型多样性为0.265，核苷酸多样性为0.002 69；cpDNA序列长度为1 976 bp，包含740个变异位点，单倍型多样性为0.907，核苷酸多样性为0.026 39。在物种水平上均表现出较高的遗传多样性。（2）分子方差分析结果表明甘草的遗传分化主要来源于居群内，居群间遗传分化水平较低，基因流（Gene flow, Nm）较高（ITS：Nm=1.349；cpDNA：Nm=1.520）。（3）通过比较遗传分化系数（Nst与Gst），发现甘草居群不存在明显的谱系地理结构。中性检验结果与失配分析曲线表明甘草居群整体并未经历扩张事件。（4）由单倍型地理分布图分析得到，陕西、青海、新疆、内蒙古和甘肃地区甘草的单倍型多样性较高，且位于地理分布图中心位置，故可能为甘草在中国西北和华北地区的冰期避难所。该研究通过不同的DNA条形码对甘草的遗传多样性和地理分布格局进行了解析，为今后甘草的种质资源的保护与合理利用提供了一定的理论依据。

Abstract:

To reveal the genetic diversity and phylogeographic structure of Glycyrrhiza uralensis, this study amplified and sequenced 100 samples from 20 populations of G. uralensis using ITS and three chloroplast gene sequences (matK, psbA-trnH, and trnS-trnG), and analyzed the data. The results were as follows: (1) The ITS sequence length was 691 bp, containing 63 mutation sites, with a haplotype diversity of 0.265 and a nucleotide diversity of 0.002 69; The cpDNA sequence length was 1 976 bp, containing 740 mutation sites, with a haplotype diversity of 0.907 and a nucleotide diversity of 0.026 39. These findings demonstrate high genetic diversity at the species level. (2) Molecular variance analysis revealed that the genetic differentiation of G. uralensis primarily occurred within populations, with low levels of genetic differentiation between populations and high gene flow (ITS: Nm=1.349; cpDNA: Nm=1.520). (3) Comparsion of genetic differentiation coefficients (Nst and Gst) indicated that there was no significant phylogeographic structure within the G. uralensis populations. Neutral tests and mismatch analysis suggested that the overall G. uralensis population did not experience expansion events. (4) Haplotype geographical distribution analysis revealed that G. uralensis in Shaanxi, Qinghai, Xinjiang, Inner Mongolia and Gansu exhibits high haplotype diversity and is located at the center of the geographical distribution map, suggesting that this region may have served as a refuge for G. uralensis during the Ice Age in northwest and North China. The study analyzed the genetic diversity and geographical distribution patterns of G. uralensis using different DNA barcodes, providing a theoretical basis for the conservation and rational utilization of G. uralensis germplasm resources in the future.