为阐明锁阳(Cynomorium songaricum)的遗传结构与遗传多样性, 以甘肃省河西走廊地区及青海省共18个居群的188个锁阳个体为研究对象, 利用现代分子生物学技术, 采用序列分析方法从核-质基因方面对遗传结构进行了分析。结果显示, 锁阳ITS序列总长度为687 bp, 含有7个变异位点, 定义9个单倍型, 整体单倍型多态性H_d=0.294 20, 核苷酸多样性π=0.000 49。在整个单倍型网络中介图中, 单倍型H1位于中心位置, 并在所有的居群中均有分布, 为核心的古老单倍型。分子方差分析结果显示, 锁阳种群变异主要来源于种群内。根据ITS序列得到的群体间遗传分化系数以及Mantel检验结果, 锁阳种群间的遗传距离与地理距离之间不存在相关性, 表明现存的锁阳居群是相对近期发生生境片段化的产物。中性检验结果表明, 锁阳拒绝中性进化, 群体历经扩张或者基因座位受到负选择作用, 其中性零假说不能被排除。该研究为锁阳的系统分类、资源鉴定以及保护措施的制定提供了分子证据。

To elucidate the genetic structure and genetic diversity of Cynomorium songaricum, modern molecular biology techniques at the DNA level were used to study the genetic structure of 188 C. songaricum individuals from 18 wild populations in the Hexi Corridor Region of Gansu and Qinghai. After alignment, all amplified sequence lengths were 687 bp. The 687 bp ITS sequence detected 7 mutation sites in 188 individuals, defining 9 haplotypes. Processing these 9 haplotype sequences led to a data matrix for calculating the haplotype diversity (H_d=0.294 20) and nucleotide diversity (π=0.000 49). In the haplotype network map, H1 is located in the center and distributed in all populations, and is the ancient and core haplotype. AMOVA revealed that the variation in C. songaricum mainly occurs in populations. According to the genetic differentiation coefficient and Mantel test of ITS sequences, we found no significant relation between genetic and geographic distances, so the current distribution of C. songaricum represents the fragmentation product in recent time. Detection of historical expansion of populations showed that the Tajima’s D test rejected a neutral mutation evolution, and the population expansion history or gene locus is under negative selection pressure, so the null hypothesis cannot be ruled out. Our study provides molecular evidence for the classification system, identification and protection measures of C. songaricum.