Abstract:

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.

Key words: Cynomorium songaricum, ITS, genetic diversity, neutral hypothesis