Analysis of Genetic Diversity in Different Artemisia frigida Willd. Populations by SSR Method

Artemisia frigida, also named as “Xiaobaihao” or “Tumaohao”, belongs to the genus of Artemisia in composite family. It is a small shrub, distributes widely in Inner Mongolia and northern part of China. Mongolians use it as medicine, and call it “Agi”. This plant has the power of stanch, detumescence, and was well applied in the cure of bleeding, arthroncus, and so on. It is an important component of “artificial holy one” of Mongolians. Besides its medical efficacy, it is also valued as a very important feeding resource, and a remarkable component of desert ecosystem. In this study, 24 populations of Artemisia frigida were collected from 5 habitats (forest steppe, typically steppe, meadow steppe, sandy land, desert steppe) to understand the genetic diversity of Artemisia frigida in different habitats. 30 samples were collected from each population with a total of 720 samples. The populations from forest steppe (L-1, L-2, L-3, L-4, L-5), typically steppe (D-1, D-2, D-3, D-4, D-5), meadow steppe (C-1, C-2, C-3, C-4, C-5), and sandy land (S-1) were located in Hulunbuir grassland in Inner Mongolia. The populations from sandy land (S-2, S-3, S-4), and desert steppe (H-1, H-2, H-3, H-4, H-5) were located in Xilingol grassland. Out of 38 SSR loci from Artemisia annual, 10 informative polymorphic SSR loci were analyzed, resulting in a total of 56 alleles with the polymorphic loci percentage of 100%. The expected heterozygosity He (0.5361~0.6817), observed heterozyogsity Ho (0.3299~0.5769), and polymorphic information content PIC index (0.4714~0.6153) were relatively high, implying high genetic diversity in each population. In addition, the degree of genetic diversity also differ between populations, with the order of Hulunbuir grassland (He=0.6361, Ho=0.4514, PIC=0.5684), Xilingol grassland (He=0.6672, Ho=0.4994, PIC=0.5375). And between the different habitats, the genetic diversity of Artemisia frigida populations from typical steppe (He=0.6009, Ho=0.4457, PIC=0.5373) was higher than that of any other habitats. Fst of 24 populations were 0.014~0.314, the index between populations L-1 and L-2, L-3 and L-4 was lowest, which was 0.014, so L-1 and L-2, L-3 and L-4 had closest relationship. Populations C-4 and H-4 were farthest, with Fst 0.314. Our study also indicated that gene flows exist between populations and genetic drift was not the factors that caused differentiation. It could be speculated that Artemisia frigida populations may be originated from typically steppe, and later to sandy land, meadow steppe and desert steppe, given the closer evolutionary relationship between typical steppe and sandy land, forest steppe and meadow steppe. High genetic diversity could be related to the adoption of plants to the dry and grazing environmental conditions. This study provides the foundation to understand the genetic basis of Artemisia frigida species, and promotes its further development and utilization as medical plants. KEY WORDS: Artemisia frigida, genetic diversity, SSR