Limited genetic diversity and high differentiation in Angelica dahurica resulted from domestication: insights to breeding and conservation

BACKGROUND: Angelica dahurica belongs to the Apiaceae family, whose dry root is a famous traditional Chinese medicine named as “Bai zhi”. There are two cultivars (A. dahurica cv. ‘Hangbaizhi’ and A. dahurica cv. ‘Qibaizhi’), which have been domesticated for thousands of years. Long term artificial selection has led to great changes in root phenotypes of the two cultivars, and also decreased their adaptability to environment. We proposed hypothesis that the cultivars may have lost some of the genetic diversity found in the wild species and may be highly differentiated from the latter during the domestication process. However, few studies have been carried out on how domestication affected the genetic variation of this species. Here, we accessed the levels of genetic variation and differentiation within and between wild A. dahurica populations and two cultivars using 12 microsatellite markers. RESULTS: The results revealed that the genetic diversity of the cultivars was much lower than that of wild A. dahurica, and A. dahurica cv. ‘Qibaizhi’ had lower genetic diversity compared to A. dahurica cv. ‘Hangbaizhi’. AMOVA analysis showed significant genetic differentiation between the wild and cultivated A. dahurica populations, and between A. dahurica cv. ‘Hangbaizhi’ and A. dahurica cv. ‘Qibaizhi’. Results from Bayesian, UPGMA, NJ and PcoA clustering analysis indicated that all 15 populations were assigned to two genetic clusters corresponding to the wild and cultivated populations. Bayesian clustering analysis further divided the cultivated populations into two sub-clusters corresponding to the two cultivars. CONCLUSIONS: Our study suggests that the domestication process is likely the major factor resulting in the loss of genetic diversity in cultivated A. dahurica populations and in significant genetic differentiation from the wild populations due to founder effect and/or artificially directional selections. This large-scale analysis of population genetics could provide valuable information for genetic resources conservation and breeding programs of Angelica dahurica.