Study on genetic diversity and distribution patterns of Bupleurum dracaenoides Huan C. Wang, Z. R. He & H. Sun

Bupleurum dracaenoides Huan C. Wang, Z. R. He & H. Sun is a recently published species characterized by a woody stem up to 1.5 m in height. It is the only woody species of the genus Bupleurum found in Asia and is endemic to the dry-hot valleys of the Jinsha River. The distribution of B. dracaenoides is quite narrow, with only a few populations found in the Pudu River area of Yunnan Province and Huidong County of Sichuan Province. It is a critically endangered species, with a limited number of individuals and threatened wild habitat. Thus, assessing its genetic diversity and distribution patterns is urgent for the protection of its wild resources. In this study, 153 individuals were studied using seven chloroplast DNA fragments and two nuclear DNA fragments to investigate the genetic diversity and distribution within and among eight populations of B. dracaenoides. Based on chloroplast DNA data analysis, B. dracaenoides showed high genetic diversity at the species level (H_d=0.862; P_i=0.00567), and genetic variations were mostly distributed among populations (F_st=0.959). However, genetic diversity at the species level was relatively low based on ITS and PZ8 (ITS:H_d=0.532, P_i=0.00121;PZ8:H_d=0.349, P_i=0.00060), and genetic variations were mostly distributed within populations (ITS:F_st=0.475; PZ8:F_st=0.093). Neutral test and mismatch distribution analyses of the chloroplast DNA, ITS, and PZ8 data indicated that B. dracaenoides has not experienced recent population expansion. STRUCTURE analysis of the combined nuclear DNA sequencing data revealed that all 153 individuals were grouped into two genetic clusters.