Background: Cultivation of medicinal plants is not only a means for meeting current and future demands for large volume production of plant-based drug and herbal remedies, but also a means of relieving harvest pressure on wild populations.Scutellaria baicalensisGeorgi (Huang-qin or Chinese skullcap) is a very important medicinal plant in China. Over the past several decades, wild resource of this species has suffered rapid declines and large-scale cultivation was initiated to meet the increasing demand for its root. However, the genetic impacts of recent cultivation onS. baicalensishave never been evaluated. In this study, the genetic diversity and genetic structure of 28 wild and 22 cultivated populations were estimated using three polymorphic chloroplast fragments. The objectives of this study are to provide baseline data for preserving genetic resource ofS. baicalensisand to evaluate the genetic impacts of recent cultivation on medicinal plants, which may be instructive to future cultivation projects of traditional Chinese medicinal plants.Results: Thirty-two haplotypes ofS. baicalensis(HapA-Y and Hap1-7) were identified when three chloroplast spacers were combined. These haplotypes constituted a shallow gene tree without obvious clusters for cultivated populations, suggesting multiple origins of cultivatedS. baicalensis. Cultivated populations (h_T= 0.832) maintained comparable genetic variation with wild populations (h_T= 0.888), indicating a slight genetic bottleneck due to multiple origins of cultivation. However, a substantial amount of rare alleles (10 out of 25 haplotypes within wild populations) lost during the course ofS. baicalensiscultivation. The genetic differentiation for cultivated group (G_ST= 0.220) was significantly lower than that of wild group (G_ST= 0.701). Isolation by distance analysis showed that the effect of geographical isolation on genetic structure was significant in wild populations (r= 0.4346,P< 0.0010), but not in cultivated populations (r =0.0599,P= 0.2710). These genetic distribution patterns suggest that a transient cultivation history and the extensive seed change among different geographical areas during the course ofS. baicalensiscultivation.Conclusions: Although cultivatedS. baicalensismaintains comparable genetic diversity relative to wild populations, recent cultivation has still imposed profound impacts on genetic diversity patterns of the cultivatedS. baicalensispopulations, i.e., the loss of rare alleles and homogenization of cultivated populations. This study suggests that conservation-by-cultivation is an effective means for protecting genetic resources ofS. baicalensis, however, the wild resources still need to be protectedin situand the evolutionary consequences of extensive seed exchange mediated by human being should be monitored carefully.

Mountains have not only provided refuge for species, but also offered dispersal corridors during the Neogene and Quaternary global climate changes. Compared with a plethora of studies on the refuge role of China’s mountain ranges, their dispersal corridor role has received little attention in plant phylogeographic studies. Using phylogeographic data of Eomecon chionantha Hance (Papaveraceae), this study explicitly tested whether the Nanling Mountains, which spans from west to east for more than 1000 km in subtropical China, could have functioned as a dispersal corridor during the late Quaternary in addition to a glacial refugium. Our analyses revealed a range-wide lack of phylogeographic structure in E. chionantha across three kinds of molecular markers [two chloroplast intergenic spacers, nuclear ribosomal internal transcribed spacer (nrITS), and six nuclear microsatellite loci]. Demographic inferences based on chloroplast and nrITS sequences indicated that E. chionantha could have experienced a strong postglacial range expansion between 6000 and 1000 years ago. Species distribution modelling showed that the Nanling Mountains and the eastern Yungui Plateau were the glacial refugia of E. chionantha. Reconstruction of dispersal corridors indicated that the Nanling Mountains also have acted as a corridor of population connectivity for E. chionantha during the late Quaternary. Our results suggest that the Nanling Mountains may acted dual roles as a dispersal corridor in east-west direction and as a glacial refugium in subtropical China during the late Quaternary. The population connectivity mediated by the mountain range and a strong postglacial range expansion are the most likely reasons for the lack of phylogeographic structure in E. chionantha. The hypothesis of dual roles of the mountain range presented here sheds new insights into the phylogeographic patterns of organisms in subtropical China.