Genetic diversity and its conservation implications of Vitex rotundifolia (Lamiaceae) populations in East Asia.

Yiqi Sun,Shichao Chen,Pan Li,Qiaoyan Zhang,Luping Qin,Tingguo Kang,Khalid Rahman,Hong Yang,Joongku Lee,Min Jia

doi:10.7717/peerj.6194

Abstract

Vitex rotundifolia is an important coastal and medicinal plant, and is recorded in the List of the Important Wild Plants for Conservation in China and Japan. However, an effective conservation strategy is lacking. In the present study, the genetic diversity and population structure were analyzed using phylogeographical methods based on the trnH-psbA and trnG-trnS intergenic spacers of the chloroplast DNA (cpDNA) sequences from 157 individuals from 25 sampling sites for V. rotundifolia and V. trifolia plus the internal transcribed spacer (ITS) of the nuclear ribosomal DNA (nrDNA) sequences of 177 individuals from 27 sampling sites. The results showed that V. rotundifolia and V. trifolia had eight cpDNA and two nrDNA haplotypes, respectively, and the V. rotundifolia has a low level of genetic diversity (haplotype diversity hd,cp = 0.360, hd,nr = 0.440), a more pronounced genetic differentiation among populations (population differentiation at the species level (GST) = 0.201, population differentiation at the allele level (NST) = 0.462), and an insignificantly different phylogeographical structure (NST > GST, P > 0.05). In addition, haplotype network analyses indicated that V. rotundifolia and V. trifolia have distinct haplotypes. Divergence dating based on BEAST software analyses showed that most cpDNA clades diverged in the late Pleistocene era. Demographic analysis indicated that V. rotundifolia underwent a rapid demographic expansion. Some scientific strategies are suggested for resource conservation of V. rotundifolia based on its genetic diversity and population structure.

Highlights

Vitex rotundifolia, which often grows on beaches and sand dunes, is a widely distributed shoreline shrub of the family Lamiaceae, (Cantino, 1992; Harley et al, 2004; Cousins et al, 2010)
The results found that V. rotundifolia and V. trifolia populations each had a relatively smooth unimodal distribution, which was consistent with distribution under an exponential growth rate (Fig. 7), indicating that the two species had a rapid demographic expansion
Based on the chloroplast DNA (cpDNA) data, the results showed that all populations of V. rotundifolia and V. trifolia had a significant phylogeographical structure (GST = 0.436, NST = 0.751; NST >GST, P

Summary

Introduction

Vitex rotundifolia, which often grows on beaches and sand dunes, is a widely distributed shoreline shrub of the family Lamiaceae, (Cantino, 1992; Harley et al, 2004; Cousins et al, 2010). V. rotundifolia plays an important ecological role in stabilizing sand dunes in coastal areas (Gresham & Neal, 2004; Kim, 2005). The fruit of V. rotundifolia, known as Manjingzi, is a herbal medicine commonly used in China and Japan to prevent and treat colds, headache, and migraine (Sung et al, 1996). The increased use of the plant as a medical resource, coastal overexploitation, and environmental destruction, have accelerated the degradation of V. rotundifolia populations, decreased the intraspecific variation, severely destroyed its natural habitats, and even threatened the survival of the species. Given the vulnerability of V. rotundifolia, it has been recorded in the List of the Important Wild Plants for Conservation in China and Japan (Endangered Species Scientific Commission, P.R.C., 2018; Ohtsuki et al, 2014). It is necessary to provide an effective conservation strategy for this species

Methods

Results

Discussion

Conclusion