基于叶绿体基因证据的民族药滇白珠复合群系统发育关系

Phylogeny of an ethnical medicinal plant, Gaultheria leucocarpa var. yunnanensis complex based on chloroplast DNA data

关键词:  滇白珠复合群, 叶绿体DNA, 系统发育, 种内遗传差异, 种内界定, 地理隔离

Key words:  Gaultheria leucocarpa var. yunnanensis complex, cpDNA, phylogeny, intraspecific genetic difference, intraspecific delimitation, geographic isolation

摘要:

滇白珠是我国重要的民族药用植物,广泛分布于长江以南地区,是一个分类困难的复合群。为了探讨其种下分类关系,该文对滇白珠复合群(包括毛滇白珠、秃果白珠和滇白珠3个变种)进行网罗式采样,基本覆盖了该复合群在中国的分布范围,同时包括菲律宾和马来西亚的各1个居群,共计81个居群241个个体,通过联合两个变异位点适中的叶绿体片段rpl33-psaJ和trnL-rpl32,构建基于最大似然法(Maximum Likelihood)和贝叶斯法(Bayesian Inference)的系统发育树,以及Neighbor-Net法构建系统发育网络。结果表明:滇白珠复合群内具有明显的遗传差异,这种差异性相比形态,与地域分布相关性更大。系统发育分析显示,滇白珠复合群分为3个支系。其中:一支包括中国台湾和菲律宾南达沃的居群,为变种秃果白珠,符合前人分类结果; 一支包括分布于横断山脉区域的居群,由变种毛滇白珠和滇白珠组成; 剩余一支包括分布于华东南区域的居群,同样由变种毛滇白珠和滇白珠组成。分子证据支持基于形态分类的秃果白珠作为变种,而不支持毛滇白珠作为变种的处理。这样的遗传分化式样可能是由地理隔离导致,这一结果为民族药滇白珠的种质资源评价和保护利用奠定了分类学框架。然而,变种滇白珠居群间的谱系发生关系却尚未得到很好地解决,特别是无法明晰华东南大部分居群间的遗传分化格局,需要进一步补充样本通过谱系地理学手段,并寻找分辨率更高的核基因分子标记进行更深入的研究。

Abstract:

As an important ethnical medicinal plant in China, Gaultheria leucocarpa var. yunnanensis is a taxonomically difficult complex and widely distributed throughout south of the Yangtze River. In order to understand its intraspecific relationship, we sampled 241 individuals in 81 populations of G. leucocarpa var. yunnanensis complex(i.e., G. leucocarpa var. crenulata, G. leucocarpa var. psilocarpa and G. leucocarpa var. yunnanensis)representing all Chinese varieties and covering almost recorded distribution ranges in China. One population of G. leucocarpa var. psilocarpa from the Philippines and one population of G. leucocarpa var. leucocarpa from Malaysia were also included. Based on the data from two plastid DNA loci with variable sites in appropriate number, i.e., rpl33-psaJ and trnL-rpl32, we reconstructed phylogenetic trees using both Maximum Likelihood and Bayesian Inference methods, and phylogenetic network using Neighbor-Net method. The results were as follows: There was a distinct genetic differentiation in the G. leucocarpa var. yunnanensis complex, and this differentiation was more correlated with geographical distribution rather than morphology. This complex was mainly divided into three clades. One clade was composed of populations from Taiwan of China and the Davao del Sur of Philippines that were previously categorized as G. leucocarpa var. psilocarpa; one clade included populations of the G. leucocarpa var. yunnanensis and G. leucocarpa var. crenulata with a distribution in the Hengduan Mountains region; and the remaining clade included the populations mainly distributed in the southeastern range of China, which was composed of G. leucocarpa var. yunnanensis and G. leucocarpa var. crenulata as well. Molecular evidence supported G. leucocarpa var. psilocarpa was treated as a variety but did not support G. leucocarpa var. crenulata as a variety. Such genetic differentiation pattern may be caused by geographical isolation. This result lays a basic taxonomic framework for the evaluation and protection of germplasm resources for this ethnical medicinal plant. However, the relationships among populations of G. leucocarpa var. yunnanensis has not been well resolved in this study. In particular, it is still unable to clarify genetic differentiation pattern among most populations in Southeast China. Therefore, it is necessary to further carry out phylogeographic study at population level using higher variable nuclear markers in future.