目的 研究绞股蓝Gynostemma pentaphyllun的遗传多样性和群体遗传结构, 为绞股蓝植物资源的保护和合理利用提供理论依据。方法 利用6对SSR引物对绞股蓝28个自然居群426份个体进行研究, 计算遗传参数, 分析遗传多样性, 进行聚类分析。结果 绞股蓝遗传多样性水平较低:平均多态性位点比率(PPL)为58.33%, Nei's遗传多样性指数(H_e)平均为0.18, Shannon指数(I)在0.02～0.50。AMOVA揭示遗传变异主要存在于居群间(居群间变异78.86%, 居群内变异21.14%), 居群遗传分化(F_ST=0.673)明显, 基因流水平(N_m=0.142)较低。聚类分析表明不同倍性的居群间遗传关系较为明显。结论 绞股蓝自然居群遗传多样性较低, 群体遗传结构清晰;建议对绞股蓝遗传多样性水平较高的居群进行原地保护, 同时对一些包含特有基因型的居群进行原地和迁地重点保护。

Objective The genetic diversity and population structure of Gynostemma pentaphyllun were investigated to give the rise to theoretical foundation for its resources protection and rational utilization. Methods Six pairs of SSR primers were screened in 28 natural populations of 426 individuals to calculate the genetic parameters of G. pentaphyllun, and further then cluster analysis was carried out. Results The genetic diversity of G. pentaphyllun was low: the average value of the percentage of polymorphic loci (PPL) and Nei's genetic diversity index (H_e) was 58.33% and 0.18, respectively. The values of Shannon index (I) within different populations were ranged from 0.02 to 0.50. AMOVA revealed that genetic variation mainly existed among the populations (inter-populations was 78.86%, intra-populations was 21.14%). Furthermore, it possessed the significant population genetic differentiation (F_ST = 0.673) with low level of gene flow (N_m = 0.142). The outcomes of cluster analysis indicated there were distinct genetic relationships and genetic structures within different ploidys of G. pentaphyllun. Conclusion The populations of G. pentaphyllun exist a low level of genetic diversity and clear genetic structure. We suggest that it is necessary to employ in-situ conservation for the natural populations of G. pentaphyllun with higher genetic diversity, while for the populations which contain specific genotypes, it is better to combine ex-situ conservation with in-situ conservation in protection.

国家自然科学基金资助项目(31270364)