Genetic diversity and structure of Lilium pumilum DC. in southeast of Qinghai–Tibet plateau

Lilium pumilum DC. is a valuable species not only for its showy flowers but also for its edible and medicinal values. As one of the distribution areas of L. pumilum, Qinghai–Tibet plateau has unique environmental features which have high impact on the evolution of the species. No population genetic studies have been done for L. pumilum so far. To provide the first reference data for evolutionary study and understanding the influence of eco-geographic factors on the distribution of genetic variation in L. pumilum, interspecific simple sequence repeat markers were used to investigate genetic diversity and population structure of 28 populations sampled from southeast of Qinghai–Tibet plateau. Fifteen selected primers generated a total of 147 polymorphic bands. The genetic diversity was low within populations (average He = 0.173), but higher at the species level (He = 0.392). A clear population structure and high level of genetic differentiation (F ST = 0.518) were detected by unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. All clustering approaches supported a division of the 28 populations into 4 major groups for which analysis of molecular variance confirmed a significant variation among groups (34.3 %). These population genetic parameters suggest limited gene flow among populations and evidence for isolation by distance (r = 0.272, P < 0.0001) was found in this study. Altitude, AMT and AMP explained 9.5, 11.5 and 14.0 % of the total variance among populations indicating that eco-geographic factors have a significant effect. Considering the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve L. pumilum in Qinghai–Tibet plateau.