Genetic Diversity and Structure of Pinus densiflora Siebold & Zucc. Populations in Republic of Korea Based on Microsatellite Markers

Pinus densiflora Siebold & Zucc. is a widely distributed conifer species in the Republic of Korea with economic and ecologic importance. However, P. densiflora is negatively influenced by various factors, such as forest fires, clearing of large numbers of trees infected with Pinus disease, and dieback. We aimed to use microsatellite markers to estimate the genetic diversity, differentiation, and structure of P. densiflora populations in the Republic of Korea. A total of 1844 samples from 60 populations were evaluated using 11 polymorphic microsatellite markers. The observed heterozygosity and expected heterozygosity were 0.652 and 0.673, respectively. The mean genetic differentiation among the populations was 0.013. Moreover, P. densiflora showed high genetic diversity and low genetic differentiation compared with conifer species, including Pinus species with similar life histories. Principal coordinates analysis and Bayesian clustering showed that P. densiflora has a weak geographical structure. The P. densiflora population at Mt. Halla, Jeju Island, showed the lowest genetic diversity and significant genetic differentiation compared with other mainland populations due to genetic drift and restricted gene flow. These findings can be useful for designing new conservation, management, and breeding strategies for P. densiflora populations in response to future environmental changes.