Genetic Diversity and Population Structure of Pinus yunnanensis by Simple Sequence Repeat Markers

Pinus yunnanensis is the main species used for reforestation in Yunnan province, China. To manage the genetic resources of this economically and ecologically important species efficiently, greater knowledge of the distribution of its genetic diversity is needed. In this study, the genetic diversity of 20 natural populations representing most of the P. yunnanensis range was examined using seven simple sequence repeats. No loci showed significant departure from Hardy-Weinberg equilibrium. Most genetic diversity was found within populations, and overall genetic differentiation was low (F-ST = 0.045). There was no sign of isolation by distance. Clustering of populations using both neighbor joining pair groups and principal coordinates analysis based on Nei's genetic distance showed the presence of two major clusters. This result was reinforced using the Bayesian software STRUCTURE, which identified two southern populations as clearly separate from the others. There were no signs of genetic erosion, but some populations should be a focus of conservation efforts because of their higher level of genetic diversity and the presence of private alleles. These results will inform conservation and management of P. yunnanensis and will guide future studies of population genetics and breeding programs.