Genetic structure variation of Pinus tabuliformis plantations in Beijing and the differences with Shanxi mountain populations

ObjectiveThe purpose of this study was to reveal the genetic diversity, genetic structure and genetic relationship of Pinus tabuliformis populations in Beijing, and to explore the impact of introduced land on population genetic structure and growth, and to provide references for the cultivation and germplasm resource management of P. tabuliformis in Beijing.

MethodBased on 7 pairs of highly and stable polymorphically nuclear genomic EST-SSR primers, the population genetic diversity, genetic structure and genetic distance were analyzed among 8 P. tabuliformis populations planted in last century in Beijing, 3 ancient P. tabuliformis populations and 5 mountain populations from Shanxi Province of northern China.

ResultThe genetic structure difference ( F_ST = 0.066) was the maximum among Beijing plantation populations, the second was population from Shanxi Province (F_ST = 0.033), and the lowest was ancient populations (F_ST = 0.023). Both of the Beijing populations and ancient populations deviated from Hardy-Weinberg equilibrium and showed heterozygote excess, and the maximum heterozygote excess was in ancient P. tabuliformis populations. All of the populations could be clustered into 3 categories when genetic distance was 0.020 based on genetic distance analysis, showing near genetic distances among different populations, the level of evolutionary divergence and genetic differentiation were relatively low. The EST-SSR loci site amplification frequency of J10, J20, J42 and J50 in Beijing populations, ancient P. tabuliformis and Shanxi populations showed significant differences, which could be used for source tracing for unknown provenances.

ConclusionThe Beijing populations of P. tabuliformis have richer genetic diversity and higher genetic differentiation than ancient P. tabuliformis; some introduced provenances eventually phased out because of the difference in fitness under stress environment, resulting in the genetic structure has a certain amount of change for the retained population. Our study provides important theoretical foundation for the follow-up studies on the evaluation, cultivation and germplasm management of P. tabuliformis populations in Beijing.