Analysis of the genetic diversity and population structure of Tilia amurensis from China using SSR markers: Implications for conservation

Tilia amurensis is a deciduous broad-leaved tree in the Malvaceae family. It is one of the second-class key protected wild plants in China. The evaluation of genetic polymorphisms of crucial protected species is necessary for conserving germplasm resources. In this study, 15 pairs of highly polymorphic SSR primers were used to analyse the genetic diversity of eight T. amurensis populations and the population structure of nine Tilia populations distributed in China. At the population level ( Na = 6.050, Ne = 2.930, I = 1.123, H O = 0.485, H E = 0.523), there was a high level of genetic diversity. The AMOVA results showed that 12 % and 88 % of the total variation occurred among and within populations, respectively. The degree of genetic differentiation was moderate ( F ST = 0.124), and the level of gene flow was high ( N m = 1.763). The results of UPGMA cluster analysis, PCoA and structure analysis (ΔK = 2) revealed different degrees of gene introgression between the eight T. amurensis populations and Tilia japonica as the outgroup. These findings have important implications for formulating appropriate conservation strategies.