Genetic Diversity and Genetic Relationship Analysis of Platycladus orientalis Germplasm Based on SSR Markers

To investigate the genetic diversity and phylogenetic relationships among Platycladus orientalis germplasm resources in Zaozhuang City, simple sequence repeat (SSR) molecular markers were used to analyze genetic diversity and relatedness in 100 P. orientalis accessions collected from four regions. The results showed that a total of 32 allelic loci were detected using seven pairs of SSR primers, with an average of 6.571 alleles per primer pair. The mean number of alleles (Na) was 3.714, the mean effective number of alleles (Ne) was 1.900, the mean Shannon’s information index (I) was 0.818, and the mean expected heterozygosity (He) was 0.440, indicating relatively high genetic diversity among the 100 sampled P. orientalis accessions. The Fst value was 0.0371, suggesting a high degree of similarity among populations, small genetic distances, and low genetic differentiation. Cluster analysis based on the estimation of the optimal K value showed that the maximum △K occurred at K=3, indicating that the 100 P. orientalis accessions could be divided into three groups rather than clustering strictly according to geographic origin, which implies the existence of gene flow among the sampled populations. Through preliminary screening and repeated validation, seven pairs of SSR primers with clear gel electrophoresis profiles were obtained, which showed stable amplification across all populations and yielded reliable, easily interpretable results. These microsatellite markers provide a useful reference for future studies on the origin and evolution of P. orientalis varieties, molecular identification and classification, hybrid breeding, and parental selection for genetic mapping.