Efficient utilization of Populus simonii germplasms through genetic diversity evaluation and superior parent selection using SSR markers

Populus simonii is an ecologically important indigenous tree species in Northern China, yet limited genetic research has constrained its efficient utilization. In this study, the genetic diversity, population structure, and core collection of 274 P. simonii accessions were analyzed using 42 SSR markers. Additionally, elite parental materials were identified through genetic evaluation of 18 newly constructed half-sib families and SSR-based paternity identification of superior seedlings. A total of 338 alleles were detected in the P . simonii germplasm collection, with mean values per locus of 8.024, 2.478, 1.042, 0.445, 0.495, and 0.460 for number of alleles ( N a ), effective number of alleles ( N e ), Shannon’s information index ( I ), observed heterozygosity ( H o ), expected heterozygosity ( H e ), and polymorphism information content ( PIC ), respectively. Three triploid accessions were first discovered in natural populations of P . simonii . STRUCTURE analysis grouped all accessions into three subpopulations (Pop1, Pop2, and Pop3). The Core Hunter subset (55 accessions), integrating high allelic richness with genetic distance metrics, was selected as the representative core collection. Eighteen half-sib families, derived from the open-pollination of flowering female plants, exhibited significant differences in plant height, ground diameter, and internode number, with Psi-120 and Psi-110 having the strongest general combining ability. Twenty-two elite combinations were identified through paternity identification of 200 superior seedlings using 19 SSR markers, and the offsprings from the hybridization of Pop3 females and Pop1 males exhibited strong heterosis. Our study provides valuable information for the efficient utilization and genetic improvement of P . simonii germplasm resources. The genetic diversity of 274 Populus simonii germplasms was comprehensively assessed using 42 SSR markers. A representative core collection with 55 accessions was constructed based on the comparison of Power Core, Core Finder, and Core Hunter methods. Two parents with high general combining ability and 22 promising combinations were identified. Three triploid accessions were first discovered in natural populations of P. simonii .