Genetic Diversity and DNA Fingerprinting of Prunus davidiana Germplasm in Gansu Province Using SSR Markers

Prunus davidiana Franch. is an important wild relative of cultivated peach and a source of stress-resistance germplasm. The genetic resources of this species in Gansu Province, which spans complex topography and climatic transition zones, have long lacked systematic evaluation. Here, 110 P. davidiana accessions from Gansu Province were genotyped with 20 highly polymorphic SSR markers to assess genetic diversity and population structure and to construct DNA fingerprints. The analyzed collection showed high diversity (mean number of alleles, Na = 22.1; expected heterozygosity, He = 0.945; and polymorphism information content, PIC = 0.938). Bayesian clustering and complementary ordination indicated only weak, largely continuous subdivision: although the ΔK method nominally selected four clusters, the mean silhouette coefficient was low (0.0396 at K = 2), locus-bootstrap stability was moderate to low (mean adjusted Rand index = 0.407), and the first two PCoA axes accounted for only 9.88% of the variation. Mean Fst was 0.035, and analysis of molecular variance (AMOVA) attributed 92.75% of the variation to within-individual differences. For fingerprinting, no duplicate, unresolved or near-match pairs were detected among the 5995 accession pairs, and a minimal three-locus panel (DW344741F, DW345934F, BU041198R) resolved all pairs within this collection. These results provide the first systematic characterization of the genetic diversity and population structure of P. davidiana germplasm in Gansu Province and a candidate identification tool for the analyzed collection, pending validation in independent material.