Genome-Wide SNP Analysis Reveals Population Structure and Genetic Diversity in Lycium ruthenicum Murr

<i>Lycium ruthenicum</i> Murr. (Black goji), a medicinal and economically valuable crop rich in bioactive compounds, remains genomically understudied despite its expanding cultivation. To overcome limitations of traditional markers in genetic diversity analysis and molecular breeding, we employed specific-locus amplified fragment sequencing (SLAF-seq) to develop genome-wide SNP markers and elucidate the genetic structure of 213 <i>L. ruthenicum</i> accessions from natural and cultivated populations in Alxa, China. We identified 827,630 SLAF tags and 33,121 high-quality SNPs uniformly distributed across 12 chromosomes, establishing the first high-density SNP database for this species. Population genetic analyses revealed three distinct genetic clusters with <60% geographic origin consistency, indicating weakened isolation due to anthropogenic germplasm exchange. The Qinghai Nuomuhong population exhibited the highest genetic diversity (Nei's index = 0.253; Shannon's index = 0.352), while low overall polymorphism (average PIC = 0.183) likely reflects SNP biallelic limitations and domestication bottlenecks. Notably, SNP-based clustering showed <40% concordance with phenotypic trait clustering (31 traits), underscoring environmental plasticity as a key driver of morphological variation. This study provides the first genome-wide SNP resource for <i>L. ruthenicum</i>, enabling marker-assisted breeding and highlighting the need for standardized germplasm management to mitigate genetic erosion.