Abstract: Elaeagnus mollis is a nationally protected species under Category Ⅱ conservation status in China. Understanding the genetic diversity and genetic structure can provide a scientific basis for the effective conservation of E. mollis. In this study, we employed whole-genome resequencing to identify single nucleotide polymorphisms across 162 individuals from 24 natural populations of E. mollis distributed in Shanxi, Shaanxi, and Henan provinces. Genetic diversity parameters, including observed heterozygosity (Ho), expected heterozygosity (He), nucleotide diversity, minor allele frequency, and linkage disequilibrium decay, were quantified. Population genetic structure was examined by principal component analysis, phylogenetic tree construction, and ADMIXTURE software. The results showed that genetic diversity of E. mollis was high across populations (Ho=0.294-0.486, He=0.316-0.367). Population clustering and phylogenetic tree analysis revealed that the 24 populations could be divided into three genetic lineages: the Eastern, Southern, and Qinling groups. The Eastern group mainly consisted of populations from Henan Province and the Pinglu, Jiangxian, and Yicheng counties of Shanxi Province. The Southern group primarily comprised populations from Xiangning and Jishan counties in Shanxi Province, while the Qinling group included populations from areas surrounding the Qinling Mountains. Analysis of molecular variance showed that 74.2% of the genetic variation occurred within populations. The isolated habitats and environmental heterogeneity caused by mountainous terrain may contribute to population genetic differentiation in E. mollis. Based on population genetic characteristics, we recommended that the Eastern, Southern, and Qinling groups should be treated as three different genetic units for targeted protection.

Key words: Elaeagnus mollis, endemic plant, genetic structure, genetic diversity, genome resequencing