Utilizing SSR-based core collection development to improve conservation and utilization of Corylus L. genetic resources

Hazelnuts are traditional woody oilseed plants. Corylus L. resources are rich in variety and widely distributed in China. However, the identification of germplasm varieties and the selection of superior varieties remain quite limited. This study aimed to analyze the genetic diversity of 331 Corylus L. germplasms using 16 simple sequence repeat (SSR) markers. Based on this, 11 pairs of core primers were selected, a fingerprint database of germplasm resources was constructed, and a primary core collection was screened. The results indicated that these tested Corylus L. germplasms exhibited a high level of genetic diversity, with an average number of alleles (Na) per locus of 14.5 and a polymorphic information content of 0.777. The phylogenetic relationships among various hazelnut cultivars were characterized by complexity, and they were delineated into four distinct groups facilitated by genetic distance analyses. An SSR fingerprint database for 331 Corylus L. germplasms was successfully constructed using the 11 obtained core SSR markers to increase the discrimination efficiency. Ultimately, 127 primary core accessions of Corylus L. were selected. The retention rate for the observed Na and MAF (the minor allele frequency) in the primary core germplasm constructed based on a sampling proportion of 38.36% was 100% and 94.7%, respectively. Shannon's information index (I) was highly consistent between the core and original germplasms, indicating that the core germplasm could fully represent the genetic diversity of the original germplasm. Additionally, the principal coordinate analysis of the selected primary core germplasm was essentially consistent with that of the entire original germplasm, further supporting the broad representativeness of the core germplasm. This study provided a basis for precisely identifying and efficiently utilizing Corylus L. accession.