Unraveling genetic diversity in 'Foşa' and 'Yomra' hazelnut accessions (Corylus avellana L.) using SSR markers and...

The Foşa hazelnut variety is commonly cultivated in Türkiye and is often confused with the Yomra variety due to morphological similarities. This study aims to determine the phenological and pomological characteristics of the Foşa and Yomra hazelnut populations and reveal their genetic diversity using multivariate statistical analysis and Simple Sequence Repeat (SSR) molecular markers. We analyzed 80 accessions (43 Foşa and 37 Yomra) using 10 SSR primers to establish genetic relationships. The polymorphic band lengths ranged from 53 to 158 bp, with 1 to 8 bands per primer, totaling 45 bands. The average genetic diversity was 0.53, observed heterozygosity was 0.31, and the polymorphism rate was 0.48. Phylogenetic analysis clearly separated 'Foşa' and 'Yomra' varieties into distinct clusters, with the population dividing into two main groups, each further subdivided into two subgroups. Several accessions within different subgroups showed identical genetic profiles, indicating clonal relationships. Genetic variation within the 'Yomra' variety (similarity coefficient: 0.646) was slightly higher than in the 'Foşa' variety (0.676). Among quantitative traits, the coefficient of variation ranged from 2.57% (nut size) to 68.12% (fibrousness), with high variation observed in yield, nuts per cluster, nut weight, kernel weight, kernel shape apex index, kernel cavity, blanching rate, and fibrousness. Phenologically, the 'Foşa' population exhibited earlier male flowering, female flowering, and leaf budburst compared to 'Yomra', with both populations showing protandrous-homogamous flowering patterns. These results demonstrate that genetically distinct accessions within these populations should be conserved in genetic resource collections and can serve as valuable parents in breeding programs.