Unraveling Genetic Diversity Amongst European Hazelnut (Corylus avellana L.) Varieties in Turkey

European hazelnut ( Corylus avellana ) is a diploid (2n = 22), monecious and wind-pollinated species, extensively cultivated for its nuts. Turkey the world-leading producer of hazelnut, supplying 70–80% world’s export capacity. Hazelnut mostly grown in Black Sea Region, maintained largely through clonal propagation. Understanding genetic variation between varieties, defining variety-specific disease resistance-associated alleles, would facilitate breeding Turkey. Widely varieties ‘Karaf?nd?k’ (2), ‘Sar?f?nd?k’ (5), ‘Yomra’ (2) were collected from Akçakoca west, while ‘Tombul’ (8), ‘Çak?ldak’ (3), ‘Mincane’ ‘Allahverdi’ ‘Sivri’ (4), ‘Palaz’ (5) Ordu Giresun provinces east (numbers parentheses indicate sample sizes each variety). Powdery mildew resistant susceptible genotypes field gene bank heavily infected orchards Giresun. Every individual was subjected to double digest restriction enzyme-associated DNA sequencing (ddRAD-seq) RADtag library created. RADtags aligned reference genome, Stacks software used identify polymorphisms. 101 private six common alleles nine four resistants only one identified diagnosis either certain variety or powdery resistance. Phylogenetic analysis population structure calculations indicated that ‘Mincane’, ‘Sar?f?nd?k’, ‘Tombul’, ‘Çak?ldak’, genetically close other; however, individuals within every varietal group found different sub-populations. Our findings years propagation some preferred across Region has resulted admixed sub-populations great diversity variety. This impedes development true For example, most favored Turkish because high quality nuts, but an elite line does not yet exist. situation continues due lack breed protection program commercially valuable varieties. study provides molecular markers suitable establishing such program.