Microsatellite variability and genetic structure in hazelnut (Corylus avellana L.) cultivars from different growing regions

The study of the genetic structure of hazelnut cultivated germplasm is an important goal and requires the choice of proper molecular markers. In the present work, microsatellite data obtained at 16 SSR loci for 75 accessions from Spain, Italy, Turkey, and Iran were elaborated for the analysis of marker information content, the genetic structure of hazelnut cultivar gene pools, and the differentiation among cultivars sampled in the four regions. Data elaborations allowed to further develop the information reported in literature and to select a set of SSR loci to be proposed as molecular descriptors for hazelnut. An excess of heterozygosity was observed in Spanish and Turkish gene pools, while a heterozygosis deficit was observed in Iranian samples. Genetic differentiation among cultivars from different regions was significant, even in the case of genetically closer groups such as the Spanish and Italian ones. Statistical analysis indicated that hazelnut appears to have been domesticated independently in the four areas, suggesting that present cultivars have a multiple origin.