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

The European AGRI GEN RES 068 (Genetic Resources in Agriculture) project acronymed SAFENUT (‘Safeguard of almond and hazelnut genetic resources: from traditional uses to modern agro-industrial opportunities’) is aimed at increasing the knowledge on the European germplasm of hazelnut (Corylus avellana L.). In this context, 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. A high level of genetic diversity was detected in all investigated cultivars. 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 close groups such as the Spanish and Italian ones. Nevertheless, the Italian accessions from Liguria region (North-West Italy) resulted genetically closer to varieties of Turkish origin than to 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.