DNA typing and genetic relations among European hazelnut (Corylus avellana L.) cultivars using microsatellite markers

In this work, 78 hazelnut (Corylus avellana L.) cultivars from various germplasm repositories were studied at 16 simple sequence repeat (SSR) loci in order to identify the genotypes and investigate their genetic relations. Polymorphism at SSR loci was evaluated on the basis of number of alleles (mean: 9.4), expected heterozygosity (mean: 0.78), and power of discrimination (mean: 0.91). Several synonyms reported in the literature were confirmed, and new cases of synonymy were identified. The parentage of North American cultivars 'Butler', 'Ennis', and 'Royal', the French selection 'Fercoril-Corabel', and 'Imperatrice Eugenie' was investigated on the basis of the alleles present at 16 loci and analysis at 8 additional loci. A dendrogram generated from cluster analysis using the unweighted pair group method with arithmetic mean grouped cultivars according to their pedigrees or geographical origins. There was an evident differentiation of the northern European cultivars from the southern European ones and from the Turkish cultivars. The latter clustered close to but separate from the Italian and Spanish clusters. It is very likely that exchanges of cultivars occurred between the central and western Mediterranean basin as a result of human migration and trade. A database containing the SSR profiles of the most important hazelnut cultivars will be useful for identification of cultivars and synonyms, legal protection, and parentage analysis.