Genetic diversity and relationships among Italian and Spanish hazelnut cultivars

In this work, 22 Italian and 36 Spanish accessions from various germplasm repositories were studied at 16 microsatellite markers in order to study: (1) the genetic diversity in the Italian cultivars and (2) their genetic relationships with Spanish cultivated varieties. The analysis of SSR data showed a high level of genetic diversity among Italian cultivars. Several synonymies reported in literature were confirmed and new cases were identified. A dendrogram generated by UPGMA cluster analysis grouped the 22 Italian cultivars according to their geographical origins. Genetic relationships among 58 Italian and Spanish cultivars were assessed using three distinct approaches: “proportion of shared alleles”, “δ μ” (delta mu), and “fuzzy set similarity”. Results were showed in three dendrograms obtained by UPGMA cluster analysis where the cultivars from South Italy always resulted closely related with the same group of Spanish varieties. ‘Tonda bianca’ and ‘Tonda rossa’ clustered separately from the other cultivars and showed a different genotype at chloroplast SRR loci. The cultivars from Liguria region were separated from the Spanish accessions, while the position of ‘Tonda Gentile delle Langhe’ and ‘Tonda Gentile Romana’ was controversial.