Filbert

Abstract: A linkage map for European hazelnut (Corylus avellana L.) was constructed using random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers and the 2-way pseudotestcross approach. A full-sib population of 144 seedlings from the cross OSU 252.146 x OSU 414.062 was used. RAPD markers in testcross configuration, segregating 1:1, were used to construct separate maps for each parent. Fifty additional RAPD loci were assigned to linkage groups as accessory markers whose exact location could not be determined. Markers in intercross configuration, segregating 3:1, were used to pair groups in one parent with their homologues in the other. Eleven groups were identified for each parent, corresponding to the haploid chromosome number of hazelnut (n = x = 11). Thirty of the 31 SSR loci were able to be assigned to a linkage group. The maternal map included 249 RAPD and 20 SSR markers and spanned a distance of 661 cM. The paternal map included 271 RAPD and 28 SSR markers and spanned a distance of 812 cM. The maps are quite dense, with an average of 2.6 cM between adjacent markers. The S-locus, which controls pollen-stigma incompatibility, was placed on chromosome 5S where 6 markers linked within a distance of 10 cM were identified. A locus for resistance to eastern filbert blight, caused by Anisogramma anomala, was placed on chromosome 6R for which two additional markers tightly linked to the dominant allele were identified and sequenced. These maps will serve as a starting point for future studies of the hazelnut genome, including map-based cloning of important genes. The inclusion of SSR loci on the map will make it useful in other populations.

Abstract: In this work, 18 microsatellite loci were developed in the European hazelnut ( Corylus avellana L.) using three enriched genomic libraries. They were evaluated on a set of 20 accessions of this species on the basis of number of alleles (mean: 7.1), expected heterozygosity (mean: 0.67), power of discrimination (mean: 0.77) and polymorphism information content (mean: 0.64). Cross-species transferability was evaluated using seven other Corylus species. All primer pairs amplified in all species, except for CaT-C505 in Corylus ferox and CaT-A114 in Corylus californica .

Abstract: Three microsatellite-enriched libraries of the european hazelnut (Corylus avellana L.) were constructed: library A for CA repeats, library B for GA repeats, and library C for GAA repeats. Twenty-fi ve primer pairs amplifi ed easy-to-score single loci and were used to investigate polymorphism among 20 C. avellana genotypes and to evaluate cross-species amplifi cation in seven Corylus L. species. Microsatellite alleles were estimated by fl uorescent capillary electrophoresis fragment sizing. The number of alleles per locus ranged from 2 to 12 (average = 7.16) in C. avellana and from 5 to 22 overall (average = 13.32). With the exception of CAC-B110, di-nucleotide SSRs were characterized by a relatively large number of alleles per locus (≥5), high average observed and expected heterozygosity (Ho and He > 0.6), and a high mean polymorphic information content (PIC ≥ 0.6) in C. avellana. In contrast, tri-nucleotide microsatellites were more homozygous (Ho = 0.4 on average) and less informative than di-nucleotide simple sequence repeats (SSRs) as indicated by a lower mean number of alleles per locus (4.5), He (0.59), and PIC (0.54). Cross-species amplifi cation in Corylus was demonstrated. These microsatellite markers were highly heterozygous and polymorphic and differentiated among genotypes of C. avellana irrespective of geographical origin. They will aid in fi ngerprinting genotypes of the european hazelnut and other Corylus species, genome mapping, and genetic diversity assessments.

Abstract: The place and time of European hazel (Corylus avellana L.) domestication is not clear, although it was already cultivated by the Romans. In this study, 75 accessions from Spain, Italy, Turkey, and Iran were analysed using 13 chloroplast microsatellite to investigate the origin and diffusion of hazelnut cultivars. Four loci were polymorphic and identified a total of four different chlorotypes. Their distribution was not uniform in each geographical group. The most frequent chlorotype A was present in all groups. An increase in chlorotype number and diversity from Spain eastward to Italy, Turkey, and Iran was observed. Results suggest that some spread of cultivars occurred from East to West and that hazelnut cultivation was not introduced from the eastern Mediterranean basin into Spain and southern Italy by Greeks or Arabs. Moreover, the results suggest considerable exchange of germplasm between Italy and Spain, probably by the Romans. Hazelnut appears to have been domesticated independently in three areas: the Mediterranean, Turkey, and Iran.