Microsatellite Markers in Hazelnut: Isolation, Characterization, and Cross-species Amplification

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-five primer pairs amplified easy-to-score single loci and were used to investigate polymorphism among 20 C. avellana genotypes and to evaluate cross-species amplification in seven Corylus L. species. Microsatellite alleles were estimated by fluorescent 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 amplification 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 fingerprinting genotypes of the european hazelnut and other Corylus species, genome mapping, and genetic diversity assessments

Population structure analysis of European hazelnut (Corylus avellana)

Eleven simple sequence repeat (SSRs) markers were used to investigate population structure of 582 accessions representing hazelnut cultivars grown in different geographical regions of the world. SSR profiles for 229 accessions were assessed for the first time, and their allele sizes were combined with those of 353 accessions previously characterized and published, for an analysis of genetic diversity and population structure. The combined data for all 582 accessions was used to construct an UPGMA (unweighted pair group method of arithmetic averages) dendrogram. The UPGMA tree showed multiple groups with clustering partly based on their geographic origin. The STRUCTURE analysis indicated that the most likely number of sub-populations is three to seven. Taken together, the results showed that cultivated hazelnuts consist of multiple genetic groups and cultivars were likely selected from local wild populations rather than originating in one or two domestication centers.</p