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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.
Microsatellite or simple sequence repeat (SSR) markers show many characteristics of the ideal molecular marker, and recent studies have shown that loci developed in one species may allow analysis in taxonomically related species. In this study, 52 primer pairs developed in two oak species—Quercus robur L. and Quercus petraea (Matt.) Lieb.—were used to amplify DNA of 5 chestnut cultivars; 28 of them yielded amplicons and 12 polymorphic loci were selected and used to fingerprint 12 european chestnut (Castanea sativa Mill.) cultivars grown in the Piedmont region of northwestern Italy. The number of alleles per locus ranged from 3 to 8, mean expected heterozygosity was 0.592 (range: 0.288 to 0.868), and mean observed heterozygosity was 0.667 (range: 0.333 to 1.000). The results demonstrate the usefulness of some SSR markers isolated in Quercus for the fingerprinting and genetic mapping of Castanea cultivars.