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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #150051


item Bassil, Nahla
item Botta, Roberto
item Mehlenbacher, Shawn

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2003
Publication Date: 8/20/2003

Interpretive Summary: The objective of this study was to find the usefulness of tiny repeated pieces of DNA, known as microsatellite markers, for different types of hazelnut. Groups of reference DNA pieces, which had lots of these repeated sequences, were made from each type of hazelnut. These reference pieces are known as libraries. Up to 92 % of the libraries contained these simple repeated pieces of DNA that scientists call simple sequence repeats, or SSRs. Specific DNA sequences (or primers) were made from regions on either side of the repeats. These were then used in a polymerase chain reaction (PCR) to make many copies of the specific repeated DNA sequence. About 88%of the primers tested found differences in the many kinds of hazelnuts. Twelve primers were marked with fluorescence and could detect differences among 19 types of European hazelnut as well as nine other species. Using these twelve primers, we could distinguish between all the hazelnut species in the world. Ten of them could reliably differentiate between 19 hazelnut types whatever their geographical origin. These DNA markers will continue to be helpful in identifying different species and cultivated types of hazelnut plants.

Technical Abstract: A tri-nucleotide (GAA) and two dinucleotide (CA, GA) microsatellite-enriched libraries of the European hazelnut, Corylus avellana L., were constructed by Genetic Identification Services (GIS) using DNA purified from germinating seeds. Up to 90% of the sequenced clones contained microsatellite repeats including simple, compound, and interrupted repeats. To date, 105 unique microsatellite-containing sequences have been isolated from the libraries and sixty primer pairs were designed using Primer3 software. Initial analysis of diversity eight cultivars of C. avellana and three Corylus species revealed considerable genetic diversity within European hazelnut and between the species examined. Only three SSR markers were monomorphic while 53 markers were polymorphic in the cultivars and species tested. Null alleles were detected at five loci. Three microsatellite loci containing trinucleotide repeats used in this study were monomorphic in cultivars of the European hazelnut and polymorphic in the other three species tested. A set of 12 fluorescently labeled primers were used to assess polymorphism among 19 European hazelnut genotypes and eight other Corylus species. Null alleles were found in the cultivar 'Gasaway' at loci Ha102 and Hc010, in 'Tonda Romana' and at Hc108, in C. cornuta subsp. californica B0509 at loci Hc111 and Hc010, and in C. americana Marshall 'Winkler' at locus Hc108. The number of alleles ranged from 4 to 17, with an average of 10.2 per locus. The observed heterozygosity ranged from 0.58 to 0.87, with an average of 0.77 per locus. Ten out of twelve SSRs could reliably distinguish genotypes of C. avellana irrespective of geographical origin and many species-specific alleles were identified. These microsatellite markers will be useful for fingerprinting genotypes of Corylus species, genome mapping, and genetic diversity assessments.