In order to investigate the comparability of microsatellite profiles obtained in different laboratories, ten partners in seven countries analyzed 46 grape cultivars at six loci (VVMD5, VVMD7, VVMD27, VVS2, VrZAG62, and VrZAG79). No effort was made to standardize equipment or protocols. Although some partners obtained very similar results, in other cases different absolute allele sizes and, sometimes, different relative allele sizes were obtained. A strategy for data comparison by means of reference to the alleles detected in well-known cultivars was proposed. For each marker, each allele was designated by a code based on the name of the reference cultivar carrying that allele. Thirty-three cultivars, representing from 13 to 23 alleles per marker, were chosen as references. After the raw data obtained by the different partners were coded, more than 97% of the data were in agreement. Minor discrepancies were attributed to errors, suboptimal amplification and visualization, and misscoring of heterozygous versus homozygous allele pairs. We have shown that coded microsatellite data produced in different laboratories with different protocols and conditions can be compared, and that it is suitable for the identification and SSR allele characterization of cultivars. It is proposed that the six markers employed here, already widely used, be adopted as a minimal standard marker set for future grapevine cultivar analyses, and that additional cultivars be characterized by means of the coded reference alleles presented here. The complete database is available at http://www.genres.de/eccdb/vitis/ Cuttings of the 33 reference cultivars are available on request from the Institut National de la Recherche Agronomique Vassal collection (didier.vares@ensam.inra.fr).

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In the course of DNA profiling of grapevine cultivars using microsatellite loci we have occasionally observed more than two alleles at a locus in some individuals and have identified periclinal chimerism as the source of such anomalies. This phenomenon in long-lived clonally propagated crops, such as grapevine, which contains historically ancient cultivars, may have a role in clonal differences and affect cultivar identification and pedigree analysis. Here we show that when the two cell layers of a periclinal chimera, Pinot Meunier, are separated by passage through somatic embryogenesis the regenerated plants not only have distinct DNA profiles which are different from those of the parent plant but also have novel phenotypes. Recovery of these phenotypes indicates that additional genetic differences can exist between the two cell layers and that the Pinot Meunier phenotype is due to the interaction of genetically distinct cell layers. It appears that grapevine chimerism can not only modify phenotype but can also impact on grapevine improvement as both genetic transformation and conventional breeding strategies separate mutations in the L1 and L2 cell layers.

In this work, 78 hazelnut (Corylus avellana L.) cultivars from various germplasm repositories were studied at 16 simple sequence repeat (SSR) loci in order to identify the genotypes and investigate their genetic relations. Polymorphism at SSR loci was evaluated on the basis of number of alleles (mean: 9.4), expected heterozygosity (mean: 0.78), and power of discrimination (mean: 0.91). Several synonyms reported in the literature were confirmed, and new cases of synonymy were identified. The parentage of North American cultivars 'Butler', 'Ennis', and 'Royal', the French selection 'Fercoril-Corabel', and 'Impératrice Eugenie' was investigated on the basis of the alleles present at 16 loci and analysis at 8 additional loci. A dendrogram generated from cluster analysis using the unweighted pair group method with arithmetic mean grouped cultivars according to their pedigrees or geographical origins. There was an evident differentiation of the northern European cultivars from the southern European ones and from the Turkish cultivars. The latter clustered close to but separate from the Italian and Spanish clusters. It is very likely that exchanges of cultivars occurred between the central and western Mediterranean basin as a result of human migration and trade. A database containing the SSR profiles of the most important hazelnut cultivars will be useful for identification of cultivars and synonyms, legal protection, and parentage analysis.

No 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.

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.

Hazelnut (Corylus avellana L.) is a traditional nut crop in southern Europe. Germplasm exploration conducted on-farm in five countries (Portugal, Spain, Italy, Slovenia, and Greece) identified 77 landraces. The present work describes phenotypic variation in nut and husk traits and investigates genetic relationships using ten simple sequence repeat (SSR) markers among these landraces, 57 well-known references cultivars, and 19 wild accessions. Among the 77 landraces, 42 had unique fingerprints while 35 showed a SSR profile identical to a known cultivar. Among the 42 unique landraces, morphological observations revealed high phenotypic diversity, and some had characteristics appreciated by\ud the market such as nut round and caliber. Analysis of genetic relationships and population structure allowed investigation of the origin and spread of the cultivated germplasm in southern Europe. Our results indicate the existence of three primary centers of diversity in the Mediterranean basin: northwestern Spain (Tarragona) and southern Italy (Campania) in the West and Black Sea (Turkey) in the East. Moreover, the data suggest the existence of secondary gene pools in the Iberian (Asturias) and Italian (Liguria and Latium) Peninsulas, where\ud local varieties were recently domesticated from wild forms and/or from introduced ancient domesticated varieties