Molecular characterization of Moroccan grapevine germplasm using SSR markers for the establishment of a reference collection

Aims: This study aims to characterize the SODEA ampelographic collection in Meknès, the only germplasm repository in Morocco. To assess the usefulness of this germplasm, a study was conducted to verify the trueness to type of the genotypes and to provide the first database for a reference collection in Morocco. A core collection was then established to define a small sample easier to handel further characterization. Methods and results: Ninety-four grapevine samples from the collection were analyzed using 20 nuclear SSR markers. From these samples, we identified 67 grapevine genotypes. The nuclear SSRs revealed a high diversity within the SODEA collection: 202 alleles were detected with a mean of 10.1 alleles per locus. Analysis of molecular data with the software DARwin was used to classify the genotypes into six groups according to their origin or their genetic relatedness. The 18 autochthonous cultivars were differentiated according to geographical origin (North vs. South). We established a core collection among this germplasm using MSTRAT: the complete diversity present in the collection was captured with only 34 individuals. Nevertheless, an optimal core collection representing 89% of the diversity was constituted by only 17 cultivars. Among these 17 individuals, 5 are autochthonous. Conclusion: The collection of SODEA represents a unique resources of grapevines for Morocco. It contains several important autochthonous cultivars in terms of diversity and agronomic utilisation. Significance and impact of the study: The study showed potential and interest of the cultivars present in the collection of SODEA, suggesting that their utilisation may be important for the farmers

Genetic structure in a large representative sample of cultivated and wild grapevines

International audienceThe genetic structure of a collection of more than 2900 unique genotypes representative of both the cultivated and the wild grapevine gene pools was studied with the help of nuclear neutral and non-neutral molecular markers. The subgroups obtained through complementary clustering methods were matched with their geographic origins and their phenotypic characterizations. The main clustering obtained with microsatellite markers on the larger genotype dataset, was confirmed by the SNP variation of 80 genes of reference, chosen as the most informative ones out of a total of 960 genes, re-sequenced on a subset of representative genotypes (corecollection). The partition of diversity of both neutral and non-neutral markers pointed to patterns that could be related to historical processes of domestication, selection and breeding, and to geography, from ancestral groups derived from opposite regions of the grapevine distribution area, down to a number of subgroups linked to specific local uses and grape features, finally merging into a family level. Within the cultivated compartment, the three most significant subgroups corresponded to the wine grapes from the Western Europe, the wine grapes from Balkans and Central Europe, and the table grapes from the East. A further subdivision evidenced family or sub-regional structures, such as the groupings of grapevines from Maghreb, from the Italian and the Iberian peninsula, from Russia and the Caucasian region, or the Muscat, the Savagnin and the Pinot-Gouais families. The study of the relationships with the wild compartment revealed that the cultivated gene pool was derived from two separate wild grapevine gene pools, one wild pool from the East that contributed to the table grapes, and a second wild pool from West Europe that contributed to the wine grapes. Presenting the more complete dataset to date, this work allows researchers to precisely account for genetic structure when sampling diversity within unstructured groups, as it is required by modern methods of genome-wide association genetics. It also adds a layer of information to the already documented national grapevine collection of Vassal, France, confirming its role as a reference for grapevine genetic studies

Genetic diversity of Moroccan grape accessions conserved ex situ compared to Maghreb and European gene pools

Equipe DAVEM = Diversité et Adaptation de la Vigne et des Espèces Méditerranéennes Contact : [email protected] diversity present in Morocco and the part of this diversity used nowadays are poorly documented. In order to choose diversified genotypes, to select them so that their agronomic interest will be tested, a group of 21 autochthonous cultivars preserved in the germplasm collections of SODEA and 18 Moroccan cultivars from "Domaine de Vassal" INRA grape collection was compared to a group of cultivars from neighbouring countries (Algeria and Tunisia), and from a core collection optimizing simple sequence repeat (SSR) allelic diversity of grape. Data from 20 nuclear and 3 chloroplastic SSR markers were obtained for this set of 211 cultivars. A total of 156 alleles (mean of 7.8 alleles per locus) were detected for the nSSRs and 7 alleles for the cpSSR in the Moroccan group. Chlorotype diversity in Moroccan and Algerian group were similar, but slightly lower than in the Tunisian group and the core collection. Similarly, the nSSR diversity was high in the core collection and low in the Moroccan and the Algerian groups compared to the two other groups. Clustering of cultivars based on nSSR data reflected their geographical origin and, to a certain extent, the use of the cultivars. The specificity of the Moroccan plant material was attested by the Bayesian analysis using Structure, while differences of the core collection were clearly revealed both by the Bayesian and a multivariate analysis. These results confirm the differentiation of the material from Maghreb and more specifically of Moroccan material, having evolved independently from Europe