Genetic diversity and parentage of Tunisian wild and cultivated grapevines (Vitis vinifera L.) as revealed by single nucleotide polymorphism (SNP) markers

Based on 261 single nucleotide polymorphism (SNP) markers, we analyzed 57 grapevine genotypes, consisting of 29 wild grapevines (Vitis vinifera subsp. sylvestris) prospected from the northwest part of Tunisia and 28 cultivated accessions (V. vinifera subsp. vinifera) maintained in the repository of the Arid Land Institute of Medenine (Tunisia). Pair-wise multilocus comparison with the ICVV SNP database allowed the identification of 13 cultivated genotypes, including ten synonymous groups with known Mediterranean or international varieties, three cases of color sports, and two misnomers. Genotypic analysis showed a high level of genetic diversity for both wild and cultivated groups. Multivariate and structure analyses clearly differentiated wild from cultivated grapevines and showed high average posterior probabilities of assignment to their group of origin. The clustering results largely supported the perceived classification and reflect that most of the present Tunisian cultivated varieties do not derive directly from the local wild populations but could correspond to materials introduced from different locations during historical times. Parentage analysis allowed the determination of the genetic origin of four Tunisian cultivars, “Garai”, “Jerbi” (from Kerkennah), “Mahdoui”, and “Reine de Vignes faux”, and showed that “Heptakilo” and “Planta Fina”, two old and widely distributed varieties in the Mediterranean basin, had an important role in the origin of Tunisian grapevines. The present study demonstrates the efficacy of SNP makers for germplasm characterization and genetic studies in grapevine.