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SUMMARY To evaluate the relationship between Sardinian and Spanish viticulture, Simple Sequence Repeat (SSR) markers were applied to define the genetic profiles of 29 cultivated and 48 wild grapevine (Vitis vinifera L.) accessions. SSR data confirmed synonymy between ‘Cannonau’ and several Spanish accessions of ‘Garnacha Tinta’. SSR analysis also suggested that the ‘Garnacha’ group consisted of a heterogeneous pool of cultivars displaying different morphological and genetic traits (Link coefficient = approx. 0.5), probably caused by somatic mutation or accidental breeding events between closely-related grapevine accessions. In contrast, the ‘Vernaccia’ - ‘Granaccia’ Sardinian group was different from ‘Cannonau’ (Link coefficient = 0.8) and all Spanish ‘Garnacha Tinta’ and ‘Blanca’ accessions analysed. To understand the ‘Cannonau’ - ‘Garnacha’ relationship, we studied the origin of these accessions and their relationships with spontaneous wild grapevine. Both cultivars are ancient grapes that have been cultivated for many centuries in both Sardinia and Spain. Although the name ‘Garnacha’ may derive from the Italian word ‘Vernaccia’, molecular analysis excluded any direct genetic origin of the Spanish ‘Garnacha’, or Sardinian ‘Cannonau’ from the ‘Vernaccia’ ‘Granaccia’ Sardinian group. Structure analysis split the samples analysed into three clusters (K = 3). The first two clusters corresponded to the cultivated samples, while the wild accessions were in the third cluster. Based on this information, we can exclude any direct origin of the ‘Cannonau’ - ‘Garnacha’ group from the wild grapevines analysed and distributed on Sardinia.

Aim: The objective of the present study is to investigate the molecular characteristics of Sardinian grapevine cultivars to evaluate cases of synonyms and false attributions to protect local agro-biodiversity.Methods and results: The SSR analysis (13 loci) has been used to define the DNA fingerprint and the relationships with Sardinian grapevine cultivars. Results highlighted a high genetic variability among the accessions, with the Dice coefficients performing from 0 to 0.8. Despite the genetic richness, thirteen groups of redundant genotypes were detected. Molecular analysis refers of cultivars harbouring the same SSR profile but different berry colours such as cultivars Licronaxu Bianco and Nero and Moscatello Bianco and Nero. It could by hypothesized that Licronaxu and Moscatello could derive from a specific retrotransposon-induced mutation event in genes regulating anthocyanin biosynthesis.Conclusion: Sardinian germplasm has a real problem of cultivar identification probably due to different factors such as the absence of an exhaustive ampelography, problems in the language to name varieties and the existence of cultivars sensitive to biotic and abiotic stresses producing evident morphological modifications leading to mistakes in recognising and identifying properly the affected plants. However, our molecular results suggest that high grape-biodiversity is still preserved in this region.Significance and impact of study: Results of this work clarified the relationships among grapevine cultivars and provided a solid basis to improve a regional grapevine collection.

Grape berries harbor a wide range of microbes originating from the vineyard environment, many of which are recognized for their role in the must fermentation process shaping wine quality. To better clarify the contribution of the microbiome of grape fruits during wine fermentation, we used high-throughput sequencing to identify bacterial and fungi communities associated with berries and musts of Cannonau. This is the most important cultivar-wine of Sardinia (Italy) where most vineyards are cultivated without phytochemical treatments. Results suggested that microbiomes of berries collected at four different localities share a core composition characterized by Enterobacteriales, Pseudomonadales, Bacillales, and Rhodospirillales. However, any area seems to enrich berries microbiome with peculiar microbial traits. For example, berries belonging to the biodynamic vineyards of Mamoiada were rich in Bacillales typical of manure (i.e. Lysinibacillus, Bacillus, and Sporosarcina), whereas in the Santadi locality, berries showed soil bacteria such as Pasteurellales and Bacteroidales as well as Rhodospirillales and Lactobacillales which are commonly involved in wine fermentation. In the case of fungi, the most abundant taxa were Dothioraceae, Pleosporaceae, and Saccharomycodaceae, and although the proportion of these families varied among localities, they occurred ubiquitously in all vineyards. During vinification processes performed at the same wine cellar under controlled conditions and without using any yeast starter, more than 50% of bacteria groups of berries reached musts, and each locality had its own private bacteria signature, even if Saccharomyces cerevisiae represented the most abundant fungal species. This work suggests that natural berries microbiome could be influenced by pedoclimatic and anthropologic conditions (e.g., farming management), and the fruits’ microorganisms persist during the fermentation process. For these reasons, a reliable wine genotyping should include the entire holobiont (plant and all its symbionts), and bioprospecting activities on grape microbiota could lead to improved viticulture yields and wine quality.