Background: In viticulture, rootstock genotype plays a critical role to improve scion physiology, berry quality and to adapt grapevine (Vitis viniferaL.) to different environmental conditions. This study aimed at investigating the effect of two different rootstocks (1103 Paulsen - P - and Mgt 101–14 - M) in comparison with not grafted plants - NGC - on transcriptome (RNA-seq and small RNA-seq) and chemical composition of berry skin inPinot noir, and exploring the influence of rootstock-scion interaction on grape quality. Berry samples, collected at veraison and maturity, were investigated at transcriptional and biochemical levels to depict the impact of rootstock on berry maturation.Results: RNA- and miRNA-seq analyses highlighted that, at veraison, the transcriptomes of the berry skin are extremely similar, while variations associated with the different rootstocks become evident at maturity, suggesting a greater diversification at transcriptional level towards the end of the ripening process. In the experimental design, resembling standard agronomic growth conditions, the vines grafted on the two different rootstocks do not show a high degree of diversity. In general, the few genes differentially expressed at veraison were linked to photosynthesis, putatively because of a ripening delay in not grafted vines, while at maturity the differentially expressed genes were mainly involved in the synthesis and transport of phenylpropanoids (e.g. flavonoids), cell wall loosening, and stress response. These results were supported by some differences in berry phenolic composition detected between grafted and not grafted plants, in particular in resveratrol derivatives accumulation.Conclusions: Transcriptomic and biochemical data demonstrate a stronger impact of 1103 Paulsen rootstock than Mgt 101–14 or not grafted plants on ripening processes related to the secondary metabolite accumulations in berry skin tissue. Interestingly, theMYB14gene, involved in the feedback regulation of resveratrol biosynthesis was up-regulated in 1103 Paulsen thus supporting a putative greater accumulation of stilbenes in mature berries.

Despite phenotypic plasticity that allows the adaptation to harsh environments, when vines experience severe abiotic stresses, they can suffer from metabolic damages affecting grape production and quality. Grafting is an affordable strategy to mitigate these negative consequences since the rootstock can increase the drought tolerance in the scion. This work explored the effects of pre-veraison water deficit on vines grafted on different rootstocks (Mgt 101-14 and 1103 Paulsen) to obtain physiological, biochemical, and molecular information about the influence on grape quality. Repeated measurements were carried out to assess vine physiology, production, technological maturity, and berry phenolic composition. qRT-PCRs were executed on berry skins at maturity to assess the expression levels of ten genes and five miRNAs involved in the phenylpropanoid pathway. Water stress caused significant alterations in grape technological maturity. The rootstock effect was not detected in primary metabolism while it was well defined in the accumulation of phenolic compounds in berries (such as anthocyanins). Finally, significant differences were identified in gene and miRNA expression between water-stressed and well-watered vines. In conclusion, the response to water stress can be modulated by rootstocks, which mainly act by regulating secondary metabolism, especially in grapes.

Vitis vinifera includes a large number of cultivars that are further distinguished in biotypes and clones, and it is actually hard to differentiate them, even through complex molecular techniques. In this work, the plant materials of 56 putative Sangiovese and 14 putative Montepulciano biotypes, two of the most widespread black-berried Italian cultivars, were collected in different wine-growing areas of Italy distributed in 13 regions, from north to south. Firstly, the samples were analyzed using SSR markers to have proper varietal identification. According to the results, the genotypes belonged to three different cultivars: Sangiovese, Sanforte, and Montepulciano. Subsequently, the samples were investigated using AFLP, SAMPL, M-AFLP, and I-SSR molecular markers to estimate their intra-varietal genetic variability. The DNA marker-based method used turned out to be performing to bring out the geographic differences among the biotypes screened, and it can therefore be considered as a powerful tool available for all the grapevine varieties.

The protection of grapevine biodiversity and the safeguarding of genetic variability are certainly primary and topical objectives for wine research, especially in territories historically devoted to viticulture. To assess the autochthonous germplasm of three different districts of Southern Umbria (Central Italy), the plant material of 70 grapevines retrieved from reforested land plots or old vineyards was collected, and their genetic identity was investigated using 13 microsatellite markers (SSR). The results revealed the presence of 39 unique genotypes, divided into 24 already-known cultivars and 15 never-reported SSR profiles. Most of the grapevine accessions were then vegetatively propagated and cultivated in a vineyard collection both to be protected from extinction and to be evaluated at the ampelographic level. Overall, this work emphasizes the need for recovering the threatened genetic variability that characterizes minor neglected grapevine cultivars or biotypes of Southern Umbria germplasm, and the requirement to revalue and exploit the more valuable genetic resources to enhance the local agri-food economy.

To explore the grapevine biodiversity of some minor viticultural districts located in the northwest coastal area of Tuscany, a total of 99 grapevine samples were collected from field borders or no longer cultivated areas and analysed at the molecular level using 12 microsatellite markers (SSR). The results revealed the presence of 58 unique genotypes among which 42 already known varieties (36 belonging to the Vitis vinifera species and 6 Vitis interspecific crosses) and 16 hitherto unreported genetic profiles. About 50 % of the accessions (52 out of 99) were vegetatively propagated and planted in a vineyard collection to protect them from extinction and to record their phenotypic characteristics. This research has highlighted the potential for using several grapevine cultivars that were probably once widespread and can henceforth be cultivated again to help revive the eco-wine tourism of the Tuscan heroic vineyards and add prestige to the local wine panorama.