Moscato Bianco Research Articles

Postharvest UV-B exposure drives changes in primary metabolism, phenolic concentration, and volatilome profile in berries of different grape (Vitis vinifera L.) varieties.

The ultraviolet-B (UV-B) radiation can alter grape metabolism during berry development, but little is known on the effect of postharvest UV-B exposure. In this study, we evaluated the effect of postharvest UV-B exposure on berry primary and secondary metabolites in four grapevine varieties (Aleatico, Moscato bianco, Sangiovese, and Vermentino) in order to evaluate the possibility to increase the grape quality and its nutraceutical properties. The treatment did not significantly affect the berry primary metabolism in terms of organic acids, carbohydrates, and amino acids profile, regardless of the variety. UV-B exposure reduced the total anthocyanin content, particularly the tri-substituted and di-substituted forms in Aleatico and Sangiovese, respectively. An overall negative effect of UV-B irradiation on the flavonols profile of Aleatico, Moscato bianco, and Vermentino berries was found, whereas it enhanced the quercetin, myricetin and kaempferol concentration in Sangiovese. The free fraction of berry volatile organic compounds increased in UV-B-treated Aleatico and Moscato bianco berries, especially C13 -norisoprenoids and volatile phenols, as well as key monoterpenes, such as the linalool derivatives. However, higher concentrations of glycosylated monoterpenes and C13 -norisoprenoids were measured in Sangiovese and Vermentino berries treated with UV-B. This study provides new insights on the effect of postharvest UV-B radiation on berry secondary metabolism, highlighting a different modulation between varieties and suggesting the potential use of this technique to increase some nutraceutical and quality characteristics of grape berry. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Parentage Atlas of Italian Grapevine Varieties as Inferred From SNP Genotyping.

The Italian grape germplasm is characterized by a high level of richness in terms of varieties number, with nearly 600 wine grape varieties listed in the Italian National Register of Grapevine Varieties and with a plethora of autochthonous grapes. In the present study an extended SNP genotyping has been carried out on Italian germplasm of cultivated Vitis vinifera subsp. sativa and Vitis hybrids. Several hundred Italian varieties maintained in the repositories of scientific Institutions and about one thousand additional varieties derived from previous studies on European, Southern Italy, Magna Graecia and Georgian germplasm were considered. The large genotyping data obtained were used to check the presence of homonyms and synonyms, determine parental relationships, and identify the main ancestors of traditional Italian cultivars and closely-related accessions. The parentage among a set of 1,232 unique varieties has been assessed. A total of 92 new parent-offspring (PO) pairs and 14 new PO trios were identified. The resulted parentage network suggested that the traditional Italian grapevine germplasm originates largely from a few central varieties geographically distributed into several areas of genetic influence: “Strinto porcino” and its offspring “Sangiovese”, “Mantonico bianco” and “Aglianico” mainly as founder varieties of South-Western Italy (IT-SW); Italian Adriatic Coast (IT-AC); and Central Italy with most varieties being offsprings of “Visparola”, “Garganega” and “Bombino bianco”; “Termarina (Sciaccarello)” “Orsolina” and “Uva Tosca” as the main varieties of North-Western Italy (IT-NW) and Central Italy. The pedigree reconstruction by full-sib and second-degree relationships highlighted the key role of some cultivars, and, in particular, the centrality of “Visparola” in the origin of Italian germplasm appeared clear. An hypothetical migration of this variety within the Italian Peninsula from South to North along the eastern side, as well as of “Sangiovese” from South to Central Italy along the Western side might be supposed. Moreover, it was also highlighted that, among the main founders of muscat varieties, “Moscato bianco” and “Zibibbo (Muscat of Alexandria)” have spread over the whole Italy, with a high contribution by the former to germplasm of the North-Western of the peninsula.

Changes in stilbene composition during postharvest ozone treatment of 'Moscato bianco' winegrapes.

Stilbenes, including trans-resveratrol and its derivatives, are compounds naturally present in grapes and have gained a growing interest due to reported health-promoting properties. The production of resveratrol-enriched table grapes has promoted recent research on stress-induced synthesis of stilbenes. The oxidizing properties of ozone have been successfully exploited to its use as sanitizing agent and stilbene elicitor during table grapes storage. In winegrapes, this study represents the first research focused on the effect of postharvest ozone treatments on the accumulation of stilbene compounds. The study was carried out on Moscato bianco winegrapes (Vitis vinifera L.) and several gaseous ozone treatments were investigated differing in ozone dose (30 and 60 μL/L), exposure time (24 h, 48 h, and several days until 30% of weight loss), and delay time until processing (just after and several days after treatment). The stilbene production induced by ozone exposure was assessed in fresh and partially dehydrated winegrapes up to 5, 10, 15, 20, and 30% of weight loss aiming to evaluate the single and combined effect of oxidative and osmotic stresses. The results obtained showed that short-term exposure of fresh winegrapes at 60 μL/L of ozone for 48 h was not effective in inducing resveratrol accumulation just after treatment, but it had an elicitor effect on total stilbenes (+36%) in grapes subsequently dehydrated up to 20% of weight loss with a significant overproduction of trans-resveratrol and trans-piaceatannol. In addition, long-term and continuous treatments under ozone-enriched atmosphere can be also used during dehydration to sanitize winegrapes without affecting negatively the concentration of stilbenes. Therefore, the use of gaseous ozone during storage and dehydration could be indicated to reduce the use of sulfur dioxide and, depending on ozone dose and exposure time, the synthesis of stilbene compounds could increase.

Grape VOCs Response to Postharvest Short-Term Ozone Treatments.

Ozone has been recently recognized as an efficient sanitizing agent in wine industry because of its powerful oxidizing properties. Furthermore, postharvest treatments of grapes with ozone can stimulate defense responses by synthetizing secondary metabolites against oxidative stress. In this study, the effect of postharvest short-term ozone treatments was assessed for the first time on free and glycosylated volatile organic compounds (VOCs) of winegrapes. Two different ozone concentrations (30 and 60 μL/L) and exposure times (24 and 48 h) were investigated just after treatment (fresh grapes) and after partial dehydration up to 20% weight loss (withered grapes). The study was carried out on Moscato bianco winegrapes (Vitis vinifera L.) due to the importance of terpenes in white aromatic cultivars to produce high quality wines. The results obtained showed that short-term ozone treatment caused a significant decrease in total contents of free VOCs in fresh grapes, mainly due to terpenes. Among them, linalool, geraniol, and nerol are the major aromatic markers of Moscato bianco grapes. Ozone entailed a significant decrease of free linalool contents in fresh grapes, the less stressful ozone treatment showing the smaller linalool degradation. However, the stronger and longer ozone treatment induced the synthesis of this compound probably in response to higher abiotic stress. Instead, significant changes were not observed in geraniol and nerol contents in fresh grapes. This last ozone treatment also reduced the loss of free linalool by water loss in withered grapes even though total VOCs and terpenes remained relatively stable. Furthermore, ozone seems to promote the synthesis of free (+)-4-carene and 4-terpineol in withered grapes under certain treatment conditions. Regarding glycosylated compounds, total VOCs and terpenes were less sensitive to ozone. Our findings highlight that ozone can be used as sanitizing agent in aromatic grape varieties prior to winemaking without affecting sharply the aromatic profile of fresh grapes and even improving it in withered grapes.

On-vine withering process of 'Moscato bianco' grapes: effect of cane-cut system on volatile composition.

Cane-cut on-vine withering is a grape dehydration technique used for dry and sweet wine production. The aim of this work was to study the influence of the cane-cut technique applied at harvest to Moscato bianco grapes during the on-vine withering process to produce dehydrated berries with a different chemical composition and a volatile profile. After 24 days of dehydration, an on-vine withering system using the cane-cut technique induced an increase in the total volatile content compared with grapes produced with a normal on-vine withering process. This increase was greater in glycosidically bound volatile compounds than in the free fraction. Bound linalool showed a significant increase of 52% when the cane-cut withering system was applied but the grapes that were normally withered appeared to be less prone to the loss of free linalool. A significant increase in the glycosylated forms of nerol and geraniol was also observed in the two on-vine withering systems on the 24th day compared with the control (fresh grapes at harvest date). A cane-cut, on-vine withering system applied at harvest induced changes in the volatile composition of Moscato bianco grapes increasing total volatile content, consisting mainly of bound compounds, by the 24th day of dehydration. The grapes dehydrated on-vine using this new system also showed significantly greater content of most of the free volatile compounds detected. © 2018 Society of Chemical Industry.

Ozone Improves the Aromatic Fingerprint of White Grapes

Ozone, a powerful oxidative stressor, has been recently used in wine industry as sanitizing agent to reduce spoilage microflora on grapes. In this study, we evaluated ozone-induced metabolic and molecular responses during postharvest grape dehydration. Ozone increased the contents of total volatile organic compounds (VOCs), which have a great impact on the organoleptic properties of grapes and wines. Among terpenes, responsible for floral and fruity aroma, linalool, geraniol and nerol were the major aromatic markers of Moscato bianco grapes. They were significantly affected by the long-term ozone treatment, increasing their concentration in the last phases of dehydration (>20% weight loss). At molecular level, our results demonstrated that both postharvest dehydration and ozone exposure induce the biosynthesis of monoterpenes via methylerythritol phosphate (MEP) pathway and of aldehydes from lipoxygenase-hydroperoxide lyase (LOX-HPL) pathway. Therefore, transcriptional changes occurred and promoted the over-production of many important volatile compounds for the quality of white grapes.

Structural dynamics at the berry colour locus in Vitis vinifera L. somatic variants

This study aims at the molecular characterization of somatic variants for the berry skin colour, taking advantage of a layer-specific approach and of the knowledge of the genomic sequence along the chromosome 2. The plant material consisted of 38 individuals belonging to 14 V. vinifera cultivars (cepage), encompassing the group A ('Calitor', 'Canaiolo', 'Carinena', 'Merlot', 'Rondinella', 'Grenache' and 'Tempranillo'), colourless variants from coloured wild-type, and the group B ('Baresana', 'Chasselas', 'Italia', 'Malvasia di Candia aromatica', 'Moscato bianco', 'Sauvignon' and 'Sultanina'), coloured variants from non-coloured wild-type. A set of 11 reference SSR markers was used to confirm the varietal identification. In order to perform the genetic character­ization at the berry colour locus, 10 SSR markers, 6 SNP regions, and 1 SCAR marker (Gret1) distributed along the chromosome 2 were analysed. The major findings of this study revealed a structural dynamics along the chromosome 2 both at inter- and intra-varietal level within the group A. In fact, a deletion of different extent and position was detected in the colourless variants at the inner layer level. Within group B, instead, the coloured variants could be distinguished mostly for the partial Gret1 retrotransposon excision from the VvMybA1 promoter. In conclusion, this study allows the discrimination of somatic variants and suggests the occurrence of different evolutionary models both among and within grapevine cultivars.

Study of the terpene profile at harvest and during berry development of Vitis vinifera L. aromatic varieties Aleatico, Brachetto, Malvasia di Candia aromatica and Moscato bianco.

In this work, we evaluated the aromatic composition of berries at harvest and during the whole berry development of Aleatico, Brachetto, Malvasia di Candia aromatica and Moscato bianco grapevine varieties, which were cultivated in the same vineyard and under the same agricultural conditions. Malvasia had a total concentration of aroma which was significantly higher than the other grapes that showed comparable amounts with each other. The class of monoterpenes was quantitatively predominant for all four grapes, in the free and in the most plentiful bound form. In Malvasia and Aleatico there was a high prevalence of geraniol derivatives throughout the entire berry development while in Brachetto and in Moscato there was a prevalence of linalool derivatives during the green phase and geraniol derivatives during ripening. The study of the monoterpene profile allowed us to highlight similarities and differences among the four aromatic varieties and to present a hypothesis about their biosynthetic dynamics. This information is useful for further studies on gene functional characterisation and the regulation of these important berry pathways. © 2016 Society of Chemical Industry.

Use of response surface methodology for the assessment of changes in the volatile composition of Moscato bianco (Vitis vinifera L.) grape berries during ripening

The changes in the volatile composition of Moscato bianco grapes were evaluated during ripening. Grape berries were sampled for five weeks (16–20 °Brix) and sorted for each date in ten density classes (1.05–1.12g/cm3). The highest total concentration of free terpenes was found at 19.3 °Brix; however, total concentration of the bound fraction increased significantly throughout ripening. Response surface methodology was used to assess the simultaneous effect of sampling time and berry density on the volatile composition, which was satisfactorily fitted to regression models for some key terpene compounds. Total free and bound terpenes were more affected by grape density than by sampling date. The same behaviour was observed for free and bound linalool and bound nerol, whereas the stronger effect of sampling date was exhibited for bound t-rose oxide, c-rose oxide and geraniol. The results showed that the sampling strategy impacted strongly on the aroma quality of berries.

The key role of “Moscato bianco” and “Malvasia aromatica di Parma” in the parentage of traditional aromatic grape varieties

A great number of flavored grape varieties, of significant oenological potential, are traditionally cultivated in north-western Italy, besides the renowned “Moscato bianco” (syn. “Muscat a petits grains blancs”). Understanding their origin, besides its historical and scientific interest, would help to increase market appeal and consequently facilitate the commercial exploitation of these products. Twenty-four aromatic genotypes were investigated for their identity, kinship relations, and genetic origins through molecular markers (SSR and SNPs) supported by plant morphology and historical information. Flavored grape genotypes from other regions, possible ancestors, and reference cultivars of known pedigree were also included in the analysis. Kinship analysis used a likelihood-based approach (IBS, IBD, relatedness coefficients, and likelihood ratios) to achieve strong statistical support. The analyses revealed two possible leading genitors, in turn closely related by a parent/offspring relationship: “Moscato bianco” and “Malvasia aromatica di Parma,” a female grape cultivar that is today almost extinct. The outlined molecular and statistical approach could be applied for the investigation on the origin of ancient traditional cultivars of other vegetative propagated species.

Grapevine root transformation with Agrobacterium rhizogenes

Grapevine shoots were obtained from tissue cultures of cvs Barbera, Moscato bianco and Nebbiolo; their stems were wounded and inoculated with the following strains of Agrobacterium rhizogenes. A4, 8196, NCPP 2659, and 15834. Root production at the inoculation site was obtained in about 25% of the stems of all cultivars with all the bacterial strains, with the exception of NCPP 2659, which gave a lower root proliferation rate. Cultures of roots obtained after inoculation were established and their growth was enhanced by some media and by addition of cytokinins and auxins to the medium. Root cultures obtained after inoculation with the strain 8196 were genetically transformed, as shown by opine production. In contrast, opines were seldom detected in the root cultures obtained with the other bacterial strains. Light microscope observation showed that the cortex of transformed roots has more cell layers and a larger average cell size than in normal roots.

Metabolite profiling elucidates communalities and differences in the polyphenol biosynthetic pathways of red and white Muscat genotypes

The chemical composition of grape berries is varietal dependent and influenced by the environment and viticulture practices. In Muscat grapes, phenolic compounds play a significant role in the organoleptic property of the wine. In the present study, we investigated the chemical diversity of berries in a Muscat collection. Metabolite profiling was performed on 18 Moscato bianco clones and 43 different red and white grape varieties of Muscat using ultra-performance liquid chromatography–quadrupole time of flight–mass spectrometry (UPLC-QTOF-MS/MS) coupled with SNP genotyping. Principle component analysis and hierarchical clustering showed a separation of the genotypes into six main groups, three red and three white. Anthocyanins mainly explained the variance between the different groups. Additionally, within the white varieties mainly flavonols and flavanols contributed to the chemical diversity identified. A genotype-specific rootstock effect was identified when separately analyzing the skin of the clones, and it was attributed mainly to resveratrol, quercetin 3-O-galactoside, citrate and malate.The metabolite profile of the varieties investigated reveals the chemical diversity existing among different groups of Muscat genotypes. The distribution pattern of metabolites among the groups dictates the abundance of precursors and intermediate metabolite classes, which contribute to the organoleptic properties of Muscat berries.

Effect of Reductive Pressing on the Concentration of Reduced Glutathione and Phenols in the Musts of Four Italian Cultivars

This research investigated the effect of pressing under air or nitrogen on the color and concentration of reduced glutathione (GSH), hydroxycinnamoyl tartaric acids (HCTA) and polyphenols in the musts of four Italian white grape cultivars: Arneis, Cortese, Moscato bianco, and Manzoni bianco. Grapes from different locations were pressed using a prototype press (500 kg capacity) under the same operating conditions as a commercial winery. The musts of the four cultivars were significantly different from one another. The trend of the measured GSH concentration in the musts was: Moscato bianco < Cortese < Manzoni bianco < Arneis, without any significant interactions between cultivar and year. The intake of oxygen during pressing in air caused large decreases in GSH concentration, yet its complete exhaustion was only observed in a few trials. When present, the residual GSH was proportional to the values observed in the respective trials pressed under nitrogen. The contact with air during pressing also lowered the amounts of total polyphenols and catechins. The loss of catechins did not depend on the composition of HCTA, GSH, and HCTA/GSH in musts, while color browning was influenced by the HCTA/GSH molar ratio. The color intensity of musts (A₄₂₀) increased exponentially with the decrease in GSH: A₄₂₀ values higher than 0.2 AU were observed for GSH concentrations less than 8 μM.

Expression of terpene synthase genes associated with the formation of volatiles in different organs of Vitis vinifera

Plants produce a plethora of volatile organic compounds (VOCs) which are important in determining the quality and nutraceutical properties of horticultural food products, including the taste and aroma of wine. Given that some of the most prevalent grape aroma constituents are terpenoids, we investigated the possible variations in the relative expression of terpene synthase (TPS) genes that depend on the organ. We thus analysed mature leaves, young leaves, stems, young stems, roots, rachis, tendrils, peduncles, bud flowers, flowers and berries of cv Moscato bianco in terms of their VOC content and the expression of 23 TPS genes.In terms of the volatile characterization of the organs by SPME/GC–MS analysis, flower buds and open flowers appeared to be clearly distinct from all the other organs analysed in terms of their high VOC concentration. Qualitatively detected VOCs clearly separated all the vegetative organs from flowers and berries, then the roots and rachis from other vegetative organs and flowers from berries, which confirms the specialization in volatile production among different organs.Our real-time RT-PCR results revealed that the majority of TPS genes analysed exhibited detectable transcripts in all the organs investigated, while only some were found to be expressed specifically in one or just a few organs. In most cases, we found that the known products of the in vitro assay of VvTPS enzymes corresponded well to the terpenes found in the organs in which the encoding gene was expressed, as in the case of (E)-β-caryophyllene synthases, α-terpineol synthase and α-farnesene synthase. In addition, we found groups of homologous TPS genes, such as (E)-β-caryophyllene and β-ocimene synthases, expressed distinctively in the various tissues. This thus confirmed the subfunctionalization events and a specialization on the basis of the organs in which they are mostly expressed.

FUNCTIONAL CHARACTERIZATION OF TERPENE SYNTHASES OF 'AROMATIC' AND 'NON-AROMATIC' GRAPEVINE CULTIVARS

Grape-derived flavour compounds and some flavour precursors modified during fermentation, wine evolution and ageing, are fundamental in determining the organolectic parameters used to define wine quality. The knowledge of the biosyn-thesis of secondary metabolites that contribute to grape and wine flavour is not well understood and only a few genes involved in berry flavour biosynthesis pathways have been discovered and characterised. The aim of this research is the functional characterization of candidate genes thought to contribute to the volatile profiles of ?aromatic? (?Aleatico?, ?Moscato bianco?) and ?non-aromatic? (?Sangiovese?) cultivars. Samples of flowers and berries covering developmental stages from fruit set to technological ripening, of ?Aleatico?, ?Moscato bianco?, and ?Sangiovese? have been analysed for their aroma content and the expression of genes that are predicted to be involved in grape sesquiterpene and monoterpene biosynthesis. The aroma com-pounds have been extracted by SPE and SPME procedures and analysed by GS-MS, while the expression of characterised grape aroma genes and some candidate genes have been analysed by real-time RT-PCR. Some of the genes studied show correlations between their expression patterns and the accumulation of certain aroma compounds during berry development. These genes have been the focus of functional character¬ization studies and include a sesquiterpene synthase (which has an expression pattern that correlates with the production of farnesene in flowers buds and open flowers), putative monoterpene synthases that are expressed when linalool accumulates in flowers or during ripening, and putative linalool epoxidases that are expressed when trans-pyran-linalool oxide accumulates during berry ripening of all three grapevine cultivars studied. Some of these genes have been cloned in E. coli and the enzymatic activity characterized. The discovery and characterization of genes that encode enzymes from grapevine flavour biosynthesis pathways and knowledge of factors that influence their expression and activity during berry development would support decisions on management of genotype, environment and viticultural practices for improving grape flavour and aroma potential.

Genetic traceability of Asti Spumante and Moscato d’Asti musts and wines using nuclear and chloroplast microsatellite markers

The final characteristics of a wine are strongly influenced by must varietal composition. Further, wine quality and value can be heavily modified if grape varieties other than those expected/allowed are used, especially in the case of monovarietal wines. ‘Moscato bianco’, which is one of the main grape varieties grown in Piedmont (north-western Italy), is used for the production of two renowned monovarietal sparkling wines: Asti Spumante and Moscato d’Asti. Here, the genetic traceability of these wines was assessed using a simple sequence repeat (SSR or microsatellite) DNA-based method. Must and wine samples from two local wineries were collected at different winemaking steps: after grape crushing and pressing, without the skins (must sample 1, M1); after static clarification or flotation (M2); halfway through fermentation (M3); and finished wines. A DNA extraction protocol was developed, and samples were analysed using a set of 9 nuclear (nSSR) and 7 chloroplast (cpSSR) markers. The application of nSSR markers was successful for M1 and M2, but was inadequate for M3 and wines. CpSSR gave better results as amplifications were achieved using DNA extracted from M1, M2 and wines, despite the lack of amplification in M3. Furthermore, the amplified cpSSR loci showed high polymorphism, allowing the identification of 5 distinct chlorotypes among 7 muscat-flavoured and 2 non-aromatic grapevines. Altogether, these results suggest that this technique could be extended to wine quality and authenticity control, as well as origin protection.

Characterisation of polymeric skin and seed proanthocyanidins during ripening in six Vitis vinifera L. cv

The polymeric proanthocyanidin (PAs) composition of skins and seeds from Vitis vinifera L. cv during ripening was evaluated. Six grape varieties (Cabernet Sauvignon, Malvasia bianca, Moscato bianco, Nascetta, Nebbiolo and Pinot bianco) cultivated in Piedmont (vintage 2008) were collected at five different ripening stages (from 6 to 20°Brix). Polymeric proanthocyanidins were determined both by vanillin assay and by phloroglucinolysis; these analytical methods were compared showing a significant correlation (r=0.8321, p<0.0001 and r=0.7406, p<0.0001 for grape skins and seeds, respectively). Acid-catalysed cleavage of the polymer, combined with HPLC separation, enabled quantification of individual polymer subunits, estimation of mean degree of polymerisation (mDP), and the evolution of the extractable polymeric fraction isolated during ripening. Antiradical activity was evaluated as inhibition percentage of DPPH radical. A significant positive correlation between total PAs content and antiradical activity was observed (r=0.6410, p<0.0001); on the contrary, the mDP appeared to be negatively correlated to the antiradical activity (r=−0.6238, p<0.0001).

Influence of skin hardness on dehydration kinetics of wine grapes

Knowledge of the influence of initial mechanical properties on the evolution of the weight loss of berries through the drying process is scarce. Therefore, the main purpose of this work was to investigate the effect of skin hardness at two different physiological stages of off-vine drying kinetics of grapes. Skin hardness was evaluated as the berry skin-break force parameter, measured by the texture analysis test. The decrease of berry weight as a function of the drying time was linear, indicating that the drying rates were constant within each cultivar studied (Moscato bianco and Erbaluce), and for each ripening stage and berry skin hardness. The drying rates decreased as berry skin hardness increased for the ripest grapes in the cultivars studied. The study allowed the assessment of the correlation between the skin hardness of fresh berries and the weight loss determined for different drying days.

The SSR-based molecular profile of 1005 grapevine (Vitis vinifera L.) accessions uncovers new synonymy and parentages, and reveals a large admixture amongst varieties of different geographic origin

A collection of 1005 grapevine accessions was genotyped at 34 microsatellite loci (SSR) with the aim of analysing genetic diversity and exploring parentages. The comparison of molecular profiles revealed 200 groups of synonymy. The removal of perfect synonyms reduced the database to 745 unique genotypes, on which population genetic parameters were calculated. The analysis of kinship uncovered 74 complete pedigrees, with both parents identified. Many of these parentages were not previously known and are of considerable historical interest, e.g. Chenin blanc (Sauvignon×Traminer rot), Covè (Harslevelu selfed), Incrocio Manzoni 2-14 and 2-15 (Cabernet franc×Prosecco), Lagrein (Schiava gentile×Teroldego), Malvasia nera of Bolzano (Perera×Schiava gentile), Manzoni moscato (Raboso veronese×Moscato d'Amburgo), Moscato violetto (Moscato bianco×Duraguzza), Muscat of Alexandria (Muscat blanc à petit grain×Axina de tres bias) and others. Statistical robustness of unexpected pedigrees was reinforced with the analysis of an additional 7-30 SSRs. Grouping the accessions by profile resulted in a weak correlation with their geographical origin and/or current area of cultivation, revealing a large admixture of local varieties with those most widely cultivated, as a result of ancient commerce and population flow. The SSRs with tri- to penta-nucleotide repeats adopted for the present study showed a great capacity for discriminating amongst accessions, with probabilities of identity by chance as low as 1.45×10(-27) and 9.35×10(-12) for unrelated and full sib individuals, respectively. A database of allele frequencies and SSR profiles of 32 reference cultivars are provided.

Microsatellite analyses for evaluation of genetic diversity among Sicilian grapevine cultivars

A total of 82 grapevine genotypes were sampled from several areas of the Italian region of Sicily where vineyards are widely spread. The grapevines were characterized using six microsatellite markers (VVS2, VVMD5, VVMD7, VVMD27, VrZAG62 and VrZAG79) to evaluate genetic diversity. Thirty-seven of the 82 cultivars sampled had their names quoted in historical and literary sources, while 45 cultivars from old vineyards did not have their names reported in ancient literature. According to their genetic profiles at SSR loci, 70 different cultivars were found, while interesting cases of synonymies (Regina and Moscato bianco, Alicante and Dolcetta or among different clones of Zibibbo and Catarratto) and cases of homonymy (Frappato and Nerello Mascalese) were discovered. Several genetic parameters were calculated to assess the efficacy of the loci chosen in this work. Pairwise genetic distances between all cultivars were calculated. A dendrogram representing the genetic similarities among cultivars was depicted using the UPGMA method to investigate their relationships, explaining them from a historical point of view. The cluster distribution of cultivars clearly does not reflect their current geographical distribution, suggesting successive introductions of cultivars in Sicily from different areas of origin.