Claudio D'Onofrio

Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white Vitis vinifera wine grapes.

A nondestructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot, and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g·kg(-1) fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a nondestructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in a linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture.

Analysis of the expression of terpene synthase genes in relation to aroma content in two aromatic Vitis vinifera varieties

Grape (Vitis vinifera L.) flavour management in the vineyard requires knowledge of the derivation of individual flavour and aroma characteristics. Some of the most prevalent wine grape aroma constituents are terpenoids and this study represents a wide report about grape terpene synthase (TPS) gene transcript profiling in different tissues of two aromatic grapevine varieties, particularly flowers and developing berries, correlated with the accumulation patterns of free aroma compounds. All investigated genes belonging to the TPS-a and TPS-b subfamilies reached the highest expression in accordance with the peak of accumulation of the respective compounds. In the TPS-g subfamily, only one of the genes characterised for linalool synthases showed major transcript abundance in ripening berries, whereas the only geraniol synthase had a peak of expression in green berries and at the beginning of ripening, when geraniol concentration started to increase and overcome the linalool concentration. The genes identified in this study as being mainly responsible for linalool and geraniol synthesis during berry development, and the phenological phases in which they are mostly expressed, should be of interest to viticulturists and wine makers to improve decision making along the chain of production.

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

BACKGROUNDnIn 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.nnnRESULTSnMalvasia 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.nnnCONCLUSIONnThe 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.

Influence of vineyard altitude on Glera grape ripening (Vitis vinifera L.): effects on aroma evolution and wine sensory profile

BACKGROUNDnEnvironmental factors have been acknowledged to greatly influence grape and wine aromas. Among them, the effect of altitude on grape aroma compounds has scarcely been debated in literature available to date. In the present study, we investigated the influence of altitude on grape composition and aroma evolution during ripening of Vitis vinifera L. cultivar Glera grown in Conegliano-Valdobbiadene DOCG area (Italy).nnnRESULTSnThe site at highest altitude (380 m above sea level) was warmer than the lowest site (200 m above sea level) and, even with differences in temperature in the range 1.5-2 °C, the impact of the cultivation site on grape ripening and aroma accumulation and preservation was significant. The lowest site demonstrated slower grape ripening, and grapes at harvest accumulated lower amounts of all of the main classes of aroma compounds typical of the Glera variety. Wines produced from the highest site were preferred in tasting trials for their more patent floral notes and elegance.nnnCONCLUSIONnAltitude strongly influences grape ripening evolution and flavour accumulation in the Glera grape, and this result accounts for the different styles in the sparkling wines subsequently produced. Moreover, the present study shows that aroma compound biosynthesis, particularly that of benzenoides, starts before véraison in Glera.

Effect of methyl jasmonate on the aroma of Sangiovese grapes and wines

Methyl jasmonate (MeJA) was applied in a vineyard on leaves and grape clusters of cv Sangiovese to test its ability to stimulate the production of aromas and identify the main genes involved in the biosynthetic pathways switched on by the elicitor. MeJA application led to a delay in grape technological maturity and a significant increase in the concentration of several berry aroma classes (about twice the total aroma: from around 3 to 6μg/g of berry). Of these, monoterpenes showed the most significant increase. An analysis of the expression of terpenoid biosynthesis genes confirmed that the MeJA application activated the related biosynthetic pathway. The expression of all the TPS genes analyzedwas higher in samples treated with MeJA. Also the wines produced by microvinification of Sangiovese treated and untreated grapes showed a rise in the aroma concentration as in berries, with an important impact on longevity and sensorial characters of wines.

Clonal Selection of cv. Aleatico (Vitis vinifera L.) Along Tuscan Coastal Area

The results of the grapevine clonal selection carried out in Tuscany in the last seven years not only provided evidence of a high concentration of viral infections, but also showed that the sanitary status of the variety Aleatico is extremely worrying. The sanitary tests conducted on 172 plants, selected in the Elba Isle, on the hills around Lucca and in Maremma region showed a critical phytovirological condition. In fact, only 5 plants passed the first sanitary screening, being found free of all viruses investigated (GFLV, ArMV, GFkV, GLRaV-1, GLRaV-3, GLRaV-7, GVA and GVB). The candidate clones selected in Maremma showed remarkable differences in their morphological traits, both from one another (ALESCA 59 and ALESCA 60 on one side, and ALCHI V on the other), and from those that had been identified on the Elba Isle (ALE 102 and ALE 119). The differences found among the 3 biotypes were statistically confirmed by cluster analysis procedures concerning the OIV traits of the shoots, leaves and bunches, and through the results of preliminary DNA analyses conducted in 6 micro-satellite loci. The general analysis of the available data showed the following decreasing scale of virus spreading values for the variety Aleatico (for the studied viruses): GLRaV-3>GLRaV-l>GVA>GFLV>GFkV. ArMV, GLRaV-7 and GVB have never been found. Differences in the infectious combinations ascertained in the 3 areas of selection are particularly interesting. The presence of mixed infections did not affect the vines that had been selected in the Maremma region and only slightly affected those from the Lucca hills, while 16 different combinations were found for the Elba Isle. The worrying sanitary status of Aleatico and the lack of registered clones of this variety seem to attach great importance to the results of this work, even if still quantitatively poor, for the improvement of the islands vine-growing activity along with the promotion of Aleatico wine, whose excellent organoleptic features and uniqueness are well-known.

Ampelographic and Biomolecular Studies on The Grapevine Variety 'Aleatico'

Aleatico has been cited several times for its peculiar aromatic characteristics. It has been cultivated in Tuscany since the Middle Ages and is present in just a few other small Mediterranean areas, among which Elba Island is certainly the most famous. The previous Aleatico clonal selection conducted in Tuscany by the Dipartimento di Coltivazione e Difesa delle Specie Legnose permitted identifying several candidate clones, free of the main virus agent, having different morphological traits. The ampelographic work was carried out on the above-mentioned presumed clones and on homologated clones cultivated in the same collection vineyard located on Elba Island. The dendrogram obtained from the cluster analysis of adult leaf OIV characters showed significant differences among the homologated clones and the presumed clones of Aleatico. In particular, biotypes Alesca 59 and Alesca 60 were morphologically different from the homologated clones and from the other candidate clones and from biotype Alchi 1, which appeared to differ the most from the other accessions. The molecular investigations conducted on 6 microsatellite loci revealed the identity among the homologated clones and the candidate clones of Aleatico coming from Elba, except for biotypes Alchi 1, Alesca 59 and Alesca 60. In particular, biotype Alchi 1 shares an allele on 5 of the 6 loci analysed, but in locus WM21 it has a configuration that is completely different from Aleatico, sharing an allele with the Ciliegiolo and Sangiovese varieties. Biotypes Alesca 59 and Alesca 60 always share an allele with Aleatico in all of the loci analysed and, therefore, they could be closely related to Aleatico.

Combining color chart, colorimetric measurement and chemical compounds for postharvest quality of white wine grapes: Postharvest quality of white wine grapes

BACKGROUNDnThis paper provides data for the potential use of a color chart to establish the best quality of white wine grapes destined for postharvest processing. Grechetto, Vermentino and Muscat of Alexandria white wine grape varieties were tested by sampling berries at different dates during their quality attribute evolution. A color chart and reflectance spectrocolorimeter were used in combination with analyses of total carotenoids and chlorophylls in all three varieties and of volatile organic compounds (VOCs) in Grechetto alone.nnnRESULTSnTotal carotenoids decreased from 0.85 to 0.76u2009µg g-1 in Grechetto berries and from 0.70 to 0.46u2009µg g-1 in Vermentino berries while increased from 0.70 to 0.80u2009µg g-1 in Muscat berries during ripening. Total chlorophylls decreased in all varieties, and a strict correlation was found between hue angle (measured by color chart or spectrocolorimeter) and chlorophyll disappearance, with R2 ranging from 0.81 to 0.95 depending on the variety. VOCs were only measured in Grechetto grapes, and a significant increase in glycosylation was found with ripening. The concentration of different classes of VOCs exhibited a clear decrease during ripening, except for terpenoids and esters which showed a peak at the beginning. The benzenoid class reached the highest concentration, which was almost 50% of the total. Cluster analysis using Wards method enabled the best grape quality to be identified.nnnCONCLUSIONnThis experimental work highlights that a color chart is cheap and easy to use to define the right quality stage for white wine grapes. The color chart enabled the enochemical features to be matched with the VOC results for the aromatic maturity of Grechetto.

Genotyping of Grapevine Varieties from Garfagnana (Northern Tuscany): Evidence of a Historical Center of Diversity

The aim of this investigation was to recover, characterize, and increase the value of local grapevine varieties from Garfagnana, a mountainous area situated in the north of Tuscany (located in central Italy). A total of 130 accessions (vines) were identified in old Garfagnana vineyards, characterized by Organisation Internationale de la Vigne et du Vin morphological-phenological and productive parameters, and genotyped with 14 microsatellite loci. The microsatellite analysis identified 50 genotypes. Some of these genotypes matched Tuscan genotypes, others corresponded to varieties cultivated in other Italian and European regions, and 18 appeared to be genotypes currently identified only in Garfagnana and presumably autochthonous to this area. Cluster and similarity analyses based on both microsatellite and morphology data indicated a clear grouping of the majority of the autochthonous genotypes from Garfagnana. A parentage analysis revealed that the Garfagnana autochthonous genotypes are highly first degree–related among each other, suggesting that Garfagnana is a distinct historical center of diversity of cultivated varieties. The data from all varieties have been entered into the Italian Vitis Database (www.vitisdb.it).