Muscat flavor is a relevant trait both in winemaking and in fresh grape consumption. From a chemical point of view, it is strongly related to the accumulation of monoterpenes in berries. However, knowledge of the genetic mechanisms underlying its regulation is still limited. The objective of this study was to dissect the genetic determinism of aroma in grapevine by applying the analysis of quantitative trait loci (QTL) and the candidate gene (CG) approach. Two F(1) segregating progenies were evaluated through high-resolution gas chromatography-mass spectrometry (HRGC-MS) for the amounts of individual monoterpenes over 3 and 2 years. In the Italia x Big Perlon cross 34 CGs, chosen according to gene ontology (GO) terms, were placed on a complete map and tested for linkage with QTLs for linalool, nerol and geraniol levels. Two CGs mapped within a QTL for linalool content on LG 10. A third one co-localized with a major QTL for the level of the three monoterpenes on LG 5; this gene encodes 1-deoxy-D: -xylulose 5-phosphate synthase (DXS), which is the first enzyme in the plastidial pathway of terpene biosynthesis. Depending on these findings, we report the first in silico analysis of grapevine DXS genes based on the whole genome sequence. Further research on the functional significance of these associations might help to understand the genetic control of Muscat flavor.

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A new method based on headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry (HS-SPME-GC/MS) to analyse 13 light and heavy volatile sulphur compounds in the same run was established. For the successful application of the procedure, various adsorption process parameters were optimised. In particular the nature of the adsorptive phase, the temperature, the ionic strength of the sample solutions and the equilibration time were considered. The best extraction conditions, in terms of the maximum signal obtainable for each compound, were obtained with a carboxen-polydimethylsiloxane-divinylbenzene (CAR-PDMS-DVB) 2 cm long coating fibre. The choice of suitable internal standards and the matrix effect were studied and the proposed method was validated by determining linearity, precision and accuracy, evaluating the critical, detection and quantification limits. This method is fast, sensitive and precise and easy to transfer to wine quality control. Finally, the proposed method was applied to the determination of the aforementioned sulphur compounds in 32 red and white wines.

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Monovarietal grape pomace distillates (orujo) of six native varieties of Vitis vinifera L. from Galicia (Albarino, Treixadura, Godello, Loureira, Dona Branca, and Torrontes) have been thoroughly analyzed considering esters, alcohols, major aldehydes, monoterpenes, sesquiterpenes, norisoprenoids, and diterpenes. Albarino and Loureira distillates showed similar profiles of terpenic compounds, with the Loureira products having higher contents of monoterpenols. Native Torrontes distillate from Galicia is principally characterized by marked levels of some sesquiterpenes such as cadinene isomers and epizonarene. On the other hand, Treixadura, Godello, and Dona Branca grape pomace distillates seem not to have any marked terpenic content, and their single separation is difficult. PCA data treatments showed a good separation among the terpenic-rich varieties. Also, the p-menthen-9-al isomers, typical flavors in honey citrus and dill herb (derived from 8-hydroxylinalool), are reported for the first time in grape pomace distillate.