Linalool, geraniol, nerol, citronellol and alpha-terpineol are isoprenoid molecules responsible for specific aromas found in grapes and wines. Total concentrations (free and bound forms) of these compounds were measured in the skins of mature berries during 2 successive years in two progenies obtained from Muscat Ottonel and Gewurztraminer selfings. Partial genetic maps based on microsatellite markers were constructed and several quantitative trait loci (QTLs) related to terpenol content were detected. A major QTL on linkage group (LG) 5 colocated with a deoxy-D: -xylulose synthase gene, coding for the first enzyme of the plastidial isoprenoid biosynthesis pathway. The number of favourable alleles at this locus determined the level of terpenol synthesis. A second QTL, on LG 10, was found to determine the balance linalool versus geraniol and nerol in the Muscat self-progeny plants.

Backgrounds and Aims:  In order to assess the suitability of some genotypes for functional genomics studies on terpenol synthesis in grapevine, two pairs of cultivars differing in their aromatic pattern were compared: Gewurztraminer and Savagnin Rose and two clones of Chardonnay (76 and 809). Methods and Results:  The genetic analysis based on microsatellite markers showed that Gewurztraminer and Savagnin Rose were clones derived from a single mother plant. The same result was found for Chardonnay clones 76 and 809. Analyses of wines, musts and berries showed that linalool and geraniol were present only at very low concentrations in Savagnin Rose and Chardonnay 76, both considered as non‐aromatic cultivars. On the contrary, Gewurztraminer was characterised by a high geraniol content and Chardonnay 809 by a profile where linalool was predominant. Results obtained in the vineyard were consistent with data on fruiting cuttings in the greenhouse. Analyses of the terpenol content of berries from self‐progenies plants of Gewurztraminer and Chardonnay 809 showed that this trait was heritable. Conclusions:  We provide evidence that clonal variation, through somatic mutations, can modify the aromatic profile of fruits. Significance of the Study:  We have characterised grapevine clones consistently differing in the terpenol content of both grapes and wines. Such plant material is appropriate for functional genomics studies.

Key message In a grapevine segregating population, genomic regions governing berry pH were identified, paving the way for breeding new grapevine varieties best adapted to a warming climate. Abstract As a consequence of global warming, grapevine berry acidity is expected to dramatically decrease. Adapting grapevine (Vitis vinifera L.) varieties to the climatic conditions of the future requires a better understanding of the genetic architecture of acidity-related traits. For this purpose, we studied during five growing seasons 120 individuals from a grapevine biparental cross. Each offspring was genotyped by simple sequence repeats markers and by hybridization on a 20-K Grapevine Illumina ® SNP chip. Quantitative trait loci (QTLs) for pH colocalized with QTLs for the ratio between potassium and tartaric acid concentrations, on chromosomes 10, 11 and 13. Strong QTLs for malic acid concentration or for the malic acid-to-tartaric acid ratio, on chromosomes 6 and 8, were not associated with variations of pH but can be useful for controlling pH stability under high temperatures. Our study highlights the interdependency between acidity parameters and consequently the constraints and degrees of freedom for designing grapevine genotypes better adapted to the expected warmer climatic conditions. In particular, it is possible to create grapevine genotypes with a high berry acidity as the result of both high tartaric acid concentrations and low K + accumulation capacities.

Background and Aims The acidity of harvested grapevine berries is likely to decrease in the future because of increasing temperature during grape ripening. The aim of the study was to evaluate the genetic variability of berry acidity descriptors in progeny from a Riesling × Gewürztraminer cross. Methods and Results The ripening process for the parent cultivars was monitored over three growing seasons; berries from Riesling had a higher tartaric acid concentration than that from Gewürztraminer, and a similar difference was observed for malic acid. A statistical model describing the decline in malic acid concentration over time was fitted to the data. With this model, the parameter that best characterised the two genotypes was the asymptotic minimum value of malic acid concentration per g of berry dry matter. In addition, the rate of decrease of malic acid was constant across years when thermal‐time scales were used. Using samples of green berries at veraison and samples picked 230 degree days after veraison (mean temperature, base 10°C), 120 genotypes from a Riesling × Gewürztraminer progeny were compared over 3 years in the vineyard and segregations for all the berry acidity descriptors were described. Conclusions A significant genotypic variability was observed for the concentration of malic and tartaric acids but also for the estimated cationic content of the berries for the same developmental stage. No genotypes, however, were detected, with a concentration of total malic and tartaric acid significantly higher than that of Riesling. Significance of the Study These results show that berry acidity descriptors are heritable traits that can be manipulated in breeding programs.