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Rotundone is an attractive wine aroma compound, especially important for cool climate Shiraz. Its presence in wine is mainly from the grape skin, but can also be found in nongrape tissues, such as leaves and stems. Whether rotundone is produced independently within different grapevine tissues or transported amongst non-grape tissues and grape berries remains unclear. The current study investigated the distribution of this compound in different vine tissues during development and studied the most likely mode of rotundone translocation--via phloem--using stable isotope feeding. In addition, local production of rotundone induced by herbivore feeding was assessed. Results showed that rotundone was firstly detected in the petioles and peduncles/rachises within the development of Vitis vinifera L. cv. Shiraz. Different grapevine tissues had a similar pattern of rotundone production at different grape developmental stages. In the individual vine shoots, non-grape tissues contained higher concentrations and amounts of rotundone compared to berries, which showed that non-grape tissues were the larger pool of rotundone within the plant. This study confirmed the local production of rotundone in individual tissues and ruled out the possibility of phloem translocation of rotundone between different tissues. In addition, other terpenes, including one monoterpenoid (geraniol) and six sesquiterpenes (clovene, α-ylangene, β-copaene, α-muurolene, δ-cadinene, and cis/trans-calamenene) were, for the first time, detected in the ethylenediaminetetraacetic acid-facilitated petiole phloem exudates, with their originality unconfirmed. Unlike other herbivore-induced terpenes, herbivorous activity had limited influences on the concentration of rotundone in grapevine leaves. [ABSTRACT FROM AUTHOR]

The soluble sugar concentration of fleshy fruit is a key determinant of fleshy fruit quality. It affects directly the sweetness of fresh fruits and indirectly the properties of processed products (e.g., alcohol content in wine). Despite considerable divergence among species, soluble sugar accumulation in a fruit results from the complex interplay of three main processes, namely sugar import, sugar metabolism, and water dilution. Therefore, inter-species comparison would help to identify common and/or speciesspecific modes of regulation in sugar accumulation. For this purpose, a process-based mathematical framework was used to compare soluble sugar accumulation in three fruits: grape, tomato, and peach. Representative datasets covering the time course of sugar accumulation during fruit development were collected. They encompassed 104 combinations of species (3), genotypes (30), and growing conditions (19 years and 16 nutrient and environmental treatments). At maturity, grape showed the highest soluble sugar concentrations (16.5-26.3 g/100 g FW), followed by peach (2.2 to 20 g/100 g FW) and tomato (1.4 to 5 g/100 g FW). Main processes determining soluble sugar concentration were decomposed into sugar importation, metabolism, and water dilution with the process-based analysis. Different regulation modes of soluble sugar concentration were then identified, showing either import-based, dilution-based, or import and dilution dual-based. Firstly, the higher soluble sugar concentration in grape than in tomato is a result of higher sugar importation. Secondly, the higher soluble sugar concentration in grape than in peach is due to a lower water dilution. The third mode of regulation is more complicated than the first two, with differences both in sugar importation and water dilution (grape vs. cherry tomato; cherry tomato vs. peach; peach vs. tomato). On the other hand, carbon utilization for synthesis of non-soluble sugar compounds (namely metabolism) was conserved among the three fruit species. These distinct modes appear to be quite species-specific, but the intensity of the effect may significantly vary depending on the genotype and management practices. These results provide novel insights into the drivers of differences in soluble sugar concentration among fleshy fruits. [ABSTRACT FROM AUTHOR]

Grapevine breeding requires renewed efforts to meet the challenge of the ongoing climate change and the societal demand for low input viticulture. A breeding program supported by Bordeaux wine professional committee (CIVB) aims at generating new cultivars that should meet these two objectives by improving traits such as disease resistance (downy and powdery mildew, black rot), while retaining the typicality of Bordeaux wines. As part of this program, two V. vinifera bi-parental mapping populations were generated by crossing, on the one hand, 'Petit Verdot' (PV) and 'Cabernet Franc' (CF) (n = 202) and, on the other hand, 'Ugni blanc' (UB) and 'Sauvignon blanc' (SB) (n = 214). These two mapping populations were investigated for quantitative trait loci (QTLs) detection of relevant segregating traits such as phenology or aromatic potential with GC-MS and LC-MS analyses. Genotyping by sequencing (GBS) by Illumina HiSeq 3000 of both mapping populations was performed on GET-plage platform (Toulouse, France). After bioinformatics treatments, the construction of the related genetic maps was achieved using JoinMap 4.1. High-density genetic maps, based on single nucleotide polymorphism (SNPs), allowed the detection of 25 QTLs related with phenology, berry quality, aroma composition and aroma precursors, as well as the identification of some relevant candidate genes. The QTLs identified typically accounted for 7-27% of the trait variation. The molecular markers identified in this project will be used for marker-assisted selection in current and future grapevine breeding programs. The project will provide the basis of the genetic architecture of useful traits for the production of red and white wines with emblematic Bordeaux typicality and will thus contribute to the design of new ideotypes. [ABSTRACT FROM AUTHOR]

Genomic prediction (GP) of breeding values has developed widely both in animal and plant breeding programs for its ability to accelerate genetic gains, saving cost and time while handling complex traits. However, its routine deployment in most of the major plant species is still not effective, mainly because of the many factors that are likely to influence prediction accuracies. In grapevine, very few studies have evaluated potential usefulness of GP in breeding contexts. Although the French grapevine breeding program for durable resistance to downy and powdery mildew (INRAE-ResDur) has now proved to be effective with about ten new varieties already officially registered, the duration of each breeding cycle remains long (about 15 years). GP can potentially help us to accelerate and diversify our breeding schemes by targeting complex traits involved in the determination of the optimal productivity and quality of the berries and wines. The main objective is to reduce as much as possible, the long intermediate selection phase of the breeding scheme where every genotype is evaluated in the yard during six years. Here we evaluated GP across four different breeding populations for main phenological and agronomic traits to identify main factor affecting accuracies. This study brings additional information to the grapevine community regarding the implementation of GP to accelerate breeding programs. [ABSTRACT FROM AUTHOR]

Vitis species, both in their cultivated and wild forms, grow in a large diversity of environments since thousands of years. Consequently, they have developed many adaptive mechanisms controlled by a range of regulatory processes. The cultivated species Vitis vinifera is fairly well-adapted to semi-arid conditions and its cultivation can be used to produce crops on marginal lands. However, this is under threat due to climate change, which is associated with a rise in temperature and CO2 atmospheric content, modifications of water availability and a higher probability of extreme events, such as heat waves and early spring frosts. Indirect effects of climate change in solar radiation and soil mineral contents are also expected. Altogether, it is likely that cultivated grapevines will have to face more abiotic constraints occurring concomitantly or successively over one or several growing cycles. In addition to climate change, viticulture worldwide has to reduce pesticide use. Adapting to climate change and reducing pesticide use are challenging and increase the need to select new grapevine varieties more resistant to disease and better adapted to abiotic constraints. In this sense, the adaptive mechanisms from wild and cultivated Vitis species have to be leveraged. While major advances have already been made for disease resistance, the polygenic nature of adaptation to abiotic factors has slowed down research progress. To tackle this limitation, ambitious integrative strategies should be designed, from collection and characterization of genetic resources, genetic architecture studies and identification of underlying genes (including those involved in epigenetic regulation), to new breeding technologies and the development of genomic selection. An up-date on the state-of-the-art regarding these aspects will be presented. [ABSTRACT FROM AUTHOR]

Climate change will impose increasingly warm and dry conditions on vineyards. Wine quality and yield are strongly influenced by climatic conditions and depend on complex interactions between temperatures, water availability, plant material, and viticultural techniques. In established winegrowing regions, growers have optimized yield and quality by choosing plant material and viticultural techniques according to local climatic conditions, but as the climate changes, these will need to be adjusted. Adaptations to higher temperatures include changing plant material (e.g., rootstocks, cultivars and clones) and modifying viticultural techniques (e.g., changing trunk height, leaf area to fruit weight ratio, timing of pruning) such that harvest dates are maintained in the optimal period at the end of September or early October in the Northern Hemisphere. Vineyards can be made more resilient to drought by planting drought resistant plant material, modifying training systems (e.g., goblet bush vines, or trellised vineyards at wider row spacing), or selecting soils with greater soil water holding capacity. While most vineyards in Europe are currently dry-farmed, irrigation may also be an option to grow sustainable yields under increasingly dry conditions but consideration must be given to associated impacts on water resources and the environment. [ABSTRACT FROM AUTHOR]

The genetic determinism of developmental stages in grapevine was studied in the progeny of a cross between grapevine cultivars Riesling and Gewurztraminer by combining ecophysiological modelling, genetic analysis and data mining of the grapevine whole genome sequence. The dates of three phenological stages, budbreak, flowering and veraison, were recorded during four successive years for 120 genotypes in the vineyard. The phenotypic data analysed were the duration of three periods expressed in thermal time (degree-days): 15 February to budbreak (Bud), budbreak to flowering (Flo) and flowering to veraison (Ver). Parental and consensus genetic maps were built using 153 microsatellite markers on 188 individuals. Six independent quantitative trait loci (QTLs) were detected for the three phases. They were located on chromosomes 4 and 19 for Bud, chromosomes 7 and 14 for Flo and chromosomes 16 and 18 for Ver. Interactions were detected between loci and also between alleles at the same locus. Using the available grapevine whole-genome sequences, candidate genes underlying the QTLs were identified. VvFT, on chromosome 7, and a CONSTANS-like gene, on chromosome 14, were found to colocalise with the QTLs for flowering time. Genes related to the abscisic acid response and to sugar metabolism were detected within the confidence intervals of QTLs for veraison time. Their possible roles in the developmental process are discussed. These results raise new hypotheses for a better understanding of the physiological processes governing grapevine phenology and provide a framework for breeding new varieties adapted to the future predicted climatic conditions.

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.