Berry secondary metabolites and leaf physiological parameters are independently regulated by exogenous methyl jasmonate application in Sangiovese grapevines (Vitis vinifera L.).

The role of jasmonates as elicitor of secondary metabolites is well known, and many experiments have been conducted in grapevine to evaluate their effects on berry and wine quality. Even though most of these studies used foliar jasmonates applications, little investigations have been done to assess the effects on leaves which, in turn, may indirectly affect grape metabolism potentially involving a long distance signaling or crosstalk. In this experiment we jointly investigated the specific effect of jasmonates on grape berry secondary metabolites and leaf physiological parameters to better comprehend their elicitation mechanisms in grapevine. A 10 mM methyl jasmonate (MeJA) solution was applied during the lag-phase only on the leaves or only on the clusters and compared to an untreated control. The MeJA specifically affected leaf physiological parameters and berry metabolism in the treated area. When applied only on the leaves, gas exchange parameters and leaf efficiency were reduced, stimulating the senescence mechanisms, without affecting berry metabolism. On the contrary, MeJA applied on the clusters significantly delayed berry ripening, leading to hypothesize a re-route of the berry carbon resources through the biosynthesis of volatile organic compounds which were strongly increased, especially the monoterpenes in their glycosylated form.

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

BACKGROUND: 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. RESULTS: 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. CONCLUSION: 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.

Water deficit before veraison is crucial in regulating berry VOCs concentration in Sangiovese grapevines.

The impact of water deficit on volatile organic compounds (VOCs) responsible for grape aroma remains quite unclear. The aim of this study was to evaluate the effect of different timing and intensity of water deficit on berry VOCs and on their biosynthetic pathways. Fully irrigated control vines were compared with the following treatments: i) two different levels of water deficit from berry pea-size through veraison, ii) one level of water deficit during the lag-phase, and iii) two different levels of water deficit from veraison through harvest. At harvest, total VOC concentrations were higher in berries of water stressed vines from berry pea size through veraison or during the lag phase, whereas post-veraison water deficit determined similar concentrations as control. This pattern was even more pronounced for the glycosylated fraction and was also observed for single compounds, mainly monoterpenes and C13-norisoprenoids. On the other hand, free VOCs were higher in berries from lag phase or post-veraison stressed vines. The significant glycosylated and free VOCs increment measured after the short water stress limited to the lag phase highlight the pivotal role played by this stage in berry aroma compound biosynthesis modulation. The severity of water stress before veraison was also important, since glycosylated VOCs showed a positive correlation with the pre-veraison daily water stress integral. The RNA-seq analysis showed a wide regulation induced by irrigation regimes on terpenes and carotenoids biosynthetic pathways. The terpene synthases and glycosyltransferases as well as genes of the network of transcription factors were upregulated, especially in berries from pre-veraison stressed vines. Since the timing and intensity of water deficit contribute to regulate berry VOCs, irrigation management can be used to achieve high-quality grapes while saving water.

The beneficial effect of leaf removal during fruit set on physiological, biochemical, and qualitative indices and volatile organic compound profile of the Cypriot reference cultivar 'Xynisteri'.

BACKGROUND: 'Xynisteri' is the reference Cypriot white cultivar that, despite its significant societal and economic impact, is poorly characterized regarding its qualitative properties, while scarce information exists regarding its aroma profile. In the current study, the effect of leaf removal during fruit set (BBCH 71) on 6-year cordon-trained, spur-pruned grapevines was assessed and an array of physiological, biochemical, and qualitative indices were monitored during successive developmental stages (BBCH 75, BBCH 85, BBCH 87, and BBCH 89). Grapes were additionally monitored for the volatile organic compounds (VOCs) profile during the advanced on-vine developmental stages (BBCH 85-BBCH 89) with the employment of gas chromatography-mass spectrometry (GC-MS), Fourier-transform near infrared (FT-NIR) spectra and electronic nose (E-nose) techniques. RESULTS: Grape berries from the vines subjected to leaf removal were characterized by higher solid soluble sugars (SSC), titratable acidity (TA), tartaric acid, and ammonium nitrogen contents, while this was not the case for assimilable amino nitrogen (primary amino nitrogen). A total of 75 compounds were identified and quantified, including aliphatic alcohols, benzenic compounds, phenols, vanillins, monoterpenes, and C13 -norisoprenoids. Leaf removal led to enhanced amounts of glycosylated aroma compounds, mainly monoterpenes, and C13 -norisoprenoids. Chemometric analysis, used through FT-NIR and E-nose, showed that the aromatic patterns detected were well associated to the grape ripening trend and differences between leaf removal-treated and control grapes were detectable during fully ripe stage. CONCLUSION: Leaf removal at fruit set resulted in an overall induction of secondary metabolism, with special reference to glycosylated aroma compounds, namely monoterpenes and C13 -norisoprenoids. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Berry flavonoids are differently modulated by timing and intensities of water deficit in Vitis vinifera L. cv. Sangiovese.

In this work, we tested the effect of different regulated deficit irrigation (RDI) regimes on berry flavonoid content and its relative biosynthetic pathways. Vines were subjected to six irrigation regimes over two consecutive years: a) full irrigation during the entire irrigation period (FI); b) moderate (RDI-1M) or c) severe (RDI-1S) water deficit between berry pea-size and veraison; d) severe water deficit during the lag-phase (RDI-LS); and e) moderate (RDI-2M) or f) severe (RDI-2S) water deficit from veraison through harvest. Berries from both RDI-1 treatments showed the highest accumulation of anthocyanins, upregulating the expression of many genes of the flavonoid pathway since the beginning of veraison until harvest, far after the water deficit was released. Although to a lesser degree than RDI-1, both post-veraison water deficit treatments increased anthocyanin concentration, particularly those of the tri-substituted forms, overexpressing the F3'5'H hydroxylases. The moderate deficit irrigation treatments enhanced anthocyanin accumulation with respect to the severe ones regardless of the period when they were applied (pre- or post-veraison). The water deficit imposed during the lag-phase downregulated many genes throughout the flavonoid pathway, showing a slight reduction in anthocyanin accumulation. The measurements of cluster temperature and light exposure highlighted that under deficit irrigation conditions, the effects induced by water stress prevailed over that of light and temperature in regulating anthocyanin biosynthesis. Flavonol concentration was higher in RDI-1S berries due to the upregulation of the flavonol synthases and the flavonol-3-O-glycosyltransferases. In this case, the higher cluster light exposure induced by water deficit in RDI-1S berries had a major role in flavonol accumulation. We conclude that the timing and intensity of water stress strongly regulate the berry flavonoid accumulation and that proper management of deficit irrigation can modulate the phenylpropanoid and flavonoid pathways.

Integrated Bayesian Approaches Shed Light on the Dissemination Routes of the Eurasian Grapevine Germplasm.

The domestication and spreading of grapevine as well as the gene flow history had been described in many studies. We used a high-quality 7k SNP dataset of 1,038 Eurasian grape varieties with unique profiles to assess the population genetic diversity, structure, and relatedness, and to infer the most likely migration events. Comparisons of putative scenarios of gene flow throughout Europe from Caucasus helped to fit the more reliable migration routes around the Mediterranean Basin. Approximate Bayesian computation (ABC) approach made possible to provide a response to several questions so far remaining unsolved. Firstly, the assessment of genetic diversity and population structure within a well-covered dataset of ancient Italian varieties suggested the different histories between the Northern and Southern Italian grapevines. Moreover, Italian genotypes were shown to be distinguishable from all the other Eurasian populations for the first time. The entire Eurasian panel confirmed the east-to-west gene flow, highlighting the Greek role as a "bridge" between the Western and Eastern Eurasia. Portuguese germplasm showed a greater proximity to French varieties than the Spanish ones, thus being the main route for gene flow from Iberian Peninsula to Central Europe. Our findings reconciled genetic and archaeological data for one of the most cultivated and fascinating crops in the world.

The arbuscular mycorrhizal fungus Funneliformis mosseae induces changes and increases the concentration of volatile organic compounds in Vitis vinifera cv. Sangiovese leaf tissue.

Arbuscular mycorrhizal fungi (AMF) are beneficial obligate symbionts of plant roots. Volatile organic compounds (VOCs) participate in plant communication and defence. The aim of this study was to analyse the effects of the arbuscular mycorrhizal fungus Funneliformis mosseae IMA1 on VOCs in Vitis vinifera cv. Sangiovese leaf tissue. Grapevine plants inoculated with F. mosseae IMA1 were incubated for 23 weeks. VOCs were extracted from leaves and identified using headspace solid-phase microextraction (HS-SPME) coupled to GC-MS. VOCs in leaf tissue were strongly enhanced (85%) by F. mosseae IMA1. The mycorrhizal fungus IMA1 modified the levels of specific VOCs synthesised in different anabolic pathways. An increase in volatiles that have been related to plant defences under pathogen/herbivore attack or linked to water stress, such as (E)-2-hexenal, 3-hexenal, geraniol, benzaldehyde and methyl salicylate, was observed in mycorrhizal plants. In contrast, some C13-norisoprenoids decreased strongly in mycorrhizal plants. The study of the effects of AMF on VOCs in grapevine plants may provide useful information to establish sustainable viticultural practices.

Genetic Structure of a Worldwide Germplasm Collection of Prunus armeniaca L. Reveals Three Major Diffusion Routes for Varieties Coming From the Species' Center of Origin.

The characterization of the largest worldwide representative data set of apricot (Prunus armeniaca L.) germplasm was performed using molecular markers. Genetic diversity and structure of the cultivated apricot genetic resources were analyzed to decipher the history of diffusion of this species around the world. A common set of 25 microsatellite markers was used for genotyping a total of 890 apricot accessions in different collections from the center of origin to the more recent regions of apricot culture. Using a Bayesian model-based clustering approach, the apricot genotypes can be structured into five different genetic clusters (FST = 0.174), correlated with the geographical regions of origin of the accessions. Accessions from China and Central Asia were clustered together and exhibited the highest levels of diversity, confirming an origin in this region. A loss of genetic diversity was observed from the center of origin to both western and eastern zones of recent apricot culture. Altogether, our results revealed that apricot spread from China and Central Asia, defined as the center of origin, following three major diffusion routes with a decreasing gradient of genetic variation in each geographical group. The identification of specific alleles outside the center of origin confirmed the existence of different secondary apricot diversification centers. The present work provides more understanding of the worldwide history of apricot species diffusion as well as the field of conservation of the available genetic resources. Data have been used to define an apricot core collection based on molecular marker diversity which will be useful for further identification of genomic regions associated with commercially important horticultural traits through genome-wide association studies to sustain apricot breeding programs.

Introgression Among Cultivated and Wild Grapevine in Tuscany.

Wild grapevine, Vitis vinifera L. subsp. sylvestris (Gmelin, Hegi) is spontaneous to Europe and common in Tuscany. In this study, wild grapevines were identified in 22 populations from eight locations in Tuscan Maremma (Grosseto and Siena province). The plants were propagated by cuttings, collected in a vineyard, genotyped by nuclear simple sequence repeats (SSRs), chloroplast SSRs and single nucleotide polymorphisms (SNPs), and compared to locally cultivated varieties (Vitis vinifera L. subsp. sativa) and to non-vinifera and non-vitis genotypes. The identity analysis revealed that some individuals were redundant genotypes, suggesting natural vegetative propagation. In addition, four of the supposed V.v. sylvestris were in fact naturalized V.v. sativa. The majority of putative sylvestris genotypes had chlorotype A, while the remainder had chlorotype D, as the majority of Vitis vinifera subsp. sativa cultivated in Italy. Some of the recovered sylvestris genotypes appeared to be natural crosses with cultivated grapevine varieties in Tuscany, and their chlorotype suggests a higher pollen flow from sativa to the sylvestris genotypes than in the opposite direction. In addition, other genotypes appeared to be crosses within sylvestris, sylvestris-sativa or sylvestris-sylvestris siblings, or equivalent relationships. These relationships suggest a noticeably level of sexual reproductive activities among sylvestris and sylvestris-sativa genotypes. A cluster and structure analysis clearly differentiated the true sylvestris from the sativa, and the non-vinifera or non-vitis genotypes, and also highlighted a possible introgression of sylvestris into some Italian and French cultivated varieties. The results therefore suggest that, in addition to the primary ancient center of domestication from the Near East to Central Asia, the introgression among cultivated and wild grapevine occurred in other centers of diversification along the migration routes, contributing to the domestication processes, and suggesting that these processes are still ongoing despite the reduction in populations of sylvestris. The results also highlight that the GrapeReSeq 18K Vitis genotyping chip are suitable for non-vitis genotyping and that the range of SNPs heterozygosity in sylvestris appears to be up to 6% less and does not overlap the heterozygosity range of sativa genotypes.

Responses of Vitis vinifera cv. Cabernet Sauvignon roots to the arbuscular mycorrhizal fungus Funneliformis mosseae and the plant growth-promoting rhizobacterium Ensifer meliloti include changes in volatile organic compounds.

Arbuscular mycorrhizal (AM) fungi and plant growth-promoting rhizobacteria (PGPR) are beneficial microorganisms that may associate with grapevine roots, improving stress tolerance, growth, and nutrition. AM fungi and PGPR enhance the production of plant secondary metabolites, including volatile organic compounds (VOCs) that play a key role in the interaction of plants with the environment and are involved in defence mechanisms. The aim of this study was to analyse the effects of an AM fungus and a rhizobacterium on plant growth and VOCs in Vitis vinifera cv. Cabernet Sauvignon roots to gain insight into the potential role of plant-rhizosphere microorganisms in vine growth and defence. Grapevines were inoculated or not with the AM fungus Funneliformis mosseae IN101 and/or the plant growth-promoting rhizobacterium Ensifer meliloti TSA41. Both microbial strains enhanced plant growth. Fifty-eight VOCs extracted from ground roots were identified using headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry. VOCs were induced by F. mosseae IN101, increasing up to 87% compared with control plants. Monoterpenes were strongly enhanced by F. mosseae IN101, increasing up to 113% compared with control plants. Interestingly, monoterpene alcohols related to plant defence, such as myrtenol, p-cymen-7-ol, and p-mentha-1.8-dien-7-ol were increased. By contrast, E. meliloti TSA41 did not significantly affect VOCs. The knowledge of the effects of AM fungi and PGPR on grapevine VOCs may contribute to an integrated and sustainable management of vineyards.

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.

Phylogenetic analysis of viruses in Tuscan Vitis vinifera sylvestris (Gmeli) Hegi.

The health status of the native grapevine Vitis vinifera subsp. sylvestris (Gmeli) Hegi in natural areas in Europe has received little attention. A survey was carried out on wild grapevines in Tuscany (Italy), where isolates of the Grapevine rupestris stem pitting virus (GRSPaV), Grapevine leafroll-associated virus 1 and 3 (GLRaV-1 and GLRaV-3) and Grapevine virus A (GVA) were detected. The complete coat protein (CP) region of these isolates was sequenced to investigate the relationship of the viral variants from Tuscan wild grapevines with isolates from different geographical origins. According to the phylogenetic analyses, GLRaV-1 and GLRaV-3 isolates from Tuscan wild grapevines clustered with isolates from cultivated grapevines with nucleotide sequence identities ranging from 66% to 87% and from 72.5% to 99% respectively, without any correlation between the distribution and geographical origin. Conversely, GRSPaV and GVA isolates clustered together with other Italian isolates from V. vinifera with nucleotide sequence identities ranging from 71.14% to 96.12% and from 73.5% to 92%, respectively. Our analysis of the whole amino acid sequences revealed a high conservation level for the studied proteins explained by a selective pressure on this genomic region, probably due to functional constraints imposed on CP, such as specific interactions with cellular receptors in the insect vectors necessary for successful transmission. In addition, analyses of genetic recombination suggest no significant point mutations that might play a significant role in genetic diversification. The dN/dS ratio also estimated a low number of non-silent mutations, highlighting the purifying selective pressure. The widespread distribution of the Rugose wood complex (GRSPaV and GVA associated disease) in comparison with the Grapevine Leafroll associated viruses (GLRaV-1 and -3) could explain the major geographical correlation found for the viral variants detected in Tuscany.

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

BACKGROUND: This 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. RESULTS: Total carotenoids decreased from 0.85 to 0.76 µg g-1 in Grechetto berries and from 0.70 to 0.46 µg g-1 in Vermentino berries while increased from 0.70 to 0.80 µg 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 Ward's method enabled the best grape quality to be identified. CONCLUSION: This 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. © 2018 Society of Chemical Industry.

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.

Cultivar-specific transcriptome prediction and annotation in Ficus carica L.

The availability of transcriptomic data sequence is a key step for functional genomics studies. Recently, a repertoire of predicted genes of a Japanese cultivar of fig (Ficus carica L.) was released. Because of the great phenotypic variability that can be found in this species, we decided to study another fig genotype, the Italian cv. Dottato, in order to perform comparative studies between the two cultivars and extend the pan genome of this species. We isolated, sequenced and assembled fig genomic DNA from young fruits of cv. Dottato. Then, putative gene sequences were predicted and annotated. Finally, a comparison was performed between cvs. Dottato and Horaishi predicted transcriptomes. Our data provide a resource (available at the Sequence Read Archive database under SRP109082) to be used for functional genomics of fig, in order to fill the gap of knowledge still existing in this species concerning plant development, defense and adaptation to the environment.

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.

BACKGROUND: 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. RESULTS: 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. CONCLUSION: 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.

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

BACKGROUND: Environmental 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). RESULTS: The 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. CONCLUSION: Altitude 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. © 2016 Society of Chemical Industry.

Distinct transcriptome responses to water limitation in isohydric and anisohydric grapevine cultivars.

BACKGROUND: Grapevine (Vitis vinifera L.) is an economically important crop with a wide geographical distribution, reflecting its ability to grow successfully in a range of climates. However, many vineyards are located in regions with seasonal drought, and these are often predicted to be global climate change hotspots. Climate change affects the entire physiology of grapevine, with strong effects on yield, wine quality and typicity, making it difficult to produce berries of optimal enological quality and consistent stability over the forthcoming decades. RESULTS: Here we investigated the reactions of two grapevine cultivars to water stress, the isohydric variety Montepulciano and the anisohydric variety Sangiovese, by examining physiological and molecular perturbations in the leaf and berry. A multidisciplinary approach was used to characterize the distinct stomatal behavior of the two cultivars and its impact on leaf and berry gene expression. Positive associations were found among the photosynthetic, physiological and transcriptional modifications, and candidate genes encoding master regulators of the water stress response were identified using an integrated approach based on the analysis of topological co-expression network properties. In particular, the genome-wide transcriptional study indicated that the isohydric behavior relies upon the following responses: i) faster transcriptome response after stress imposition; ii) faster abscisic acid-related gene modulation; iii) more rapid expression of heat shock protein (HSP) genes and iv) reversion of gene-expression profile at rewatering. Conversely, that reactive oxygen species (ROS)-scavenging enzymes, molecular chaperones and abiotic stress-related genes were induced earlier and more strongly in the anisohydric cultivar. CONCLUSIONS: Overall, the present work found original evidence of a molecular basis for the proposed classification between isohydric and anisohydric grapevine genotypes.

Physiological parameters and protective energy dissipation mechanisms expressed in the leaves of two Vitis vinifera L. genotypes under multiple summer stresses.

Photosynthetic performances and energy dissipation mechanisms were evaluated on the anisohydric cv. Sangiovese and on the isohydric cv. Montepulciano (Vitis vinifera L.) under conditions of multiple summer stresses. Potted vines of both cultivars were maintained at 90% and 40% of maximum water availability from fruit-set to veraison. One week before veraison, at predawn and midday, main gas-exchange and chlorophyll fluorescence parameters, chlorophyll content, xanthophyll pool and cycle and catalase activity were evaluated. Under water deficit and elevated irradiance and temperature, contrary to cv. Montepulciano and despite a significant leaf water potential decrease, Sangiovese's leaves kept their stomata more open and continued to assimilate CO2 while also showing higher water use efficiency. Under these environmental conditions, in comparison with the isohydric cv. Montepulciano, the protective mechanisms of energy dissipation exerted by the anisohydric cv. Sangiovese were: (i) higher stomatal conductance and thermoregulation linked to higher transpiration rate; (ii) greater ability at dissipating more efficiently the excess energy via the xanthophylls cycle activity (thermal dissipation) due to higher VAZ pool and greater increase of de-epoxidation activity.

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)-ß-caryophyllene synthases, α-terpineol synthase and α-farnesene synthase. In addition, we found groups of homologous TPS genes, such as (E)-ß-caryophyllene and ß-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.