Stilbene Content Research Articles

Foliar applications of a Malvaceae-derived protein hydrolysate and its fractions differentially modulate yield and functional traits of tomato under optimal and suboptimal nitrogen application.

Protein hydrolysates (PHs) can enhance plant nitrogen nutrition and improve the quality of vegetables, depending on their bioactive compounds. A tomato greenhouse experiment was conducted under both optimal (14 mM) and suboptimal (2 mM) nitrogen (N-NO3) conditions. Tomatoes were treated with a new Malvaceae-derived PH (MDPH) and its molecular fractions (MDPH1, >10 kDa; MDPH2, 1-10 kDa and MDPH3, <1 kDa). Under optimal N conditions, the plants increased biomass and fruit yield, and showed a higher photosynthetic pigment content in leaves in comparison with suboptimal N, whereas under N-limiting conditions, an increase in dry matter, soluble solid content (SSC) and lycopene, a reduction in firmness, and changes in organic acid and phenolic compounds were observed. With 14 mM N-NO3, MDPH3 stimulated an increase in dry weight and increased yield components and lycopene in the fruit. The MDPH2 fraction also resulted in increased lycopene accumulation in fruit under 14 mM N-NO3. At a low N level, the PH fractions showed distinct effects compared with the whole MDPH and the control, with an increase in biomass for MDPH1 and MDPH2 and a higher pigment content for MDPH3. Regardless of N availability, all the fractions affected fruit quality by increasing SSC, whereas MDPH2 and MDPH3 modified organic acid content and showed a higher concentration of flavonols, lignans, and stilbenes. The molecular weight of the peptides modifies the effect of PHs on plant performance, with different behavior depending on the level of N fertilization, confirming the effectiveness of fractioning processes. © 2024 Society of Chemical Industry.

Stimulation of secondary metabolism in grape berry exocarps by a nature-based strategy of foliar application of polyols

In grapes under drought stress, polyols accumulate through tight coordination at the molecular level between increased membrane transport of polyols and inhibition of polyol oxidation. Here, the effects on grape metabolism of an exogenous foliar application of polyols as a potential sustainable viticultural practice to increase grapevine performance and berry quality were thoroughly assessed. Grapevines were pulverised with a polyol solution containing 2 mM mannitol and 2 mM sorbitol, and the metabolome of grape berry exocarps and important metabolic pathways associated with berry quality and polyol metabolism were analysed at véraison and mature stages. By combining metabolomics analysis using UPLC-MS, enzyme activity assays and targeted transcriptional analyses, it was demonstrated that foliar application of polyols stimulated by 3.5-fold and 6-fold abscisic acid (ABA) biosynthesis at véraison and mature grape berries, respectively. It also stimulated the concentration of anthocyanins, stilbenes and total phenolics in exocarps through the upregulation of phenylpropanoid, stilbenoid and anthocyanin biosynthetic pathways shown by increases in phenylalanine-ammonia lyase (PAL) activity (3-fold) and VviPAL1 expression, stilbene synthase 1 (VviSTS1) transcripts (ca. 5-fold), UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT) activity and VviUFGT1 expression, among other results, at the mature stage, when these changes were most noticeable. Many secondary metabolites synthesised in these pathways identified by UPLC-MS analysis were present at higher quantities in exocarps from polyol-treated plants such as fertaric acid, E-resveratrol, E-piceatannol, piceid, pallidol, E-ε-viniferin, myricetin-hexoside 1, cyanidin-3-O-glucoside and malvidin-3-O-(6-p-coumaroyl)-glucoside. Foliar application of low-concentration polyols is, therefore, a promising biostimulant-based strategy to improve grape berry quality and nutritional value in the current context of climate change.

Influence of Quercus alba oak geographical origin on the colour characteristics and phenolic composition of Tempranillo wines

AbstractThis research analyzes the influence of Quercus alba barrels from four different forests of the USA [Missouri (M), Ohio (O), Kentucky (K) and Pennsylvania (P)] on the colour parameters, phenolic composition, and visual and gustatory sensory characteristics of 12 Tempranillo red wines from different wineries after 12 months of aging. Oak origin significantly affected the colour parameters of the wines, except for tonality, and the content of anthocyanins, stilbenes and ellagitannins but had little effect on the rest of the phenolic compounds. Wines aged in K and O barrels showed the highest content of ellagitannins. Wines aged in P barrels had the lowest content of phenolic compounds and colour intensity (CI), while K and O barrels produced the highest levels of ellagitannins. K wines were the best value in the global perception of the taste analysis. The influence of the barrel origin on the phenolic composition of the wines was also evaluated according to their initial phenolic composition. Wines with the highest initial CI and phenol content also showed the highest content of ellagitannins after barrel aging. When aging wines with high CI and phenol content, M barrels provided the wines with the highest content of ellagitannins.

Applying Different Vinification Techniques in Teran Red Wine Production: Impact on Bioactive Compounds and Sensory Attributes.

Six different vinification treatments, including a control treatment (7-day standard maceration) (K7), were performed to study the effects of non-standard techniques on bioactive compounds and sensory attributes of Teran red wine. Pre-fermentative mash cooling (8 °C; 48 h) and heating (50 °C; 48 h) followed by prolonged post-fermentative maceration of 13 days (C15;H15) or 28 days (C30;H30) were applied. In another treatment, after cooling, saignée was performed followed by 13-day prolonged maceration (CS15). Wine phenols and vitamins were analyzed by HPLC-DAD-FLD, minerals by ICP-OES, and sensory analysis was performed using the QDA and 100-point O.I.V./U.I.O.E. methods. Obtained results showed total phenolic concentration was the highest in the H30 treatment. The concentration of anthocyanins, flavan-3-ols and phenolic acids was significantly higher in wines of all vinification techniques compared to the control. Stilbene content was highly affected by pre-fermentative heating. Treatments CS15, H15, C30 and H30 resulted in the highest scores by both the QDA and 100-point sensory methods. The obtained results suggest that advanced non-standard vinification techniques have a significant impact on Teran wine by enhancing its composition of bioactive compounds and improving its sensory profile, which gives it an additional market value. Furthermore, a comprehensive comparison of such techniques applied simultaneously in one study is of substantial importance for additional research in wine production.

Timing of defoliation affects anthocyanin and sugar decoupling in Grenache variety growing in warm seasons

Warming trends over the winegrowing regions lead to an advance of grapevine phenology, decreased yield and increased sugar content with a lower polyphenol content. We hypothesized that different leaf removal timings may counteract these effects. A two-year experiment was conducted in La Rioja (Spain) with Vitis vinifera L. cv. Grenache trained in an open-vase system. Trial consisted in a complete block design with two leaf removal treatments differing in the moment of manipulation: i) severe leaf removal treatment conducted after fruit set (ELR); and ii) severe leaf removal at veraison (LLR) compared to an untreated control (Control). Both leaf removal treatments tended to decrease sugar content with no effect on yield, these effects being highly affected by the year. Defoliation accounted for a decreased flavanol and stilbene contents in berries at harvest. An ELR increased anthocyanin and phenolic acid contents at harvest, while warming during 2022 accounted for decreased contents of all the monitored groups of flavonols. ELR was only effective for delaying ripening by means of impairing the sugar:anthocyanin decoupling during the 2021 growing season which was related to lower % of kaempferol. Altogether, results suggested that defoliation should still be applied under currently warming trends in some viticulture regions.

Tissue-specific stilbene accumulation is an early response to wounding/grafting as revealed by using spatial and temporal metabolomics.

Grafting is widely used in horticulture. Shortly after grafting, callus tissues appear at the graft interface and the vascular tissues of the scion and rootstock connect. The graft interface contains a complex mix of tissues, we hypothesised that each tissue has its own metabolic response to wounding/grafting and accumulates different metabolites at different rates. We made intact and wounded cuttings and grafts of grapevine, and then measured changes in bulk flavonoid, phenolic acid and stilbenoid concentration and used metabolite imaging to study tissue-specific responses. We show that some metabolites rapidly accumulate in specific tissues after grafting, for example, stilbene monomers accumulate in necrotic tissues surrounding mature xylem vessels. Whereas other metabolites, such as complex stilbenes, accumulate in the same tissues at later stages. We also observe that other metabolites accumulate in the newly formed callus tissue and identify genotype-specific responses. In addition, exogenous resveratrol application did not modify grafting success rate, potentially suggesting that the accumulation of resveratrol at the graft interface is not linked to graft union formation. The increasing concentration of complex stilbenes often occurs in response to plant stresses (via unknown mechanisms), and potentially increases antioxidant activity and antifungal capacities.

Comprehensive comparison of different parts of Paeonia ostii, a food-medicine plant, based on untargeted metabolomics, quantitative analysis, and bioactivity analysis.

Paeonia ostii T. Hong & J.X. Zhang (s.s.) (Chinese name, Fengdan) is a widely cultivated food-medicine plant in China, in which root bark, seed kernels, and flowers are utilized for their medicinal and edible values. However, other parts of the plant are not used efficiently, in part due to a poor understanding of their chemical composition and potential biological activity. Untargeted ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC-Q-TOF-MS) metabolomics was applied to characterize the metabolic profiles of 10 different parts of P. ostii. A total of 160 metabolites were alternatively identified definitely or tentatively, which were significantly different in various plant parts by multivariate statistical analysis. Quantitative analysis showed that underutilized plant parts also contain many active ingredients. Compared with the medicinal part of root bark, the root core part still contains a higher content of paeoniflorin (17.60 ± 0.06 mg/g) and PGG (15.50 ± 2.00 mg/g). Petals, as an edible part, contain high levels of quercitrin, and stamens have higher methyl gallate and PGG. Unexpectedly, the ovary has the highest content of methyl gallate and rather high levels of PGG (38.14 ± 1.27 mg/g), and it also contains surprisingly high concentrations of floralalbiflorin I. Paeoniflorin (38.68 ± 0.76 mg/g) is the most abundant in leaves, and the content is even higher than in the root bark. Branches are also rich in a variety of catechin derivatives and active ingredients such as hydrolyzable tannins. Seed kernels also contain fairly high levels of paeoniflorin and albiflorin. Fruit shells still contain a variety of components, although not at high levels. Seed coats, as by-products removed from peony seeds before oil extraction, have high contents of stilbenes, such as trans-gnetin H and suffruticosol B, showing significant potential for exploitation. Except for the seed kernels, extracts obtained from other parts exhibited good antioxidant activity in DPPH, ABTS, and ferric ion reducing antioxidant power (FRAP) assays (0.09-1.52 mmol TE/g). Five compounds (gallic acid, PGG, trans-resveratrol, kaempferol, and quercitrin) were important ingredients that contributed to their antioxidant activities. Furthermore, P. ostii seed cakes were first reported to possess agonistic activity toward CB1/CB2 receptors. This study provides a scientific basis for the further development and utilization of P. ostii plant resources.

HPLC fingerprints of polygonum cuspidatum power and polygonum cuspidatum ointment and simultaneous determination of six constituents

Polygonum Cuspidate (P. cuspidatum) is a traditional topical preparation of Chinese medicine. The aim of this study was to develop HPLC fingerprints for P. cuspidatum Powder and P. cuspidatum Ointment, as well as to determine the total stilbene and total anthraquinone contents in them. A XB-C18 column (250 ​mm ​× ​4.6 ​mm, 5 ​μm) was used with a mobile phase consisting of 0.1% phosphoric acid solution-acetonitrile and a gradient elution. The flow rate was 1.0 ​ml/min and the detection wavelength was 286 ​nm. The column temperature was 30 ​°C and injection volume was 10 ​μl. The similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine (2012 edition) was employed to confirm the common peaks at 13 batches of samples and to assess the similarity. The study revealed that 20 common peaks were identified in both P. cuspidatum powder and P. cuspidatum ointment, with a similarity greater than 0.95. Amongst them, seven components were attributed and confirmed, which were identified as polydatin, resveratrol, emodin-8-glucoside, aloe-emodin, rhein, emodin and physcion. Under the established conditions of the chromatography, quantitative analysis of six components could be well separated, and had a good linearity and linear range, the precision, repeatability and stability were good. The method's efficacy in assessing the quality of P. cuspidatum powder and P. cuspidatum ointment is validated, and it can be employed for quality control purposes.

Inhibitory Potential of Different Bilberry (Vaccinium myrtillus L.) Extracts on Human Salivary α-Amylase.

Recently, consumer preferences for bilberries have increased markedly. This fact is probably related to their natural constituents, such as phenolic compounds including anthocyanins and tannins, as well as the vitamins and minerals they contain. Phenolic compounds are known for their numerous beneficial effects on human health. Moreover, bilberry fruits have been shown to inhibit the activity of carbohydrate hydrolyzing enzymes, which can significantly decrease the postprandial increase in blood glucose levels. Thus, the aim of the present study is to investigate the inhibitory effect of Vaccinium myrtillus L. extracts on key enzyme α-amylase, linked to type 2 diabetes. No data have been published on the inhibitory properties of Vaccinium myrtillus L. fruits growing wild in Bulgaria against carbohydrate enzymes. Bilberry extracts were analyzed for total polyphenols, total anthocyanin content, antioxidant activity and their inhibitory properties against α-amylase. The contents of flavonols, anthocyanins and stilbenes were determined by HPLC analysis. The identified flavonols in the analyzed bilberry extracts were mainly represented by quercetin derivatives as rutinoside. The predominant anthocyanins for both aqueous and organic solvents were delphinidin-3-galactoside and malvidin-3-glucoside. The results revealed that bilberry extracts are effective inhibitors of α-amylase, with IC50 values from 20.8 to 194.8 μg GAE/mL. All the samples proved to have antioxidant activity measured by three different in vitro assays (FRAP, CUPRAC and DPPH). The inhibitory properties of V. myrtillus L. extracts may provide a new direction in the development and research of new pharmaceuticals for the suppression of postprandial hyperglycemia in diabetic patients.

Study of the effects of climatic conditions on the phenolic content and antioxidant activity of Austrian and Montenegrin red wines

We evaluated the chemical composition and antioxidant activity of 30 red wines from Austria (cv. Cabernet-Sauvignon, Blaufraenkisch and Zweigelt) and 20 wines from Montenegro (cv. Cabernet-Sauvignon and Vranac) from three consecutive vintages: 2014, 2015 and 2016. We determined spectrophotometrically the contents of total phenol (TP), total anthocyanin (TA) and low- and high-molecular-weight proanthocyanidins (LMP and HMP respectively). We identified and quantified 18 phenolic compounds (hydroxycinnamic acids, hydroxybenzoic acids, stilbenes and flavan-3-ols) by high-performance liquid chromatography. In addition, we used Fourier-transform infrared spectroscopy for chemical analyses of the main wine parameters. Austrian autochthonous wines exhibited a similar chemical composition (alcohol 12.4 vol%, pH 3.38). Blaufraenkisch wines showed higher TP, HMP and LMP than Zweigelt wines; however, TA content was similar. Blaufraenkisch wines also showed higher phenolic acid, flavan-3-ol and stilbene contents than Zweigelt wines. Montenegrin autochthonous Vranac wines showed a typical chemical composition (alcohol 13.0 vol%, pH 3.42), and medium to high levels of phenols: TP, HMP, LMP, TA, HCA and flavan-3-ols. On the other hand, they showed a moderate stilbene content. Cabernet-Sauvignon wines from Austria and Montenegro exhibited some similarities in phenolic composition: TP, HMP, LMP and TA. There were notable variations in the phenolic acid and flavan-3-ol contents, especially the stilbene content, which was much higher in the Austrian wines than in the Montenegrin wines. These findings evidence an important impact of climatic conditions on these compounds. The antioxidant activity in all investigated wines was high and correlated strongly with TP, total phenol index, HMP and LMP in wines. The vintage influenced the chemical composition and content of all examined phenolic groups, except flavan-3-ols. Wines from the vintage with the best maturity (2015) contained the highest content of spectrophotometrically determined phenolic compounds and lowest level of phenolic acids and stilbenes. Principle component analysis showed that wines were mainly discriminated by variety and origin but not by vintage.

Evolution of the Polyphenolic Content of Moravian White Grape Variety Wines of Different Vintages During Storage

Wine is known as a source of bioactive compounds and is one of the alcoholic beverages with the highest phenolic content. There has been growing interest in the composition of wine due to its beneficial properties for human health. This work focuses on biologically active and sensory attributes of white wine and presents research on wine chemical profiles in relation to their geographical origin, varieties and storage. The aim of this study was to investigate the phenolic compound evolution of 35 selected white wine varieties from the Moravian region in the Czech Republic. To separate and identify individual phenolic compounds in the wines, the high-performance liquid chromatographic method was used. A spectrophotometric method was applied for the determination of total polyphenol and total flavonoid content. This research presents results for the total benzoic and cinnamic acid derivatives, flavonols, flavanols and stilbene content of Moravian white grape varieties. Differences were found in the content of these compounds, and the results show that the phenolic concentrations depend on grape variety and storage time.

Stilbene Content and Expression of Stilbene Synthase Genes in Korean Pine Pinus koraiensis Siebold &amp; Zucc

Stilbenes are a large group of plant phenolic compounds that have a wide range of biologically active properties, such as antioxidant, immunomodulatory, anti-inflammatory, and anti-angiogenic effects. In plants, stilbenes are involved in the defense against environmental stresses, including fungal infections and insect attacks. The biosynthesis of stilbenes is well described for those plant species where resveratrol and its derivatives are the predominant stilbenes. However, there is little information on stilbene biosynthesis in the Pinaceae family, although the highest content of stilbenes was found in plants of this family. In this study, seasonal variations in stilbene compositions and contents in different parts of Pinus koraiensis was described (needles, bark, wood, young branches, and strobiles). HPLC-ESI-MS analysis showed the presence of seven stilbenes in P. koraiensis: t-astringin; t-piceid; cis-piceid; t-isorapontin; t-pinostilbenoside; t-resveratrol; and t-pinostilbene. Glycosylated and methylated forms of stilbenes, such as t-astringin, t-piceid, and t-pinostilbenoside, prevailed over other stilbenoids. The highest content of stilbenes was detected in the bark collected in spring and winter (up to 54.8 mg/g dry weight). The complete protein-coding sequences of three stilbene synthase genes, PkSTS1, PkSTS2, and PkSTS3, were obtained from the RNA isolated from the P. koraiensis needles. The expression of the PkSTS1, PkSTS2, and PkSTS3 genes was analyzed using real-time PCR and frequency analysis of cloned RT-PCR products in the needles of P. koraiensis collected in different seasons. Thus, we first analyzed stilbene biosynthesis in the different organs of pine P. koraiensis and PkSTS expression depending on the year seasons.

Influence of the 135 bp Intron on Stilbene Synthase VaSTS11 Transgene Expression in Cell Cultures of Grapevine and Different Plant Generations of Arabidopsis thaliana

Modern plant biotechnology often faces the problem of obtaining a stable and powerful vector for gene overexpression. It is known that introns carry different regulatory elements whose effects on transgene expression have been poorly studied. To study the effect of an intron on transgene expression, the stilbene synthase 11 (VaSTS11) gene of grapevine Vitis amurensis Rupr. was selected and overexpressed in grapevine callus cell cultures and several plant generations of Arabidopsis thaliana as two forms, intronless VaSTS11c and intron-containing VaSTS11d. The STS genes play an important role in the biosynthesis of stilbenes, valuable plant secondary metabolites. VaSTS11d contained two exons and one intron, while VaSTS11c contained only two exons, which corresponded to the mature transcript. It has been shown that the intron-containing VaSTS11d was better expressed in several generations of transgenic A. thaliana than VaSTS11c and also exhibited a lower level of cytosine methylation. As a result, the content of stilbenes in the VaSTS11d-transgenic plants was much higher than in the VaSTS11c-transgenic plants. Similarly, the best efficiency in increasing the content of stilbenes was also observed in grapevine cell cultures overexpressing the intron-containing VaSTS11d transcript. Thus, the results indicate that an intron sequence with regulatory elements can have a strong positive effect on both transgene expression level and its biological functions in plants and plant cell cultures.

Bioconversion of Grape Pomace with Rhizopus oryzae under Solid-State Conditions: Changes in the Chemical Composition and Profile of Phenolic Compounds.

Grape pomace is a sustainable source of bioactive phenolic compounds used in various industries. The recovery of phenolic compounds could be improved by biological pretreatment of grape pomace, as they are released from the lignocellulose structure by the activity of the enzymes produced. The influence of grape pomace pretreatment with Rhizopus oryzae under solid-state conditions (SSF) on the phenolic profile and chemical composition changes was studied. SSF was performed in laboratory jars and in a tray bioreactor for 15 days. Biological pretreatment of grape pomace resulted in an increase in the content of 11 individual phenolic compounds (from 1.1 to 2.5-fold). During SSF, changes in the chemical composition of the grape pomace were observed, including a decrease in ash, protein, and sugar content, and an increase in fat, cellulose, and lignin content. A positive correlation (r > 0.9) was observed between lignolytic enzymes and the hydrolytic enzyme's xylanase and stilbene content. Finally, after 15 days of SSF, a weight loss of GP of 17.6% was observed. The results indicate that SSF under experimental conditions is a sustainable bioprocess for the recovery of phenolic compounds and contributes to the zero-waste concept by reducing waste.

Improvement of Stilbene Content in Concord and Isabel Precoce Grapes and Juice through Methyl Jasmonate Application

In this research, the effect of methyl jasmonate (MJ) preharvest treatment was studied on grapes and their juice from two different regions. Concord and Isabel Precoce grapes from south and southeast Brazil received the treatment during two vintages (2017 and 2019). MJ preharvest treatment was able to increase stilbenes in the grape seeds and peels of Isabel Precoce in both regions. The juice elaborated with the treated grapes also has higher stilbene levels, especially piceid, that were detected even after 6 months of storage. Additionally, we performed a small study for this market niche; 189 consumers were interviewed, and it was observed that those with a higher frequency of grape juice consumption were willing to pay 25% more for grape juice with a higher resveratrol content. In conclusion, this work has evidenced the potential of MJ preharvest treatment to improve stilbenes in grapes and their juice, despite regional differences.

Chromosome-scale genomics, metabolomics, and transcriptomics provide insight into the synthesis and regulation of phenols in Vitis adenoclada grapes.

Vitis adenoclada is a wild grape unique to China. It exhibits well resistance to heat, humidity, fungal disease, drought, and soil infertility. Here, we report the high-quality, chromosome-level genome assembly of GH6 (V. adenoclada). The 498.27 Mb genome contained 221.78 Mb of transposable elements, 28,660 protein-coding genes, and 481.44 Mb of sequences associated with 19 chromosomes. GH6 shares a common ancestor with PN40024 (Vitis vinifera) from approximately 4.26-9.01 million years ago, whose divergence occurred later than Vitis rotundifolia and Vitis riparia. Widely-targeted metabolome and transcriptome analysis revealed that the profiles and metabolism of phenolic compounds in V. adenoclada varieties significantly were differed from other grape varieties. Specifically, V. adenoclada varieties were rich in phenolic acids and flavonols, whereas the flavan-3-ol and anthocyanin content was lower compared with other varieties that have V. vinifera consanguinity in this study. In addition, ferulic acid and stilbenes content were associated with higher expressions of COMT and STSs in V. adenoclada varieties. Furthermore, MYB2, MYB73-1, and MYB73-2 were presumably responsible for the high expression level of COMT in V. adenoclada berries. MYB12 (MYBF1) was positively correlated with PAL, CHS, FLS and UFGT.Meanwhile, MYB4 and MYBC2-L1 may inhibit the synthesis of flavan-3-ols and anthocyanins in two V. adenoclada varieties (YN2 and GH6). The publication of the V. adenoclada grape genome provides a molecular foundation for further revealing its flavor and quality characteristics, is also important for identifying favorable genes of the East Asian species for future breeding.

Pilot Study of Sap Properties of Norway Spruce (Picea abies (L.) Karst.) Trees Used and Not Used for Sap-Feeding by Three-Toed Woodpeckers (Picoides tridactylus)

The ecophysiology of the Norway spruce (Picea abies (L.) Karst.) trees that were used by three-toed woodpeckers (TTW) (Picoides tridactylus) for their sap-feeding activities were investigated. The pilot study was conducted in southern Finland (61°15′ N, 25°00′ E). During April–June 2015, three different tree categories of Norway spruce were selected for monitoring: trees that were frequently used by the TTWs for phloem sap-feeding for several previous years; trees that were only recently used by TTWs for sap-feeding; and control trees that were not used at all for sap-feeding. Phloem sap and phloem tissue samples were frequently extracted from tree trunks and analyzed for the content and composition of nonstructural carbohydrates, phloem sap osmolality, solute, and water content, as well as for the content and composition of secondary metabolites typical for defense reactions in the phloem. Simple crown characteristics were also measured, including tree height, diameter at breast height, and their ratio (slenderness index). According to our results, the TTWs preferred Norway spruce trees that showed advanced spring phenology to feed on, as evidenced especially by the lower ratio of raffinose (typically high during the winter months) to total soluble sugars of phloem tissues as compared to non-used control trees. The lower slenderness index of the trees chosen by the TTWs indicates low canopy competition pressure with good access to light (i.e., the sun heats the trunks well in spring). There were no differences in the phloem osmolality or solute content between the used or unused control trees. The trees used by the TTWs had significantly higher concentrations of antioxidant phenolic (+)-catechins and stilbene glycosides in phloem tissue, and the stilbene content was also higher in the extracted sap. The phenolics content of the phloem tissue had a clear seasonal trend, being the highest in the early spring and lower towards the onset of the cambial growth processes. The phloem sap is rich in antioxidants and soluble sugars that are potentially beneficial for the TTWs, but more quantitative research is needed to explore the importance of the sap properties to TTWs.

Effect of Methyl Jasmonate and Methyl Jasmonate Plus Urea Foliar Applications on Wine Phenolic, Aromatic and Nitrogen Composition

Foliar application has been studied to enhance grape composition and, therefore, wine quality. This work examined, for first time, the effects of foliar applications of methyl jasmonate (MeJ) and methyl jasmonate plus urea (MeJ+Ur) to Tempranillo vineyard on wine phenolic, aromatic and nitrogen composition over two vintages (2019 and 2020). A reduction in alcoholic degree was observed in MeJ and MeJ+Ur wines. The effect of foliar treatments was season-dependent. MeJ and MeJ+Ur wines were characterized, in the first vintage, by a higher content of total acylated anthocyanins, but a low content of total esters, alcohols and acids when compared with control wines. MeJ+Ur wines presented a higher total amino acids content than control and MeJ wines. However, in the second vintage, MeJ and MeJ+Ur wines presented an increase in some non-acylated anthocyanins, but only MeJ+Ur treatment increased the total content of flavonols, flavanols, hydroxycinnamic acids, stilbenes and total amino acids when compared with control wines. MeJ wines presented a low content of esters and acids, whereas MeJ+Ur did not show differences with control wines. Overall, the effect of MeJ+Ur foliar treatment was greater than the effect of MeJ application in order to improve the wine chemical composition.

Phenolic and colour characteristics of must and wine obtained from red grapes treated by pulsed electric fields. Efficacy of PEF to reduce maceration time in elaboration of red wines

Pulsed electric fields effect was studied on the physico-chemical and general phenolic composition as colour characteristics and stilbene content in must and wine. For this purpose, a continuous pulsed electric fields equipment was used to treat three red grape varieties of DOCa Rioja. Graciano, Tempranillo and Grenache wines from these grapes were elaborated with different maceration times, 2 days in the untreated sample (control) and the PEF-treated sample (PEF), and normal maceration time in another untreated sample (control-NM). Parameters as colour intensity, anthocyanin content, total polyphenol index and tannin content showed no differences between the PEF sample with 2 days of maceration and the control-NM sample, except in the case of Tempranillo wines. Total stilbenes, trans-resveratrol and trans-piceid of Graciano wines elaborated from PEF samples showed a higher concentration than the control wines. Alternatively, PEF wines and control-NM wines showed no differences between them. Tempranillo variety wines presented no differences between the three types of samples. In the Grenache variety, only trans-piceid levels showed differences between control and PEF wines. Moreover, relationship between must and wine characteristics was evaluated and compared between different samples. The trend lines obtained for the CI, TPI and AC parameters for samples of Graciano, Tempranillo and Garnacha indicate that the initial content of compounds extracted significantly affected the days of maceration necessary to obtain the appropriate wine. The results obtained increase the knowledge of pulsed electric fields as a technology available for use in the winery to elaborate red wines with reduced maceration time.

Preliminary Studies on Endotherapy Based Application of Ozonated Water to Bobal Grapevines: Effect on Wine Quality.

The application of ozonated water in the vineyard is an increasingly popular tool for disease management, but the quality of grapes and resulting wines is likely to be affected. Endotherapy, or trunk injection, is a particularly useful method to apply phytosanitary products since many fungal pathogens colonize the grapevine woody tissues. Thus, the present study aimed to evaluate the effect on wine quality of the ozonated water applied to Bobal grapevines, one of the most cultivated red varieties in Spain, through endotherapy (E) or its combination with spraying (E + S). Endotherapy was carried out four times before harvest for both E and E + S treatments, and spraying was performed 2 days before and after each endotherapy application. Grapes were harvested, vinified, and the quality of the finished wines was evaluated through several enological parameters and the phenolic and volatile composition. Both treatments resulted in less alcoholic and more acidic wines. The E treatment, although it reduced the content of phenolic acids, stilbenes and flavanols, significantly increased anthocyanins, whereas E + S decreased the overall amount of phenolics, which had different implications for wine colour. In terms of aroma, both treatments, but E to a greater extent, reduced the content of glycosylated precursors and differentially affected free volatiles, both varietal and fermentative. Thus, the dose of ozonated water, frequency and/or method of application are determining factors in the effect of these treatments on wine quality and must be carefully considered by winegrowers to establish the optimum treatment conditions so as not to impair the quality of wines.