Search Results (81)

Discovering, analyzing, and finding a key to understanding the physiological and biochemical responses that Vitis vinifera L. undertakes against drought stress is of fundamental importance for this profitable crop. Today’s considerable climatic fluctuations force researchers and farmers to focus on this issue with solutions inclined to respect the ecosystem. In this academic work, we focused on describing the drought stress consequences on several parameters of secondary metabolites on Vitis vinifera leaves (quercetins, kaempferol, resveratrol, proline, and xanthophylls) and on some ecophysiological characteristics (e.g., water potential, stomatal conductance, and leaf temperature) to compare the answers that diverse agronomic management techniques (i.e., irrigation with and without zeolite, pure zeolite and no application) could instaurate in the metabolic pathway of this important crop with the aim to find convincing and thought-provoking responses to use this captivating and versatile mineral, the zeolite known as the “magic rock”. Stressed grapevines reached 56.80 mmol/m²s gs at veraison and a more negative stem Ψ (+10.63%) compared to plants with zeolite. Resveratrol, in the hottest season, fluctuated from 0.18–0.19 mg/g in zeolite treatments to 0.37 mg/g in stressed vines. Quercetins were inclined to accumulate in response to drought stress too. In fact, we recorded a peak of quercetin (3-O-glucoside + 3-O-glucuronide) of 11.20 mg/g at veraison in stressed plants. It is interesting to note how the pool of metabolites was often unchanged for plants treated with zeolite and for plants treated with water only, thus elevating this mineral to a “stress reliever”. Full article

Downy mildew, caused by Plasmopara viticola, is a major threat to grapevine (Vitis vinifera) cultivation in humid climates. Restrictions on synthetic pesticides and inconsistent efficacy of current biocontrol agents, especially under rainy conditions, complicate disease management. This study evaluated the potential of compost tea to suppress downy mildew in a two-year field experiment (2023 and 2024), combined with reduced synthetic fungicide applications. The study design compared two phytosanitary management strategies on a commercial vineyard: a conventional fungicide against a compost tea strategy supplemented with two cymoxanil applications. The experiment set up had three replicated blocks, each consisting of 100 plants for a total of 600 plants. Mechanistic insights were provided through controlled laboratory experiments involving pre- and post-infection leaf assays, vineyard bacteriome profiling, via 16S rRNA gene sequencing for bacterial communities, across vineyard compartments, i.e., bulk soil, rhizosphere, and phyllosphere, and grapevine metabolomic analysis by GC-MS analysis. Field trials demonstrated that compost tea combined with two fungicide applications effectively reduced disease severity, notably outperforming the fungicide alone in the particularly rainy year of 2023. Bacteriome analysis revealed that compost tea treatment enriched beneficial bacterial genera, including Pseudomonas, Sphingomonas, Enterobacter, Massilia, and Bacillus, known for their growth-promoting and biocontrol activity in the rhizosphere and phyllosphere. Laboratory assays on detached leaves further showed that compost tea alone could suppress both infection and sporulation of P. viticola. Metabolomic analysis highlighted the accumulation of compounds such as tartaric and shikimic acids in compost tea treated leaves, suggesting a potential role in induced resistance. The findings indicate that applying compost tea with reduced fungicide treatments represents a promising and sustainable strategy for managing grapevine downy mildew, even in challenging climates. Full article

Entomopathogenic fungi (EPF) are substantial biocontrol agents reducing the populations of economically important pests in numerous crops. Recent findings indicate that their role in agroecosystems is more complex and extends to affecting plant physiology and growth. This study examined the effects of Beauveria bassiana and Isaria fumosorosea, as well as Salicylic acid (SA), on physiological parameters of grapevine (Vitis vinifera cv. Sauvignon Blanc). Additionally, the impact of SA on spore germination and pathogenicity of EPF against larvae of the European grapevine moth (Lobesia botrana) was tested. Foliar application of EPF was found to increase the electron transport rate (ETR) from PSII to PSI, indicating higher photosynthetic activity compared to control plants. EPF also elevated the transpiration rate (E) and stomatal conductance (gs). In contrast, SA treatments decreased E and gs, while the high dose (10 mM) exhibited reduced Fv/Fm value, accompanied by phytotoxic spots on leaves. Spore germination of both fungi was significantly reduced only by the SA concentration of 2 mM, while 0.5 and 1 mM did not affect germination. Combination EPF and SA treatments presented the highest larval mortality of L. botrana (87.5% at 28 °C and 77.5% at 24 °C for B. bassiana and I. fumosorosea, respectively). However, SA reduced larval mycosis in most cases. Overall, the results suggest that EPF and SA can be co-applied and included in vineyard integrated strategies to support grapevine health. Full article

Biochar has attracted interest in viticulture for its potential to enhance nutrient uptake and improve grapevine physiology under changing climatic conditions, particularly in Mediterranean regions. However, the widespread adoption of biochar has been limited due to economic and logistical constraints associated with its large-scale application. To address these barriers hindering the widespread adoption of biochar, this study investigates the effects of foliar-applied water suspensions of biochar at concentrations of 300 mg/L (B300), 600 mg/L (B600), and 1200 mg/L (B1200), compared to a water-only control (C), as a practical alternative application method. The research focused on Malvazija istarska (Vitis vinifera L.), an indigenous Croatian grapevine variety, conducted in an experimental vineyard in Poreč, Croatia. The key physiological parameters examined included photo-synthetic activity, leaf water potential, the elemental composition of the grapevine leaves, and grape yield. Foliar applications were administered three times during the growing season, with five replicates per treatment. The results indicated that biochar treatments had no significant impact on photosynthetic activity, suggesting that foliar application did not cause leaf shading. However, higher biochar concentrations (B600 and B1200) led to increased leaf concentrations of nitrogen (2.1–3.8%), potassium (10.1–18.4 g/kg), sulfur (2.2–2.5 g/kg), boron (65.1–83.6 mg/kg), and manganese (42.4–69.8 mg/kg) compared to B300 and C treatments. Conversely, magnesium content decreased (2.1–2.7 g/kg), likely due to potassium–magnesium antagonism. Furthermore, the B600 treatment produced the highest grape yield (2.67 kg/vine), representing up to a 37% increase compared to other treatments. These findings suggest that the foliar application of biochar can be an effective and sustainable strategy to enhance vineyard productivity. Moreover, it offers a circular economy approach by valorizing grapevine pruning waste as a biochar source. Full article

Grape (Vitis vinifera L.) is one of the most extensively cultivated crops in temperate climates, with its primary fate being wine production, which is paired with a great generation of grape pomace (GP). GP contains a plethora of antioxidant phenolic compounds, being well-known for its high content of various tannins, liable for the astringency of this fruit. Winemaking produces a great mass of by-products that are rich in tannins. Grape seed (GSd) and pulp waste, as well as leaves and stems (GSt), are rich in condensed tannins (CTs), while its skin (GSk) contains more flavonols and phenolic acids. CTs are polymers of flavan-3-ols, and their antioxidant and anti-inflammatory properties are well-accounted for, being the subject of extensive research for various applications. CTs from the diverse fractions of grapefruit and grapevine share similar structures given their composition but diverge in their degree of polymerization, which can modulate their chemical interactions and may be present at around 30 to 80 mg/g, depending on the grape fraction. Thus, this prominent agroindustrial by-product, which is usually managed as raw animal feed or further fermented for liquor production, can be valorized as a source of tannins with high added value. The present review addresses current knowledge on tannin diversity in grapefruit and grapevine by-products, assessing the differences in composition, quantity, and degree of polymerization. Current knowledge of their reported bioactivities will be discussed, linking them to their current and potential applications in food and feed. Full article

Drought ranks among the key abiotic stresses that limit the growth and yield of grapevines (Vitis vinifera L.). Flavonols, a class of antioxidants commonly found in grapevines, play a crucial role in combating drought stress. In this study, we characterized the function and regulatory mechanism of the grapevine VviMYC4 in mediating flavonol biosynthesis in response to drought stress. VviMYC4 encodes a protein of 468 amino acids with conserved bHLH-MYC_N and bHLH domains. Phylogenetic analysis confirmed its homology with the grapevine VviMYC2 and similarity in function. The expression of VviMYC4 in ‘Cabernet Sauvignon’ grapevine seedling leaves increased initially and then decreased during prolonged drought stress. The homologous and heterologous transformation of VviMYC4 in grape suspension cells, Arabidopsis plants, tobacco leaves, and grapevine leaves demonstrated its ability to positively regulate flavonol biosynthesis and accumulation by promoting the expression of flavonol-related genes, thereby enhancing the drought tolerance of transgenic plants. Furthermore, VviMYC4 could bind to specific E-box sites on the promoters of VviF3H and VviFLS to improve their activities. This study highlights VviMYC4 as a pivotal positive regulator of drought tolerance in grapevines and proposes that VviMYC4 enhances the antioxidant and reactive oxygen species (ROS) scavenging abilities of grapevines in challenging environments and improves their stress resilience by mediating flavonol biosynthesis. Our findings offer crucial candidate genes and valuable insights for the molecular breeding of grapevine drought resistance. Full article

Semi-arid viticultural regions globally are experiencing severe and frequent growing-season heat waves that negatively impact grapevine (Vitis vinifera L.) physiological performance and productivity. At the leaf level, heat stress can photodamage both Photosystem I (PSI) and Photosystem II (PSII). In order to study the self-protection mechanism of grapevine leaves, in this study, 3-year-old potted ‘Merlot’ and ‘Muscat Hamburg’ grapevines were exposed to a 5-day simulated heatwave (45/25 °C day/night) and compared to vines maintained at 25/18 °C. After heat exposure, ‘Merlot’ demonstrated superior thermotolerance and superior physiological performance as measured by gas exchange, oxidative parameters, chlorophyll loss, and photoinhibition of PSI and PSII. Additionally, non-photochemical quenching (NPQ) dissipated the excess light energy in the form of heat. Y(NPQ) progressively rose from 0 to 0.6, signaling the start of the grapevine leaves’ self-defense against temperature stress. Furthermore, the stimulation of cyclic electron flow (CEF) under high temperatures contributed to the energy balance of PSI. The CEF of ‘Muscat Hamburg’ under high light intensities increased dramatically from 1 to 4. NAD(P)H dehydrogenase-dependent CEF around PSI increased markedly, suggesting its role in self-protection. These results demonstrate that both NPQ and CEF play key photoprotective roles by generating a proton gradient under heat stress. Full article

Vitis vinifera is a plant known since ancient times mainly for the interest of its fruits. However, its leaves have traditionally been consumed as food in some regions of the Mediterranean basin and as a medicinal remedy. In this work, the phytochemical profile of this part of the plant, which is considered a bio-residue of viticultural processes, was analyzed (UHPLC-ESI(±)-QTOF-MS). Hydroxybenzoic acids, flavonols, and stilbenes are the main phenolic compounds identified. Its antioxidant and anti-inflammatory capacity were studied both in vitro and in cell culture. Grapevine leaves have a high capacity to scavenge free radicals, as well as to reduce oxidative stress induced by H₂O₂ in the HepG2 cell line. On the other hand, the methanolic extract of these leaves is capable of inhibiting lipoxygenase, an enzyme involved in inflammatory responses, with an IC₅₀ of 1.63 μg/mL. In addition, the extract showed potent inhibition of NO production in LPS-stimulated RAW 264.7 cells. These results pointed out V. vinifera leaves as a powerful functional food with a high content of biologically active compounds. The enhancement of these by-products can be highly beneficial to food systems and contribute to the development of sustainable agriculture. Full article

Nitrogen, an indispensable macronutrient, significantly affects the appearance, quality, and yield of grapes (Vitis vinifera). Adequate nitrate uptake and intracellular transport, facilitated primarily by nitrate transport (NRT) proteins, are crucial for maintaining nutritional balance. However, there are no reports on the NRT gene family in grapes. In this study, we identified 53 Nitrate Transporter 1/Peptide Transporter Family (NPF), 3 nitrate transporter 2 family (NRT2), and 1 Nitrate Assimilation-Related 2 (NAR2) genes in the grapevine Pinot Noir PN40024 genome. A comprehensive analysis of these gene families, including their physicochemical properties, structural organization, chromosomal distribution, collinearity, cis-acting element distribution, and phylogenetic relationships, revealed the rich diversity and evolutionary conservation of the grapevine Nitrate Transporter (NRT) genes. Furthermore, the expression profiles of VvNRTs in different tissues demonstrated that the NRT genes possess spatio-temporal expression specificity. The expression patterns of the NRT genes were examined by transcriptome sequencing in grapevines across various tissues under nitrogen-deficiency conditions. The expression patterns in grapevine leaves under nitrogen-deficiency conditions showed upregulation of the VvNPF2.3 gene in conditions of nitrogen deficiency. This upregulation was strongly associated with a 62.2% reduction in indole-3-acetic acid (IAA) levels and a 21.3% increase in hydrogen peroxide (H₂O₂) levels, suggesting a complex regulatory response to nitrogen-induced stress. These findings emphasize the potential involvement of NRT genes in the adaptive reaction to nitrogen deficiency and set the stage for future investigations into the molecular mechanisms of nitrogen transportation in grapevines. Full article

Grapevine downy mildew, caused by Plasmopara viticola, is one of the most destructive vineyard diseases worldwide, with the potential to devastate up to 90% of harvests under adverse conditions. Traditional chemical-based control strategies are increasingly restricted due to environmental concerns and the development of resistant pathogen strains, prompting the search for sustainable alternatives. This study evaluated the efficacy of two yeast-based biostimulants (YE1, an experimental formulation, and YE2, Romeo, a commercial preparation containing Cerevisane^®) in mitigating P. viticola infections in Vitis vinifera cv Cabernet Sauvignon under open field conditions. Field trials were designed to monitor the effects of these bioproducts on grapevine metabolism, with a focus on the biosynthesis of phenolic compounds linked to plant defense responses. Both biostimulants demonstrated significant efficacy against downy mildew, achieving protection levels above 93% during critical growth stages. Metabolic analyses of leaves revealed distinct impacts of YE1 and YE2 on secondary metabolite dynamics. YE1 primarily promoted the accumulation of flavonols, such as quercetin glycosides and kaempferol glucosides, which are known to contribute to pathogen resistance through antimicrobial activity and ROS detoxification. Compared to the untreated sample, quercetin glycosides levels in YE1 leaves were approximately 700 µg/g higher (+9.6%), in comparison to control conditions, on a dry weight basis after the first treatment in 2019 and about 900 µg/g higher (+13.7%) after the final treatment in 2020. A similar trend was observed for kaempferol concentrations, which were 70 µg/g (+98.7%) and 100 µg/g higher (+24.6%) on the same dates. In contrast, YE2 enhanced the biosynthesis of caftaric and coutaric acids, known for their antioxidant and antimicrobial properties. These compounds were induced by YE2 over time and, after the last treatment, in 2019 caftaric acid levels were approximately 345 µg/g higher (+25.9%), than control condition, while coutaric acid levels were 30 µg/g higher (+33.8%). The stilbene piceid was also induced at early stages by treatments, indicating its role in enhancing plant defenses. In 2019, after the first treatment, both YE1 and YE2 applications induced an increase in piceid concentration, compared to the control, of approximately 2.5 µg/g (+104.8%) for YE1 and 1.3 µg/g for Y2 (+55.0%). In contrast, in 2020, the effect was more pronounced for YE2, with concentrations exceeding the control by 2 µg/g (+46.2%). The results suggest that these yeast-based bioproducts act as elicitors, effectively enhancing grapevine immunity and reducing reliance on synthetic inputs. This study provides novel insights into the metabolic mechanisms underlying the efficacy of yeast-based biostimulants against downy mildew and offers practical guidance for their strategic application. Full article

The color of the plant leaves is a major concern in many areas of agriculture. Pigmentation and its pattern provide the possibility to distinguish genotypes and a basis for annual crop management practices. For example, the nutrient and water status of plants is reflected in the chlorophyll content of leaves that are strongly linked to the lamina coloration. Pests and diseases (virus or bacterial infections) also cause symptoms on the foliage. These symptoms induced by biotic and abiotic stressors often have a specific pattern, which allows for their prediction based on remote sensing. In this report, an RGB (red, green and blue) image processing system is presented to determine leaf lamina color variability based on RGB-based color indices. LeafLaminaMap was developed in Scilab with the Image Processing and Computer Vision toolbox, and the code is available freely at GitHub. The software uses RGB images to visualize 29 color indices and the R, G and B values on the lamina, as well as to calculate the statistical parameters. In this case study, symptomatic (senescence, fungal infection, etc.) and healthy grapevine (Vitis vinifera L.) leaves were collected, digitalized and analyzed with the LeafLaminaMap software according to the mean, standard deviation, contrast, energy and entropy of each channel (R, G and B) and color index. As an output for each original image in the sample set, the program generates 32 images, where each pixel is constructed using index values calculated from the RGB values of the corresponding pixel in the original image. These generated images can subsequently be used to help the end-user identify locally occurring symptoms that may not be visible in the original RGB image. The statistical evaluation of the samples showed significant differences in the color pattern between the healthy and symptomatic samples. According to the F value of the ANOVA analysis, energy and entropy had the largest difference between the healthy and symptomatic samples. Linear discriminant analysis (LDA) and support vector machine (SVM) analysis provided a perfect recognition in calibration and confirmed that energy and entropy have the strongest discriminative power between the healthy and symptomatic samples. The case study showed that the LeafLaminaMap software is an effective environment for the leaf lamina color pattern analysis; moreover, the results underline that energy and entropy are valuable features and could be more effective than the mean and standard deviation of the color properties. Full article

Repeated expeditions across various regions of Georgia in the early 2000s led to the identification of 434 wild grapevine individuals (Vitis vinifera L. subsp. sylvestris (C.C. Gmel.) Hegi) across 127 different sites, with 45% of these sites containing only a single vine and only 7% more than 9 vines. A total of 70 accessions were propagated in a germplasm collection, 41 of them were descripted from the ampelographic point of view and 32 from the phenological one. The geographical and ecological analysis confirmed that wild grapevines primarily grow in humid environments with warm and fully humid climates, often near rivers. They favor deep, fertile, and evolved soils, mainly alluvial and cinnamonic types (80%), with a marginal presence on strongly eroded soils. Their main natural vegetations are forests and open woodlands, with some individuals in the Southeast found in steppes. The altitudinal range spans from 0 to 1200 m, with 80% of vines distributed between 400 and 900 m. The phenological analysis revealed significant differences among the accessions but no difference among populations, with only a slight variation in bud-break timing, indicating a high level of synchronicity overall. Flowering timing proved to be the most uniform stage, suggesting minimal environmental pressure on genetic adaptation. The mature leaf morphology exhibited significant polymorphism, though leaves were generally three- or five-lobed, weak-wrinkling, and -blistering, with a low density of hairs. Bunch and berry morphology were more uniform. Bunches were consistently very small, cylindrical, and never dense or winged. Berries were also very small, mostly globular, always blue-black in color, and non-aromatic. A striking feature was the frequency of red flesh coloration, which ranged from weak to strong, with uncolored flesh being rare. The Georgian population of wild grapevines was found to be fragmented, often consisting of scattered single individuals or small groups. Therefore, we believe it is urgent for Georgia to implement specific protection measures to preserve this vital genetic resource. Full article

The grapevine (Vitis vinifera) is a major fruit crop of economic importance worldwide. Commercial grapevine cultivars are susceptible to infection by pathogenic microorganisms that cause diseases both in leaves and fruits, and it is known that the leaf microbiome plays an important role in plant health and fitness. In this study, shotgun metagenomic sequencing was used to characterize the microbial communities associated with grapevine leaves in three commercial varieties, Cabernet Sauvignon, Garnacha, and Marselan, grown in the same biogeographical unit. Metagenomic data revealed a differential enrichment of the microbial communities living inside grapevine leaves or on the leaf surface in the three varieties. The most abundant fungal taxa associated with grapevine leaves belong to the phylum Ascomycota, which included relevant pathogenic fungi for grapevines, such as Botrytis cinerea, Sclerotinia sclerotium, and Alternaria alternata, as well as several fungal species potentially pathogenic for grapevines (e.g., members of the Colletotrichum, Aspergillus, and Penicillium genera). Basidiomycota constituted a minor fraction of the fungal microbial communities. Grapevine leaves also harbored a diversity of bacterial taxa. At the phylum level, bacterial communities in all three varieties were primarily composed of Pseudomonadata, Bacillota, Bacteroidota, and a lower proportion of Actinomycetota. Differences in the fungal and bacterial community structures were observed between varieties, although they were more important in fungi. In particular, S. sclerotiorum and B. cinerea were found to preferentially colonize leaves in the Marselan and Garnacha varieties, respectively. These findings further support that the host genotype can shape its own microbiome in grapevines. A better understanding of the leaf microbiome in grapevines will provide the basis for the development of tailored strategies to prevent diseases in vineyards while helping to increase sustainability in grapevine production. Full article

Prostrate hairs are one of the anatomic barriers for grapevine resistance to pests and diseases, as well as in environmental adaptability, making them valuable for breeding programs. This study investigates the genetic determinants underlying prostrate hair density in grapevine, a key trait associated with resistance to pests and pathogens. Using an F₁ hybrid population derived from Vitis vinifera L. ‘Cabernet Sauvignon cv.’ and V. pseudoreticulata W.T.Wang ‘Huadong1058’, we performed a combination of quantitative trait locus (QTL) mapping and genome-wide association study (GWAS) to identify the genomic regions influencing the density of prostrate hair. We identified a major locus on 9.56–10.54 Mbp of chromosome 17, designated as ‘LH2’, which accounts for 43% of the phenotypic variation. This locus was delineated with high precision, and 92 candidate genes were identified within the region. Functional enrichment analysis suggested that these genes are potentially involved in binding, catalytic activity, and various cellular processes. In particular, the SNP markers ‘chr17_10130288’ and ‘chr17_10428273’ were significantly associated with prostrate hair density, providing valuable information for marker-assisted selection. These findings offer a reliable target for analyzing the hair development mechanism of grapevine leaves and breeding new cultivars rich in prostrate hair on the back of the leaves. Full article

According to the climate projections, drought will increase in frequency and severity. Since water stress (WS) impacts a grapevine’s physiology and yield negatively, the evaluation and selection of tolerant genotypes are needed. To analyse the WS effects on the morphology and cell division of three grapevines (Vitis vinifera L.) varieties, “Touriga Franca” (TF), “Touriga Nacional” (TN) and “Viosinho” (VS), in vitro-grown plants were exposed to 10% polyethylene glycol 6000 (PEG) (−0.4 MPa) or 20% PEG (−0.8 MPa), incorporated in the culture medium, for four weeks. Control plants were kept in culture media without PEG. The VS and TN plants showed the highest mean numbers of nodes, shoots and leaves and average mitotic indexes under 20% PEG. The TF and TN plants showed the lowest frequencies of mitotic anomalies under 10% PEG. The VS plant growth was less affected by WS, but TF and TN presented more regular mitosis under moderate WS. Globally, in vitro culture constitutes a cost-effective experimental system for studying grapevine responses to WS and the preliminary selection of resilient genotypes. These approaches could be applied to study plant responses to other abiotic stresses based on additional evaluation techniques (e.g., transcriptional analyses or genome-wide association studies). Full article