Grape Research Articles

Smart Viniculture: Applying Artificial Intelligence for Improved Winemaking and Risk Management

This review explores the transformative role of artificial intelligence (AI) in the entire winemaking process, from viticulture to bottling, with a particular focus on enhancing food safety and traceability. It discusses AI’s applications in optimizing grape cultivation, fermentation, bottling, and quality control, while emphasizing its critical role in managing microbiological risks such as mycotoxins. The review aims to show how AI technologies not only refine operational efficiencies but also raise safety standards and ensure traceability from vineyard to consumer. Challenges in AI implementation and future directions for integrating more advanced AI solutions into the winemaking industry will also be discussed, providing a comprehensive overview of AI’s potential to revolutionize traditional practices.

The microbiome analysis of ripen grape berries supports the complex etiology of sour rot

The microbiome analysis of ripen grape berries supports the complex etiology of sour rot

Evaluation of the Suitability of Horticultural Crops under Prevailing Environmental Conditions - A Case Study of Punjab

Alternate land use options such as horticultural crops help in ensuring efficient land resource utilization. Thus, it is essential to evaluate the agri-environmental conditions for economically viable and sustainable horticultural production. A study was carried out for land use planning of Rajpura block in Patiala district of Punjab. Under this study, soil-site suitability of horticultural crops were evaluated by considering key soil parameters such as texture, depth, slope, EC, pH, organic carbon content, erosion, drainage, and climate factors viz., rainfall and temperature, etc. The soils of the block were interpreted to assess their suitability for various horticultural crops viz., mango, grapes, banana, sapota, guava, pomegranate and citrus fruits. The mango cultivation was found suitable for almost 50% area and moderately suitable for 34% area. Soil-site suitability characteristics evaluation for grape cultivation revealed that around 34% area of the block is suitable while 50% area is moderately suitable. The banana and sapota crop cultivation was found to be highly suitable for approximately 45% area, whereas moderately suitable for 40% area. In context of guava and pomegranate, nearly 34% area was covered under suitable class and 50% area was covered under moderately suitable class, respectively. The citrus crops are highly suitable for this block which covers the maximum area of the block about 61% and moderately suitable for almost 23% area, respectively. The small fraction of the block, only 1.68% (476 ha) exhibits marginal suitability for the cultivation all fruit crops. The horticultural crop suitability maps were generated by using remote sensing and GIS tools. Hence, it can be concluded, the Rajpura block has vast dimensions for the horticultural farming which will lead to land resource management, sustainable land use planning and livelihood security of farmers of the block. This study will also help policy makers and stake holders for the horticultural developmental planning of this block.

Free monoterpenoid accumulation in ‘Riesling’ (Vitis vinifera L.) is light-sensitive and uncoupled from grape hexose accumulation

Monoterpenoid biosynthesis mirrors hexoses accumulation in grape berries during ripening and is affected by environmental factors such as solar radiation. However, no research has confirmed the dependency of monoterpenoid accumulation on grape maturity. Using potted ‘Riesling’ (Vitis vinifera L.) vines, we girdled (GD) shoots at veraison to halt leaf photoassimilate translocation to berries and also utilized light-impenetrable bags to exclude light exposure (LE) to grape clusters to <2 μmol m-2s-1 during ripening. GD and LE were compared to an untreated control (CT), and a combined (GDxLE) treatment. GD caused leaf photosynthetic assimilation to decline from one-week post-treatment until harvest maturity due to feedback inhibition of photosynthesis. This was coupled to a decrease in hexoses and ABA accumulation in GD berries. Meanwhile, LE did not affect photosynthetic assimilation, or hexoses and ABA accumulation. We hypothesized that the accumulation of free and bound monoterpenoids in ‘Riesling’ berries would also be reduced by GD, if monoterpenoid accumulation was dependent on grape maturity. LE significantly decreased free monoterpenoids compared to CT. However, GD did not alter total free and bound monoterpenoid concentrations. GD decreased free Linalool Oxide I and II and bound Linalool Oxide I compared to CT, and increased Citral I and II and α-Terpineol. Although exogenous jasmonate applications stimulate monoterpenoid biosynthesis in grapes, we showed that endogenous jasmonate concentrations were not altered by GD or LE; therefore, any monoterpenoid modulation by GD and LE treatments was not mediated by endogenous jasmonate levels. This study indicates that free monoterpenoid biosynthesis during ripening is “uncoupled” from hexose accumulation and is strongly regulated by solar radiation.

Quality maintenance and metabolite changes of grape berry treated by high voltage alternating electric field during near-freezing temperature storage

High Voltage Alternating Electric Field (HVAEF), as an emerging postharvest preservation technology, is environmentally friendly and has garnered significant attention from scholars. This study investigated the effects of HVAEF on the postharvest quality and metabolite changes in ‘Shine Muscat’ grapes stored at near-freezing temperatures. The results demonstrated that HVAEF halved the weight loss and decay rate, inhibited browning by preserving polyphenol content, and reduced polyphenol oxidase and peroxidase activities, thereby extending the storage time by more than 20 days. Metabolomic analysis of the grape berries from the upper, middle, and bottom parts of the bunch revealed that the upper berries contained higher sugar levels and were more significantly influenced by HVAEF treatment. Additionally, HVAEF notably reduced the accumulation of amino acids, such as valine, leucine, and lysine, compared to the control. This study provides new insights into the enhancement of quality in fresh fruits and vegetables through HVAEF technology.

On-the-go table grape ripeness estimation via proximal snapshot hyperspectral imaging

The monitoring of grapes for ripeness estimation is a practice that enables fruit harvesting at the optimal time. Hyperspectral Imaging (HSI) represents a non-destructive and high-throughput alternative to traditional laboratory analyses. Current literature approaches perform hyperspectral measurements using line scan sensors or low-resolution static snapshot cameras, which hinder a fast per-bunch ripeness characterization. We propose a framework for on-the-go collection and processing of proximal snapshot hyperspectral images to estimate single bunch ripeness parameters. Focusing on table grapes (Vitis vinifera L. cv. Red Globe), we collected images under natural illumination with a hyperspectral camera (500–900 nm) mounted on a moving vehicle in an experimental block sited in Piacenza, Italy. We investigated images collected in August and September 2021 representing two ripening stages. The composition of the imaged grape bunches was determined through laboratory chemical analyses to predict Total Soluble Solids (TSS) and anthocyanin concentration. The images were pre-processed via multimodal image registration to correct the unalignment of bands due to the vehicle motion, and the single bunches were automatically identified on false RGB images through a Mask Region-Convolutional Neural Network (Mask R-CNN) instance segmentation network. The mean spectra of the bunches were used as input features of a Partial Least Squares Regression (PLSR) model to predict the chemical parameters at single bunch and whole vine scales. The regression model of TSS had an R2 (10-fold nested cross-validation) of 0.75 and 0.85 on a per-bunch and per-vine basis, respectively. The regression model of anthocyanin had an R2 of 0.68 and 0.49 on a per-bunch and per-vine basis, respectively. The results suggest the potential of using snapshot hyperspectral images for high-throughput analysis of a per-bunch grape ripeness estimation. The method described in this study could give valuable information to improve grape ripening monitoring and management of harvest operations and even allow for precise and automated robotic harvesting.

Integrative Analysis of Transcriptome and Metabolome Reveals the Regulatory Network Governing Aroma Formation in Grape

The aroma metabolites in grape berries have received attention in recent years, but a global analysis of gene-regulated metabolites is still lacking. In this study, three grape cultivars, “Kyoho”, “Adenauer Rose”, and “Mei Xiangbao”, were used to determine the differential accumulation of metabolites and identify candidate genes related to grape berry aroma. A total of 27,228 genes were detected from the transcriptome, and 128 differentially accumulated metabolites (DAMs) were identified. Terpenoids and ester were the major substances in these three cultivars. KEGG enrichment showed that 12, 8, and 5 compounds were significantly enriched during the maturation process of these three grape cultivars, with most being terpenoids. A combined transcriptome and metabolome analysis found that the associated genes and metabolites were enriched in the following pathways: “Glycine, serine, and threonine metabolism”, “Cysteine and methionine metabolism”, “Tyrosine metabolism”, “Phenylalanine metabolism”, and “Phenylalanine, tyrosine, and tryptophan biosynthesis”. Seven structural genes (VvOMR1, VvGLYK, VvLPD2, VvAK2, VvSHM7, VvASP3, and VvASP1) and four transcription factors (VvERF053, VvERF4, VvMYB46, and VvMYB340) related to grape berry aroma accumulation were discovered. Our findings provide new insights into grape aroma formation and regulatory mechanism research, and the results will be beneficial for grape aroma breeding in the future.

Effect of Calcium Formulations to Increase Yield and Shelf Life of Manjri Naveen Grapes

The application of Calcium at veraison stage maintain the quality of grapes. Hence to evaluate the effect of Calcium formulations for increasing yield and the shelf life of Manjri Naveen grapes. The experiment was designed as randomized block design (RBD) having seven treatments and four replications (1 replicate = 4 vines). Three calcium formulations were used i.e. CaCl2, CaO, Ca(No3)2 as a dose of (2.5 g/l) and (5 g/l). Foliar application of calcium was done 10 days before harvest at veraison stage. Results obtained from the experiment showed the lowest weight loss was found in bunches of calcium oxide and calcium chloride spray treatments (8.14 %), (8.61 %) respectively, while the highest weight loss (10.36 %) occurred in untreated control. The PLW increased significantly at successive from 1.32 % on 1st day to 10.36 % on 7th day of storage at room temperature. CaO at 5 g/l recorded the lowest fallen berries 2.70 (%), followed by Ca(NO3)2 at 2.5 g/l recorded 3.38 (%). It might be due to calcium accumulated mostly in the rachis and less in the flesh during grape berry development. Yield and quality components like bunch weight, berry weight, total yield/vine, TSS, TSS/Acidity ratio were significantly influenced by calcium spray. Hence from this study it is concluded that the foliar application of CaO at 5 g/l was found to be effective for increasing the shelf life and yield of Manjri Naveen grapes.

Design and evaluation of an active vineyard heating system to simulate temperature increase in the context of climate change

The current study introduces an innovative direct and active heating system designed for precise temperature control in vineyards. This system serves as a valuable tool for investigating the influence of climate change on grapevine physiology and, consequently, the characteristics of the resulting wine. The research took place in an experimental vineyard located in Mendoza, Argentina, with V. vinifera cvs. trained to a vertical shoot positioning trellis system over two consecutive growing seasons. The system design utilized electric hot water tanks and polypropylene pipes attached to the foliage catch wires. Over two growing seasons, the system consistently elevated the ambient air temperatures within the canopy by 2.5 ± 0.12 °C compared to the control group. This temperature increase emulated the temperature projections for Mendoza as forecasted by the IPCC by the end of this century. The system displayed heating uniformity, as evidenced by the absence of both vertical and horizontal temperature gradients. Additionally, the significant variation in mean daytime and night-time temperatures between the control and heated treatments highlighted the effectiveness of the system in modifying temperature conditions on a diurnal basis. The heated treatment applied with this system proved to have an effective biological impact on the physiology of grapevines. In both seasons, plants under the heated treatment advanced their bud break and harvest dates. The study showed a significant growth enhancement in the heated treatment, with apical shoots extending significantly longer than those in the control treatment. Additionally, the total soluble solids content increased in the heating treatment, while yield decreased, for both experimental seasons. These results illustrate the robust performance of the system throughout the entire growth period, regardless of fluctuations in atmospheric conditions. This study establishes a new foundation for future research on grapevine responses to climate change. It also opens the door to the implementation of effective adaptation strategies in vineyards, promising a more resilient and adaptable future for grape cultivation.

Evaluation of green residues management of selected grape varieties

The paper presents the possibilities of energy management of residues from the cultivation of grapes of the ‘Regent’, ‘Rondo’ and ‘Seyval Blanc’ cultivars. The research was conducted in southeastern Poland in the Sandomierska Upland in 2022. The aim of the research was to demonstrate the influence of grape variety on yield capacity in relation to the extraction of biomass residues in the form of leaves. An attempt was made to identify the variety that is characterised by obtaining the most effective and average parameters, i.e. yield size and quality, leaf mass and surface area, and their impact on energy and fuel parameters. The study analysed the following crop parameters, i.e. number and mass of grapes, number and mass of berries; leaf quality parameters, i.e. mass including petioles and area. An energy assessment in Laboratory in Department of Power Engineering and Transportation was carried out by performing proximate and ultimate analysis and estimating emission factors and volumetric composition of exhaust gas. The study showed that the material with the highest energy potential was characterised by ‘Regent’, while the lowest potential was shown for ‘Rondo’. Grapevines of the ‘Rondo’ cultivar were characterised by the highest obtained biomass among the evaluated varieties. The research showed that the most effective in practical cultivation is the use of the Regent variety, which was characterised by the average parameters of the obtained yield and growth values, and the highest fuel energy potential.

Influence of Grape Heterogeneity on Berry Quality Traits in Table Grapes A Study on the ‘Alphonse Lavallée’ Variety

The study, conducted in 2023 at the vineyard of the Agricultural Research and Application Center of Tokat Gaziosmanpaşa University, focused on the Alphonse Lavallée grape variety, a significant cultivar among table grapes. The research aimed to assess the impact of berry density on various quality parameters. Grape berries were selected across five different density categories (Y0-Y4), including a control group, to evaluate their physical characteristics (including width, length, weight, firmness, and skin color), chemical properties (pH, total titratable acidity, and soluble solids content), and phytochemical attributes (encompassing total phenol content, total antioxidant capacity, and total monomeric anthocyanin levels). The findings revealed that critical quality indicators—namely, soluble solids content, pH, total antioxidant capacity, and total monomeric anthocyanin—were maximized under the Y4 treatment. In contrast, the highest total phenol content was recorded in the Y2 and Y3 treatments. These results underscore the importance of berry density and berry/skin volume as key determinants of grape berry quality. The study contributes valuable insights into the role of these factors in enhancing the overall quality of table grapes, particularly in the context of the Alphonse Lavallée variety.

CHH hypermethylation contributes to the early ripening of grapes revealed by DNA methylome landscape of “Kyoho” and its bud mutant

Abstract DNA methylation is a stable epigenetic mark that plays a crucial role in plant life processes. However, the specific functions of DNA methylation in grape berry development remain largely unknown. In this study, we performed whole-genome bisulfite sequencing on “Kyoho” grape and its early-ripening bud mutant “Fengzao” at different developmental stages. Our results revealed that transposons (TEs) and gene flanking regions exhibited high levels of methylation, particularly in “Fengzao”, attributed to CHH site methylation. Interestingly, the methylation patterns in these two cultivars showed distinct dynamics during berry development. While methylation levels of genes and TEs increased gradually in “Kyoho” throughout berry development, “Fengzao” did not display consistent changes. Notably, “Fengzao” exhibited higher methylation levels in promoters compared to “Kyoho”, suggesting that hypermethylation of promoters may contribute to its early ripening phenotype. Integration of methylome and transcriptome data highlighted differentially methylated genes (DMGs) and expressed genes (DEGs) associated with secondary metabolite biosynthesis, with 38 genes identified as potential candidates involved in grape berry development. Furthermore, the study identified a jasmonate-induced oxygenase gene (JOX1) as a negative regulator of ripening in Arabidopsis and grapes, indicating that hypermethylation of JOX1 may play a role in the early ripening of “Fengzao”. Overall, our findings provide insights into the distinct DNA methylation patterns during grape berry development, shedding light on the epigenetic regulatory mechanisms underlying the early-ripening bud mutant.

Soil-Mulching Treatment Enhances the Content of Stilbene in Grape Berries: A Transcriptomic and Metabolomic Analysis

Soil mulching is a useful agronomic practice that promotes early fruit maturation and affects fruit quality. However, the regulatory mechanism of fruit metabolites under soil-mulching treatments remains unknown. In this study, variations in the gene sets and metabolites of grape berries after mulching (rice straw + felt + plastic film) using transcriptome and metagenomic sequencing were investigated. The results of the cluster analysis and orthogonal projection to latent structures discriminant analysis of the metabolites showed a difference between the mulching and control groups, as did the principal component analysis results for the transcriptome. In total, 36 differentially expressed metabolites were identified, of which 10 (resveratrol, ampelopsin F, piceid, 3,4′-dihydroxy-5-methoxystilbene, ε-viniferin, trans resveratrol, epsilon-viniferin, 3′-hydroxypterostilbene, 1-methyl-resveratrol, and pterostil-bene) were stilbenes. Their content increased after mulching, indicating that stilbene synthase activity increased after mulching. The weighted gene co-expression network analysis revealed that the turquoise and blue modules were positively and negatively related to stilbene compounds. The network analysis identified two seed genes (VIT_09s0054g00610, VIT_13s0156g00260) and two transcription factors (VIT_13s0156g00260, VIT_02s0025g04590). Overall, soil mulching promoted the accumulation of stilbene compounds in grapes, and the results provided key genetic information for further studies.

Towards an Inclusive Village: Literacy and Education for People with Disabilities Through the Development of Grape Planting Techniques (Vitis Vinifera L) Taman Ayu Village

People with disabilities are identical to people who are disabled, weak, stupid and backward. People with disabilities are no longer seen as problematic people, by providing equal access and being inclusive for everyone in their society (168 169). Equal roles for people with disabilities are an important issue for the government. Recognition of equal rights for groups with disabilities, both in terms of education, employment opportunities and others. Community service activities carried out by Herdiana, et al. in Taman Ayu village, in 2023 became the main basis for empowering people with disabilities and knowledge for people with disabilities, especially in the equality garden by involving groups with disabilities. Taman Ayu Village, Gerung District, West Lombok Regency, West Nusa Tenggara (NTB) in the "Equality Garden" group consisting of 15 people consisting of people with hearing and speech impairments which was carried out in June-December 2024 with the community service implementation team being a collaboration of 3 fields of science, namely agribusiness, accounting and agroecotechnology and involving 3 students from different study programs (fields of science). The purpose of this activity is to provide literacy and education about grape cultivation techniques, improve grape cultivation technique skills, financial management in business through ongoing training and mentoring. The forms of activities include literacy counseling and education for people with disabilities in grape cultivation techniques (Vitis Vinifera L), business management training and financial recording management, mentoring and coaching in marketing using digital marketing (marketplace: Facebook, Shopie, Tokopedia) and mentoring in submitting business legality. The hope of this activity is that groups with disabilities have skills in the field of grape cultivation, skills in management and financial recording of businesses so that from this activity a new business can be formed so that the goal of this activity is the independence of the disabled group's business. Collaboration between the service team (academics) and the village in the form of ongoing mentoring and coaching will be carried out until they have an independent business

Grape Endophytic Microbial Community Structures and Berry Volatile Components Response to the Variation of Vineyard Sites

Vitis vinifera L. is a commercially important horticultural plant with abundant microbial resources. However, the impact of grape-associated microbiota on grape quality and flavor has been largely overlooked. We integrated volatomics and microbiomics to explore temporal variations in berry volatiles and microbial diversity of ‘Cabernet Sauvignon’ in Ningxia (NX) and Shanxi (SX), and the correlation between microbial communities and volatiles. A total of 38 and 35 free and bound aroma compounds, respectively, were identified in NX berries and SX berries. For free aroma, these 38 compounds were classified into aldehydes (69%), alcohols (22%), acids (4%), aromatics (4%), terpenes (0.6%), esters (0.37%), and norisoprenoids (0.3%). Similarly, the 35 bound aromas were attributed to aromatics (58%), acids (29%), terpenes (4%), esters (3%), alcohols (2.82%), aldehydes (2.78%), and norisoprenoids (0.4%). Additionally, a total of 616 bacterial genera and 254 fungal genera were detected in all samples from both regions. The results demonstrated that vineyard sites significantly shaped the characteristics of berry volatiles and microbial biogeographic patterns. SX berries exhibited more abundant free aroma and higher microbial diversity than NX berries, with three key taxa (Sphingomonas, Massilia, and Bacillus) identified in the bacterial network. Correlation analysis results highlighted that these key taxa might play an important role in berry-free aroma. This study reveals the crucial role of microbes in shaping grape flavor and uncovers the link between microbial diversity and the regional attributes of grapes and wine.

Anthocyanin Accumulation in Grape Berry Skin Promoted by Endophytic Microbacterium sp. che218 Isolated from Wine Grape Shoot Xylem.

Grape berry skin coloration is a key determinant of the commercial value of red wines. Global warming caused by climate change has inhibited anthocyanin biosynthesis in berry skins, leading to poor coloration. Through two-year field experiments, the endophyte che218 isolated from grape shoot xylem promoted anthocyanin accumulation in berry skins. The che218 enhanced anthocyanin biosynthesis in grapevine cultured cells. In the 2022 growing season, applying che218 to grape bunches enhanced anthocyanin accumulation in berry skins on day 20 post-treatment. However, the anthocyanin accumulation enhancing effect of che218 became negligible at harvest. In the 2023 growing season, che218 enhanced anthocyanin accumulation in berry skins on day 15 post-treatment and at harvest (day 30 post-treatment) and also upregulated the transcription of mybA1 and UFGT, two genes that regulate anthocyanin biosynthesis in berry skins. Whole genome sequencing demonstrated that che218 is an unidentified Microbacterium species. However, it remains unknown how che218 is involved in the biosynthesis of anthocyanin in berry skins. This study provides insights into the development of an eco-friendly endophyte-mediated technique for improving grape berry skin coloration, thereby mitigating the effects of global warming on berry skin coloration.

The changing geography of wine climates and its implications on adaptation in the Italian Alps

AbstractWine production and quality both strongly depend on suitable climatic conditions. Increasing the climate resilience of wine regions is therefore of critical importance but requires instruments to evaluate shifts in climatic conditions and growing suitability. This evaluation is particularly challenging in mountain viticultural areas due to their complex topoclimatic patterns, yet they offer the possibility to analyze climate change impacts and adaptation strategies across various climatic conditions and cultivated varieties. Here, we assessed historical and future bioclimatic conditions and identified effective adaptation strategies toward more sustainable and climate‐resilient wine production in the mountain winegrowing regions within South Tyrol in the Italian Alps. We found significant changes in climatic conditions under future scenarios, such as an increase in the Huglin index (HI) and cool night index (CNI) as well as a decreased dryness index (DI), causing an expansion of suitable areas for viticulture as well as a spread of unprecedented climatic conditions in traditional vineyards. Impacts and suitable adaptation options varied depending on climate type and grape variety, highlighting the need for targeted solutions that balance the need for high‐quality wine production with environmental protection and sustainability. Higher elevated areas over 1000 m a.s.l. will experience an increased suitability raising the need for restrictions regarding the expansion of vineyards to avoid degradation of natural ecosystems and biodiversity declines. In contrast, many traditional winegrowing areas will need to implement a combination of short‐ and long‐term adaptation measures to maintain traditional wine styles. Our findings provide a framework for the assessment of viticultural suitability and the formulation of appropriate adaptation strategies for the sustainable cultivation of wine grapes in a changing climate that applies to a variety of climates and grape varieties.

Inhibitors of abscisic acid synthesis or signaling affect anthocyanin synthesis and photoreceptors in grape berries

Effects of endogenous abscisic acid (ABA) and ABA signal transduction on anthocyanin and photoreceptors in grape berries (Vitis labruscana) were examined using NDGA, the inhibitor of the rate-limiting ABA biosynthesis enzyme in grapes, and PANMe, an ABA receptor interaction antagonist. Both NDGA and PANMe treatments decreased anthocyanin concentrations. The expressions of VvSnRK2.6, VvABF2, and VvPP2C9 in NDGA treatment were not significantly different from the untreated control; by contrast, PANMe treatment decreased the expressions of VvSnRK2.6, VvABF2, and VvPP2C9. Both NDGA and PANMe treatments decreased the expressions of VvPhot2 and VvCRYa. These results suggest that both endogenous ABA concentrations and ABA signaling affect anthocyanin synthesis and photoreceptor genes such as VvPhot2 and VvCRYa in grape skins.

Unraveling the key molecular events of Pinot noir berry ripening under varying crop load

Aligned to exploring the physiological and molecular complexity of grape berry development, there is a need to characterize the influence of the source:sink relationships on the genetic regulation of fruit composition. Crop load, as defined by the amount of fruit produced per unit vegetative growth at dormancy, is a common measure of source:sink relationships used to evaluate vineyard production efficiency. We studied the impact of varying crop load on the transcriptome and metabolome of Pinot noir grape berries by comparing the development and ripening of fruit grown on vines with either 50 % or 75 % of their grape clusters removed immediately following fruit set compared to unthinned vines for three consecutive vintages. A clear impact on the general phenylpropanoid pathway resulting in a redistribution between stilbenes and anthocyanins was revealed under varying crop loads and consistent with the transcriptomic profiles of the corresponding branches. Moreover, we identified genes, such as LBDIa3 and AG2, modulated by crop load around veraison, representing putative transcriptional key triggers of the berry ripening phase responding to differences in the vine source:sink ratio generated by the application of cluster thinning. Genes, specifically EXPA1 and EXPA18, involved in softening and other crucial events of ripening initiation responded to crop load and likely influenced the progression of the ripening process. Beyond the major impacts represented by a shift of the onset and completion of ripening, we were able to highlight more subtle effects of the crop load, related to the rate at which the molecular and metabolic changes occur. This study asserts that grape metabolism and transcriptome are remarkably flexible, and that manipulations such as cluster thinning induce extensive, genome-wide changes in expression during berry development. The insights gained here pave the way to progress towards the construction of robust models depicting the molecular network that characterizes berry development and the impact of crop load on its molecular regulation.

Transcriptome analysis reveals activation of detoxification and defense mechanisms in smoke-exposed Merlot grape (Vitis vinifera) berries

A significant consequence of climate change is the rising incidence of wildfires. When wildfires occur close to wine grape (Vitis vinifera) production areas, smoke-derived volatile phenolic compounds can be taken up by the grape berries, negatively affecting the flavor and aroma profile of the resulting wine and compromising the production value of entire vineyards. Evidence for the permeation of smoke-associated compounds into grape berries has been provided through metabolomics; however, the basis for grapevines’ response to smoke at the gene expression level has not been investigated in detail. To address this knowledge gap, we employed time-course RNA sequencing to observe gene expression-level changes in grape berries in response to smoke exposure. Significant increases in gene expression (and enrichment of gene ontologies) associated with detoxification of reactive compounds, maintenance of redox homeostasis, and cell wall fortification were observed in response to smoke. These findings suggest that the accumulation of volatile phenols from smoke exposure activates mechanisms that render smoke-derived compounds less reactive while simultaneously fortifying intracellular defense mechanisms. The results of this work lend a better understanding of the molecular basis for grapevines’ response to smoke and provide insight into the origins of smoke-taint-associated flavor and aroma attributes in wine produced from smoke-exposed grapes.