Wine Research Articles

Valorization of the solid fraction of wine lees through optimized accelerated autolysis: Effect of temperature, pH and solid concentration on free-amino acid concentration

Winemaking, as an agro-industrial process, generates substantial amounts of by-products, notably grape pomace and wine lees. The latter constitutes the residue left behind during the racking or bottling of wine, consisting mainly of dead yeast cells, ethanol, phenolic compounds, tartrates, and other compounds. Within the framework of by-products’ valorization, the rich content of dead yeast cells in wine lees render them conducive to the production of a yeast extract substitute through autolysis. In the present study, the effect of pretreatment, temperature, pH, and solid concentration on the efficiency of white wine lees autolysis was investigated. Moreover, the effect of enzyme addition and dynamic thermal protocols were investigated. Efficiency assessment was based on the increase of free α-amino nitrogen (FAN) found in the autolysate. The finding revealed a significant increase of FAN in all cases, with treated and untreated white wine lees reaching a maximum increase of 477% and 834%, respectively. Furthermore, the amino acid profile of autolysates was significantly affected by the autolysis temperature. These results hold promise for the comprehensive, holistic valorization of wine lees, suggesting their potential use as a nutrient source for microorganisms, such as wine yeast, or even as a grape must nitrogen modulator. Consequently, this by-product can be integrated back into the same industrial process from which it originates, namely winemaking. This not only aligns with the principles of circular economy but also underscores the potential for sustainable development within wineries.

Effects of grapevine canopy leaning on grape composition and wine quality of ‘Bobal’

Exploring new field strategies for adapting winegrowing regions to the adverse effects of climate change becomes imperative. This study focuses on the effects of canopy architecture through the trellis systems leaning of North–South oriented vineyard’s rows vertical shoot positioned (VSP) system by 30° towards either the East (ESP) or the West (WSP) as a possible adaptation technique. The trial was conducted over two seasons in a Vitis vinifera L. cv. Bobal vineyard located in Requena (Valencia), eastern Spain, under a temperate-warm climate. The canopy leaning was considered to affect the radiation load and its timing with potential effects on vine physiology and grape metabolism and, consequently, on grape and wine quality. Leaning treatments affected vegetative growth, likely due to slight differences in vine water status. In comparison to VSP and ESP, WSP intercepts more light in the morning, when the photosynthetic capacity of the vines is at its highest. However, this results in a more negative vine water potential, which in turn leads to a reduction in vigour with no impact on yield. Musts from the WSP showed a tendency to increase total acidity compared to VSP, while ESP tended to decrease it. This was likely due to the reduction in temperature within the cluster microclimate in WSP in comparison to the ESP and VSP treatments. In addition, musts from the WSP treatment showed higher colour intensity, anthocyanins and polyphenols, potentially attributable to its more negative potentials, likely due to its more negative potentials, which may have prompted the synthesis of phenolic compounds. Consequently, wines from the WSP treatment displayed higher total acidity and lower pH, as well as higher colour intensity, anthocyanins, and polyphenolic content. In addition, WSP wines had higher concentrations of esters and higher alcohols. The improvements in grape and wine composition are likely due to an increased cluster radiation interception in the morning and reduced heating in the afternoon when VPD is higher. Our findings demonstrate that canopy management by leaning VSP vines towards the West can be a useful technique for adapting grape and wine composition to climate change and provide insights into its physiological basis.

Valorization of Grape Pomace: A Review of Phenolic Composition, Bioactivity, and Therapeutic Potential.

Vitis vinifera L., commonly known as grapes, is one of the most widely cultivated crops worldwide, with over 80% used for wine production. However, the winemaking process generates substantial residues, including grape pomace (GP), wine lees, and wastewater, which can pose significant environmental and economic challenges. Among these, GP stands out not only as a waste product but also as a rich source of polyphenols-bioactive compounds with recognized antioxidant and anti-inflammatory properties. Recent advancements have expanded the application of GP-derived extracts, particularly in the health and food industries, due to their potent bioactive properties. This review provides a comprehensive overview of the valorization of GP, focusing on its phenolic composition and therapeutic potential. It evokes innovative, environmentally friendly extraction techniques and integrated methods for the chemical analysis of these valuable compounds. Additionally, the health benefits of GP polyphenols are explored, with recent experimental findings examining their metabolism and highlighting the key role of gut microbiota in these processes. These insights contribute to a deeper understanding of the biological activity of GP extracts and underscore their growing significance as a high-added-value product. By illustrating how winemaking by-products can be transformed into natural therapeutic agents, this review emphasizes the importance of sustainable development and eco-friendly waste management practices, significantly contributing to the advancement of a circular economy.

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.

A New Approach for CRISPR/Cas9 Editing and Selection of Pathogen-Resistant Plant Cells of Wine Grape cv. 'Merlot'.

Grape is one of the most economically significant berry crops. Owing to the biological characteristics of grapes, such as the long juvenile period (5-8 years), high degree of genome heterozygosity, and the frequent occurrence of inbreeding depression, homozygosity during crossbreeding leads to loss of varietal characteristics and viability. CRISPR/Cas editing has become the tool of choice for improving elite technical grape varieties. This study provides the first evidence of a decrease in the total fraction of phenolic compounds and an increase in the concentration of peroxide compounds in grape callus cells upon the addition of chitosan to the culture medium. These previously unreported metabolic features of the grape response to chitosan have been described and used for the first time to increase the probability of selecting plant cells with MLO7 knockout characterised by an oxidative burst in response to the presence of a pathogen modulated by chitosan in the high-metabolite black grape variety 'Merlot'. This was achieved by using a CRISPR/Cas9 editing vector construction with the peroxide sensor HyPer as a reporter. This research represents the first CRISPR/Cas9 editing of 'Merlot', one of the most economically important elite technical grape varieties.

On-vine drying (passérillage) improves the quality of “Hutai No. 8” table grape wine: Focusing on phenolics, aromas, color and sensory attributes

On-vine drying (passérillage) was employed for Hutai No.8 table grapes with different water loss rates and that are used for winemaking to alter the qualities of wine. Results showed that on-vine drying increased sugar content, thereby elevating alcohol and glycerol contents in the resulting wine. A moderate drying treatment (D2, 18 % water loss) produced wine with optimal red color characteristics. The D2 wine contained abundant individual phenolics such as caffeic acid, salicylic acid, resveratrol, p-coumaric acid, and proanthocyanidin B1, which exhibited strong positive correlations with color parameters (a⁎, C*ab and △E*ab). Similar trends were observed in aroma compounds, with ethyl acetate, ethyl caproate, diethyl succinate, geraniol, linalool, 4-terpinenol, α-terpineol, and β-ionone contents showing significant increment in D2, aligning with enhanced sensory evaluations of wines. Thus, improvement of wine quality can be achieved through moderate on-vine drying (18 % water loss)，serving as a valuable reference for table grape winemaking.

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.

Anthocyanin-rich grape pomace extract encapsulated in protein fibers: Colorimetric profile, in vitro release, thermal resistance, and biological activities

Red wine grape pomace is an important source of bioactive compounds with biological activities of interest. Grape pomace extract can be encapsulated in ultrafine fibers using the electrospinning technique. Encapsulation is used to increase stability and protect the phenolic compounds in the extract. In this study, zein fibers were developed for encapsulation of grape pomace extract (0 %, 5 %, 10 %, and 15 % w/w). The extract was evaluated for colorimetric profile, whereas the ultrafine zein fibers carrying the extract were assessed for morphology, loading capacity, in vitro release profile, thermal and thermogravimetric properties, thermal resistance, hydrophilicity, and antioxidant and antimicrobial activities. The grape pomace extract changed color depending on pH, ranging from pink (pH 1) to yellow (pH 13 and 14). The fibers presented a smooth and uniform structure, with diameters of approximately 450 nm and a loading capacity of up to 82 %. The membranes of ultrafine fibers demonstrated hydrophilic behavior, and the in vitro release profile was dependent on the concentration of the added extract. Furthermore, the fibers were observed thermally protect the encapsulated compounds and maintain their antioxidant and antimicrobial activities. These findings indicate that the produced material has potential applications in the development of active and intelligent packaging for the food industry.

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.

Assessing the Potential of Tortistilus (Hemiptera: Membracidae) from Northern California Vineyards as Vector Candidates of Grapevine Red Blotch Virus.

Ceresini treehoppers are present in northern California vineyard ecosystems, including the closely related Spissistilus and Tortistilus (Hemiptera: Membracidae). These membracids are not direct pests of wine grapes, but S. festinus is a vector of grapevine red blotch virus (GRBV). No information is available on the ability of Tortistilus spp. to transmit GRBV. In this study, Tortistilus were collected on yellow panel cards across 102 vineyard sites and surrounding areas in Napa Valley, California, USA in 2021-2023. Specimens were morphotyped, sexed and tested for GRBV ingestion and acquisition by multiplex PCR or qPCR. Phylogenetic analysis of the partial sequence of mt-COI and ITS gene fragments of a subset of 40 Tortistilus specimens revealed clustering in a monophyletic clade with T. wickhami with the former barcode sequence. Only 6% (48/758) of the T. wickhami tested positive for GRBV, but none of the heads with salivary glands (0%, 0/50) of the dissected specimens tested positive for GRBV, indicating no virus acquisition. In contrast, half of the dissected heads with salivary glands of S. festinus (52%, 12/23), from the same collection vineyard sites, tested positive for GRBV. Together, our findings confirmed the presence of T. wickhami in northern California vineyards and suggested a dubious role of this treehopper as a vector of GRBV.

The molecular basis of flavonoid biosynthesis response to water, light, and temperature in grape berries.

Flavonoids, including proanthocyanidins (PAs), anthocyanins and flavonols are essential secondary metabolites that contribute to the nutritional value and sensory quality of grape berry and red wine. Advances in molecular biology technology have led to substantial progress in understanding the regulation of flavonoid biosynthesis. The influence of terroir on grape berries and wine has garnered increasing attention, yet its comprehensive regulatory network remains underexplored. In terms of application, environmental factors such as water, light, and temperature are more easily regulated in grapevines compared to soil conditions. Therefore, we summarize their effects on flavonoid content and composition, constructing a network that links environmental factors, hormones, and metabolites to provide a deeper understanding of the underlying mechanisms. This review enriches the knowledge of the regulatory network mechanisms governing flavonoid responses to environmental factors in grapes.

Yeast Diversity in Wine Grapes from Japanese Vineyards and Enological Traits of Indigenous Saccharomyces cerevisiae Strains.

Japan has numerous vineyards with distinct geographical and climatic conditions. To the best of our knowledge, there is no comprehensive analysis of the diversity of yeasts associated with wine grapes from Japan. This study aimed to determine yeast diversity in wine grapes from four wine-producing regions in Japan and to evaluate the physicochemical characteristics of wines produced with indigenous Saccharomyces cerevisiae strains isolated from two regions. A total of 2648 strains were isolated from nine wine grape samples. MALDI-TOF MS and 26S rDNA sequence analyses revealed that the strains belonged to 21 non-Saccharomyces yeasts and 1 Saccharomyces yeast (S. cerevisiae). Non-Saccharomyces yeasts were found in high quantities and were highly distributed among the wine grape samples. Differences in the distribution of the identified yeast species were noted among the different wine grape varieties and regions. Indigenous S. cerevisiae strains of different genotypes from different regions exhibit distinct physiological traits. Our findings are expected to enhance our understanding of the local yeasts associated with Japanese vineyards and contribute to obtaining cultures that can provide region-specific organoleptic characteristics to local wines produced in Japan.

Variation and fractionation of δ2H, δ18O, and δ17O stable isotopes from irrigation water to soil, grapes, and wine for the traceability of geographical origins

To investigate the variation and fractionation of stable isotopes from irrigation water to soil, grapes, and wine, δ2H, δ18O, and δ17O in different samples from 10 regions in China were determined using a water isotope analyser. The values were significantly different among regions according to the chemometric analysis. All isotopes were significantly and positively correlated with irrigation water–soil and grape–wine. A significant water isotopic fractionation effect was observed from the irrigation water to the soil, grapes, and wine. Stable isotope distribution characteristics correlated with longitude, latitude, altitude, temperature, precipitation, station pressure and wind speed. The linear discriminant analysis (LDA), random forest (RF), support vector machine (SVM), and feed-forward neural network (FNN) models 58.33–100 %, 80–100 %, 53.33–100 %, and 73.33–100 % accurate for distinguishing the geographical origins of all samples from training and test data, respectively. These findings provide a theoretical basis for authenticating the geographic origin of Chinese wines using stable isotope analysis.

Canopy-Applied Benzothiadiazole (BTH) during the Pre-Harvest Period as a Tool to Increase Polyphenol Accumulation and Color Intensity in Cabernet Gernischt and Cabernet Franc

Despite the wealth of studies on benzothiadiazole (BTH) and its capacity to modulate grape polyphenol metabolism, comprehensive data detailing polyphenol accumulation at various grape growth stages remain scarce. Therefore, the present study utilized pre-harvest (at 21 days after flowering) canopy-applied BTH (50 mg/L) on Cabernet Gernischt and Cabernet Franc grapes to investigate the physicochemical and polyphenolic changes during grape maturation. The results showed that BTH treatment significantly affected the accumulation of total phenols, flavonoids, flavanols, anthocyanins, and tannins. Concurrently, it induced an increase in colorimetric parameters (CIRG, L*, b*, a*, and C*ab), resulting in the treated grapes exhibiting a greater color intensity and enhanced red-bluish colorimetric characteristics. Moreover, the BTH treatment amplified the anthocyanin content in the grapes, with the levels of petunidin-3-O-glucoside and peonidin-3-O-glucoside exhibiting remarkable increases, particularly in the Cabernet Franc grape. Notably, the content of peonidin-3-O-glucoside even surpassed that of malvidin-3-O-glucoside throughout the growth stages, indicating significant advantages in the treated samples. Additionally, the levels of flavanol, flavonols, phenolic acids, and stilbenes experienced a significant boost post-treatment. In conclusion, the application of BTH treatment can effectively enhance the accumulation of polyphenols and intensify the color of Cabernet Gernischt and Cabernet Franc grapes, thereby significantly improving the overall quality of wine grapes and ensuring the production of higher-quality wines. The research findings will serve as a theoretical foundation and provide scientific data for the appropriate utilization of BTH in wine grape cultivation.

Quantification of lactic acid in wines using an amperometric biosensor

The objective of this study was to develop an analytical method that allows for the rapid and cost-effective detection and quantification of lactic acid in wines. The analysis of lactic acid is a time-consuming and costly process in the food industry. Therefore, the use of an enzymatic amperometric sensor that employs lactate oxidase (LacOx) immobilized on an oxygen electrode enabled the determination of lactic acid in wine. This study utilizes a voltage of −500mV and recorded the amperometric signal was obtained during oxygen consumption while lactic acid oxidation occurred in the sensor reactor. The detection time was at 10 s. A positive linear relationship was obtained between oxygen consumed as a function of time (mg O2/L x s−1). The lactic acid concentration ranged from 1 to 7 mM with a coefficient R2 = 0.994. The sensor exhibited good specificity KM = 0.675. The immobilized enzyme retained over 85% activity for 60 days, allowing for the reuse of the previously modified membrane up to 22 times. In comparison to other methods documented in the literature, the results demonstrate a favourable analytical quality. Furthermore, other aspects, such as the low residual formation, also exhibit a positive outcome. The analysis of lactic acid showed good correlation when compared to HPLC methodology, which occupies the same linear range. This validates the use of the sensor as an alternative method for quantifying lactic acid in wine. The value of this study lies in its presentation of a technique that is more straightforward to implement than traditional methods for quantifying lactic acid in grape wines.

Foliar Co-Applications of Nitrogen and Iron on Vines at Different Developmental Stages Impacts Wine Grape (Vitis vinifera L.) Composition.

The co-application of N and Fe can improve wine grape composition and promote the formation of flavor compounds. To understand the effects of foliar co-application of N and Fe on wine grape quality and flavonoid content, urea and EDTA-FE were sprayed at three different developmental stages. Urea and EDTA-Fe were sprayed during the early stage of the expansion period, at the end of the early stage of the expansion period to the late stage of the veraison period, and during the late stage of the veraison period. The results demonstrated that the co-application of urea and EDTA-Fe, particularly N application during the late stage of the veraison period and Fe application during the early stage of the berry expansion period (N3Fe1), significantly improved grape quality. Specifically, the soluble solid content of berries increased by 2.78-19.13%, titratable acidity decreased by 6.67-18.84%, the sugar-acid ratio became more balanced, and yield increased by 13.08-40.71%. Further, there was a significant increase in the relative content of amino acids and flavonoids. In conclusion, the application of Fe and N fertilizers at the pre-expansion and late veraison stages of grapes can significantly improve the quality and yield of berries; ultimately, this establishes a foundation for future improvement in the nutritional value of grapes and wine.

The Metabolomic Profiling of the Flavonoid Compounds in Red Wine Grapes and the Impact of Training Systems in the Southern Subtropical Region of China.

Flavonoids play an important role in forming wine grapes and wine quality characteristics. The flavonoids of three winter red wine grapes, Yeniang No. 2 (YN2), Marselan (Mar), and Guipu No. 6 (GP6), were analyzed by ultra-high-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QQQ-MS). Furthermore, the flavonoids in GP6 grapevines using two types of training systems, namely, trellis (T) and espaliers (E), were also compared in this study. Overall, 196 flavonoid metabolites, including 96 flavones, 38 flavonols, 19 flavanones, 18 polyphenols, 15 anthocyanins, 7 isoflavones, and 3 proanthocyanidins, were identified. The flavonoid profiles were remarkably different among these three grape varieties, while they did not change much in the GP6 managed on trellis and espaliers. Grape varieties with different genetic backgrounds have their own unique flavonoid profiles. Compared with Mar-T, isoflavones and flavonols presented higher contents in GP6-T and YN2-T, which mainly contain glycitein, genistin, calycosin, kaempferide, isotrifoliin, and ayanin. The anthocyanin content was significantly higher in YN2-T than in the other two varieties. YN2 and GP6-T present a more stable color, with significantly more acetylated diglucosides and methylated anthocyanins in YN2-T and GP6-T than in Mar-T. Notably, GP6 had more varied flavonoids and the better characteristics to its flavonoid profile out of these three varieties, due to it containing a higher number of anthocyanins, flavone, and flavonols and the greatest number of different flavonoid metabolites (DFMs), with higher contents than YN2 and Mar. Compared with the trellis training system, the espaliers training system increased the content of flavonoids detected in GP6 grape berries; however, the composition of flavonoids strictly depends on the grape variety.

Vitis species for stress tolerance/resistance

AbstractMany wild plant species are actually true treasures of our world. The value of these treasures is better understood today and many wild species are used for different purposes. Also Vitis species are among the most important species with their ancient history. China and North America are the native ranges of many Vitis species that survive to the present day, most of which have survived by natural selection. These species have attracted the attention of plant breeders for many years due to their resistance to various biotic and abiotic stress conditions, and they have used these species to develop new cultivars. In parallel with the developments in the field of biotechnology, interspecific hybrid genotypes obtained in breeding research for resistance to different stress conditions can be obtained in accordance with the targets in a much shorter time. In these investigations, gene regions in Vitis species with resistance genes were transferred to new hybrid genotypes. Additionally, these species have been used as parents in many breeding programs in different countries due to their resistance to biotic stress conditions, especially fungal diseases. Similar breeding research has been carried out on tolerance to abiotic stress conditions, and interspecific cross-breeding have been made to develop hybrid genotypes that are more tolerant to many abiotic stress conditions. In recent years, resistance and high-quality wine and table grape cultivars obtained from rossbreeding have begun to be used in production. As a result, newly developed interspecific hybrid grapes can be grown with much lower production costs in accordance with the sustainable viticulture model.

Transcriptome and Metabolome Analyses of Aroma Differences between Chardonnay and a Chardonnay Bud Sport.

Chardonnay is one of the most popular white grape wine varieties in the world, but this wine lacks typical aroma, considered a sensory defect. Our research group identified a Chardonnay bud sport with typical muscat characteristics. The goal of this work was to discover the key candidate genes related to muscat characteristics in this Chardonnay bud sport to reveal the mechanism of muscat formation and guide molecular design breeding. To this end, HS-SPME-GC-MS and RNA-Seq were used to analyze volatile organic compounds and the differentially expressed genes in Chardonnay and its aromatic bud sport. Forty-nine volatiles were identified as potential biomarkers, which included mainly aldehydes and terpenes. Geraniol, linalool, and phenylacetaldehyde were identified as the main aroma components of the mutant. The GO, KEGG, GSEA, and correlation analysis revealed HMGR, TPS1, TPS2, TPS5, novel.939, and CYP450 as key genes for terpene synthesis. MAO1 and MAO2 were significantly downregulated, but there was an increased content of phenylacetaldehyde. These key candidate genes provide a reference for the development of functional markers for muscat varieties and also provide insight into the formation mechanism of muscat aroma.

Wine grape grower perceptions and attitudes about soil health

Developing and adopting strategies that preserve soil health from degradation due to drastic changes in climate is critical for securing sustainable viticulture. For example, healthy soils promote water infiltration, nutrient cycling, and retention functions that support grape production. However, little research has evaluated drivers of growers' decision-making processes and actions towards soil management practices that impact soil health in vineyards. The objective of this study was to assess wine grape growers' perceptions and attitudes of soil health to identify grower's most important soil health functions and definition, and to understand how these might influence behavior related to soil management practices. Therefore, we conducted semi-structured interviews with 16 wine grape growers understand current barriers, motivations, and opportunities for adopting and/or maintaining practices for building soil health in vineyards. Most growers described healthy vineyard soils as balanced, biodiverse, self-sustaining, and resilient systems that provide nutrient, and water cycling functions and support high-quality wine grape production. Three categories of growers emerged based on soil health attitudes including Early Adopter (n = 3), Early Majority (n = 4) and Late Majority (n = 9) groups. The main barriers for adoption and maintenance of soil health practices were high costs, potential economic risks, and lack of information on how these practices influence grape production especially for the Late Majority group. Most growers were willing to adopt more soil heath practices if additional specific, practical information could be provided on outcomes of soil health practices for wine grape production systems—especially economic benefits. The outcomes of this study guide future soil health research and outreach activities to better support growers in building and protecting vineyard soil health while achieving viticultural goals.