Grapevine Quality Research Articles

Exogenous Strigolactone Alleviates Post-waterlogging Stress in Grapevine

With global climate change, the frequent occurrence of intense rainfall and aggravation of waterlogging disasters have severely threatened the plant growth and fruit quality of grapevines, which are commercially important fruit crops worldwide. There is accordingly an imperative to clarify the responses of grapevine to waterlogging and to propose appropriate remedial measures. Strigolactone (SL) is a phytohormone associated with plant abiotic stress tolerance, while, its function in plant responses to waterlogging stress remain undetermined. In this study, systematic analyses of the morphology, physiology, and transcriptome changes in grapevine leaves and roots under post-waterlogging and GR24 (a synthetic analog of SL) treatments were performed. Morphological and physiological changes in grapevines in response to post-waterlogging stress, including leaf wilting and yellowing, leaf senescence, photosynthesis inhibition, and increased anti-oxidative systems, could be alleviated by the application of GR24. Moreover, transcriptome analysis revealed that the primary gene functions induced by post-waterlogging stress changed over time; however, they were consistently associated with carbohydrate metabolism. The GR24-induced leaf genes were closely associated with carbohydrate metabolism, photosynthesis, antioxidant systems, and hormone signal transduction, which were considered vital aspects that were influenced by GR24 in grapevine to induce post-waterlogging tolerance. Concerning the roots, an enhancement of microtubules and cytoskeleton for cell construction in GR24 application was proposed to facilitate root system recovery after waterlogging. With this study, we comprehend the knowledge regarding the responses of grapevines to post-waterlogging and the ameliorative effect of GR24 with the insight to the transcriptome changes during these processes.

Potassium fertigation and organic fertilisation in ‘Syrah’ grape in Northeastern Brazil: yield, must characteristics and phenolic compounds

The effect of both potassium and organic fertilisation on grape yield and must composition originating from wine grapevines cultivated in the São Francisco river basin, in the semi-arid region of Northeastern Brazil, is not well known. Since soils from that region usually have low organic matter content, we hypothesise that soil application of organic fertiliser and potassium application through drip irrigation enhances the availability of this nutrient in the soil, and it influences grape yield and quality. Hence, five doses of potassium (0, 20, 40, 80 and 160 kg ha-1) applied through a drip irrigation system and two doses of goat manure as organic fertiliser applied into the soil (0 and 7.5 m3 ha-1) after pruning were evaluated concerning yield and berry quality of grapevine ‘Syrah’ over four growing seasons (April 2013 to July 2015) in Petrolina, state of Pernambuco, Brazil. The experimental design was randomised blocks with 5 replications. We evaluated yield (t ha-1), weight of 100 berries (g), must volume (mL), total soluble solids (°Brix), pH and total titratable acidity (‰), K, Mg and Ca contents and phenolic compounds (total polyphenols, anthocyanins and flavonoids). The increasing application of potassium at the different doses of organic fertiliser did not alter the crop yield, except in the second season. Nonetheless, K concentration in grape must was influenced in the four growing seasons, with higher values at fitted K2O doses by polynomial regression of 83.62 kg ha-1 (first season), 101.25 kg ha-1 (second season), 120.00 kg ha-1 (third season) and 77.99 kg ha-1 (0 m3 ha-1 organic fertiliser) and 96.07 kg ha-1 (7.5 m3 ha-1 organic fertiliser) in the fourth season. The addition of increasing doses of potassium interfered with the wine grape quality, which is an important factor to be considered in relation to its acidity. Organic fertilisation did not affect the most quality characteristics of the grapes.

In Vitro Evaluation of Some Endophytic Bacillus to Potentially Inhibit Grape and Grapevine Fungal Pathogens

Romania has a long history of grapevine culturing and winemaking. However, like any agricultural sector, viticulture faces devastating biological threats. Fungi responsible for grapevine trunk diseases (GTDs) and grape spoilage lead to considerable yield losses and a decline in grapevine quality. In the actual context, many countries, including Romania, have reoriented their approaches to minimize chemical inputs, which have been proven to be toxic and to have negative impacts on the environment, and to replace them with sustainable biocontrol strategies for the wine-growing sector. Within biocontrol strategies, Bacillus spp. is a well-known plant-protective bacteria with antifungal properties. Within this paper, six endophytic bacteria from various plant sources were studied. The bacterial strains were identified as B. pumilus, B. subtilis, and B. velezensis by sequencing their 16S rDNA region. Regardless of the in vitro test methods (using living bacterial cells, bacterial-cell-free supernatant (CFS), and volatile active compounds (VOCs)), B. velezensis strains revealed strong and broad antifungal activity against grape and grapevine fungal pathogens such as Aspergillus spp., Botrytis cinerea, Penicillium expansum, Diplodia seriata, Eutypa lata, Fusarium spp., Clonostachys rosea, Neofusicoccum parvum, and Stereum hirsutum. The functional antifungal genes encoding for difficidin, fengycin, iturins, macrolactin, and mycosubtilin were molecularly detected, which could support the proven antifungal activity of the endophytic strains. Lytic enzymes involved in fungal growth inhibition, such as chitinase, cellulase, and proteases, were also revealed to be produced by some of these bacterial strains. Various other in vitro tests, such as phosphate and phytate solubilization, phytohormone synthesis, the production of enzymes involved in the polyamine biosynthetic pathway, and pH as well as temperature tolerance tests were carried out to reveal the plant-beneficial potential of these bacterial strains. These results revealed that the B. velezensis strains, especially BAHs1, are the most suitable endophytes for grapevine biologic control, which could lead to the future development of sustainable management strategies.

Soil properties of vineyards on arkoses as a basis to understand their suitability and optimum performance

AbstractThe study of the soil properties and geochemistry of vineyard soils of the Méntrida Protected Designation of Origin (PDO) (central Spain) was performed to better understand the role of soil as a terroir component and to contribute to sustainable vineyard management. Soil physico‐chemical characteristics were determined, along with the content of trace elements (by placing emphasis on rare earths) in topsoils and subsoils. The dominant soil types were Inceptisols, Alfisols and Entisols (USDA soil classificacion), i.e., Cambisols, Luvisols and Regosols in the World Reference Base for Soil Resources (WRB) system. They were all deep and well‐structured. Our findings reveal that soil‐available nitrogen (N) ranged from 0.03 to 0.21 (%), with soil‐available phosphorus (P) ranging from 0.20 to 40.50 (mg·kg−1). pH had a mean of 6.33 (range: 4.4–8.7) in the ten observations, and a degree of mesotrophic saturation in bases (V%), except in one that had a 100% value (soils where carbonates were absent, save exceptional cases). A medium to high cation exchange capacity (CEC) was found (range: 9.8–38.3 cmol·kg−1). The mean values of elements' contents were (mg·kg−1): Sc 14.8, V 32.13, Cr 23.09, As 4.01, Ni 8.57, Cu 6.43, Zn 30.13, Rb 143.49, Sr 63.03, Y 15.39, Ba 374,44, La 25.87, Ce 43.77, Pb 22.25, Nd 21.28. They decreased in this order: Ba > Rb > Sr > Ce > V > Zn > La > Cr > Pb > Nd > Y > Sc > Cu > As. The results confirm the importance of soils for the PDO, with an optimum condition to produce grapevine quality laying the foundations to obtain a good wine. Our findings provide insights into the importance of pedological properties for regulating soil nutrient availability across soil types, and support soil resource utilization management in regional viticulture.

An Improved Method for Efficient DNA Extraction from Grapevine

Grapevine (Vitis vinifera L.) is one of the oldest and most important perennial crops worldwide which has been the subject of extensive genetic studies including gene mapping, genetic transformation, and DNA fingerprinting. Grapevines are rich in polysaccharides, polyphenolic compounds, and various secondary metabolites, many of which have significant importance in food, agrochemical, and pharmaceutical industries. While metabolites are one of the indicators of quality of grapevines, the presence of them makes grapevine one of the most difficult plants to extract DNA from. These metabolites not only affect DNA extraction procedures but also downstream reactions such as restriction digestion and PCR. Development of new genotyping techniques based on sequencing such as genotyping by sequencing (GBS) requires high-quality DNA for digestion and sequencing. To date, several protocols have been developed for DNA extraction from grapevine. In this study, three different protocols with modifications were compared for DNA extraction performance from grapevine leaves from four different cultivars. Efficiencies of these methods were determined by extracted DNA’s quantity and quality. To confirm the suitability for GBS, extracted DNA was digested with restriction enzymes. Although all protocols were based on the traditional CTAB method, they resulted in different DNA yield and restriction digestion efficiency. The modified protocol including PVP-40 and ß-mercaptoethanol was found to be the most efficient method to obtain high quality and quantity grapevine DNA that is amenable to restriction digestion.

Effect of Tipping and Foliar Application of Proline and Botminn Plus on Yield and Quality of Grapevine (Vitis vinifera L.) cv. Khoshnaw

This study was carried out on 20 years old grapevine (Vitis vinifera L.) cv. Khoshnaw, which was growing in Chwarta town northeastern Sulaymaniyah, Kurdistan Region/Iraq, during the growing season 2021, to investigate the effect of tipping, foliar application of proline (0, 100, and 200 mg.L-1), botminn plus (0, 3 and 6 ml.L-1) and their interaction on yield and chemical characteristics of the grape. The vineyard was rain-fed cultivation and its elevation is 974 m above sea level. The results showed that tipping, foliar application of proline especially at 200 mg.L-1, and botminn plus especially at 6 ml.L-1 gave the highest cluster weight, the number of clusters.vine-1, total yield, TSS, total sugar, vitamin C, and Anthocyanin, While both of them did not significantly affect the percentage of phenols. The triple interaction between tipping, proline, and botminn plus significantly enhanced all detected traits since tipped vine + 200 mg.L-1 proline + 6 ml.L-1 botminn plus significantly outshine in yield and chemical characteristics of grape except total sugar and phenols compared to the untreated trees (control).

Zonation of a Viticultural Territorial Context in Piemonte (NW Italy) to Support Terroir Identification: The Role of Pedological, Topographical and Climatic Factors

Grapevine production and quality greatly depend on site-specific features such as topography, soil, and climate. The possibility of recognizing and mapping local specificities of a wine-production area is highly desirable, as environmental conditions are the main drivers of wine production in terms of both quality and quantity. Areas showing similar features able to determine specific traits in vine and wine production are referred to as terroirs. It is commonly considered that soil and climate represent the main elements for a functional and balanced viticultural ecosystem; if they change, grapevine quality and yield change too, and this occurs in spite of any agronomic practice. Terroir mapping based on traditional methodology requires a considerable investment of time and money by producers and wine consortia; moreover, it preserves an important subjective component. In this work, the authors propose an approach to map territorial differences, possibly conditioning the definition of terroir, of an important wine-production area located in Piemonte (NW Italy) based on free and open data and free GIS. The resulting zones were related to the main local vine varieties looking for possible relationships. The results proved that, with reference to the pedological, topographical, and climatic factors, six zones were recognized as significantly different in the study area. These were compared against the six main vine varieties in the area (i.e., Barbera, Brachetto, Chardonnay, Dolcetto, Moscato Bianco, and Nebbiolo), finding that: (i) Nebbiolo is highly specialized, covering almost a single zone; (ii) Moscato, Dolcetto, and Chardonnay showed no significant preference for any zone, being almost equally distributed over all of them; and (iii) Barbera and Brachetto are averagely specialized, being distributed mainly over two clusters (out of six) different from the one where Nebbiolo appears to be majorly present.

A digital twin application for vineyards sustainable management

Environmental protection and production sustainability are the key actions required to the farming activities, especially to those with higher add value as wine production. Vineyard are one of the most demanding activities in terms of water consumption and environmental impacts, which can be mitigated only with a systematic approach based on smart agriculture to support and optimize vineyard management. This paper proposes a vineyard digital twin (VDT) based on a mathematical model able to predict the vegetative and productive growth of a vineyard (leaf area, shoot length, crop and yield mass), qualitative product parameters (sugar and acid) and the water footprint associated with production. The model implements a soil-atmosphere source-sink model, where water balance across vine is coupled with potential carbon demand functions to estimate water and temperature stresses and, through a mechanistic model for sugar accumulation and acid concentration, will evaluate the expected grape quality. The distinctive trait of this model is the integration and feedback among prediction of grapevine quality and vegetative growth, using a common boundary data set and integrating the agronomical operations on vineyard seasonal development. The VDT prototype will help producers to systematize, formalize, and accumulate knowledge to improve and optimize management processes to achieve sustainable production, increasing products healthy and reducing environmental footprint.

Post-veraison increase in source-sink ratio via manipulation of sink availability gradually reduces leaf functionality in grapevine (cv. Pinot noir)

The vegetative-reproductive balance is critical in determining grapevine quality and productivity. Many agricultural practices (bunch thinning, defoliation, green pruning) can modify the source-sink relationships leading to altered vineyard efficiency and berry quality. Field experiments aimed at understanding how a decrease in sink availability influences leaf physiology of the reproductive shoot. In Pinot noir trained to guyot, control shoots were compared to shoots subjected to basal girdling (G), bunch removal (BR) or a combination of both treatments (G + BR). Morpho-physiological traits including leaf water status, gas-exchange, leaf temperature, chlorophyll fluorescence, leaf starch and soluble sugars, petiole and leaf dry weight were collected at different time of the day and over several days to evaluate the dynamics of leaf functionality following treatments application. The gradual reduction in sink availability induced significant reductions in leaf gas-exchange and PSII efficiency from the second day after the treatments’ application. Nonetheless, while reductions in photosynthetic capacity and increases in leaf temperature associated with a compromised stomatal physiology were present in the G + BR shoots, no differences were observed between bunch removal and control treatments. Girdling and G + BR showed a significant reduction in leaf chlorophyll a and b as well as carotenoids content when compared to control shoots. The increase in the source-sink ratio subsequently produced a marked increase in leaf starch, hexoses and sucrose accompanied by a reduction in the specific leaf area while the girdling did not affect the weight and brix degree of the bunches. This work shows how the progressive reduction in sink availability compromises leaf physiological functionality putatively owing to a reduction in assimilates translocation capacity from the leaf and hence starch storage and accumulation. However, limited effects were observed for shoots in which only the bunch was removed suggesting that assimilates allocation to other vegetative and/or reproductive sinks can maintain leaf functionality even in days characterized by unfavourable environmental conditions. • Sink availability greatly influences source dynamics • Reducing sink availability in grapevine resulted in higher diurnal susceptibility of the leaf to environmental stresses such as high VPD and air temperature • Source-sink relationships can indirectly govern water status via stomatal regulation of transpiration • Source-sink dynamics should be considered as a potential mechanism to exploit for reducing the impact of climate change in grapevine.

A Panoramic View on Grapevine Trunk Diseases Threats: Case of Eutypa Dieback, Botryosphaeria Dieback, and Esca Disease.

Grapevine trunk diseases (GTD) are currently one of the most devastating and challenging diseases in viticulture, leading to considerable yield losses and a remarkable decline in grapevine quality. The identification of the causal agents is the cornerstone of an efficient approach to fighting against fungal diseases in a sustainable, non-chemical manner. This review attempts to describe and expose the symptoms of each pathology related to GTD, the modes of transmission, and the harmfulness of recently reported agents. Special attention was given to new diagnostic tests and technologies, grapevine defense mechanisms, molecular mechanisms of endophytes fungal colonization, and management strategies used to control these threats. The present extended review is, therefore, an updated state-of-the-art report on the progress in the management of vineyards.

The Impact of Foliar Spray of Chitosan Nano-particles and Bulk Form on Crimson Seedless Grapevine Quality and Productivity

The Impact of Foliar Spray of Chitosan Nano-particles and Bulk Form on Crimson Seedless Grapevine Quality and Productivity

The effect of regulated deficit irrigation on growth, yield, and berry quality of grapevines (cv. Sangiovese) grafted on rootstocks with different resistance to water deficit

The aim of this work was to investigate the effect of full irrigation (FI), pre-veraison water deficit (RDI 1), or post-veraison water deficit (RDI 2) on growth, yield, and berry quality in container-grown, mature vines of cv. Sangiovese grafted onto either 1103P or SO4 rootstock over two consecutive growing seasons. Deficit irrigation regimes significantly affected vine water status of both rootstocks before and after veraison. Trunk diameter (TD) increment was markedly affected when water was restricted early, but not in the post-veraison period. Deficit irrigation from fruit set to veraison inhibited vegetative growth (TD, canopy volume, and weight of pruned wood) more than that applied from veraison to harvest. Yield was unaffected by either irrigation or rootstock in both years. Irrigation had a marked effect on berry and juice quality: the RDI 1 treatment induced the highest berry anthocyanin concentration, and the lowest titratable acidity (TA), which, instead, increased in the RDI 2 treatment. RDI treatments did not modify berry dry weight, soluble solid content, TA, anthocyanins, and epicarp total phenols in vines on both rootstocks.

Biochemical Changes in Vitis vinifera Buds between Dormancy and Forced Bursting: A Case Study of Three Portuguese White Varieties

The transition between the dormancy and budburst is accompanied by physiological and biochemical changes, which include variations in the carbohydrates, enzymatic activity, as well as hormones present inside the buds. The present study aimed to evaluate the biochemical changes that occur in dormant buds and forced bursting of three Vitis vinifera L. white varieties (Alvarinho, Fernão-Pires, and Loureiro) from two vineyards located in the Vinhos Verdes Demarcated Region, NW Portugal. For this purpose, the contents of malondialdehyde (MDA), proline, carbohydrates, and gibberellic acid (GA3), as well as antioxidant enzymes activity were analysed. The results showed that the MDA, proline, total soluble sugars, and GA3 contents tended to be higher at budburst. In contrast, the starch content was higher at dormancy. The enzymatic activities of ascorbate peroxidase (APX), peroxidase (POX), and superoxide dismutase (SOD) were lower at budburst, compared with dormancy, while the reverse was observed in catalase (CAT). Significant differences were also observed between varieties for most biochemical parameters analysed, with the exception of CAT activity. Alvarinho stood out from other varieties for presenting higher MDA, proline, soluble sugars, and GA3 content, while Fernão-Pires displayed higher values of APX and POX activities and starch content. To our knowledge, the present work is the first attempt to examine the biochemical changes in dormant buds and bursting, which determine the vegetative and reproductive continuity of grapevines. This information contributes to better vineyard management, particularly important in light of the climate change scenarios, which can affect the biochemical mechanisms of the buds and compromise the yield and quality of grapevines.

Comparative fungal diversity and dynamics in plant compartments at different developmental stages under root-zone restricted grapevines

BackgroundThe root-zone restriction cultivation technique is used to achieve superior fruit quality at the cost of limited vegetative and enhanced reproductive development of grapevines. Fungal interactions and diversity in grapevines are well established; however, our knowledge about fungal diversity under the root-zone restriction technique is still unexplored. To provide insights into the role of mycobiota in the regulation of growth and fruit quality of grapevine under root-zone restriction, DNA from rhizosphere and plant compartments, including white roots (new roots), leaves, flowers, and berries of root-zone restricted (treatment) and conventionally grown plants (control), was extracted at three growth stages (full bloom, veraison, and maturity).ResultsDiversity analysis based on the ITS1 region was performed using QIIME2. We observed that the root-zone restriction technique primarily affected the fungal communities of the soil and plant compartments at different growth stages. Interestingly, Fusarium, Ilyonectria, Cladosporium and Aspergillus spp observed in the rhizosphere overlapped with the phyllosphere at all phenological stages, having distinctive abundance in grapevine habitats. Peak richness and diversity were observed in the rhizosphere at the full bloom stage of control plants, white roots at the veraison stage of treatment, leaves at the maturity stage of treatment, flowers at the full bloom stage and berries at the veraison stage of control plants. Except for white roots, the diversity of soil and plant compartments of treated plants tended to increase until maturity. At the maturity stage of the treated and control plants, the abundance of Aspergillus spp. was 25.99 and 29.48%, respectively. Moreover, the total soluble sugar content of berries was 19.03 obrix and 16 obrix in treated and control plants, respectively, at the maturity stage.ConclusionsThis is the first elucidative study targeting the fungal diversity of conventional and root-restricted cultivation techniques in a single vineyard. Species richness and diversity are affected by stressful cultivation known as root zone restriction. There is an association between the abundance of Aspergillus spp. and fruit quality because despite causing stress to the grapevine, superior quality of fruit is retrieved in root-zone restricted plants.

Soil and grapevine leaf quality in organic vineyards of different ages in DO Rioja-Alavesa, northern Spain

The soil from three organically cultivated plots in Rioja Alavesa vineyards, specifically in Lanciego (Álava, Spain), and the foliage of their vines were analyzed. The aim of this study was to determine differences in soil and grapevine quality between different aged vineyards. The first 20 centimeters of the soil were sampled and leaves were collected during the growing season. The results show that the quality of the soil in the three plots was optimal and did not differ from reported values of soils from traditionally cultivated plots. The only element found at a lower concentration in the three plots and the leaves was iron. Organic cultivation of vineyards is a viable mode of cultivation and could help reduce greenhouse gas emissions and contamination by pesticides and fertilizers.

Biostimulant-induced drought tolerance in grapevine is associated with physiological and biochemical changes

BackgroundIn this research, the effects of exogenous application of certain biostimulants [amino acid (AA), humic acid (HA), fulvic acid (FA), and seaweed extract (SE)] on the fruit yield and quality, leaf mineral contents, and some critical physio-chemical characteristics of grapevine (Vitis vinifera L.) cv. ‘Yaghouti’ were investigated under well-watered (WW) and drought-stressed (DS) conditions.ResultsDrought stress caused a remarkable reduction in the weight of 20 berries and fruit yield, and meanwhile a marked increase in the titratable acidity (TA) and total soluble solid (TSS) content of fruits. Application of biostimulants, especially SE, enhanced the weight of 20 berries, fruit yield, and TSS content, and decreased TA in fruits of DS vines. Although drought stress had a negative effect on the chlorophyll content of grapevine, this effect was alleviated by the application of biostimulants, especially SE. Moreover, drought stress made the accumulation of abscisic acid (ABA), proline, total phenol, and soluble carbohydrates, the level of hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as the activity of guaiacol peroxidase (GPX) and catalase (CAT) enzymes increased in leaves. Application of biostimulants, especially SE, further increased the accumulation of ABA, proline, total phenol, and soluble carbohydrates and the activity of the antioxidant enzymes, but reduced the level of MDA and H2O2 in DS vines. Under drought stress conditions, concentrations of N, P, and K increased, and concentrations of Fe and Zn decreased; however, DS grapevines treated with biostimulants and especially SE accumulated a higher level of these mineral nutrients than CON vines.ConclusionIn sum, as evidenced by the study results, biostimulants have a high potential for promoting fruit yield and quality of grapevine in drought-prone regions.

Genome Assembly and Transcriptome Analysis of the Fungus Coniella diplodiella During Infection on Grapevine (Vitis vinifera L.).

Grape white rot caused by Coniella diplodiella (Speg.) affects the production and quality of grapevine in China and other grapevine-growing countries. Despite the importance of C. diplodiella as a serious disease-causing agent in grape, the genome information and molecular mechanisms underlying its pathogenicity are poorly understood. To bridge this gap, 40.93 Mbp of C. diplodiella strain WR01 was de novo assembled. A total of 9,403 putative protein-coding genes were predicted. Among these, 608 and 248 genes are potentially secreted proteins and candidate effector proteins (CEPs), respectively. Additionally, the transcriptome of C. diplodiella was analyzed after feeding with crude grapevine leaf homogenates, which reveals the transcriptional expression of 9,115 genes. Gene ontology enrichment analysis indicated that the highly enriched genes are related with carbohydrate metabolism and secondary metabolite synthesis. Forty-three putative effectors were cloned from C. diplodiella, and applied for further functional analysis. Among them, one protein exhibited strong effect in the suppression of BCL2-associated X (BAX)-induced hypersensitive response after transiently expressed in Nicotiana benthamiana leaves. This work facilitates valuable genetic basis for understanding the molecular mechanism underlying C. diplodiella-grapevine interaction.

Grapevine VlbZIP30 improves drought resistance by directly activating VvNAC17 and promoting lignin biosynthesis through the regulation of three peroxidase genes

Drought stress severely affects grapevine quality and yield, and recent reports have revealed that lignin plays an important role in protection from drought stress. Since little is known about lignin-mediated drought resistance in grapevine, we investigated its significance. Herein, we show that VlbZIP30 mediates drought resistance by activating the expression of lignin biosynthetic genes and increasing lignin deposition. Transgenic grapevine plants overexpressing VlbZIP30 exhibited lignin deposition (mainly G and S monomers) in the stem secondary xylem under control conditions, which resulted from the upregulated expression of VvPRX4 and VvPRX72. Overexpression of VlbZIP30 improves drought tolerance, characterized by a reduction in the water loss rate, maintenance of an effective photosynthesis rate, and increased lignin content (mainly G monomer) in leaves under drought conditions. Electrophoretic mobility shift assay, luciferase reporter assays, and chromatin immunoprecipitation-qPCR assays indicated that VlbZIP30 directly binds to the G-box cis-element in the promoters of lignin biosynthetic (VvPRX N1) and drought-responsive (VvNAC17) genes to regulate their expression. In summary, we report a novel VlbZIP30-mediated mechanism linking lignification and drought tolerance in grapevine. The results of this study may be of value for the development of molecular breeding strategies to produce drought-resistant fruit crops.

Qualitative und quantitative Reaktionen von frühreifenden Tafeltraubensorten (Vitis vinifera L.) auf verschiedene Bestäubungsverfahren im geschützten Anbau

The production of fruits and seeds of many crops is increased when external pollination occurs. Although self pollination is a widespread biological process in cultivated grapevines, there are still some uncertainties about the consequences of cross fertilization regarding productivity and quality of grapevines. Fertilization biology of grapevines becomes an essential issue when protected cultivation in particular is considered. The present investigations were therefore performed to clarify the possible effects of different pollination treatments on the agronomic features of ‘Perle de Csaba’ and ‘Trakya Ilkeren’ table grape cultivars. Before the anthesis, clusters of self-pollination treatment were enclosed within cheesecloth frames to avoid extraneous pollination. For the free pollination group, flowers of twelve similar clusters were allowed to bloom and pollinate spontaneously, while hand pollination was performed by transporting the mixture of external pollens gathered from different cultivars at bloom stage. In ‘Perle de Csaba’ cultivar, hand pollination and free pollination treatments significantly increased the overall agronomic parameters on berry set rate, berry development, cluster size, seed weight and seed size in comparison to self pollination. Treatments had similar effects in ‘Trakya Ilkeren’, except for a few parameters such as cluster length, berry diameter and seed thickness. Overall results indicated that cross pollination would considerably increase the quantity and quality of table grapes when cultivated under protected conditions such as glass or greenhouses.

Berry Quality of Grapevine under Water Stress as Affected by Rootstock–Scion Interactions through Gene Expression Regulation

Despite phenotypic plasticity that allows the adaptation to harsh environments, when vines experience severe abiotic stresses, they can suffer from metabolic damages affecting grape production and quality. Grafting is an affordable strategy to mitigate these negative consequences since the rootstock can increase the drought tolerance in the scion. This work explored the effects of pre-veraison water deficit on vines grafted on different rootstocks (Mgt 101-14 and 1103 Paulsen) to obtain physiological, biochemical, and molecular information about the influence on grape quality. Repeated measurements were carried out to assess vine physiology, production, technological maturity, and berry phenolic composition. qRT-PCRs were executed on berry skins at maturity to assess the expression levels of ten genes and five miRNAs involved in the phenylpropanoid pathway. Water stress caused significant alterations in grape technological maturity. The rootstock effect was not detected in primary metabolism while it was well defined in the accumulation of phenolic compounds in berries (such as anthocyanins). Finally, significant differences were identified in gene and miRNA expression between water-stressed and well-watered vines. In conclusion, the response to water stress can be modulated by rootstocks, which mainly act by regulating secondary metabolism, especially in grapes.