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This study investigates how grapevines (Vitis vinifera L.) respond to shading induced by artificial nets, focusing on physiological and metabolic changes. Through a multidisciplinary approach, grapevines' adaptations to shading are presented via biochemical analyses and hyperspectral data that are then combined with systems biology techniques. In the study, conducted in a 'Moscatel Galego Branco' vineyard in Portugal's Douro Wine Region during post-veraison, shading was applied and predawn leaf water potential ( Ψ p d ) was then measured to assess water stress. Biochemical analyses and hyperspectral data were integrated to explore adaptations to shading, revealing higher chlorophyll levels (chlorophyll a-b 117.39% higher) and increased Reactive Oxygen Species (ROS) levels in unshaded vines (52.10% higher). Using a self-learning artificial intelligence algorithm (SL-AI), simulations highlighted ROS's role in stress response and accurately predicted chlorophyll a (R2: 0.92, MAPE: 24.39%), chlorophyll b (R2: 0.96, MAPE: 17.61%), and ROS levels (R2: 0.76, MAPE: 52.17%). In silico simulations employing flux balance analysis (FBA) elucidated distinct metabolic phenotypes between shaded and unshaded vines across cellular compartments. Integrating these findings provides a systems biology approach for understanding grapevine responses to environmental stressors. The leveraging of advanced omics technologies and precise metabolic models holds immense potential for untangling grapevine metabolism and optimizing viticultural practices for enhanced productivity and quality. [ABSTRACT FROM AUTHOR]

Grapevine varieties from "Douro Superior" (NE Portugal) experience high temperatures, solar radiation, and water deficit during the summer. This summer's stressful growing conditions induce nucleic acids, lipids, and protein oxidation, which cause cellular, physiological, molecular, and biochemical changes. Cell cycle anomalies, mitosis delay, or cell death may occur at the cellular level, leading to reduced plant productivity. However, the foliar application of kaolin (KL) can mitigate the impact of abiotic stress by decreasing leaf temperature and enhancing antioxidant defence. Hence, this study hypothesised that KL-treated grapevine plants growing in NE Portugal would reveal, under summer stressful growing conditions, higher progression and stability of the leaf mitotic cell cycle than the untreated (control) plants. KL was applied after veraison for two years. Leaves, sampled 3 and 5 weeks later, were cytogenetically, molecularly, and biochemically analysed. Globally, integrating these multidisciplinary data confirmed the decreased leaf temperature and enhanced antioxidant defence of the KL-treated plants, accompanied by an improved regularity and completion of the leaf cell cycle relative to the control plants. Nevertheless, the KL efficacy was significantly influenced by the sampling date and/or variety. In sum, the achieved results confirmed the hypothesis initially proposed. [ABSTRACT FROM AUTHOR]

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum—ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run. [ABSTRACT FROM AUTHOR]

BACKGROUND: Plant‐based extracts have been recently used as sustainable tools to improve biotic and abiotic stress tolerance and increase grape (Vitis vinifera L.) quality. However, knowledge about the effect of these extracts on secondary metabolism compounds, that are fundamental for grape and wine quality, is still scarce. In this study, a trial was installed in an experimental vineyard with the variety Touriga Franca located at University of Trás‐os‐Montes e Alto Douro, Baixo Corgo sub‐region of the Douro Demarcated Region, Portugal in two growing seasons: 2019 and 2020. The aim was to evaluate the effect of foliar application of nettle (Urtica spp.) extract (NE) and Japanese knotweed (Reynoutria japonica) extract (JKE) on grapevines leaves and berries bioactive compounds contents and antioxidant activity, at veraison and harvest. RESULTS: The application of NE increased the total carotenoids in leaves and the total phenolics content and the antioxidant activity (ferric reducing antioxidant power, FRAP) in berries while JKE increased flavonoids content in leaves and the antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl, DPPH) in berries. CONCLUSION: These extracts seem to have a stimulatory effect on grapevine, enhancing bioactive compounds contents and antioxidant capacity and, consequently, the physiological performance of the plant and the quality of the berries. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The wine industry is one of the most important industries globally, particularly for Portugal, making a significant contribution to the Portuguese Bioeconomy. The Douro Demarcated Region (DDR) stands out as one of the largest wine-producing areas in the country. Its centuries-old culture has fostered a rich diversity, developed through vegetative and genetic breeding. Within the wine market, the highest prices for grapes are attained only under optimal edaphoclimatic conditions and when phenotypic characteristics, such as berry size and color, flowering and seed number, align favorably. Viticulture is influenced by environmental factors, diseases, and pests, impacting its economic value, profitability, and, ultimately, the employment and economic conditions of those dependent on the crops. Genetic improvement of phenotypic traits offers a faster and more cost-effective means of achieving desirable characteristics, translating into enhanced productivity and wine quality. This work focuses on presenting information about Douro grapes (region, varieties, diseases/pest, and economic value) and explores grapevine genetic diversity, along with approaches to identify genes associated with various desired traits. [ABSTRACT FROM AUTHOR]

Predawn leaf water potential (Ψpd) is the main parameter to determine plant water status, and it has been broadly used to support irrigation management. However, the Scholander pressure chamber methodology is laborious, time-consuming and invasive. This study examined a low-cost hyperspectral proximal sensor to estimate the Ψpd in grapevine (Vitis vinifera L.). For this, both the Ψpd and spectral reflectance (340–850 nm) were accessed in grapevines in a commercial vineyard located in the Douro Wine Region, northeast Portugal. A machine-learning algorithm was tested and validated to assess grapevine's water status. The experiment was performed in a randomized design with 12 grapevines (cv. Touriga Nacional) per irrigation treatment: non-irrigated, 30% crop evapotranspiration (Etc), and 60% Etc. The dataset was analyzed using Principal Component Analysis (PCA), and the machine-learning regression algorithm applied was Extreme Gradient Boosting (Xgboost). Results from the validation dataset (n = 108) for the Xgboost tested exhibited a root mean square error (RMSE) of 0.23 MPa, a mean absolute error (MAPE) of 16.57% and an R² value of 0.95. These results demonstrate that the hyperspectral sensor and Xgboost algorithm show potential for predicting the Ψpd in vineyards, regardless of a plant's water status. [ABSTRACT FROM AUTHOR]

Sustainable and efficient agricultural production is a growing priority in modern society. Viticulture, an important agricultural and food sector, also faces this challenge. Precision Viticulture (PV) has gained prominence as it aims to foster high-quality, efficient, and environmentally sustainable practices. The Soluble Solids Content (SSC) is essential for assessing grape ripeness and quality in the winemaking process. Conventional methods for determining SSC values (expressed in °Brix) are invasive, expensive, and labour-intensive, necessitating sample preparation, making large-scale analysis impractical. In response to these limitations, this study presents an innovative approach within the field of Precision Viticulture. It focuses on the non-invasive prediction of SSC using low-cost proximal hyperspectral optical sensors. These sensors rely on spectral reflectance measurements in the range of 340–850 nm. This study was conducted in a commercial vineyard in the Demarcated Douro Region, Cima-Corgo sub-region, Portugal, over six weeks during ripening. In total, 169 grape berries from Touriga Nacional vines were analysed under three irrigation regimes (no irrigation, 30% ETc, and 60% ETc). After organising and preprocessing the data, machine learning algorithms, namely Partial Least Squares Regression (PLS), Random Forest (RF), and the Generalised Linear Model (GLM), were applied to predict SSC values. These models' performance was thoroughly evaluated using cross-validation techniques. The performance of different models was evaluated, showing significant differences according to the metrics used (R2, RMSE, and MAPE). The RF model demonstrated effectiveness and precision. A high R² value of 0.9312, coupled with low RMSE (0.9199 °Brix) and MAPE (3.88%), signifies a strong fit to the data and accurate predictive capabilities. The results of this benchmarking study on predictive models of SSC provide valuable insights into the performance of various models, aiding winegrowers and winemakers in decision making. [ABSTRACT FROM AUTHOR]

Soil characteristics, land management practices, and plant genotypes influence arbuscular mycorrhizal fungi (AMF) communities, leading to the proliferation of AMF taxa with different growth and nutritional outcomes in their hosts. However, the specific patterns driving these relationships are still not well understood. This study aimed to (1) evaluate the influence of soil characteristics, land use, and rootstock on AMF diversity and community structure and (2) assess the effect of those AMF communities on grapevine growth and nutrition. Soil samples were collected from vineyard and non-agricultural areas in Lisbon and Pegões, Portugal, and trap cultures established using Richter 110 and 1103 Paulsen rootstocks. After 3.5 months growth under greenhouse conditions, root-associated AMF communities were assessed by amplicon metagenomic sequencing using AMF-specific primers. Alpha diversity was only influenced by the soil type, while in β-diversity, an interaction was found between the soil type and land use. Both diversity measures were positively correlated with foliar K and negatively with leaf Mn and Mg. Notably, the concentrations of these nutrients were highly correlated with the relative abundance of operational taxonomic units (OTUs) within the genera Glomus, Rhizophagus, and Claroideoglomus. These results are valuable for supporting AMF selection for improved plant nutrition based on varying soil types and land uses. [ABSTRACT FROM AUTHOR]

Climate change in the Mediterranean area is making summers warmer and dryer. Grapevine (Vitis vinifera L.) is mostly important for wine production in Mediterranean countries, and the variety Tempranillo is one of the most cultivated in Spain and Portugal. Drought decreases yield and quality and causes important economic losses. As full irrigation has negative effects on quality and water is scarce in this region, deficit irrigation is often applied. In this research, we studied the effects of two deficit irrigation treatments, Sustained Deficit Irrigation (SDI) and Regulated Deficit Irrigation (RDI), on the transcriptome of grape berries at full maturation, through RNAseq. The expression of differentially regulated genes (DEGs) was also monitored through RT-qPCR along berry development. Most transcripts were regulated by water stress, with a similar distribution of up- and down-regulated transcripts within functional categories (FC). Primary metabolism was the more severely affected FC under water stress, followed by signaling and transport. Almost all DEGs monitored were significantly up-regulated by severe water stress at veraison. The modulation of an auxin response repression factor, AUX22D, by water stress indicates a role of this gene in the response to drought. Further, the expression of WRKY40, a TF that regulates anthocyanin biosynthesis, may be responsible for changes in grape quality under severe water stress. [ABSTRACT FROM AUTHOR]

Fungal pathogens involved in grapevine trunk diseases (GTDs) may infect grapevines throughout their lifetime, from nursery to vineyard, via open wounds in stems, canes or roots. In vineyards, pruning wound protection products (PWPPs) offer the best means to reduce the chance of infection by GTD fungi. However, PWPPs may affect non-target microorganisms that comprise the natural endophytic mycobiome residing in treated canes, disrupting microbial homeostasis and indirectly influencing grapevine health. Using DNA metabarcoding, we characterized the endophytic mycobiome of one-year-old canes of cultivars Cabernet Sauvignon and Syrah in two vineyards in Portugal and Italy and assessed the impact of established and novel PWPPs on the fungal communities of treated canes. Our results reveal a large fungal diversity (176 taxa), and we report multiple genera never detected before in grapevine wood (e.g., Symmetrospora and Akenomyces). We found differences in mycobiome beta diversity when comparing vineyards (p = 0.01) but not cultivars (p > 0.05). When examining PWPP-treated canes, we detected cultivar- and vineyard-dependent alterations in both alpha and beta diversity. In addition, numerous fungal taxa were over- or under-represented when compared to control canes. Among them, Epicoccum sp., a beneficial genus with biological control potential, was negatively affected by selected PWPPs. This study demonstrates that PWPPs induce alterations in the fungal communities of grapevines, requiring an urgent evaluation of their direct and indirect effects on plants health with consideration of factors such as climatic conditions and yearly variations, in order to better advise viticulturists and policy makers. [ABSTRACT FROM AUTHOR]

Insects of the order Coleoptera play an essential role in agricultural sustainability by supporting many ecosystem services (such as biological control, nutrient cycling or pollination). In agroecosystems, the Coleoptera community may be influenced by the surrounding landscape, which can provide living resources, like food or shelter, during different seasons, originating spillover movements between different environments.The present study aimed to evaluate the response of the Coleoptera community to the landscape surrounding vineyards at different buffers. For that, Coleoptera were sampled in six wine protected designation of origin (PDO) regions of Portugal (35 vineyards), and landscape configuration and composition metrics were calculated at buffers of 500, 750, 1000, 1500 and 2000 m radii around the vineyards.In total, 2954 Coleoptera individuals belonging to 36 families were collected. The most abundant families were Chrysomelidae, Coccinellidae and Latridiidae. Results indicated that intermediate habitat fragmentation levels, particularly in semi‐natural areas and vineyards, favoured Coleoptera biodiversity in vine‐producing regions. Moreover, the range of activity of Coleoptera seems to be larger than 1000 m.This work constitutes an important contribution to understanding the response of the Coleoptera community to the landscape context in vineyards in Portugal and contributes to the theoretical framework about the influence of habitat fragmentation on biodiversity. [ABSTRACT FROM AUTHOR]

The grapevine (Vitis vinifera) is widely cultivated for the production of wine and other commodities. Wine is globally traded, with an annual market value of approximately USD 4 billion in Portugal alone. However, climate change is expected to profoundly alter regional temperature and precipitation regimes across the Iberian Peninsula and, thus, in continental Portugal, potentially threatening to impact viticulture. We used boosted regression trees and environmental variables describing the climate, soil, topography, and irrigation with a large number of presences (N = 7002) to estimate grapevine suitability for a baseline (1981–2010) and three future periods spanning from 2011 to 2100 using two climate trajectories (SSP3-7.0 and SSP5-8.5) and irrigation scenarios (continued and ceased). Under SSP3-7.0 with irrigation and SSP5-8.5 without irrigation, our results suggest a decline in suitable viticulture area across continental Portugal of ~20% and ~80% by 2041–2070 and 2011–2041, respectively. Following this decline, our data suggest a potential recovery by 2071–2100 of ~6% and ~186%, respectively. However, regional change is more complex: by 2071–2100, the Região Norte, the Douro wine region, and the Algarve, for example, each would experience future changes in suitable area in the range of approximately −92% to −48%, −86% to −24%, and −59% to 267%, respectively, depending mostly on the practicality of irrigation. [ABSTRACT FROM AUTHOR]

This paper focuses on predicting predawn leaf water potential through a self-learning artificial intelligence (SL-AI) algorithm, a novel spectral processing algorithm that is based on the search for covariance modes, providing a direct relationship between spectral information and plant constituents. The SL-AI algorithm was applied in a dataset containing 847 observations obtained with a handheld hyperspectral spectroradiometer (400–1010 nm), structured as: three grapevine cultivars (Touriga Nacional, Touriga Franca and Tinta Barroca), collected in three years (2014, 2015 and 2017), in two test sites in the renowned Douro Wine Region, northeast of Portugal. The Ψ pd SL-AI quantification was tested both in regressive (R2 = 0.97, MAPE = 18.30%) and classification (three classes; overall accuracy = 86.27%) approaches, where the radiation absorption spectrum zones of the chlorophylls, xanthophyll and water were identified along the vegetative growth cycle. The dataset was also tested with Artificial Neural Networks with Principal Component Analysis (ANN-PCA) and Partial Least Square (PLS), which presented worse performance when compared to SL-AI in the regressive (ANN-PCA - R2 = 0.85, MAPE = 43.64%; PLS - R2 = 0.94, MAPE = 28.76%) and classification (ANN-PCA - overall accuracy: 72.37%; PLS - overall accuracy: 73.79%) approaches. The Ψ pd modelled with SL-AI demonstrated, through hyperspectral reflectance, a cause-effect of the grapevine's hydric status with the absorbance of bands related to chlorophyll, xanthophylls and water. This cause-effect interaction could be explored to identify cultivars and cultural practices, hydric, heating and lighting stresses. [Display omitted] • VIS-NIR spectroscopy was used to predict predawn leaf water potential (Ψ pd). • Benchmark of SL-AI against state-of-the-art chemometrics methods in modelling Ψ pd. • Chlorophyll, xanthophyll, and water absorbance bands related to the Ψ pd. • Cause-effect of plant response to abiotic stresses explained through VIS-NIR bands. [ABSTRACT FROM AUTHOR]

Pin nematodes (Paratylenchus spp.) currently comprise 132 species of polyphagous plant ectoparasites with at least seven species that are plant pathogenic emphasizing the need for correct identification to establish an appropriate management strategy. Sequences of highly conserved regions of ribosomal and mitochondrial RNA genes are a powerful species-level diagnostic tool within Tylenchulidae. A nematological survey was conducted from 2019 to 2021 in commercial vineyards distributed in four major wine-producing regions in the Central and South Portugal. Nine populations of Paratylenchus spp. were isolated from the rhizosphere of grapevines that were characterized from morphological data and molecular phylogenetic analysis using two rRNA genes (D2–D3 expansion segments of the 28S, and partial 18S) and a region partial of the COI mtRNA gene. Contrasting morphological hypotheses with molecular data provided rapid detection of six species, specifically P. goodeyi, P. hamatus, P. pedrami, P. tenicaudatus, P. variabilis, and P. veruculatus. Bayesian inference (BI) phylogenetic trees for these molecular markers established phylogenetic relationships underscore the importance of using genomic and molecular phylogenetic data for accurate pin nematode identification at the species level. To our knowledge, this is the first report of Paratylenchus spp. in Portugal, extending the geographical distribution of these species in the Mediterranean Basin, and the first record of P. goodeyi, P. pedrami, P.variabilis, P. veruculatus and P. tenicaudatus parasitizing grapevine. [ABSTRACT FROM AUTHOR]

Wine is one the most important products from Portugal, being the grapevine variety very important to ensure uniqueness, authenticity and classification. In the Douro Demarcated Region, only certain grapevine varieties are allowed, implying the need for an identification mechanism. The ampelographs, professionals that use visual analysis to classify grapevines, are disappearing. In this situation, one possible replacement for ampelographs can be deep learning models. In previous experiments, we successfully classified 12 grapevines varieties, fine-tuning the Xception model, achieving ~0.9 in F1 score, raising the question, "what is the impact of the fine-tuning layers' configuration in our results?". This paper presents an analysis of the impact of different layers' configuration in fine-tuning Xception model to classify 12 grapevine varieties with images acquired in a natural environment. Despite the model achieved F1-score of 0.92 in all configurations, using the Grad-CAM approach, we show that layers' configuration in fine-tuning implies the quality of the models' prediction. As analysis' result, we can see that the model acting as feature extractor and fully fine-tuned obtains similar results in terms of metrics and pixel contribution, and fine-tuning only the last two blocks lead the model to look at more features in the image. [ABSTRACT FROM AUTHOR]

Wine is the most important product from the Douro Region, in Portugal. Ampelographs are disappearing, and farmers need new solutions to identify grapevine varieties to ensure high-quality standards. The development of methodology capable of automatically identify grapevine are in need. In the scenario, deep learning based methods are emerging as the state-of-art in grapevines classification tasks. In previous work, we verify the deep learning models would benefit from focus classification patches in leaves images areas. Deep learning segmentation methods can be used to find grapevine leaves areas. This paper presents a methodology to segment grapevines images automatically based on the U-net model. A private dataset was used, composed of 733 grapevines images frames extracted from 236 videos collected in a natural environment. The trained model obtained a Dice of 95.6% and an Intersection over Union of 91.6%, results that fully satisfy the need of localise grapevine leaves. [ABSTRACT FROM AUTHOR]

Pest control services provided by naturally occurring species (the so-called biocontrol services) are widely recognized to provide key incentives for biodiversity conservation. This is particularly relevant for vertebrate-mediated biocontrol services as many vertebrate species are of conservation concern, with most of their decline associated to landscape modification for agricultural purposes. Yet, we still lack rigorous approaches evaluating landscape-level correlates of biocontrol potential by vertebrates over broad spatial extents to better inform land-use and management decisions. We performed a spatially-explicit interaction-based assessment of potential biocontrol services in Portugal, using 1853 pairwise trophic interactions between 78 flying vertebrate species (birds and bats) and 53 insect pests associated to two widespread and economically valuable crops in the Euro-Mediterranean region, olive groves (Olea europaea subsp. europaea) and vineyards (Vitis vinifera subsp. vinifera). The study area was framed using 1004 square cells, each 10 × 10 km in size. Potential biocontrol services were determined at all those 10 × 10 km grid-cells in which each crop was present as the proportion of the realized out of all potential pairwise interactions between vertebrates and pests. Landscape correlates of biocontrol potential were also explored. Our work suggests that both birds and bats can effectively provide biocontrol services in olive groves and vineyards as they prey many insect pest species associated to both crops. Moreover, it demonstrates that these potential services are impacted by landscape-scale features and that this impact is consistent when evaluated over broad spatial extents. Thus, biocontrol potential by vertebrates significantly increases with increasing amount of natural area, while decreases with increasing area devoted to target crops, particularly olive groves. Overall, our study highlights the suitability of our interaction-based approach to perform spatially-explicit assessments of potential biocontrol services by vertebrates at local spatial scales and suggest its utility for integrating biodiversity and ecosystem services in conservation planning over broad spatial extents. [ABSTRACT FROM AUTHOR]

Background and Aims: Recently, early defoliation (ED) has been used widely to regulate yield and reduce bunch compactness to improve tolerance to bunch rot. The aim of this study was to test ED, as an alternative to the conventional crop thinning (CT), to regulate yield and improve tolerance to bunch rot of the Vitis vinifera L. cv. Aragonez. Methods and Results: Early defoliation and CT were compared with an untreated Control over three consecutive seasons in a commercial vineyard in Portugal. Early defoliation had little effect on tolerance to bunch rot and led to progressive loss of yield reducing fruitset, bunch number, berry number and mass, compared to Control vines. Reduced bunch number is likely to be a function of reduced bud fertility. Crop thinning also reduced yield but, unlike ED, the yield reduction was less and remained constant over the seasons studied. Both ED and CT had little effect on berry composition. Conclusions: Among the two crop‐regulating techniques, CT appears more suitable than ED to control grape yields in regions where yield limitations are imposed. The progressive yield decline caused by ED is likely to be not economically viable in the region studied. Significance of the Study: Early defoliation reduces bud fertility in unirrigated vineyards under Mediterranean conditions. Therefore, this practice should be avoided under those conditions. [ABSTRACT FROM AUTHOR]

Flavescence dorée (FD), caused by the phytoplasma Candidatus Phytoplasma vitis, is a major threat to vineyard survival in different European grape-growing areas. It has been recorded in French vineyards since the mid-1950s, and rapidly spread to other countries. In Portugal, the phytoplasma was first detected in the DOC region of 'Vinhos Verdes' in 2006, and reached the central region of the country in 2009. The infection causes strong accumulation of carbohydrates and phenolics in the mesophyll cells and a simultaneous decrease of chlorophylls, events accompanied by a down regulation of genes and proteins involved in the dark and light-dependent reactions and stabilization of the photosystem II (PSII). In the present study, to better elucidate the basis of the leaf chlorosis in infected grapevine cv. Loureiro, we studied the isoprenoid transcript–metabolite correlation in leaves from healthy and FD-infected vines. Specifically, targeted metabolome revealed that twenty-one compounds (out of thirty-two), including chlorophylls, carotenoids, quinones and tocopherols, were reduced in response to FD-infection. Thereafter, and consistently with the biochemical data, qPCR analysis highlighted a severe FD-mediated repression in key genes involved in isoprenoid biosynthetic pathways. A more diverse set of changes, on the contrary, was observed in the case of ABA metabolism. Principal component analysis (PCA) of all identified metabolites clearly separated healthy from FD-infected vines, therefore confirming that the infection strongly alters the biosynthesis of grapevine isoprenoids; additionally, forty-four genes and metabolites were identified as the components mostly explaining the variance between healthy and infected samples. Finally, transcript–metabolite network correlation analyses were exploited to display the main hubs of the infection process, which highlighted a strong role of VvCHLG , VvVTE and VvZEP genes and the chlorophylls intermediates aminolevulunic acid and porphobilinogen in response to FD infection. Overall, results indicated that the FD infection impairs the synthesis of isoprenoids, through the repression of key genes involved in the biosynthesis of chlorophylls, carotenoids, quinones and tocopherols. [ABSTRACT FROM AUTHOR]

Phenological models applied to grapevines are valuable tools to assist in the decision of cultural practices related to winegrowers and winemakers. The two-parameter sigmoid phenological model was used to estimate the three main phenological stages of the grapevine development, i.e., budburst, flowering, and veraison. This model was calibrated and validated with phenology data for 51 grapevine varieties distributed in four wine regions in Portugal (Lisboa, Douro, Dão, and Vinhos Verdes). Meteorological data for the selected sites were also used. Hence, 153 model calibrations (51 varieties × 3 phenological stages) and corresponding parameter estimations were carried out based on an unprecedented comprehensive and systematized dataset of phenology in Portugal. For each phenological stage, the centroid of the estimated parameters was subsequently used, and three generalized sigmoid models (GSM) were constructed (budburst: d = −0.6, e = 8.6; flowering: d = −0.6, e = 13.7; veraison: d = −0.5, e = 13.2). Centroid parameters show high performance for approximately 90% of the varieties and can thereby be used instead of variety-specific parameters. Overall, the RMSE (root-mean-squared-error) is < 7 days, while the EF (efficiency coefficient) is > 0.5. Additionally, according to other studies, the predictive capacity of the models for budburst remains lower than for flowering or veraison. Furthermore, the F-forcing parameter (thermal accumulation) was evaluated for the Lisboa wine region, where the sample size is larger, and for the varieties with model efficiency equal to or greater than 0.5. A ranking and categorization of the varieties in early, intermediate, and late varieties was subsequently undertaken on the basis of F values. These results can be used to more accurately monitor and predict grapevine phenology during a given season, thus supporting decision making in the Portuguese wine sector. [ABSTRACT FROM AUTHOR]

• Tinto-Cão (TC) kept a better water status than Touriga Nacional (TN) and Tinta Roriz (TR). • TC had lower chlorophylls than TN and TR. • TC had lower efficiency of PSII photochemistry than TN and TR. • TC had higher thermal energy dissipation than TN and TR. • Boosted photoprotection in TC photosynthetic apparatus, relative to TN and TR. In certain regions, especially those with a Mediterranean climate, that are highly susceptible to climate change, viticulture is expected to become less suitable for the production of high-quality wines. From an evolutionary perspective, grapevine varieties have evolved genetic adaptations in the form of protective mechanisms to withstand summer stress, reflecting the climatic conditions in which grapevines were initially domesticated. The in-depth knowledge of the structural and functional characteristics of grapevines can aid in the identification and selection of varieties that are better suited to adverse environmental conditions and to the increasingly challenging conditions imposed by climate change. Following, this study aims to evaluate the extent to which the water status adjustment and the leaf biophysical and biochemical processes influence the respective photosynthetic performance of a currently neglected grapevine variety, Tinto Cão (TC) and two commonly used varieties in the Douro region, Touriga-Nacional (TN) and Tinta-Roriz (TR). The experiment was undertaken in the Baixo-Corgo sub-region of the Demarcated Douro Region in the north of Portugal. Grapevine water status, chlorophyll contents, leaf reflectance indices, chlorophyll a fluorescence (modulated and transient) and leaf gas exchange (including A/PPFD and A/Ci curves) were evaluated in three different phenological stages. The results indicate that, compared to TN and TR varieties, the TC minimizes the light-harvesting system while promoting thermal energy dissipation, which can be interpreted as photoprotective mechanisms at the photosynthetic apparatus level. These mechanisms imply the downregulation of the photochemical reactions but without significant losses of net productivity compared to TN, while TR remained increased. Despite the minor expression of Tinto-Cão nowadays, this variety can also have great adaptability for very hot and sunny wine-growing regions. [ABSTRACT FROM AUTHOR]

Thermal conditions in mainland Portugal were evaluated using a new hourly database over the recent period of 2000–2018 (19 years). The number of hours within each different temperature interval was calculated from the long-term means of the hourly temperatures of a network of 63 meteorological stations. A geostatistical approach, using elevation, distance to coastline and latitude, was subsequently applied to provide gridded patterns at a high spatial resolution (1 km grid spacing). Eight fruit species (almond tree, carob tree, chestnut tree, citrus fruits, cork oaks, holm oaks, olive trees, and grapevines) were selected to assess their hourly thermal growing conditions. The results highlight the strong spatial variability of temperature levels in mainland Portugal, providing new insights into their spatial distribution. The number of hours in the year with cool conditions (4–12 °C) is higher in the northern-central regions, mainly in mountainous areas. Additionally, the number of hours in the year with temperate conditions (12–20 °C) emphasizes the importance of the distance to the coastline (maritime influence). The warm conditions (20–28 °C) are most prevalent in the south of the country and in the Douro valley, whereas the very warm conditions (number of hours with temperature between 28–36 °C) are essentially restricted to inner-southern Portugal and to the upper Douro valley. This study also reveals, with high accuracy, the thermal growing conditions of main fruit species in mainland Portugal, giving particular emphasis to olive trees and grapevines. These findings may help decision support systems providing more reliable and accurate guidelines to stakeholders, decision-makers, and farmers. The main maps are available in a widely used file format (shapefile), thus allowing their application to a wide range of other areas of interest. [ABSTRACT FROM AUTHOR]

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In this work, fungi present in the grapevine's phyllosphere collected from the main demarcated wine regions of Portugal were identified, and their phylogenetic relationships were analysed. A total of 46 vine samples (leaves and berries) were collected from different parts of the country, being isolated a total of 117 fungal colonies that were identified to the genus level and sequenced in the following genetic regions: internal transcribed spacer region and 18S rRNA and β-tubulin gene. Next, a phylogenetic tree reconstruction for each genetic region was built. The isolates retrieved from environmental samples belonged to the genera Alternaria (31%), Cladosporium (21%), Penicillium (19%), Aspergillus (7%) and Epicoccum (3%). No genetic signatures of exchange of genetic material were detected, and consequently, the reconstructed phylogenetic trees allowed to distinguish between these different species/genera. In the fungal composition of the Vitis vinifera phyllosphere, several potential pathogens were identified that can be associated with decreases in crop productivity. Knowledge of fungi identification and genetic diversity is pivotal for the development of more adequate crop management strategies. Furthermore, this information will provide guidelines for a more specific and wiser use of fungicides. Significance and Impact of the Study The knowledge on the composition of the phyllosphere microbial community is still limited, especially when fungi are concerned. These micro-organisms not only play a crucial role in crop health and productivity but also interact with the winemaking process, determining the safety and quality of grape and grape-derived products. The elucidation of the micro-organisms present in the phyllosphere will have a notorious impact on plant breeding and protection programmes and disease management strategies, allowing a better control of pesticide applications. [ABSTRACT FROM AUTHOR]

Sixty-eight isolates of Phaeomoniella chlamydospora obtained from symptomatic esca and Petri-diseased grapevines, and mostly from within the Portuguese Dão appellation, were investigated for phenotypic and molecular diversity, in order to determine intraspecific variability and population structure. In vitro growth features, including colony texture, colour, growing margin zonation, hyphal morphology and colony growth rate, were evaluated. Molecular characterization was performed through the sequencing of the total ITS region, and molecular analyses were used to infer phylogenetic relationships, using the Maximum Likelihood approach. Isolates were separated in two groups, supported by phenotypic and molecular analyses, but no clear correspondence was found between the two approaches. Nevertheless, both analyses revealed strong homogeneity among all isolates, despite their diverse geographical origin, year of isolation and scion/rootstock combination, supporting the clonal reproduction strategy described for this species. [ABSTRACT FROM AUTHOR]

Grapevine (Vitis vinifera L.) is the most important fruit crop in Portugal. Associated with a long history of wine production, there is also a significant diversity and richness in the Portuguese germplasm, both in the cultivated subspecies vinifera as well as in wild vine populations, (subspecies sylvestris). In the second half of the nineteenth century pest management became one of the main tasks in European viticulture after the introduction of the fungal pathogens causing powdery and downy mildew. Atlantic climate areas in Portugal may need up to 10 treatments per season to control these diseases. One of the most promising approaches to control these diseases is to introgress resistance traits relying on the breeding of new grapevine varieties. A number of crosses between Portuguese varieties well adapted to the local terroir and with high enologic importance (Arinto, Fernão Pires and a Touriga Nacional) and varieties with known resistance (Chambourcin, Regent and two lines A and B of resistant grapevine varieties) were carried out in 2018 and 2019. More than 3000 seeds were obtained, these were germinated in 2020 at control condicions (temperature, humidity and light) in the greenhouse. During the 2021 growing season theses progenies were challenged with downy mildium (near 30000 sporangia ml-1concentration, spread on lower suface of leafs) and with powdery mildium (direct brusch strocks on upper suface of leafs). Both challenges were done in the absence of Phytosanitary treatments at two growing stages (Baggiolini scale E and I). Only tolerante plants will be further studied, so far we have 239 progenies. As future perspective these new varieties will be screened with identified locus that identify the genetic profile of these grapevine varieties and check the correct progenitors. Additionaly resistant locus identified in the used progenitors, hermaphroditism flower and berry skin color will to be used to select the new grapevine varieties to be used on wine production or in new backcrosses in order to obtain F2 varieties. [ABSTRACT FROM AUTHOR]

An important aspect of wine geographic origin is related to grapevine varieties used for wine productionin specific winegrowing regions or countries. Grapevine germplasm is highly variable and classified into geographical groups. These classifications were recently confirmed by genetic studies, and further classified into genetic-geographic (GEN-GEO) groups. Secondary metabolites, namely polyphenolic and volatile organic compounds (VOCs), have crucial role in winemaking industry due to their influence on quality, colour, and sensory properties of wine. The aim of the research was to investigate the polyphenolic and volatile profiles of 50 grapevine varieties from different GEN-GEO groups. The groups are C2 (varieites from Italy and France), C7 (varieites from Croatia), and C8 (varieites from Spain and Portugal). Polyphenolic compounds analysed belonged to the classes of anthocyanins, flavan-3-ols, flavonols, phenolic acids, and stilbenes. Classes of VOCs analysed were carbonyls, alcohols, acids, esters, and terpenoids. The most abundant class of polyphenols were anthocyanins, followed by flavan-3-ols and flavonols, while carbonyls were the most abundant class of VOCs, followed by alcohols and sesquiterpenes. Using discriminant analysis, the GEN-GEO groups were clearly separated by their polyphenolic and volatile profiles. In the case of polyphenolic profiles, compounds contributing the most to the discrimination of groups belong to classes of hydroxycinnamic acids, flavan-3-ols, and flavonols. Furthermore, some of the compounds contributing to discrimination are found in relatively small amounts. Regarding the discrimination based on volatile profiles, GEO groups were discriminated by their overall volatile profile. C2 group contains higher amounts of carbonyl compounds and alcohols, while C8 group contains higher amounts of sesquiterpenes and acids. Group C7 is characterized by low content of VOCs. This data demonstrates that geographical origin, combined with genotype, also influences the overall polyphenolic and volatile profiles. [ABSTRACT FROM AUTHOR]

Abstract: Thirty-nine grapevine cultivars widely grown in Portugal, especially in Vinhos Verdes and Douro regions, and two well known international cultivars as standards, were genotyped at 12 microsatellite loci. The number of alleles per locus ranged from 6 to 12, and the number of allelic combinations per locus from 13 to 26. The total number of unique genotypes in the 12 analysed loci was 120, having most of the cultivars (38 out of 41) at least one unique genotype in any of the loci. The microsatellite profiles were adequate to discriminate 41 cultivars. The level of observed heterozygosity at each locus varied from 70.7% to 95.1%. VVMD28 has been revealed as one of the most informative markers. Several synonymies between Spanish and Portuguese cultivars were confirmed, and some homonymies are discussed. The genetic profiles of all 41 cultivars were searched for possible parent-offspring groups. The data obtained revealed the possible descendence of Touriga Franca from Touriga Nacional and Marufo. [ABSTRACT FROM AUTHOR]

Abstract: Acacia longifolia is a widespread invasive plant species in Portugal. In South Africa, it is controlled by a bud-galling wasp, Trichilogaster acaciaelongifoliae, which could also be used in Portugal. Biological control of invasive alien plants has received little consideration anywhere in Europe and has never been attempted in Portugal. The lack of a suitably-large quarantine facility necessitated the use of a novel approach to test non-target species in Portugal. Mature T. acaciaelongifoliae galls were shipped to Portugal from South Africa to obtain adult female wasps which were confined in Petri dishes each with a bud-bearing branch of one of 40 non-target plant species. The time spent by the wasps exploring and probing the buds was measured after which buds were dissected to detect any egg deposition. The results showed that T. acaciaelongifoliae did not respond to the buds of most (23) species. The females spent time on the buds of the other 17 species but only laid eggs in three species besides A. longifolia. Oviposition on Acacia melanoxylon was expected but was not anticipated on Vitis vinifera, vines, (where eggs were deposited externally in the pubescent coat of the buds) or on Cytisus striatus, broom, (where eggs were inserted into the buds as they are on A. longifolia). Subsequent trials on potted plants showed that galls only developed on A. longifolia. Field surveys in South Africa and Australia showed that galls never occur on either vines or broom. The implications of these findings for the use of T. acaciaelongifoliae for biological control of A. longifolia in Portugal are considered in relation to the wealth of experience and knowledge about the specificity of the wasp and the reliability of conducting host-specificity tests under confined conditions of cages. [Copyright &y& Elsevier]

This work compares the effects of two different rootstocks (110R and SO4) on a number of ampelographic and production variables in two grape cultivars ('Albarino' and 'Caino Tinto') of great importance in north-western Spain and in northern Portugal. Plants growing under the same conditions were studied over a period of three years. The effect of the two rootstocks differed depending on the cultivar. No influence of rootstock was seen on production in 'Albarino', but significant differences were seen in terms of cluster weight and weight of pruning wood in 'Caino Tinto'. The rootstock type did not influence the ampelographic characteristics of either cultivar. [ABSTRACT FROM AUTHOR]

As the ancestor of cultivated grape, Vitis vinifera subsp. sylvestris represents a unique, invaluable genetic resource for the improvement of cultivated grapevines. Recently, five populations of wild grapevines were identified in Portugal. Sixty vines were characterized with 11 nuclear SSR markers and further compared with 70 genotypes of Portuguese Vitis vinifera subsp. sativa. The obtained data demonstrate moderate genetic differentiation between wild grapevine populations and moderate to high genetic differentiation between wild and cultivated grapevines. However, the identification of high degrees of similarity between wild and cultivated grapes (up to 87%) and a putative parent-progeny relationship between wild and cultivated grapes with 17 additional SSR markers is indicative of gene flow between local wild grapevine populations and Portuguese domesticated vines. Also, the ancestry of some Azorean cultivars was ascertained. The obtained data further support the hypothesis of several domestication centres, with Portugal, Spain, and Italy playing a particular role after the last glaciation, giving rise to many of the Western European cultivars. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Most thermal methods for the study of drought responses in plant leaves are based on the calculation of ‘stress indices’. This paper proposes and compares three main extensions of these for the direct estimation of absolute values of stomatal conductance to water vapour ( gs) using infrared thermography (IRT). All methods use the measured leaf temperature and two environmental variables (air temperature and boundary layer resistance) as input. Additional variables required, depending on the method, are the temperatures of wet and dry reference surfaces, net radiation and relative humidity. The methods were compared using measured gs data from a vineyard in Southern Portugal. The errors in thermal estimates of conductance were of the same order as the measurement errors using a porometer. Observed variability was also compared with theoretical estimates of errors in estimated gs determined on the basis of the errors in the input variables (leaf temperature, boundary layer resistance, net radiation) and the partial derivatives of the energy balance equations used for the gs calculations. The full energy balance approach requires accurate estimates of net radiation absorbed, which may not be readily available in field conditions, so alternatives using reference surfaces are shown to have advantages. A new approach using a dry reference leaf is particularly robust and recommended for those studies where the specific advantages of thermal imagery, including its non-contact nature and its ability to sample large numbers of leaves, are most apparent. Although the results suggest that estimates of the absolute magnitude of gs are somewhat subjective, depending on the skill of the experimenter at selecting evenly exposed leaves, relative treatment differences in conductance are sensitively detected by different experimenters. [ABSTRACT FROM AUTHOR]

Water is a key resource in commercial wine production and both large excesses and deficits have undesirable effects upon the amount and quality of the wine produced. A balance between the water requirements of a fully developed canopy and the induced stress necessary for the commercial quality of the wine must be reached. Thus we need a physiological indicator that integrates both soil and climatic conditions to use as a management tool. An experimental field was established in the eastern part of the Demarcated Region of Douro – Portugal, to study the effect of water supply on the quality of the musts produced and we need a physiological indicator that relates to the water use and stress of the grapevines ( Vitis vinifera L.) and to the later evaluation of the effect of irrigation practices upon the quality of the musts. We chose as indicators sap flow, leaf water potential at pre-dawn (0600 h), mid-morning (1000 h), solar noon (1400 h) and sunset (1900 h), stomatal conductance and leaf transpiration both measured at mid-morning and at solar noon, and related them to our experimental treatments that induce differences in soil water content, evaluated with time-domain reflectometry probes, with the objective of selecting the indicator that best describes the plant water status under different amounts of available water. Sap flow, leaf water potential and leaf transpiration rate measured at solar noon had highly significant correlations with soil water content and their regression on soil water content was also highly significant. Each of these parameters has shortcomings and none has a clear advantage over the other two as an integrator of the environmental conditions under these experimental conditions. Further studies of the parameters and their relationship with the quality characteristics of the produced musts are needed to achieve the ultimate objective of manipulating the soil water content. [ABSTRACT FROM AUTHOR]

The European grapevine moth (Lobesia botrana; Denis and Schiffermüller, 1775) is considered a key pest for grapevine (Vitis vinifera L.) in the Douro Region, Portugal. The phenology of both the grapevine and the pest has changed in the last decades due to the increase in temperature. Here, we assess the potential impact of climate change on the (a)synchrony of both species. The results show that the phenological stages (budburst, flowering and veraison) undergo an advancement throughout the region (at an ~1 km resolution) under a climate change scenario (Representative Concentration Pathways, RCP8.5) for the period 2051–2080, with respect to the historic period (1989–2015). For cv. Touriga Nacional and Touriga Franca, the budburst advances up to 14 days, whereas for flowering and veraison the advancements are up to 10 days (mainly at low elevations along the Douro River). For the phenology of Lobesia botrana, earliness was also verified in the three flights (consequently there may be more generations per year), covering the entire region. Furthermore, the third flight advances further compared to the others. For both varieties, the interaction between the third flight (beginning and peak) and the veraison date is the most relevant modification under the future climate change scenario (RCP8.5, 2051–2080). The aforementioned outcomes from the phenology models help to better understand the possible shifts of both trophic levels in the region under future climate, giving insights into their future interactions. [ABSTRACT FROM AUTHOR]

More than 100 grapevine varieties are registered as suitable for wine production in "Douro" and "Trás-os-Montes" Protected Designations of Origin regions; however, only a few are actually used for winemaking. The identification of varieties cultivated in past times can be an important step to take advantage of all the potential of these regions grape biodiversity. The conservation of the vanishing genetic resources boosts greater product diversification, and it can be considered strategic in the valorisation of these wine regions. Hence, one goal of the present study was to prospect and characterise, through molecular markers, 310 plants of 11 old vineyards that constitute a broad representation of the grape genetic patrimony of "Douro" and "Trás-os-Montes" wine regions; 280 samples, grouped into 52 distinct known varieties, were identified through comparison of their genetic profiles generated via 6 nuclear SSR and 43 informative SNP loci amplification; the remaining 30 samples, accounting for 13 different genotypes, did not match with any profile in the consulted databases and were considered as new genotypes. This study also aimed at evaluating the population structure among the 65 non-redundant genotypes identified, which were grouped into two ancestral genetic groups. The mean probability of identity values of 0.072 and 0.510 (for the 6 SSR and 226 SNP sets, respectively) were determined. Minor differences were observed between frequencies of chlorotypes A and D within the non-redundant genotypes studied. Twenty-seven pedigrees were confirmed and nine new trios were established. Ancestors of eight genotypes remain unknown. [ABSTRACT FROM AUTHOR]

The natural cosmetics market has grown since consumers became aware of the concept of natural-based ingredients. A significant number of cosmetics have an ecological impact on the environment and carry noxious and chemically potent substances. Thus, the use of natural and organic cosmetics becomes increasingly important since it is clear that topical treatment with cosmeceuticals can help improve skin rejuvenation. A substantial investigation into the benefits that fruits and plants can bring to health is required. Studies have shown that antigenotoxic properties are linked to anti-aging properties. Several studies have shown potential antigenotoxicity in natural ingredients such as Almonds (Prunus dulcis), Elderberry (Sambucus nigra), Olives (Olea europaea), and Grapes (Vitis vinifera). This review presents an overview of research conducted on these natural ingredients, the most common in the Northeast of Portugal. This region of Portugal possesses the most organic farmers, and ingredients are easily obtained. The Northeast of Portugal also has climatic, topographic, and pedological differences that contribute to agricultural diversity. [ABSTRACT FROM AUTHOR]

• Varieties with different GEN-GEO background have different polyphenolic profiles. • The most abundant classes of phenols are anthocyanins, flavan-3-ols, and flavonols. • Polyphenolic profiles discriminated GEN-GEO groups. Relevant aspect of wine geographic origin is related to grapevine varieties used for wine production in specific wine country or region. The grapevine germplasm is highly variable and classified into geographic groups. These classifications were recently confirmed using genetic studies, and further classified varieties into geographic-genetic (GEN-GEO) groups. Polyphenolic compounds are important secondary metabolites in grapes and have an important impact on wine quality and sensory properties. The aim of this research was to investigate the polyphenolic profiles of 50 grape varieties from different GEN-GEO groups. The groups were C2 (varieties from Italy and France), C7 (varieties from Croatia), C8 (varieties from Spain and Portugal). Polyphenolic compounds analysed belonged to the classes of anthocyanins, flavan-3-ols, flavonols, phenolic acids, and stilbenes. The most abundant classes of polyphenols were anthocyanins, followed by flavan-3-ols and flavonols. Using discriminant analysis, the genetic-geographic groups were clearly separated based on their polyphenolic profiles, with all classes of compounds contributing to discrimination. [ABSTRACT FROM AUTHOR]

Under a climate change scenario, vineyards will experience serious challenges in the future. In an attempt to overcome such difficulties, this experiment offers a study on the effect of regulated deficit irrigation as a method for short-term adaptation to climate change in cv. Touriga Francesa, grafted into the rootstock 110R in the Douro region during a three-year period. Water stress on the plant and its effects on canopy, production, and quality of musts were analyzed. Rainfed vines (R0) were compared to three deficit irrigation regimes as a function of estimated crop evapotranspiration (ETc): R25 (25% ETc), R50 (50% ETc), and R75 (75% ETc). Water was applied on a weekly basis whenever predawn water potential showed moderate water stress until 15 days prior to harvest. The results suggest that rainfed plants under these circumstances suffered, in general, a negative impact on vine performance, while moderate water stress had more favorable effects on fruit composition, as well as in yield. Nonetheless, further studies should be conducted as irrigation did not show consistent effects on yield or berry composition. [ABSTRACT FROM AUTHOR]

Differences In maximum leaf conductance in grapevine plants growing In soils with contrasting water availabilities during mid-summer in Portugal could be accounted for by differences in the concentration of ABA in xylem sap. This conclusion is reinforced by the observation that the relationship between leaf conductance and endogenous ABA concentration can be mimicked by the application of exogenous ABA to leaves detached from Irrigated plants. During the day, leaf conductance decreased after a morning peak, even when the leaves remained in a constant environment at a moderate temperature and leaf-to-air vapour pressure difference. This decline in leaf conductance was not a consequence of an Increase In the xylem ABA concentration or the rate of delivery of this compound by the transpiratory stream. The afternoon depression in leaf conductance was associated with an apparent limitation In stomatal opening potential, which persisted even when detached leaves were fed with water and rehydrated. The reason for this Inhibition has still to be Identified. [ABSTRACT FROM AUTHOR]

Perennial woody plants undergo a period of dormancy from the beginning of autumn until the end of spring. Whereas the molecular and physiological events that characterize dormancy release of buds have been described in detail, those occurring in woody tissues underneath the buds are mostly unknown. To bridge this gap, the mRNA populations of cane segments located underneath the bud were analyzed at bud dormancy (E-L 1) and at bud burst (E-L 4). They revealed an important reprogramming of gene expression suggesting that cell division, cell wall metabolism and the mobilization of sugars are the main metabolic and cellular events occurring in cane woody tissues at bud burst. Also, the upregulation of several genes of sugar metabolism, encoding starch- and sucrose-degrading enzymes and sugar transporters, correlates with the decrease in starch and soluble sugars in woody tissues concomitant with increased sucrose synthase and α-amylolytic biochemical activities. The latter is likely due to the VviAMY2 gene that encodes a functional α-amylase as observed after its heterologous expression in yeast. Taken together, these results are consistent with starch and sugar mobilization in canes being primarily involved in grapevine secondary growth initiation and supporting the growth of the emerging bud., (Copyright © 2021. Published by Elsevier B.V.)

Kaolin protective effect was assessed in a white grapevine cultivar 'Cerceal' in 'Alentejo' Region (southeast Portugal) where plants face extreme conditions during the summer season. We addressed the hypothesis that kaolin effects lead to several changes in leaves, fruits, and wine characteristics on the primary and secondary metabolism. Results showed that kaolin reduces leaf temperature which provokes an improvement in physiological parameters such as net photosynthesis and water use efficiency. This protection interferes with berry color, leaving them more yellowish, and an increase in phenolic compounds were observed in all fruit tissues (skin, seed, and pulp). Additionally, both berry and wine characteristics were strongly affected, with an increase of tartaric and malic acid and consequently high total acidity, while the sugar concentration decreased 8.9% in berries provoking a low wine alcohol level. Results also showed that kaolin induces high potassium, magnesium, and iron, and low copper and aluminum concentrations. Moreover, the control wine showed higher content of esters related with hostile notes whereas wine from kaolin treated vines presented higher content of esters associated with fruity notes. Overall, the results strengthen the promising nature of kaolin application as a summer stress mitigation strategy protecting grapevine plants and improving fruit quality and creating more balanced wines. [ABSTRACT FROM AUTHOR]

The present research aimed to evaluate the water dynamics of grapevines trained in Cordon and Guyot systems by coupling sap flow and trunk diameter measurements under Mediterranean climate conditions. The study was conducted in a vineyard with Touriga-Nacional located at the Douro Valley, Portugal, during 2017. The results showed daily trunk diameter fluctuations (TDFs), with the contraction, recovery and increment phases and higher sap flow (SF) rates at earlier stages. Under harsh pedoclimatic conditions, SF was reduced and TDF flattened. Rehydration and stomatal mechanisms were mostly associated with these responses. Guyot vines showed higher changes in TDF for the same SF values, whereas the TDFs of Cordon vines remained practically unchanged over maturation. Guyot vines generally showed increased values of cumulative increment and maximum daily trunk shrinkage. Although Guyot vines had a similar leaf area index (LAI), they showed higher SF/LAI ratios than Cordon vines. These results highlight the effect of the shorter length of the hydraulic pathways of the Guyot training system, in contrast to the higher trunk and the permanent horizontal branch (cordon) of the Cordon training system, indicating good adaptation to local pedoclimatic conditions. The study pointed to the complementary use of both techniques in the evaluation of grapevine water dynamics. [ABSTRACT FROM AUTHOR]

• RFLP analyses of infected grapevine cv. Loureiro identified a FD-D strain. • FD infected leaves showed high callose and lipid accumulation in the phloem cells. • FD phytoplasma presence led to a delay in grapevine development and to drastic production losses. • FD decreased berry quality resulting in higher acidity. • Leaf ultrastructure modifications partly explain the FD impairment on vine growth. "Flavescence dorée" (FD) is a quarantine disease associated with the presence of a phytoplasma transmitted by the insect vector Scaphoideus titanus. This disease affects grapevines and is of a great concern to the stability and sustainability of the wine industry, due to the harvest losses and death of infected plants. In Portugal, FD has seriously affected the "Vinhos Verdes" region, but so far the research on this topic is very limited. The current study confirmed that the FD phytoplasma strain involved in the outbreak in Vitis vinifera cv. Loureiro belongs to the 16SrV-D subgroup and shows very low RFLP variability in the tuf and secY genes. Transmission electron microscopy analysis of leaf midribs from infected grapevine plants revealed that the shape and structure of phloem cells were altered, presenting collapsed cells, callose accumulation in sieve plates and lipid accumulation in chloroplasts of phloem parenchyma cells. Moreover, data from two subsequent years showed that FD presence was associated with an average delay of 10 to 15 days on the time to visible inflorescences and to veraison, compared to healthy plants. At veraison, FD also lead to a significant decrease in the budburst percentage (7% to 12%), fertility index (35% in 2015), leaf area (56% to 63%), and chlorophyll content (18% to 35% lower SPAD values). Hence, infected plants showed a drastic reduction in the yield, corresponding to a decrease between 51% and 92% compared to healthy plants, which mostly resulted from a lower number of bunches (63% to 92% less), but also a decreased bunch weight (35% lower in 2015). Concerning berry quality, there were no significant differences in terms of total soluble solids and titrable acidity in both years. Here, this study concluded that the FD infection delays the grapevine development and leads to drastic production losses, which may be partly linked to the ultrastructural modifications observed in the phloem cells of infected plants. [ABSTRACT FROM AUTHOR]

The article presents the first report of Flavescence dorée (FD) phytoplasma affecting Vitis vinifera, a grapevine in Portugal. During an official FD survey in 2007, FD symptoms linked with leaf yellowing on white grapevine variety, irregular maturation of wood and leaf reddening were obseved in vineyards from Amares region of Portugal. Samples were collected from plants without symptoms and all plants with symptoms revealed polymerase chain reaction (PCR) products.