Phenotyping grapevine resistance to downy mildew: deep learning as a promising tool to assess sporulation and necrosis.

BACKGROUND: Downy mildew is a plant disease that affects all cultivated European grapevine varieties. The disease is caused by the oomycete Plasmopara viticola. The current strategy to control this threat relies on repeated applications of fungicides. The most eco-friendly and sustainable alternative solution would be to use bred-resistant varieties. During breeding programs, some wild Vitis species have been used as resistance sources to introduce resistance loci in Vitis vinifera varieties. To ensure the durability of resistance, resistant varieties are built on combinations of these loci, some of which are unfortunately already overcome by virulent pathogen strains. The development of a high-throughput machine learning phenotyping method is now essential for identifying new resistance loci. RESULTS: Images of grapevine leaf discs infected with P. viticola were annotated with OIV 452-1 values, a standard scale, traditionally used by experts to assess resistance visually. This descriptor takes two variables into account the complete phenotype of the symptom: sporulation and necrosis. This annotated dataset was used to train neural networks. Various encoders were used to incorporate prior knowledge of the scale's ordinality. The best results were obtained with the Swin transformer encoder which achieved an accuracy of 81.7%. Finally, from a biological point of view, the model described the studied trait and identified differences between genotypes in agreement with human observers, with an accuracy of 97% but at a high-throughput 650% faster than that of humans. CONCLUSION: This work provides a fast, full pipeline for image processing, including machine learning, to describe the symptoms of grapevine leaf discs infected with P. viticola using the OIV 452-1, a two-symptom standard scale that considers sporulation and necrosis. If symptoms are frequently assessed by visual observation, which is time-consuming, low-throughput, tedious, and expert dependent, the method developed sweeps away all these constraints. This method could be extended to other pathosystems studied on leaf discs where disease symptoms are scored with ordinal scales.

Volatile Characterization of Recovery Minority Grape Varieties from Castilla-La Mancha Region (Spain).

Nowadays, the identification and characterization of grapevine cultivars resilient to climate and water stress while preserving quality traits is crucial for the wine industry. Therefore, the objective of this work was to characterize according to their aromatic potential nine white and six red minority cultivars recently recovered from Castilla-La Mancha region (Spain), subjected to two different water-deficit regimes: rainfed, with subsistence irrigation, and irrigated. For this, the varietal aromatic potential index (IPAv) and the detailed aromatic composition were analyzed via HS-SBSE-GC/MS in extracts of two different pHs. For IPAv values, red varieties did not show a clear trend with respect to irrigation. However, in white minority varieties, higher values were obtained under irrigation conditions. Thus, a clear differentiation of the minority varieties in comparison to the references was observed, primarily attributed to the content of esters and acids, in both white and red varieties. A notable contrast was observed at different pHs, indicating a greater extractability of certain compounds like linalool, under more acidic conditions. This suggests that some recovered minority cultivars could be promising for cultivation in semi-arid regions with limited water, contributing to the sustainability of the wine sector in the future.

Molecular Evolution of SNAREs in Vitis vinifera and Expression Analysis under Phytohormones and Abiotic Stress.

SNARE proteins (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) play a key role in mediating a variety of plant biological processes. Currently, the function of the SNARE gene family in phytohormonal and abiotic stress treatments in grapevine is currently unknown, making it worthwhile to characterize and analyze the function and expression of this family in grapevine. In the present study, 52 VvSNARE genes were identified and predominantly distributed on 18 chromosomes. Secondary structures showed that the VvSNARE genes family irregular random coils and α-helices. The promoter regions of the VvSNARE genes were enriched for light-, abiotic-stress-, and hormone-responsive elements. Intraspecific collinearity analysis identified 10 pairs collinear genes within the VvSNARE family and unveiled a greater number of collinear genes between grapevine and apple, as well as Arabidopsis thaliana, but less associations with Oryza sativa. Quantitative real-time PCR (qRT-PCR) analyses showed that the VvSNARE genes have response to treatments with ABA, NaCl, PEG, and 4 °C. Notably, VvSNARE2, VvSNARE14, VvSNARE15, and VvSNARE17 showed up-regulation in response to ABA treatment. VvSNARE2, VvSNARE15, VvSNARE18, VvSNARE19, VvSNARE20, VvSNARE24, VvSNARE25, and VvSNARE29 exhibited significant up-regulation when exposed to NaCl treatment. The PEG treatment led to significant down-regulation of VvSNARE1, VvSNARE8, VvSNARE23, VvSNARE25, VvSNARE26, VvSNARE31, and VvSNARE49 gene expression. The expression levels of VvSNARE37, VvSNARE44, and VvSNARE46 were significantly enhanced after exposure to 4 °C treatment. Furthermore, subcellular localization assays certified that VvSNARE37, VvSNARE44, and VvSNARE46 were specifically localized at the cell membrane. Overall, this study showed the critical role of the VvSNARE genes family in the abiotic stress response of grapevines, thereby providing novel candidate genes such as VvSNARE37, VvSNARE44, and VvSNARE46 for further exploration in grapevine stress tolerance research.

Organic mulches slightly influence the wine phenolic profile and sensory evaluation.

Organic mulching offers numerous agronomical benefits, but its impact on wine quality remains unclear. This study assessed the effect of this practice on wine physicochemical, phenolic composition and sensory properties. Over four years, three organic mulches (grape pruning debris (GPD), straw (STR), and spent mushroom compost (SMC)) and two conventional practices (tillage (TILL) and herbicide (HERB)) were evaluated in two locations. Wines from mulching treatments exhibited higher pH, potassium, hue, and lower tartaric acid. Moreover, the SMC mulch treatment showed lower amounts of wine anthocyanins, flavonols and hydroxycinnamics, probably due to increased nutrient availability. However, no differences were detected in the wine sensory analysis. Therefore, organic mulches could be alternative practices to mitigate the consequences of climate change without significant impact on young wine's phenolic profile and sensory properties compared to HERB and TILL conventional soil management. However, future studies should focus on wine evolution during aging.

Evidence of Grapevine enamovirus 1 Infecting Grapevine (Vitis vinifera L.) in Canada.

Grapevine enamovirus 1 (GEV1) belongs to the genus Enamovirus, in the family Solemoviridae. It has been reported from several countries infecting grapevines including Brazil (Silva et al. 2017), China (Ren et al. 2021) and France (Hily et al. 2022). To assess the prevalence and diversity of economically important grapevine viruses in nine Canadian vineyards, total RNA and double-stranded RNA (dsRNA) (Fall et al. 2020) were extracted from 30 and 100 composite samples respectively, with each consisting of five vines of the same cultivars. The cultivars included in this study are Frontenac noir (n=34), Vidal (n=32), Marquette (n=33), Riesling (n=31), and Pinot noir (n=31). The total RNA and dsRNA samples were subsequently multiplexed and diagnosed by high-throughput sequencing (HTS) on NovaSeq (600 S4 PE100) and MiSeq (2 × 250 cycle PE) respectively. From NovaSeq and MiSeq sequencing, an average of 410,000 to 1.3 million reads/sample were obtained, respectively, with mapped viral reads representing 10.92% to 12.48% of the total reads. After sequence quality was verified using Trimmomatic v.0.40 (Bolger et al. 2014), the clean sequences were screened against all possible viruses in the databases using the Virtool (Rott et al. 2017) and VirFind virus detection pipelines (Ho and Tzanetakis 2014). GEV1 was detected in clean sequences from two, three, and two leaf samples of cultivars 'Marquette' 'Riesling' and 'Frontenac noir' respectively. Six of the seven HTS-assembled GEV1 genomes were partial, ranging from 4,523 to 6,000 nucleotide (nt) with genome coverage varying from 71% to 89%. Only one 6,314 nt long assembled contig (Accession No. OR021829), represented a nearly complete genome, being only 53 and 3 nt shorter than Sd-CG (MT536978) at 5' and 3' untranslated regions (UTR), respectively. Isolate 3- Riesling-CAN (OR021829) shares 90.56 to 94.19% nt identities with several GEV1isolates at 96-99% of query coverage. Phylogenetically, OR021829 is closer to GEV1 isolates from France and China (Figure S1). To validate the HTS results, the developed primer pair SetF and Set1R (Silva et al., 2017) was used for RT-PCR detection. The amplicons from all seven HTS-positive samples were sequenced using Sanger sequencing, confirming the presence of GEV-1 in three studied grape cultivars in Canadian vineyards. Symptoms associated with the specific GEV1-infected vines could not be explained as composite samples were used. Each of the combined samples HTS library also tested positive for at least one of the known grape virus/viroids, namely grapevine leafroll associated-virus -3, grapevine pinot gris virus, grapevine rupestris stem pitting-associated virus, Marafivirus syrahense grapevine Syrah virus-1 and hop stunt viroid. To our knowledge, this is the first report of GEV1 being detected in grapevines in Canada, or in any North American vineyard. GEV1 is a relatively new virus, and its biology remains largely unknown. Based on this sequence new GEV1 primers can be developed to know the genetic variability among GEV-1 and improve the detection of this virus in vineyards.

Trichoderma carraovejensis: a new species from vineyard ecosystem with biocontrol abilities against grapevine trunk disease pathogens and ecological adaptation.

Trichoderma strains used in vineyards for the control of grapevine trunk diseases (GTDs) present a promising alternative to chemical products. Therefore, the isolation and characterization of new indigenous Trichoderma strains for these purposes is a valuable strategy to favor the adaptation of these strains to the environment, thus improving their efficacy in the field. In this research, a new Trichoderma species, Trichoderma carraovejensis, isolated from vineyards in Ribera de Duero (Spain) area, has been identified and phylogenetically analyzed using 20 housekeeping genes isolated from the genome of 24 Trichoderma species. A morphological description and comparison of the new species has also been carried out. In order to corroborate the potential of T. carraovejensis as a biological control agent (BCA), confrontation tests against pathogenic fungi, causing various GTDs, have been performed in the laboratory. The compatibility of T. carraovejensis with different pesticides and biostimulants has also been assessed. This new Trichoderma species demonstrates the ability to control pathogens such as Diplodia seriata, as well as high compatibility with powdered sulfur-based pesticides. In conclusion, the autochthonous species T. carraovejensis can be an effective alternative to complement the currently used strategies for the control of wood diseases in its region of origin.

Seasonal Dynamics and Damage of Halyomorpha halys in Italian Vineyards.

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive polyphagous pest often observed in vineyards. In Europe, a gap needs to be filled in the knowledge on H. halys seasonal dynamics and damage on grapes. With this study, we described the seasonal dynamics of H. halys and its distribution in multi-cultivar vineyards, and we evaluated the damage on grape clusters induced by different pest densities. In vineyards, the seasonal occurrence of H. halys varied across time and grape cultivars, and the pest was more abundant on Cabernet Franc, Merlot and, to a lesser extent, Pinot gris. Moreover, higher densities of H. halys were found on red berry cultivars than on white ones, and on cultivars ripening late in the season. An edge effect was also detected in pest distribution within vineyards, with more stink bugs observed in the borders. In the study on pest infestation density, H. halys caused damage on berries, showing differences in susceptibility among different cultivars and with regard to the time of infestation (i.e., plant phenological stages). Halyomorpha halys infestation induced an increase in Botrytis cinerea and sour rot incidence, which probably represents the main issue related to the impact of brown marmorated stink bug on grapevine.

Assessing the influence of autumnal temperature fluctuations on cold hardiness in different grapevine cultivars: variations across vine age and bud positions.

The dynamic fluctuations in autumn temperatures, particularly the marked diurnal variations and the subsequent precipitous drops are key and a pivotal role in viticulture, as they critically influence the acclimation process of grapevines to cold, thereby directly impacting their survival and productivity in cold-climate regions. In this comprehensive study, we investigated the cold hardiness of four grapevine cultivars: 'Itasca', 'Frontenac', 'La Crescent', and 'Marquette', focusing on how these cultivars and their individual buds (1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, and 9th) respond to fluctuating weather and low temperatures typical of autumn [-1.1°C (30°F) -9.4°C (15°F) and -17.8°C (0°F)]. Our results illuminated the striking variability in cold hardiness that was manifest not only among the different cultivars but also within individual buds on the same vine, underscoring the critical influence of bud position on a vine for cold hardiness. 'Frontenac' showed greater cold hardiness at critical temperatures at which 10%, and 50% of the dormant buds were lethally affected by cold (LT10 and LT50) compared to 'Itasca' and 'La Crescent', with 'Marquette' exhibiting intermediate values. However, in cultivars such as 'Itasca' and 'Marquette', certain buds demonstrated a pronounced hardiness when faced with colder temperatures, while others exhibited a heightened sensitivity, thereby revealing a nuanced interplay between bud position and a vine's ability to withstand cold stress. Our study revealed a notable divergence from traditional viticulture understanding; apical buds demonstrated greater cold hardiness than basal buds and opened new paths for research into grapevine physiology. Our results also indicated a significant trend wherein older vines across all studied cultivars displayed enhanced cold hardiness, particularly pronounced at the critical LT50 and the critical temperature at which 90% of the dormant buds were lethally affected by cold (LT90) thresholds, in comparison to younger vines. Moreover, our findings shed light on the impact of autumn's diurnal temperature variations and the subsequent drop in temperatures on vine cold hardiness, thus highlighted the complex interplay between environmental temperature dynamics and dormant bud hardiness. In conclusion, our study showed that the cold damage observed in grapevines in North Dakota was not a result of extreme temperature fluctuations in the fall. This was confirmed by testing the vines after they had reached various threshold temperatures through differential thermal analysis (DTA) and optical differential nucleation and expansion analysis (ODNEAL) methodologies, particularly before the onset of severe pre-winter cold conditions. These comprehensive findings highlighted the complexity of the vine's response to climatic conditions and viticultural management, pointing to the need for specific strategies in vineyard management and cultivar selection to optimize bud hardiness and productivity in the face of various environmental challenges, especially in cold climate viticulture.

Epigenetic differences between wild and cultivated grapevines highlight the contribution of DNA methylation during crop domestication.

The domestication process in grapevines has facilitated the fixation of desired traits. Nowadays, vegetative propagation through cuttings enables easier preservation of these genotypes compared to sexual reproduction. Nonetheless, even with vegetative propagation, various phenotypes are often present within the same vineyard due to the accumulation of somatic mutations. These mutations are not the sole factors influencing phenotype. Alongside somatic variations, epigenetic variation has been proposed as a pivotal player in regulating phenotypic variability acquired during domestication. The emergence of these epialleles might have significantly influenced grapevine domestication over time. This study aims to investigate the impact of domestication on methylation patterns in cultivated grapevines. Reduced-representation bisulfite sequencing was conducted on 18 cultivated and wild accessions. Results revealed that cultivated grapevines exhibited higher methylation levels than their wild counterparts. Differential Methylation Analysis between wild and cultivated grapevines identified a total of 9955 differentially methylated cytosines, of which 78% were hypermethylated in cultivated grapevines. Functional analysis shows that core methylated genes (consistently methylated in both wild and cultivated accessions) are associated with stress response and terpenoid/isoprenoid metabolic processes. Meanwhile, genes with differential methylation are linked to protein targeting to the peroxisome, ethylene regulation, histone modifications, and defense response. Collectively, our results highlight the significant roles that epialleles may have played throughout the domestication history of grapevines.

Potential to take root in viticulture? An evaluation of mycorrhizal inoculants on the growth and nutrient uptake of young wine grapes planted in live field soil.

AIMS: Incorporating biofertilizers, such as arbuscular mycorrhizal fungal (AM) fungal inoculants, into vineyard management practices may enhance vine growth and reduce environmental impact. Here, we evaluate the effects of commercially available and local AM fungal inoculants on the growth, root colonization, and nutrient uptake of wine grapes (Vitis vinifera) when planted in a field soil substrate. METHODS AND RESULTS: In a greenhouse experiment, young wine grapes were planted in a field soil substrate and inoculated with one of three commercially available mycorrhizal inoculant products, or one of two locally collected whole soil inoculants. After 4 months of growth, inoculated vines showed no differences in plant biomass, colonization of roots by AM fungi, or foliar macronutrient concentrations compared to uninoculated field soil substrate. However, vines grown with local inoculants had greater shoot biomass than vines grown with mycorrhizal inoculant products. CONCLUSIONS: Although effects from inoculations with AM fungi varied by inoculant type and source, inoculations may not improve young vine performance in field soils with a resident microbial community.

Combination of irradiated chitosan and microbial agent to reduce downy mildew on grapevine cv. Thompson seedless.

Globally sustainable disease management ensuring high quality in grapes is in demand as it holds significant importance as a versatile fruit for consumption, winemaking, and production of various products such as grape juice, raisin, and grape-seed oil. The present paper reports a combination of nano-biotechnology as a promising strategy for enhancing plant health and fruit productivity in grapes combining Irradiated chitosan nanoparticles and bio-control agents. The Irradiated Chitosan with Bacillus subtilis and Trichoderma viridae and pesticides were evaluated for disease management. Percent disease index, percent disease control, and percent yield enhancement in Cymoxanil 8% + Mamcozeb 64% WP @ 0.2% treatment were as 17. 24%, 67.97% and 33.91% in 150 ppm Irradiated chitosan+B. subtilis were 19.83, 63.16, 30.41 and in Trichoderma 150 ppm Irradiated chitosan were 24.58, 54.33, and 27.40, respectively as compared to untreated crop with disease severity 53.84% PDI. Thus, irradiated chitosan and Bacillus subtilis elucidated a synergistic combination for residue-free efficient phytosanitary measures, which harnessed the strength of chitosan and bio-control agents for sustainable grape productivity. These findings will also pave the way for a deeper understanding of the synergistic interaction between Irradiated nanochitosan and bio-control agents for an eco-friendly and economically viable disease management strategy. The minimum temperature and morning relative humidity (RH I) had positive significance, with correlation coefficients of 0.484 and 0.485, respectively. The evening relative humidity (RH II) had a positive highly significant positive correlation coefficient of 0.664. Chitosan merits as a multiple stress tolerance enhancing agent that will further help in mitigating climate change adaptations in grapevines reducing reliance on chemical agro-inputs.

Construction of an Infectious DNA Clone of Grapevine Geminivirus A Isolate GN and Its Biological Activity in Plants Analyzed Using an Efficient and Simple Inoculation Method.

The pathogenicity of grapevine geminivirus A (GGVA), a recently identified DNA virus, to grapevine plants remains largely unclear. Here, we report a new GGVA isolate (named GGVAQN) obtained from grapevine 'Queen Nina' plants with severe disease symptoms. The infectious clone of GGVAQN (pXT-GGVAQN) was constructed to investigate its pathogenicity. Nicotiana benthamiana plants inoculated with GGVAQN by agroinfiltration displayed upward leaf curling and chlorotic mottling symptoms. A simple, quick, and efficient method for delivering DNA clones of GGVAQN into grapevine plants was developed, by which Agrobacterium tumefaciens cells carrying pXT-GGVAQN were introduced into the roots of in vitro-grown 'Red Globe' grape plantlets with a syringe. By this method, all 'Red Globe' grape plants were systemically infected with GGVAQN, and the plants exhibited chlorotic mottling symptoms on their upper leaves and downward curling, interveinal yellowing, and leaf-margin necrosis symptoms on their lower leaves. Our results provide insights into the pathogenicity of GGVA and a simple and efficient inoculation method to deliver infectious viral clones to woody perennial plants.

Monitoring and Genotyping of Wild Grapevine (Vitis vinifera L. subsp. sylvestris) in Slovenia.

Vitis vinifera L. subsp. sylvestris (sylvestris) is the only native wild grapevine in Eurasia (Europe and western Asia) and is the existing ancestor of the grapevine varieties (for wine and table grape production) belonging to the subsp. sativa. In Slovenia, the prevailing opinion has been that there are no Slovenian sylvestris habitats. This study describes sylvestris in Slovenia for the first time and aims to present an overview of the locations of the wild grapevine in the country. In this project, a sample set of 89 accessions were examined using 24 SSR and 2 SSR markers plus APT3 markers to determine flower sex. The accessions were found in forests on the left bank of the Sava River in Slovenia, on the border between alluvial soils and limestone and dolomite soils, five different sites, some of which are described for the first time. The proportion of female to male accessions differed between sites. At two sites, female plants dominated; at others, the ratio was balanced. The plants' genetic diversity and structure were compared with autochthonous and unique varieties of subsp. sativa from old vineyards in Slovenia and with rootstocks escaped from nature from abandoned vineyards. Sylvestris was clearly distinguishable from vinifera and the rootstocks. Based on genetic analyses, it was confirmed that Slovenian sylvestris is closest to the Balkan and German sylvestris groups. Meanwhile, a safety duplication of the wild grapevine accessions has been established at the University Centre of Viticulture and Enology Meranovo, Faculty of Agriculture and Life Sciences at the University of Maribor.

Plant-Derived Bioactive Compounds: Exploring Neuroprotective, Metabolic, and Hepatoprotective Effects for Health Promotion and Disease Prevention.

There is a growing trend among consumers to seek out natural foods and products with natural ingredients. This shift in consumer preferences had a direct impact on both food and pharmaceutical industries, leading to a focus of scientific research and commercial efforts to meet these new demands. The aim of this work is to review recent available scientific data on foods of interest, such as the artichoke, gooseberry, and polygonoideae plants, as well as olive oil and red raspberries. Interestingly, the urgency of solutions to the climate change emergency has brought new attention to by-products of grapevine bunch stem and cane, which have been found to contain bioactive compounds with potential health benefits. There is a pressing need for a faster process of translating scientific knowledge from the laboratory to real-world applications, especially in the face of the increasing societal burden associated with non-communicable diseases (NCDs), environmental crises, the post-pandemic world, and ongoing violent conflicts around the world.

Evaluating treatments for the protection of grapevine pruning wounds from natural infection by trunk disease fungi.

Infection of grapevines by fungal pathogens causing grapevine trunk diseases (GTDs) primarily arises from annual pruning wounds made during the dormant season. While various studies have showcased the efficacy of products in shielding pruning wounds against GTDs infections, most of these investigations hinge on artificial pathogen inoculations, which may not faithfully mirror real field conditions. This study aimed to evaluate and compare the efficacy of various liquid formulation fungicides (pyraclostrobin + boscalid) and paste treatments, as well as biological control agents (BCA: Trichoderma atroviride SC1, T. atroviride I-1237, and T. asperellum ICC012 + T. gamsii ICC080), for their potential to prevent natural infection of grapevine pruning wounds by trunk disease fungi in two field trials located in Samaniego (Northern Spain) and Madiran (Southern France) over three growing seasons. Wound treatments were applied immediately after pruning in February. One year after pruning, canes were harvested from vines and brought to the laboratory for assessment of Trichoderma spp. and fungal trunk pathogens. More than 1,200 fungal isolates associated with five GTDs (esca, Botryophaeria, Diaporthe and Eutypa diebacks, and Cytospora canker) were collected from the two vineyards each growing season. Our findings reveal that none of the products under investigation exhibited complete effectiveness against all the GTDs. The efficacy of these products was particularly influenced by the specific year of study. A notable exception was observed with the biocontrol agent T. atroviride I-1237, which consistently demonstrated effectiveness against Botryosphaeria dieback infections throughout each year of the study, irrespective of the location. The remaining products exhibited efficacy in specific years or locations against particular diseases, with the physical barrier (paste) showing the least overall effectiveness. The recovery rates of Trichoderma spp. in treated plants were highly variable, ranging from 17% to 100%, with both strains of T. atroviride yielding the highest isolation rates. This study underscores the importance of customizing treatments for specific diseases, taking into account the influence of environmental factors for BCA applications.

Effects of Growing Areas, Pruning Wound Protection Products, and Phenological Stage on the Stilbene Composition of Grapevine (Vitis vinifera L.) Canes.

Applying plant protection products (PPP) on grapevine pruning wounds is a viticultural practice used to mitigate the spread of grapevine tuck disease, which is posing serious economic losses in the vine-wine industry. However, the impact of PPP on woody tissues remains unclear. Our study, conducted in two European vineyards, investigated the effects of Cuprocol, Tessior, Esquive, and Bentogran on stilbenes, in canes of Cabernet sauvignon and Syrah, at three phenological stages. Main stilbenes, quantified by HPLC-UV-DAD (1260 Agilent Infinity System) and identified by HPLC-ESI/MS (Thermo Scientific LCQ FLEET system), included E-resveratrol, E-ε-viniferin, E-piceatannol, and E-polydatin. Canes exhibited varying proportions of individual stilbenes, reflecting differences based on climatic conditions and phenological phases, rather than on the application of specific PPP. Vines grown in cool-climate conditions exhibited higher levels of E-resveratrol, whereas vines from the Mediterranean climate area exhibited higher levels of E-ε-viniferin. We also observed divergences in the accumulation trend of wood stilbenes throughout the season in canes collected in the two different growing areas.

Water deficit differentially modulates leaf photosynthesis and transpiration of fungus-tolerant Muscadinia x Vitis hybrids.

Screening for drought performance among novel fungi-tolerant grapevine genotypes is a key point to consider in semiarid regions where water scarcity is a common problem during fruit ripening period. It is therefore important to evaluate the genotypes' responses at the level of carbon metabolism and water demand, under water deficit conditions. This study aimed to characterize leaf and plant water use efficiency (respectively named WUEi and WUEpl) of novel INRAE fungi-tolerant genotypes (including LowSugarBerry (LSB) genotypes), under mild and high-water deficit (WD) and to decipher the photosynthetic parameters leading to higher WUEi. For this purpose, experiments were conducted on potted plants during one season using a phenotyping platform. Two stabilized soil moisture capacity (SMC) conditions, corresponding to mild (SMC 0.6) and high (SMC 0.3) WD, were imposed from the onset of berry ripening until the physiological ripeness stage, which was defined as the point at which fruits reach their maximum solutes and water content. At the whole plant level, all genotypes increased WUEpl under high WD. The highest WUEpl was reached for 3176N, which displayed both a high rate of non-structural carbon accumulation in fruits due to high fruit-to-leaf ratio and low plant transpiration because of low total leaf area. However, when normalizing the fruit-to-leaf ratio among the genotypes, G14 reached the highest normalized WUEpl_n under high WD. At the leaf level, WUEi also increased under high WD, with the highest value attained for G14 and 3176N and the lowest value for Syrah. The higher WUEi values for all genotypes compared to Syrah were associated to higher levels of photosynthesis and changes in light-harvesting efficiency parameters (ΦCO2, qP and qN), while no clear trend was apparent when considering the photosynthetic biochemical parameters (Vcmax, Jmax). Finally, a positive correlation between leaf and plant WUE was observed regardless of genotypes. This study allowed us to classify grapevine genotypes based on their grapes primary metabolite accumulation and water consumption during the critical sugar-loading period. Additionally, the study highlighted the potential drought adaptation mechanism of the LSB genotypes.

Physiological and developmental disturbances caused by Botryosphaeria dieback in the annual stems of grapevine.

Botryosphaeria dieback is a grapevine trunk disease caused by fungi of the Botryosphaeriaceae family, which attacks more specifically the woody tissues. The infection leads to different symptoms including a severe form with a leaf drop as well as premature plant death. Botryosphaeria dieback causes major economic losses, since no effective treatment is yet available. A better understanding is necessary to find solutions to fight this disease. In this study, our objective was to characterize the "leaf drop" form by (1) looking for the presence of pathogens in the basal internodes of stems, (2) quantifying blocked vessels by tylosis and/or gummosis, and (3) describing the impact of the disease on vine physiology (gene expression and metabolome) and development (establishment and functioning of the cambium and phellogen) at the level of xylem and phloem of basal stem internodes. Our study has shown that Botryosphaeriaceae were present in both phloem and xylem of the basal internodes of the annual stem, with xylem vessels obturated. We have also clearly demonstrated that gene expression and metabolite profiles were strongly modified in both xylem and phloem of diseased plants. Differences in stems between healthy (control, C) and diseased (D) plants were low at flowering (vines not yet symptomatic), higher at the onset of symptom expression and still present, although less marked, at full disease expression. qRT-PCR analysis showed in both phloem and xylem an overexpression of genes involved in plant defense, and a repression of genes related to meristematic activity (i.e. vascular cambium and phellogen). Metabolomic analysis showed specific fingerprints in stems of healthy and diseased plants from the onset of symptom expression, with an increase of the level of phytoalexins and mannitol, and a decrease of 1-kestose one. At the structural level, many alterations were observed in internodes, even before the onset of symptoms: a classical obstruction of xylem vessels and, for the first time, a disorganization of the secondary phloem with an obstruction of the sieve plates by callose. The disease modifies the development of both secondary phloem (liber) and phellogen. Altogether, this study combining different approaches allowed to highlight deep vine dysfunction in the internodes at the base of stems, that may explain vine decline due to Botryosphaeria dieback.

The Role of Terroir on the Ripening Traits of V. vinifera cv 'Glera' in the Prosecco Area.

The grapevine (Vitis vinifera L.) is widely cultivated worldwide owing to the substantial commercial value of the grapes and other products derived from their processing, wines in particular. The grapevine is characterized by a remarkable phenotypic plasticity within the same variety, which shapes the final berry quality attributes hence reflecting the complex interactions between the plant and the environment leading to the expression of wine typicity. In this study, we explored the metabolomic and transcriptomic basis of the plasticity of Glera, a white berry grapevine variety particularly renowned for the production of wine Prosecco. The two selected vineyards varied for site altitude and pedoclimatic conditions. We highlighted that these environments determined different berry ripening dynamics at the level of both technological parameters and the total abundance and intrafamily distribution of phenolic compounds. Moreover, a clear impact on the grape aroma profile was observed. The genome-wide gene expression analysis of the berries revealed remarkable differences in the ripening transcriptomic program, reflecting the differences in water status, light exposure, and temperature experienced by the plants while growing at the two sites. Overall, this survey portrayed how the quality attributes of the cv 'Glera' grape berries may be affected by different environmental conditions within the typical area of Prosecco wine production.

Transcriptome Profiling of a Salt Excluder Hybrid Grapevine Rootstock 'Ruggeri' throughout Salinity.

Salinity is one of the substantial threats to plant productivity and could be escorted by other stresses such as heat and drought. It impairs critical biological processes, such as photosynthesis, energy, and water/nutrient acquisition, ultimately leading to cell death when stress intensity becomes uncured. Therefore, plants deploy several proper processes to overcome such hostile circumstances. Grapevine is one of the most important crops worldwide that is relatively salt-tolerant and preferentially cultivated in hot and semi-arid areas. One of the most applicable strategies for sustainable viticulture is using salt-tolerant rootstock such as Ruggeri (RUG). The rootstock showed efficient capacity of photosynthesis, ROS detoxification, and carbohydrate accumulation under salinity. The current study utilized the transcriptome profiling approach to identify the molecular events of RUG throughout a regime of salt stress followed by a recovery procedure. The data showed progressive changes in the transcriptome profiling throughout salinity, underpinning the involvement of a large number of genes in transcriptional reprogramming during stress. Our results established a considerable enrichment of the biological process GO-terms related to salinity adaptation, such as signaling, hormones, photosynthesis, carbohydrates, and ROS homeostasis. Among the battery of molecular/cellular responses launched upon salinity, ROS homeostasis plays the central role of salt adaptation.