Genotyping-by-sequencing-based high-resolution mapping reveals a single candidate gene for the grapevine veraison locus Ver1.

Veraison marks the transition from berry growth to berry ripening and is a crucial phenological stage in grapevine (Vitis vinifera): the berries become soft and begin to accumulate sugars, aromatic substances, and, in red cultivars, anthocyanins for pigmentation, while the organic acid levels begin to decrease. These changes determine the potential quality of wine. However, rising global temperatures lead to earlier flowering and ripening, which strongly influence wine quality. Here, we combined genotyping-by-sequencing with a bioinformatics pipeline on ∼150 F1 genotypes derived from a cross between the early ripening variety 'Calardis Musqué' and the late-ripening variety 'Villard Blanc'. Starting from 20,410 haplotype-based markers, we generated a high-density genetic map and performed a quantitative trait locus analysis based on phenotypic datasets evaluated over 20 years. Through locus-specific-marker-enrichment and recombinant screening of ∼1000 additional genotypes, we refined the originally postulated 5 Mb veraison locus, Ver1, on chromosome 16 to only 112 kb, allowing us to pinpoint the ethylene response factor (ERF) VviERF027 (VCost.v3 gene ID: Vitvi16g00942, CRIBIv1 gene ID: VIT_16s0100g00400) as veraison candidate gene. Furthermore, the early veraison allele could be traced back to a clonal 'Pinot' variant first mentioned in the 17th century. 'Pinot Precoce Noir' passed this allele over 'Madeleine Royale' to the maternal grandparent 'Bacchus Weiss' and, ultimately, to the maternal parent 'Calardis Musqué'. Our findings are crucial for ripening time control, thereby improving wine quality, and for breeding grapevines adjusted to climate change scenarios that have a major impact on agro-ecosystems in altering crop plant phenology.

Determination of Sugars and Acids in Grape Must Using Miniaturized Near-Infrared Spectroscopy.

An automatic determination of grape must ingredients during the harvesting process would support cellar logistics and enables an early termination of the harvest if quality parameters are not met. One of the most important quality-determining characteristics of grape must is its sugar and acid content. Among others, the sugars in particular determine the quality of the must and wine. Chiefly in wine cooperatives, in which a third of all German winegrowers are organized, these quality characteristics serve as the basis for payment. They are acquired upon delivery at the cellar of the cooperative or the winery and result in the acceptance or rejection of grapes and must. The whole process is very time-consuming and expensive, and sometimes grapes that do not meet the quality requirements for sweetness, acidity, or healthiness are destroyed or not used at all, which leads to economic loss. Near-infrared spectroscopy is now a widely used technique to detect a wide variety of ingredients in biological samples. In this study, a miniaturized semi-automated prototype apparatus with a near-infrared sensor and a flow cell was used to acquire spectra (1100 nm to 1350 nm) of grape must at defined temperatures. Data of must samples from four different red and white Vitis vinifera (L.) varieties were recorded throughout the whole growing season of 2021 in Rhineland Palatinate, Germany. Each sample consisted of 100 randomly sampled berries from the entire vineyard. The contents of the main sugars (glucose and fructose) and acids (malic acid and tartaric acid) were determined with high-performance liquid chromatography. Chemometric methods, using partial least-square regression and leave-one-out cross-validation, provided good estimates of both sugars (RMSEP = 6.06 g/L, R2 = 89.26%), as well as malic acid (RMSEP = 1.22 g/L, R2 = 91.10%). The coefficient of determination (R2) was comparable for glucose and fructose with 89.45% compared to 89.08%, respectively. Although tartaric acid was predictable for only two of the four varieties using near-infrared spectroscopy, calibration and validation for malic acid were accurate for all varieties in an equal extent like the sugars. These high prediction accuracies for the main quality determining grape must ingredients using this miniaturized prototype apparatus might enable an installation on a grape harvester in the future.

A cool climate perspective on grapevine breeding: climate change and sustainability are driving forces for changing varieties in a traditional market.

A multitude of diverse breeding goals need to be combined in a new cultivar, which always forces to compromise. The biggest challenge grapevine breeders face is the extraordinarily complex trait of wine quality, which is the all-pervasive and most debated characteristic. Since the 1920s, Germany runs continuous grapevine breeding programmes. This continuity was the key to success and lead to various new cultivars on the market, so called PIWIs. Initially, introduced pests and diseases such as phylloxera, powdery and downy mildew were the driving forces for breeding. However, preconceptions about the wine quality of new resistant selections impeded the market introduction. These preconceptions are still echoing today and may be the reason in large parts of the viticultural community for: (1) ignoring substantial breeding progress, and (2) sticking to successful markets of well-known varietal wines or blends (e.g. Chardonnay, Cabernet Sauvignon, Riesling). New is the need to improve viticulture´s sustainability and to adapt to changing environmental conditions. Climate change with its extreme weather will impose the need for a change in cultivars in many wine growing regions. Therefore, a paradigm shift is knocking on the door: new varieties (PIWIs) versus traditional varieties for climate adapted and sustainable viticulture. However, it will be slow process and viticulture is politically well advised to pave the way to variety innovation. In contrast to the widely available PIWIs, competitive cultivars created by means of new breeding technologies (NBT, e.g. through CRISPR/Cas) are still decades from introduction to the market.

A 69 kbp Deletion at the Berry Color Locus Is Responsible for Berry Color Recovery in Vitis vinifera L. Cultivar 'Riesling Rot'.

'Riesling Weiss' is a white grapevine variety famous worldwide for fruity wines with higher acidity. Hardly known is 'Riesling Rot', a red-berried variant of 'Riesling Weiss' that disappeared from commercial cultivation but has increased in awareness in the last decades. The question arises of which variant, white or red, is the original and, consequently, which cultivar is the true ancestor. Sequencing the berry color locus of 'Riesling Rot' revealed a new VvmybA gene variant in one of the two haplophases called VvmybA3/1RR. The allele displays homologous recombination of VvmybA3 and VvmybA1 with a deletion of about 69 kbp between both genes that restores VvmybA1 transcripts. Furthermore, analysis of 'Riesling Weiss', 'Riesling Rot', and the ancestor 'Heunisch Weiss' along chromosome 2 using SSR (simple sequence repeat) markers elucidated that the haplophase of 'Riesling Weiss' was inherited from the white-berried parent variety 'Heunisch Weiss'. Since no color mutants of 'Heunisch Weiss' are described that could have served as allele donors, we concluded that, in contrast to the public opinion, 'Riesling Rot' resulted from a mutational event in 'Riesling Weiss' and not vice versa.

Mutations in the miR396 binding site of the growth-regulating factor gene VvGRF4 modulate inflorescence architecture in grapevine.

Bunch rot caused by Botrytis cinerea infections is a notorious problem in grapevine cultivation. To produce high quality fruits, grapevine plants are treated with fungicides, which is cost intensive and harmful to the environment. Conversely, loose cluster bunches show a considerably enhanced physical resilience to bunch diseases. With the aim to identify genetic determinants that modulate the development of bunch architecture, we have compared loose and compact 'Pinot noir' clones. Loose cluster architecture was found to be correlated with increased berry size, elongated rachis and elongated pedicels. Using transcriptome analysis in combination with whole genome sequencing, we have identified a growth-regulating factor gene, VvGRF4, upregulated and harbours heterozygous mutations in the loose cluster clones. At late stages of inflorescence development, the mRNA pools of loose cluster clones contain predominantly mRNAs derived from the mutated alleles, which are resistant to miR396 degradation. Expression of the VvGRF4 gene and its mutated variants in Arabidopsis demonstrates that it promotes pedicel elongation. Taken together, VvGRF4 modulates bunch architecture in grapevine 'Pinot noir' clones. This trait can be introduced into other cultivars using marker-assisted breeding or CRISPR-Cas9 technology. Related growth-regulating factors or other genes of the same pathway may have similar functions.

Transcriptomic analysis of temporal shifts in berry development between two grapevine cultivars of the Pinot family reveals potential genes controlling ripening time.

BACKGROUND: Grapevine cultivars of the Pinot family represent clonally propagated mutants with major phenotypic and physiological differences, such as different colour or shifted ripening time, as well as changes in important viticultural traits. Specifically, the cultivars 'Pinot Noir' (PN) and 'Pinot Noir Precoce' (PNP, early ripening) flower at the same time, but vary in the beginning of berry ripening (veraison) and, consequently, harvest time. In addition to genotype, seasonal climatic conditions (i.e. high temperatures) also affect ripening times. To reveal possible regulatory genes that affect the timing of veraison onset, we investigated differences in gene expression profiles between PN and PNP throughout berry development with a closely meshed time series and over two separate years. RESULTS: The difference in the duration of berry formation between PN and PNP was quantified to be approximately two weeks under the growth conditions applied, using plant material with a proven PN and PNP clonal relationship. Clusters of co-expressed genes and differentially expressed genes (DEGs) were detected which reflect the shift in the timing of veraison onset. Functional annotation of these DEGs fit to observed phenotypic and physiological changes during berry development. In total, we observed 3,342 DEGs in 2014 and 2,745 DEGs in 2017 between PN and PNP, with 1,923 DEGs across both years. Among these, 388 DEGs were identified as veraison-specific and 12 were considered as berry ripening time regulatory candidates. The expression profiles revealed two candidate genes for ripening time control which we designated VviRTIC1 and VviRTIC2 (VIT_210s0071g01145 and VIT_200s0366g00020, respectively). These genes likely contribute the phenotypic differences observed between PN and PNP. CONCLUSIONS: Many of the 1,923 DEGs show highly similar expression profiles in both cultivars if the patterns are aligned according to developmental stage. In our work, putative genes differentially expressed between PNP and PN which could control ripening time as well as veraison-specific genes were identified. We point out connections of these genes to molecular events during berry development and discuss potential candidate genes which may control ripening time. Two of these candidates were observed to be differentially expressed in the early berry development phase. Several down-regulated genes during berry ripening are annotated as auxin response factors / ARFs. Conceivably, general changes in auxin signaling may cause the earlier ripening phenotype of PNP.

Differential expression of transcription factor- and further growth-related genes correlates with contrasting cluster architecture in Vitis vinifera 'Pinot Noir' and Vitis spp. genotypes.

Grapevine (Vitis vinifera L.) is an economically important crop that needs to comply with high quality standards for fruit, juice and wine production. Intense plant protection is required to avoid fungal damage. Grapevine cultivars with loose cluster architecture enable reducing protective treatments due to their enhanced resilience against fungal infections, such as Botrytis cinerea-induced gray mold. A recent study identified transcription factor gene VvGRF4 as determinant of pedicel length, an important component of cluster architecture, in samples of two loose and two compact quasi-isogenic 'Pinot Noir' clones. Here, we extended the analysis to 12 differently clustered 'Pinot Noir' clones from five diverse clonal selection programs. Differential gene expression of these clones was studied in three different locations over three seasons. Two phenotypically opposite clones were grown at all three locations and served for standardization. Data were correlated with the phenotypic variation of cluster architecture sub-traits. A set of 14 genes with consistent expression differences between loosely and compactly clustered clones-independent from season and location-was newly identified. These genes have annotations related to cellular growth, cell division and auxin metabolism and include two more transcription factor genes, PRE6 and SEP1-like. The differential expression of VvGRF4 in relation to loose clusters was exclusively found in 'Pinot Noir' clones. Gene expression studies were further broadened to phenotypically contrasting F1 individuals of an interspecific cross and OIV reference varieties of loose cluster architecture. This investigation confirmed PRE6 and six growth-related genes to show differential expression related to cluster architecture over genetically divergent backgrounds.

Identification of co-located QTLs and genomic regions affecting grapevine cluster architecture.

Loose cluster architecture is an important aim in grapevine breeding since it has high impact on the phytosanitary status of grapes. This investigation analyzed the contributions of individual cluster sub-traits to the overall trait of cluster architecture. Six sub-traits showed large impact on cluster architecture as major determinants. They explained 57% of the OIV204 descriptor for cluster compactness rating in a highly diverse cross-population of 149 genotypes. Genetic analysis revealed several genomic regions involved in the expression of this trait. Based on the linkage of phenotypic features to molecular markers, QTL calculations shed new light on the genetic determinants of cluster architecture. Eight QTL clusters harbor overlapping confidence intervals of up to four co-located QTLs. A physical projection of the QTL clusters by confidence interval-flanking markers onto the PN40024 reference genome sequence revealed genes enriched in these regions.

High-Precision Phenotyping of Grape Bunch Architecture Using Fast 3D Sensor and Automation.

Wine growers prefer cultivars with looser bunch architecture because of the decreased risk for bunch rot. As a consequence, grapevine breeders have to select seedlings and new cultivars with regard to appropriate bunch traits. Bunch architecture is a mosaic of different single traits which makes phenotyping labor-intensive and time-consuming. In the present study, a fast and high-precision phenotyping pipeline was developed. The optical sensor Artec Spider 3D scanner (Artec 3D, L-1466, Luxembourg) was used to generate dense 3D point clouds of grapevine bunches under lab conditions and an automated analysis software called 3D-Bunch-Tool was developed to extract different single 3D bunch traits, i.e., the number of berries, berry diameter, single berry volume, total volume of berries, convex hull volume of grapes, bunch width and bunch length. The method was validated on whole bunches of different grapevine cultivars and phenotypic variable breeding material. Reliable phenotypic data were obtained which show high significant correlations (up to r² = 0.95 for berry number) compared to ground truth data. Moreover, it was shown that the Artec Spider can be used directly in the field where achieved data show comparable precision with regard to the lab application. This non-invasive and non-contact field application facilitates the first high-precision phenotyping pipeline based on 3D bunch traits in large plant sets.

Phenoliner: A New Field Phenotyping Platform for Grapevine Research.

In grapevine research the acquisition of phenotypic data is largely restricted to the field due to its perennial nature and size. The methodologies used to assess morphological traits and phenology are mainly limited to visual scoring. Some measurements for biotic and abiotic stress, as well as for quality assessments, are done by invasive measures. The new evolving sensor technologies provide the opportunity to perform non-destructive evaluations of phenotypic traits using different field phenotyping platforms. One of the biggest technical challenges for field phenotyping of grapevines are the varying light conditions and the background. In the present study the Phenoliner is presented, which represents a novel type of a robust field phenotyping platform. The vehicle is based on a grape harvester following the concept of a moveable tunnel. The tunnel it is equipped with different sensor systems (RGB and NIR camera system, hyperspectral camera, RTK-GPS, orientation sensor) and an artificial broadband light source. It is independent from external light conditions and in combination with artificial background, the Phenoliner enables standardised acquisition of high-quality, geo-referenced sensor data.

Quantitative trait loci affecting pathogen resistance and ripening of grapevines.

Grapevines (Vitis vinifera L.) form the basis of viticulture, and are susceptible to diseases such as downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator). Therefore, successful viticulture programs require the use of pesticides. Breeding for resistance is the only eco-friendly solution. Marker-assisted selection is currently widely used for grapevine breeding. Consequently, traits of interest must be tagged with molecular markers linked to quantitative trait loci (QTL). We herein present our findings regarding genetic mapping and QTL analysis of resistance to downy and powdery mildew diseases in the progenies of the GF.GA-47-42 ('Bacchus' × 'Seyval') × 'Villard blanc' cross. Simple sequence repeats and single nucleotide polymorphisms of 151 individuals were analyzed. A map consisting of 543 loci was screened for QTL analyses based on phenotypic variations observed in plants grown in the field or under controlled conditions. A major QTL for downy mildew resistance was detected on chromosome 18. For powdery mildew resistance, a QTL was identified on chromosome 15. This QTL was replaced by a novel QTL on chromosome 18 in 2003 (abnormally high temperatures) and 2004. Subsequently, both QTLs functioned together. Additionally, variations in the timing of the onset of veraison, which is a crucial step during grape ripening, were studied to identify genomic regions affecting this trait. A major QTL was detected on linkage group 16, which was supplemented by a minor QTL on linkage group 18. This study provides useful information regarding novel QTL-linked markers relevant for the breeding of disease-resistant grapevines adapted to current climatic conditions.

Towards Automated Large-Scale 3D Phenotyping of Vineyards under Field Conditions.

In viticulture, phenotypic data are traditionally collected directly in the field via visual and manual means by an experienced person. This approach is time consuming, subjective and prone to human errors. In recent years, research therefore has focused strongly on developing automated and non-invasive sensor-based methods to increase data acquisition speed, enhance measurement accuracy and objectivity and to reduce labor costs. While many 2D methods based on image processing have been proposed for field phenotyping, only a few 3D solutions are found in the literature. A track-driven vehicle consisting of a camera system, a real-time-kinematic GPS system for positioning, as well as hardware for vehicle control, image storage and acquisition is used to visually capture a whole vine row canopy with georeferenced RGB images. In the first post-processing step, these images were used within a multi-view-stereo software to reconstruct a textured 3D point cloud of the whole grapevine row. A classification algorithm is then used in the second step to automatically classify the raw point cloud data into the semantic plant components, grape bunches and canopy. In the third step, phenotypic data for the semantic objects is gathered using the classification results obtaining the quantity of grape bunches, berries and the berry diameter.

Field phenotyping of grapevine growth using dense stereo reconstruction.

BACKGROUND: The demand for high-throughput and objective phenotyping in plant research has been increasing during the last years due to large experimental sites. Sensor-based, non-invasive and automated processes are needed to overcome the phenotypic bottleneck, which limits data volumes on account of manual evaluations. A major challenge for sensor-based phenotyping in vineyards is the distinction between the grapevine in the foreground and the field in the background - this is especially the case for red-green-blue (RGB) images, where similar color distributions occur both in the foreground plant and in the field and background plants. However, RGB cameras are a suitable tool in the field because they provide high-resolution data at fast acquisition rates with robustness to outdoor illumination. RESULTS: This study presents a method to segment the phenotypic classes 'leaf', 'stem', 'grape' and 'background' in RGB images that were taken with a standard consumer camera in vineyards. Background subtraction is achieved by taking two images of each plant for depth reconstruction. The color information is furthermore used to distinguish the leaves from stem and grapes in the foreground. The presented approach allows for objective computation of phenotypic traits like 3D leaf surface areas and fruit-to-leaf ratios. The method has been successfully applied to objective assessment of growth habits of new breeding lines. To this end, leaf areas of two breeding lines were monitored and compared with traditional cultivars. A statistical analysis of the method shows a significant (p <0.001) determination coefficient R (2)= 0.93 and root-mean-square error of 3.0%. CONCLUSIONS: The presented approach allows for non-invasive, fast and objective assessment of plant growth. The main contributions of this study are 1) the robust segmentation of RGB images taken from a standard consumer camera directly in the field, 2) in particular, the robust background subtraction via reconstruction of dense depth maps, and 3) phenotypic applications to monitoring of plant growth and computation of fruit-to-leaf ratios in 3D. This advance provides a promising tool for high-throughput, automated image acquisition, e.g., for field robots.

Impedance of the grape berry cuticle as a novel phenotypic trait to estimate resistance to Botrytis cinerea.

Warm and moist weather conditions during berry ripening provoke Botrytis cinerea (B. cinerea) causing notable bunch rot on susceptible grapevines with the effect of reduced yield and wine quality. Resistance donors of genetic loci to increase B. cinerea resistance are widely unknown. Promising traits of resistance are represented by physical features like the thickness and permeability of the grape berry cuticle. Sensor-based phenotyping methods or genetic markers are rare for such traits. In the present study, the simple-to-handle I-sensor was developed. The sensor enables the fast and reliable measurement of electrical impedance of the grape berry cuticles and its epicuticular waxes (CW). Statistical experiments revealed highly significant correlations between relative impedance of CW and the resistance of grapevines to B. cinerea. Thus, the relative impedance Zrel of CW was identified as the most important phenotypic factor with regard to the prediction of grapevine resistance to B. cinerea. An ordinal logistic regression analysis revealed a R2McFadden of 0.37 and confirmed the application of Zrel of CW for the prediction of bunch infection and in this way as novel phenotyping trait. Applying the I-sensor, a preliminary QTL region was identified indicating that the novel phenotypic trait is as well a valuable tool for genetic analyses.

An automated field phenotyping pipeline for application in grapevine research.

Due to its perennial nature and size, the acquisition of phenotypic data in grapevine research is almost exclusively restricted to the field and done by visual estimation. This kind of evaluation procedure is limited by time, cost and the subjectivity of records. As a consequence, objectivity, automation and more precision of phenotypic data evaluation are needed to increase the number of samples, manage grapevine repositories, enable genetic research of new phenotypic traits and, therefore, increase the efficiency in plant research. In the present study, an automated field phenotyping pipeline was setup and applied in a plot of genetic resources. The application of the PHENObot allows image acquisition from at least 250 individual grapevines per hour directly in the field without user interaction. Data management is handled by a database (IMAGEdata). The automatic image analysis tool BIVcolor (Berries in Vineyards-color) permitted the collection of precise phenotypic data of two important fruit traits, berry size and color, within a large set of plants. The application of the PHENObot represents an automated tool for high-throughput sampling of image data in the field. The automated analysis of these images facilitates the generation of objective and precise phenotypic data on a larger scale.

QTL mapping of black rot (Guignardia bidwellii) resistance in the grapevine rootstock 'Börner' (V. riparia Gm183 × V. cinerea Arnold).

KEY MESSAGE: In the grapevine cultivar 'Börner' QTLs for black rot resistance were detected consistently in several independent experiments. For one QTL on chromosome 14 closely linked markers were developed and a detailed map provided. Black rot is a serious grapevine disease that causes substantial yield loss under unfavourable conditions. All traditional European grapevine cultivars are susceptible to the causative fungus Guignardia bidwellii which is native to North America. The cultivar 'Börner', an interspecific hybrid of V. riparia and V. cinerea, shows a high resistance to black rot. Therefore, a mapping population derived from the cross of the susceptible breeding line V3125 ('Schiava grossa' × 'Riesling') with 'Börner' was used to carry out QTL analysis. A resistance test was established based on potted plants which were artificially inoculated in a climate chamber with in vitro produced G. bidwellii spores. Several rating systems were developed and tested. Finally, a five class scheme was applied for scoring the level of resistance. A major QTL was detected based on a previously constructed genetic map and data from six independent resistance tests in the climate chamber and one rating of natural infections in the field. The QTL is located on linkage group 14 (Rgb1) and explained up to 21.8 % of the phenotypic variation (LOD 10.5). A second stable QTL mapped on linkage group 16 (Rgb2; LOD 4.2) and explained 8.5 % of the phenotypic variation. These two QTLs together with several minor QTLs observed on the integrated map indicate a polygenic nature of the black rot resistance in 'Börner'. A detailed genetic map is presented for the locus Rgb1 with tightly linked markers valuable for the development for marker-assisted selection for black rot resistance in grapevine breeding.

QTL analysis of flowering time and ripening traits suggests an impact of a genomic region on linkage group 1 in Vitis.

In the recent past, genetic analyses of grapevine focused mainly on the identification of resistance loci for major diseases such as powdery and downy mildew. Currently, breeding programs make intensive use of these results by applying molecular markers linked to the resistance traits. However, modern genetics also allows to address additional agronomic traits that have considerable impact on the selection of grapevine cultivars. In this study, we have used linkage mapping for the identification and characterization of flowering time and ripening traits in a mapping population from a cross of V3125 ('Schiava Grossa' × 'Riesling') and the interspecific rootstock cultivar 'Börner' (Vitis riparia × Vitis cinerea). Comparison of the flowering time QTL mapping with data derived from a second independent segregating population identified several common QTLs. Especially a large region on linkage group 1 proved to be of special interest given the genetic divergence of the parents of the two populations. The proximity of the QTL region contains two CONSTANS-like genes. In accordance with data from other plants such as Arabidopsis thaliana and Oryza sativa, we hypothesize that these genes are major contributors to control the time of flowering in Vitis.

Phased grapevine genome sequence of an Rpv12 carrier for biotechnological exploration of resistance to Plasmopara viticola.

The downy mildew disease caused by the oomycete Plasmopara viticola is a serious threat for grapevine and can cause enormous yield losses in viticulture. The quantitative trait locus Rpv12, mediating resistance against P. viticola, was originally found in Asian Vitis amurensis. This locus and its genes were analyzed here in detail. A haplotype-separated genome sequence of the diploid Rpv12-carrier Gf.99-03 was created and annotated. The defense response against P. viticola was investigated in an infection time-course RNA-seq experiment, revealing approximately 600 upregulated Vitis genes during host-pathogen interaction. The Rpv12 regions of the resistance and the sensitivity encoding Gf.99-03 haplotype were structurally and functionally compared with each other. Two different clusters of resistance-related genes were identified within the Rpv12 locus. One cluster carries a set of four differentially expressed genes with three ACCELERATED CELL DEATH 6-like genes. The other cluster carries a set of six resistance gene analogs related to qualitative pathogen resistance. The Rpv12 locus and its candidate genes for P. viticola resistance provide a precious genetic resource for P. viticola resistance breeding. Newly developed co-segregating simple sequence repeat markers in close proximity to the R-genes enable its improved applicability in marker-assisted grapevine breeding.

Deep incorporation of organic amendments into soils of a 'Calardis Musqué' vineyard: effects on greenhouse gas emissions, vine vigor, and grape quality.

Background: Traditional wine growing regions are increasingly endangered by climatic alterations. One promising approach to mitigate advancing climate change could be an increase of soil organic matter. Here, especially subsoils are of interest as they provide higher carbon storage potential than topsoils. In this context, vineyard subsoils could be particularly suitable since they are deeply cultivated once before planting and afterwards, left at rest for several decades due to the perennial nature of grapevines. Methods: For this purpose, a biochar compost substrate and greenwaste compost were incorporated in up to 0.6 m depth before planting a new experimental vineyard with the fungus-resistant grapevine cultivar 'Calardis Musqué'. The influence of this deep incorporation on greenhouse gas emissions and grapevine performance was evaluated and compared to a non-amended control using sensor-based analyses. Results: Increased CO2 emissions and lower N2O emissions were found for the incorporation treatments compared to the control, but these differences were not statistically significant due to high spatial variability. Only few plant traits like chlorophyll content or berry cuticle characteristics were significantly affected in some of the experimental years. Over the course of the study, annual climatic conditions had a much stronger influence on plant vigor and grape quality than the incorporated organic amendments. Discussion: In summary, organic soil amendments and their deep incorporation did not have any significant effect on greenhouse gas emissions and no measurable or only negligible effect on grapevine vigor, and grape quality parameters. Thus, according to our study the deposition of organic amendments in vineyard subsoils seems to be an option for viticulture to contribute to carbon storage in soils in order to mitigate climate change.

Wild grapes of Armenia: unexplored source of genetic diversity and disease resistance.

The present study is the first in-depth research evaluating the genetic diversity and potential resistance of Armenian wild grapes utilizing DNA-based markers to understand the genetic signature of this unexplored germplasm. In the proposed research, five geographical regions with known viticultural history were explored. A total of 148 unique wild genotypes were collected and included in the study with 48 wild individuals previously collected as seed. A total of 24 nSSR markers were utilized to establish a fingerprint database to infer information on the population genetic diversity and structure. Three nSSR markers linked to the Ren1 locus were analyzed to identify potential resistance against powdery mildew. According to molecular fingerprinting data, the Armenian V. sylvestris gene pool conserves a high genetic diversity, displaying 292 different alleles with 12.167 allele per loci. The clustering analyses and diversity parameters supported eight genetic groups with 5.6% admixed proportion. The study of genetic polymorphism at the Ren1 locus revealed that 28 wild genotypes carried three R-alleles and 34 wild genotypes carried two R-alleles associated with PM resistance among analyzed 107 wild individuals. This gene pool richness represents an immense reservoir of under-explored genetic diversity and breeding potential. Therefore, continued survey and research efforts are crucial for the conservation, sustainable management, and utilization of Armenian wild grape resources in the face of emerging challenges in viticulture.