Grapevine Breeding Research Articles

Genetic diversity, population structure and parentage analysis of Brazilian grapevine hybrids after half a century of genetic breeding

In the 1940s, the Agronomic Institute of Campinas (IAC) started a grapevine breeding program to develop new cultivars adapted to the tropical and subtropical regions of Brazil. More than 2,000 crosses were carried out over 50 years, using 850 varieties as parents. However, among the thousands of hybrids developed by the program, only 130 are still maintained in the IAC grapevine germplasm collection. Little is known about their genetic makeup and usefulness for current breeding programs. In this study, we genotyped 130 Brazilian grape hybrids at 21 polymorphic microsatellite markers to evaluate the genetic diversity and population structure of the hybrids and verified their disclosed pedigrees. The results showed that the hybrid collection is highly diverse, with an expected heterozygosity (HE) of 0.80 and an observed heterozygosity (Ho) of 0.78. Strong structure in three subgroups based mainly on the usage and combination of parental groups was revealed by STRUCTURE software and confirmed by discriminant analysis of principal components (DAPC). Through molecular profiling analysis, fourteen synonyms, one homonym and one duplicate were identified. Parentage analysis confirmed 24 full parentages, as well as 33 half-kinships. In addition, 18 pedigrees were invalidated, and seven mislabeling events were identified. No compatible parent was identified for 33% of the IAC hybrids, highlighting severe genetic erosion in the IAC germplasm. The molecular characterization of the breeding hybrid bank collection contributes to our understanding of the genetic basis of the varieties, guiding the efficient utilization of available genetic diversity. Together, our results could be applied to other breeding programs and assist in the selection of parents, management of the breeding collection, and conservation of grapevine genetic resources.

Integrative genomic and transcriptomic analyses of a bud sport mutant 'Jinzao Wuhe' with the phenotype of large berries in grapevines.

Bud sport mutation occurs frequently in fruit plants and acts as an important approach for grapevine improvement and breeding. 'Jinzao Wuhe' is a bud sport of the elite cultivar 'Himord Seedless' with obviously enlarged organs and berries. To date, the molecular mechanisms underlying berry enlargement caused by bud sport in grapevines remain unclear. Whole genome resequencing (WGRS) was performed for two pairs of bud sports and their maternal plants with similar phenotype to identify SNPs, InDels and structural variations (SVs) as well as related genes. Furthermore, transcriptomic sequencing at different developmental stages and weighted gene co-expression network analysis (WGCNA) for 'Jinzao Wuhe' and its maternal plant 'Himord Seedless' were carried out to identify the differentially expressed genes (DEGs), which were subsequently analyzed for Gene Ontology (GO) and function annotation. In two pairs of enlarged berry bud sports, a total of 1,334 SNPs, 272 InDels and 74 SVs, corresponding to 1,022 target genes related to symbiotic microorganisms, cell death and other processes were identified. Meanwhile, 1,149 DEGs associated with cell wall modification, stress-response and cell killing might be responsible for the phenotypic variation were also determined. As a result, 42 DEGs between 'Himord Seedless' and 'Jinzao Wuhe' harboring genetic variations were further investigated, including pectin esterase, cellulase A, cytochromes P450 (CYP), UDP-glycosyltransferase (UGT), zinc finger protein, auxin response factor (ARF), NAC transcription factor (TF), protein kinase, etc. These candidate genes offer important clues for a better understanding of developmental regulations of berry enlargement in grapevine. Our results provide candidate genes and valuable information for dissecting the underlying mechanisms of berry development and contribute to future improvement of grapevine cultivars.

Desempenho vitícola de diferentes seleções avançadas de videiras resistentes a doenças fúngicas em três diferentes altitudes no Sul do Brasil

Abstract The objective of this work was to characterize the phenology and the viticultural performance of advanced selections of grapevines resistant to fungal diseases obtained by the Julius Kühn Institute, Institute for Grapevine Breeding Geilweilerhof. The experiment was conducted in three different grape-growing regions of Santa Catarina State, Brazil, in the municipalities of Videira (840 m), São Joaquim (1110 m) and Curitibanos (1000 m) during the seasons of 2018/2019 and 2019/2020. The advanced selections evaluated were the reds Gf.2004-043-0010 (Gf.10), Gf.2004-043-0013 (Gf.13), Gf.2004-043-0021(Gf.21) and the white Gf.2004-043-0004 (Gf.04). We found that pyramided loci Rpv1+Rpv3.1 and Run1+Ren3 were present, which confer resistance to downy mildew and powdery mildew, respectively. The phenological stages events evaluated were budbreak, full bloom, veraison and maturity. The productive variables evaluated were fertility index, number of clusters, cluster weight and yield. Technological maturity parameters were soluble solids, total acidity and pH. To understand the relationship between the variables and whether these relationships changed depending on the cultivation environment the Multi-Trait Genotype–Ideotype Distance Index was used to rank the genotypes based on the analyzed traits. For most selections, the budbreak occurred in the second half of September; full bloom occurred from late October to mid-November; the veraison occurred between the end of December and mid-January; and maturity occurred between the end of January and February. The earliest budbreak occurred in the vineyard located at the highest altitude (1110 m - São Joaquim), while the earliest full bloom, veraison and maturity occurred in the lowest altitude vineyard (840 m – Videira). All selections produced grapes with adequate concentrations of pH and total acidity to produce quality wines. Except for Gf.13, all selections produced grapes with levels of soluble solids suitable to produce quality wines. Based on the Multi-Trait Genotype–Ideotype Distance Index (MGIDI) the selections Gf.13 and Gf.10 are the most promising genotypes for the Videira region (840 m) and Gf.10 is the most promising genotype for the regions of higher altitude, 1000 m and 1110 m.

Dissection of the Pearl of Csaba pedigree identifies key genomic segments related to early ripening in grape.

Pearl of Csaba (PC) is a valuable backbone parent for early-ripening grapevine (Vitis vinifera) breeding, from which many excellent early ripening varieties have been bred. However, the genetic basis of the stable inheritance of its early ripening trait remains largely unknown. Here, the pedigree, consisting of 40 varieties derived from PC, was re-sequenced for an average depth of ∼30×. Combined with the resequencing data of 24 other late-ripening varieties, 5,795,881 high-quality single nucleotide polymorphisms (SNPs) were identified following a strict filtering pipeline. The population genetic analysis showed that these varieties could be distinguished clearly, and the pedigree was characterized by lower nucleotide diversity and stronger linkage disequilibrium than the non-pedigree varieties. The conserved haplotypes (CHs) transmitted in the pedigree were obtained via identity-by-descent analysis. Subsequently, the key genomic segments were identified based on the combination analysis of haplotypes, selective signatures, known ripening-related quantitative trait loci (QTLs), and transcriptomic data. The results demonstrated that varieties with a superior haplotype, H1, significantly (one-way ANOVA, P < 0.001) exhibited early grapevine berry development. Further analyses indicated that H1 encompassed VIT_16s0039g00720 encoding a folate/biopterin transporter protein (VvFBT) with a missense mutation. VvFBT was specifically and highly expressed during grapevine berry development, particularly at veraison. Exogenous folate treatment advanced the veraison of "Kyoho". This work uncovered core haplotypes and genomic segments related to the early ripening trait of PC and provided an important reference for the molecular breeding of early-ripening grapevine varieties.

Development of a High-Density Genetic Map for Muscadine Grape Using a Mapping Population from Selfing of the Perfect-Flowered Vine ‘Dixie’

Intraspecific diversity of the immune grape Muscadinia rotundifolia Michaux. can serve as a rich source of valuable resistance loci to the most widespread pathogens and pests of grapevine. While only one Run1/Rpg1 resistance locus has been introgressed from M. rotundifolia to the Vitis vinifera gene pool, a number of other genes conferring resistance to powdery mildew and downy mildew have been identified in various Muscadinia cultivars. A larger introduction of Muscadinia varieties to the European continent would greatly facilitate experiments of interspecific crosses as well as stimulate biotechnological efforts to overcome the main barrier to F1 fertility caused by the differences in chromosome number. For the successful introduction of Muscadinia into the new European environment, it is necessary to overcome the difficulties associated with the physiological characteristics of the species, such as insufficient cold tolerance and very late fruit ripening. To facilitate the further discovery of valuable loci in Muscadinia and their transfer to grapevine breeding programs, we constructed a high-density linkage map using an S1 mapping population obtained from the self-pollination of M. rotundifolia cv. Dixie maintained on the southern coast of Crimea. Using ddRADseq, 3730 SNPs were ordered across 20 linkage groups spanning 2753.6 cM of the total map length. No segregation in resistance to diseases and pests was observed among the 'Dixie' S1 population, suggesting the presence of homozygous non-segregating resistant loci in the genetic background of 'Dixie'. Markers with high segregation distortion showed a bias towards chromosomal intervals on linkage groups 10 and 20, where loci affecting the survival of 'Dixie' S1 progeny may be localized. QTLs with significant additive and dominance effects were discovered on LG14 and LG18, affecting the morphological traits associated with the vigor of growth and adaptability of young Muscadinia vines in the conditions of Crimea.

Relieving the Phenotyping Bottleneck for Grape Bunch Architecture in Grapevine Breeding Research: Implementation of a 3D-Based Phenotyping Approach for Quantitative Trait Locus Mapping

In viticulture, winemakers and the industry demand grape bunches that have a reduced degree of bunch compactness. The major aspect is that a loose bunch compactness reduces the risk of severe Botrytis bunch-rot infections. Grapevine breeders focus hereby on several bunch-architecture-related traits. For specific breeding approaches and breeding-research-related topics, such as Quantitative Trait Locus (QTL) analysis or molecular marker development, the exact and objective phenotyping of such traits is mandatory. In this study, a precise and high-throughput 3D phenotyping pipeline was applied to screen 1514 genotypes from three mapping populations with different genetic backgrounds to investigate its applicability for QTL mapping approaches. In the first step, the phenotypic data of one population containing 150 genotypes were collected and analyzed with the 3D phenotyping pipeline. Additionally, corresponding reference data were obtained. Phenotypic values and results of a QTL analysis were compared with each other. Strongly positive correlations up to r = 0.93 between 3D and reference measurements could be detected for several traits. The ten-times-faster 3D phenotyping pipeline revealed 20, and the reference phenotyping methods revealed 22 QTLs. Eighteen of these QTLs were consistent between both procedures. In the next step, screening was extended to four different mapping populations across several seasons. In total, up to 1500 genotypes were screened during one season (&gt;5000 grape bunches in total). The data analysis revealed significant differences across years and populations. Three bunch-architecture traits, including total berry volume, bunch width, and berry diameter, explained the highest amount of variability in the phenotypic data. A QTL analysis was performed on the phenotypic data of the involved populations to identify comparative genetic loci for bunch-architecture traits. Between 20 and 26 stable and reproducible QTLs for the investigated populations were detected. A common QTL for berry diameter could be identified for all populations. Our results strongly conclude that this locus is co-located on chromosome 17 when mapped to the grapevine reference genome. The results show that the implementation of the 3D phenotyping platform allows for precise and extended screenings of different, genetic diverse mapping populations and thus opens up the possibility to uncover the genomic architecture of this highly complex quantitative grapevine trait.

ПЕРСПЕКТИВНАЯ МЯГКОСЕМЯННАЯ СТОЛОВАЯ ФОРМА ВИНОГРАДА

The paper is devoted to varietal study and evaluation of grapevine hybrid form 4-6-15, selected for the elite as promising in terms: of high yield, good taste and commercial qualities, and increased disease resistance. The soft-seeded elite seedling of grapevine was obtained by crossing varieties Talisman and Kishmish Luchisty in All-Russian Re-search Ya.I. Potapenko Institute for Viticul-ture and Winemaking – Branch of Federal State Budget Scientific Institution «FRARC». An ampelographic description of the seedling was compiled for leading fea-tures. The vineyards are non-irrigated, graft-ed, covered, fan-shaped, planting scheme 3×1.5 m. In the variety study, methods gen-erally accepted in viticulture and standard vineyard cultivation technology were used. The hybrid form 4-6-15 is characterized by a very early ripening period (106 days from bud break to full ripeness of berries), large berries for the seedless variety (5.3 g), seed-less class IV (weight of rudiments 16,7 mg), very large loose clusters (average weight 705 g), attractive color of berries, increased re-sistance to fungal diseases (mildew 3.0‒3.5 points, oidium 3.5 points, botrytis 2.0‒2.5 points). Frost resistance is average, covering for winter is recommended. The yield is high, 11.5 t/ha, gives a second crop on lateral shoots. We believe that, based on the combination of economically valuable traits, the seedling 4-6-15 can be recom-mended for further use in grapevine breed-ing for seedlessness, the quality of berries in combination with high yields, as well as for backyards viticulture.

Comparing Selection Criteria to Select Grapevine Clones by Water Use Efficiency

The current climate change is forcing growth-adapted genotypes with a higher water use efficiency (WUE). However, the evaluation of WUE is being made by different direct and indirect parameters such as the instantaneous leaf WUE (WUEi) and isotopic discrimination of carbon (δ13C) content of fruits. In the present work, WUE has been evaluated in these two ways in a wide collection of grapevine genotypes, including Tempranillo and Garnacha clones, and Tempranillo on different rootstocks (T-rootstocks). A total of 70 genotypes have been analysed in four experimental fields over two years. The parameters used to measure WUE were the bunch biomass isotopic discrimination (δ13C) and the intrinsic WUE (WUEi), defined as the ratio between net CO2 assimilation and stomatal conductance. The genotypes with the highest and lowest WUE were identified, differences between them being found to be of more than 10%. Generally, the two parameters showed coincidences in the clones with the highest and lowest WUE, suggesting that both are valuable tools to classify genotypes by their WUE in grapevine breeding programs. However, δ13C seemed to be a better indicator for determining WUE because it represents the integration over the synthesis time of the sample analysed (mainly sugars from ripening grapes), which coincides with the driest period for the crop. Moreover, the WUEi is a variable parameter in the plant and it is more dependent on the environmental conditions. The present work suggests that carbon isotopic discrimination could be an interesting parameter for the clonal selection criteria in grapevines by WUE. The main reasons were its better discrimination between clones, the fact that sampling is less time-consuming and easier to do than WUEi, and that the samples can be stored for late determinations, increasing the number of samples that can be analysed.

Genome-Wide Identification of the Hsp70 Gene Family in Grape and Their Expression Profile during Abiotic Stress

Plants encounter a variety of abiotic stresses such as global climate change. Hsp70, as one of the main families of heat shock proteins (Hsps), has a great role in maintenance of the development and growth, and response to abiotic stress. Grape is a very popular fruit worldwide with a high economic value. However, the Hsp70 gene family has not been thoroughly identified in grape (Vitis vinifera L.). In this study, a total of 33 VvHsp70 genes were identified and divided into four clades in V. vinifera. Phylogenetic analysis, gene structure, conserved motif, and duplication events were performed for VvHsp70 genes. The detailed information showed that the VvHsp70 genes clustered together based on the phylogenetic tree had similar subcellular localization, gene structures, and conserved motifs, although there are exceptions. The expression patterns of VvHsp70, VdHsp70, or VaHsp70 were explored in development and abiotic stress including heat, osmotic, and cold stresses by transcription data or qRT-PCR. The results showed that grape Hsp70 genes had strong response for these abiotic stresses, particularly in heat and cold treatments in a different expression pattern. Most of the VdHsp70 genes were upregulated in response to heat treatments while VaHsp70 genes were downregulated in response to cold treatments. Together, our results revealed a new insight for the Hsp70 gene family in grape and will afford fundamental knowledge for further functional analysis and breeding of stress-tolerant grapevines.

Powdery Mildew Resistance Genes in Vines: An Opportunity to Achieve a More Sustainable Viticulture.

Grapevine (Vitis vinifera) is one of the main fruit crops worldwide. In 2020, the total surface area planted with vines was estimated at 7.3 million hectares. Diverse pathogens affect grapevine yield, fruit, and wine quality of which powdery mildew is the most important disease prior to harvest. Its causal agent is the biotrophic fungus Erysiphe necator, which generates a decrease in cluster weight, delays fruit ripening, and reduces photosynthetic and transpiration rates. In addition, powdery mildew induces metabolic reprogramming in its host, affecting primary metabolism. Most commercial grapevine cultivars are highly susceptible to powdery mildew; consequently, large quantities of fungicide are applied during the productive season. However, pesticides are associated with health problems, negative environmental impacts, and high costs for farmers. In paralleled, consumers are demanding more sustainable practices during food production. Therefore, new grapevine cultivars with genetic resistance to powdery mildew are needed for sustainable viticulture, while maintaining yield, fruit, and wine quality. Two main gene families confer resistance to powdery mildew in the Vitaceae, Run (Resistance to Uncinula necator) and Ren (Resistance to Erysiphe necator). This article reviews the powdery mildew resistance genes and loci and their use in grapevine breeding programs.

A 3D grape bunch reconstruction pipeline based on constraint-based optimisation and restricted reconstruction grammar

• Wine grape bunch architecture reconstruction from a 2D image. • Prediction of invisible bunch elements including their connectivity. • Element-wise comparison improves on existing methods. • Application on a larger scale would facilitate grapevine breeding trials. Phenotypic traits of grapevines are known to be closely related to grapevine yield, wine flavour and sensitivity to disease. Traditional phenotyping methods based on manual measurements face the bottleneck of intensely repetitive and time consuming measurement. As viticulturists turning their focus to the 3D automatic phenotyping domain, existing work on grape bunch phenotyping indicates deficiencies in incomplete reconstruction information, poor element coincidence with the ground truth and poor performance under field conditions. To this end, the proposed work introduces a novel reconstruction pipeline by dividing it into sub-problems of visible-berry-related reconstruction and invisible element prediction. By taking a 2D image of the target bunch as the only sensor input, visible berries are detected using image processing algorithms. With the detected berry information, their morphological positions are predicted, from which internodes that are associated with the detected berries are derived. Parameters of derived internodes are then estimated employing constraint-based optimisation theory, from which the visible-berry-related reconstruction is able to be achieved. Invisible element prediction is then conducted by filling elements according to a Restricted Reconstruction Grammar (RRG). A fully reconstructed bunch model is finally presented. Compared with existing work, the proposed grape bunch reconstruction pipeline achieved an improvement in quantity estimation of rachis internodes, tertiary internodes and pedicels, whose percentage errors were indicated as 21.2, 42.2 and 31.2% respectively. A better performance was also revealed in length estimations of secondary internodes and pedicels with percentage errors of 3.5 and 0.5%. This may largely facilitate related studies on disease control of grape bunches since internode numbers and lengths are closely related to bunch compactness which is the indicator of disease sensitivity. Especially, the proposed reconstruction pipeline shows an promising improvement in element coincidence with F 1 scores of 0.90, 0.77, 0.45, 0.43 for respective element types. Knowing that element coincidence may influence the inner space utilisation of a bunch, the proposed work provides a better option for 3D grape bunch phenotyping.

Marker assisted selection (MAS) for downy mildew resistance in grapevines using Rpv3.1 associated markers

Powdery mildew and downy mildew are primary fungal diseases that cause significant damage in viticulture. Therefore, breeding powdery and/or downy mildew resistance is one of the priority subjects in grapevine breeding programs. This study aims to conduct early-selection by marker assisted selection (MAS) method among 869 genotypes obtained through crossbreeding ‘Alphonse Lavallee’ × ‘Regent’ cultivars using the markers (GF18-06 and GF18-08) associated with downy mildew resistance gene region Rpv3.1 to develop new grapevine cultivars resistant to downy mildew caused by Plasmopara viticola. A total of 869 hybrid plants which were obtained after crossing ‘Alphonse Lavallee’ × ‘Regent’ in a 3-year breeding program were used in the study. The hybrid plants were scored for the resistance level based on their sporulation intensity after artificial inoculation of P. viticola. DNA samples of the hybrid plants were amplified with GF18-06 and GF18-08 markers in Polymerase Chain Reaction (PCR) for MAS. The alleles which were associated to Rpv3.1 resistance locus and the results of resistance scoring were compared, and the applicability of the markers in MAS was verified. It was determined that the GF18-08/410 bp marker can be used successfully for MAS. Gf 18-06 marker 385 bp, 390 bp and 407 bp gave false positive results in our population, respectively 8.86%, 9.02% and 37.94%. Therefore, this may limit its use for MAS.

Leaf Polyphenolic Profile as a Determinant of Croatian Native Grapevine Varieties' Susceptibility to Plasmopara viticola.

Since grapevine is highly susceptible to various pathogens, enormous amounts of pesticides are applied each season to achieve profitable production. One of the most destructive grapevine diseases is downy mildew, and their interaction has been in the spotlight for more than a decade. When it comes to a metabolome level, phenolic compounds are relevant to investigate due to their involvement in the plant immune system and known antifungal properties. Croatian grapevine germplasm is highly heterogeneous due to its long history of cultivation in diversified geographical regions. Since it has been found that native varieties react differently to the infection of Plasmopara viticola, the intention of this study is to define if the chemical background of the leaves, i.e., polyphenolic composition, is responsible for these dissimilarities. Therefore, the leaves of 17 genotypes, among which 14 were native and 3 were controls, were analyzed using high-performance liquid chromatography (HPLC) in four terms: before inoculation and 24, 48, and 96 h post inoculation (hpi). During this early phase, significant differences were found neither between the terms nor between the non-inoculated and inoculated samples, except for resveratrol-3-O-glucoside. By applying principal component analysis (PCA) using initial leaf polyphenolic composition, varieties of V. vinifera were clearly separated into three different groups corresponding to their International Organization of Vine and Wine (OIV) classes of susceptibility to P. viticola. Results obtained in this research suggest that the initial constitutive polyphenolic composition of the cultivar leaves has a crucial influence on their susceptibility to P. viticola, and this finding can be used to improve the success of grapevine breeding programs toward downy mildew resistance.

Towards Sensor-Based Phenotyping of Physical Barriers of Grapes to Improve Resilience to Botrytis Bunch Rot.

Botrytis bunch rot is one of the economically most important fungal diseases in viticulture (aside from powdery mildew and downy mildew). So far, no active defense mechanisms and resistance loci against the necrotrophic pathogen are known. Since long, breeders are mostly selecting phenotypically for loose grape bunches, which is recently the most evident trait to decrease the infection risk of Botrytis bunch rot. This study focused on plant phenomics of multiple traits by applying fast sensor technologies to measure berry impedance (ZREL), berry texture, and 3D bunch architecture. As references, microscopic determined cuticle thickness (MSCT) and infestation of grapes with Botrytis bunch rot were used. ZREL hereby is correlated to grape bunch density OIV204 (r = −0.6), cuticle thickness of berries (r = 0.61), mean berry diameter (r = −0.63), and Botrytis bunch rot (r = −0.7). However, no correlation between ZREL and berry maturity or berry texture was observed. In comparison to the category of traditional varieties (mostly susceptible), elite breeding lines show an impressive increased ZREL value (+317) and a 1-μm thicker berry cuticle. Quantitative trait loci (QTLs) on LGs 2, 6, 11, 15, and 16 were identified for ZREL and berry texture explaining a phenotypic variance of between 3 and 10.9%. These QTLs providing a starting point for the development of molecular markers. Modeling of ZREL and berry texture to predict Botrytis bunch rot resilience revealed McFadden R2 = 0.99. Taken together, this study shows that in addition to loose grape bunch architecture, berry diameter, ZREL, and berry texture values are probably additional parameters that could be used to identify and select Botrytis-resilient wine grape varieties. Furthermore, grapevine breeding will benefit from these reliable methodologies permitting high-throughput screening for additional resilience traits of mechanical and physical barriers to Botrytis bunch rot. The findings might also be applicable to table grapes and other fruit crops like tomato or blueberry.

Evaluation of Wild, Wine, Table, and Raisin Grapevine (Vitis spp.) Genotypes in Gedeo Zone, Southern Ethiopia.

Grapevine is one of the major horticultural crops of the world with the cultivated area exceeding 7.5 million ha used for a myriad of products ranging through fresh table grape, preserves, juice, wine, and raisins. The main objective of this study was to introduce twenty-eight grapevine cultivars (ten wild, ten wine, four table, and four raisin grapes) into Gedeo Zone for the first time and ampelographically characterize them in Dilla and Yirgacheffe agroecological conditions in Gedeo Zone, Southern Ethiopia, from August 2018 to July 2021. Ten Vitis abyssinica wild grapevine cultivars were collected from Adama, Addis Ababa, Alamata, Arba Minch, Bahir Dar, Dire Dawa, Gondar, Hawassa, Jimma, and Jinka areas. Additional ten world class wine grapes were gathered from Ziway Castel Winery, and four table and four raisin grapes were also collected from Raya Horti Farm and Koka Vineyard at the same time. The experiment was a 2 × 28 factorial arranged in randomized complete block design (RCBD) with three replications, and data were analyzed using the R-software. The analysis of variance revealed that the interaction of cultivar and location significantly (P < 0.001) affected grapevine plant height, leaf number, number of fruits per plant, and tendril number per vine, while grapevine trunk diameter, flower cluster, root length, and number of suckers per vines were not significantly (P > 0.05) influenced by the interaction of the two factors. Generally, the wine grapevine cultivars had lower canopy such as plant height, leaf number, number of tendrils, and suckering vines while these registered a higher number of fruits per plant, trunk diameter, flower cluster, and root length compared to the wild grapevine cultivars. The results of the present study suggested that Syrah, Chenin Blanc, and Grenache can produce high grapevine berry yield and wine quality in Gedeo Zone agroecology particularly in Dilla location. The wild grapevines collected from Dire Dawa, Arba Minch, Jinka, and Alamata were the potential candidates for the world class wine, raisin, and table grapevines which could open new frontiers in the future for Ethiopian native Vitis abyssinica wild grapevine breeding and genetic engineering that will help to move the national and international viticulture and enology industry forward. As the Ethiopian native grapevines are at the risk of total extinction, adequate conservation strategies are required. Breeding, detailed identification, and introducing the potential grapes in different regions of the country are needed. This finding represents a step forward in efforts to understand hybridization of Vitis abyssinica grapevine with Vitis vinifera and other new world Vitis species.

Across-population genomic prediction in grapevine opens up promising prospects for breeding.

Crop breeding involves two selection steps: choosing progenitors and selecting individuals within progenies. Genomic prediction, based on genome-wide marker estimation of genetic values, could facilitate these steps. However, its potential usefulness in grapevine (Vitis vinifera L.) has only been evaluated in non-breeding contexts mainly through cross-validation within a single population. We tested across-population genomic prediction in a more realistic breeding configuration, from a diversity panel to ten bi-parental crosses connected within a half-diallel mating design. Prediction quality was evaluated over 15 traits of interest (related to yield, berry composition, phenology and vigour), for both the average genetic value of each cross (cross mean) and the genetic values of individuals within each cross (individual values). Genomic prediction in these conditions was found useful: for cross mean, average per-trait predictive ability was 0.6, while per-cross predictive ability was halved on average, but reached a maximum of 0.7. Mean predictive ability for individual values within crosses was 0.26, about half the within-half-diallel value taken as a reference. For some traits and/or crosses, these across-population predictive ability values are promising for implementing genomic selection in grapevine breeding. This study also provided key insights on variables affecting predictive ability. Per-cross predictive ability was well predicted by genetic distance between parents and when this predictive ability was below 0.6, it was improved by training set optimization. For individual values, predictive ability mostly depended on trait-related variables (magnitude of the cross effect and heritability). These results will greatly help designing grapevine breeding programs assisted by genomic prediction.

АВТОХТОННЫЕ СОРТА ВИНОГРАДА ГРУЗИИ КАК ИСТОЧНИКИ ДЛЯ СЕЛЕКЦИИ

The paper presents the results of a varietal study of autochthonous Georgian wine varieties with white berries: Goruli mtsvane, Grdzelmtevana, Grubela and with colored berries: Adreuli Shavi, Alexandrouli, Mujuretuli, Nakutvneuli. Control varieties were Riesling Reinskiy for white vines and Cabernet Sauvignon for red ones. The stud-ies were carried out in 2018–2020. The study of grapevine varieties was carried out using meth-ods generally accepted in viticulture. According to the results of the study, based on research re-ports and journals of the collection, data of ag-robiological indicators, yields, crop conditions, and degustation evaluations are presented. A high percentage of blossoming eyes had the vari-eties Adreuli Shavi – 84.2, Grdzelmtevana – 82.8 and Mujuretuli – 81.5. In the control varie-ties Riesling Rhine and Cabernet Sauvignon, this indicator was at the level of 70.7% and 75.8%, respectively. The highest sugar accumulation had varieties: Mujuretuli (23.6 g/100 cm3), Cabernet Sauvignon (23.2 g/100 cm3) and Goruli Mtsvane (23.0 g/100 cm3). In the group of white varieties, tasting scores at the level of the control variety Riesling Reinskiy (8.7 points) were received by wines from varieties – Grubela and Goruli Mtsvane. In the group of red wine grape varie-ties, the Alexandrouli wine received the highest score – 8.7 points, the control variety Cabernet Sauvignon was rated at 8.6 points. According to the results of the study, the varieties Goruli mtsvane, Grubela, Alexandrouli exceed the con-trol ones in terms of the totality of indicators and are recommended for use in grapevine breeding as sources of wine quality.

Induction of polyploidy in grapevine (Vitis vinifera L.) seedlings by in vivo colchicineapplications

Polyploidization is an important technique used in grape breeding to create new genetic resources and can be induced using some antimitotic agents, including colchicine. Plants with increased ploidy can gain better quality than their original diploids in some characteristics. In this study, which was carried out to obtain polyploid genotypes under in vivo conditions, the effects of six (1 g L-1, 2 g L-1, 3 g L-1, 4 g L-1, 5 g L-1, 6 g L-1) doses of colchicine were applied to the shoot tip meristem regions of the seedlings obtained from the seeds of grapevine cv. Ekşi Kara and cv. Trakya İlkeren, for three consecutive days and twice a day (at 08.30 and 18.00 h) were investigated. The effects of mutagen were evaluated by following the treated seedlings? morphological changes and comparing them with the 'Kyoho' (4x) by flow cytometry (FC) analysis. In surviving plants after treatment, stomatal characteristics differed to varying degrees from their original diploids, and stomatal density decreased inversely with the increase in stomatal size in polyploid genotypes. Among cv. Ekşi Kara seedlings, 1 tetraploid (5 g L-1), and cv. Trakya İlkeren seedlings, 1 mixoploid (2 g L-1), and 1 tetraploid (6 g L-1) genotypes were selected by stomatal characteristics, chloroplast numbers, and confirmed by FC analysis. It was determined that colchicine is an effective mutagen in the breeding of polyploid grapevine, and stomatal observations, chloroplast numbers, and FC analysis are useful methods for obtaining confirmed results in the selection of polyploid genotypes.

Overcoming germination barriers through in vitro culture of mature zygotic embryos of grapevine cultivars

Grape seeds have physical and physiological dormancy. Conventional germination methods are not very efficient. The in vitro culture of seeds and of mature zygotic embryos can be an alternative for overcoming germination barriers. The objective was to develop methodologies that increase seed germination and reduce the time to obtain seedlings. The following assays were developed: (1) conventional ex vitro germination, in a 2 × 3 factorial arrangement, of seeds with or without stratification for 90 days, from cultivars 'Niágara Rosada', 'Itália' and 'Red Globe'; (2) in vitro seed germination, in a 3 × 3 factorial arrangement, of the three cultivars and three explants (intact seeds, seeds sectioned in the micropyle region and seeds with a cross-section); and (3) in vitro germination of mature zygotic embryos, in a 4 × 2 factorial arrangement represented by four concentrations of mineral salts (MS, ½MS, WPM and ½WPM) and two cultivars ('Niágara Rosada' and 'Itália'). The conventional ex vitro germination assay resulted in a low seed germination for the three cultivars. The two types of section associated with in vitro culture provided an increase in seed germination. However, the highest germination rate (over 90%) in the shortest time (17 days) was achieved by the embryos grown in vitro. This study defines an efficient methodology to obtain high germination in grape seeds— over 85%—with uniformity and in a short time, using mature zygotic embryos grown in ½WPM culture medium. This methodology can accelerate grapevine breeding programs. Index terms: Vitis vinifera; Vitis labrusca; dormancy; seed scarification.

Phenological diversity in wild and hybrid grapes (Vitis) from the USDA-ARS cold-hardy grape collection

Wild grape relatives and hybrids have been useful in breeding for tolerance to biotic and abiotic stress, however, few studies have emphasized wild and hybrid grapevines for phenological diversity. Utilization of phenological diversity in grapevine breeding could facilitate expansion of grape production into more varied climate regions. Budbreak, bloom, and veraison observations for 1583 accessions from 20 taxa from the United States Department of Agriculture Vitis collection in Geneva, New York, USA. Genotypic and species variation were estimated. Vitis vinifera ancestry was estimated in Vitis hybrids using principal components analysis. Observations ranged 26.6–162.1 (79–141 JD) with an average of 82.6 GDD (118 JD) for budbreak, 206.8–1055.2 (141–222 JD) with an average of 371.9 GDD (163 JD) for bloom, and 849.9–1627.0 (202–290 JD) with an average of 1207.9 GDD (235 JD) for veraison. Seasonal correlations were high for bloom and veraison (0.85–0.95) and moderate for budbreak (0.61–0.65). Moderate heritability was estimated for veraison (0.62) and bloom (0.49), and weak heritability for budbreak (0.2). The species effect was greatest in bloom and explained 42% of the variation, with increasing bloom GDD associated with increasing contribution of V. vinifera in Vitis hybrids.