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Hybrid ( × ) table grape cultivars grown in the subtropics often fail to accumulate sufficient anthocyanins to achieve good uniform berry color. Growers of table grapes in temperate regions generally use ethephon and, more recently, ( )- -abscisic acid ( -ABA) to overcome this problem. The objective of this study was to determine if -ABA applications at different timings and concentrations have an effect on anthocyanin regulatory and biosynthetic genes, pigment accumulation, and berry color of the Selection 21 cultivar, a new × hybrid seedless grape that presents lack of red color when grown in subtropical areas. Applications of -ABA 400 mg/L resulted in a higher accumulation of total anthocyanins and of the individual anthocyaninsanthocyanins: delphinidin-3-glucoside, cyanidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside in the berry skin and improved the color attributes of the berries. Treatment with two applications at 7 days after véraison (DAV) and 21 DAV of -ABA 400 mg/L resulted in a higher accumulation of total anthocyanins in the skin of berries and increased the gene expression of , , , and and of the and transcription factors in the seedless grape cultivar.

Grapes are important sources of phenolics, which are recognized to possess high biological value. In this work, we evaluated the total phenol content (TPC), total anthocyanin content (TAC), antioxidant activity (AA) and volatile composition of unstudied seedless table grape varieties (i.e., Autumn Crisp and Pristine as white cultivars, Scarlotta and Crimson as red cultivars and Adora and Melody as black cultivars). As a result, Adora and Melody exhibited higher TPCs, TACs and AA, measured by the 2,2-diphenyl-2-picrylhydrazil (DPPH) and photochemiluminescence (PCL) assays, than the rest of the varieties. A comparison between the two black cultivars proved that Adora possessed higher TPC (62.70 mg GAE 100 g−1), DPPH radical scavenging activity (IC50 of 3.69 mg ml−1) and PCL antiradical activity (72.14 µg Trolox ml−1) than Melody (47.30 mg GAE 100 g−1, IC50 of 5.0 mg ml−1 and 42.36 µg Trolox ml−1, respectively). The volatile composition, determined by solid phase microextraction (SPME)–gas chromatography/mass spectrometry (GC/MS), indicated a similar qualitative aroma profile for all varieties. However, quantitative differences were measured among them, which were reflected in distinct sensory perception by sensorial testing. From these results, Adora was selected for its antioxidant properties and flavor characteristics.

In viticulture, choosing the most suitable rootstock for a specific scion cultivar is an efficient and cost-effective way to increase yield and enhance the physicochemical characteristics of the fruit. The objective of this study was to evaluate the agronomic performance of the ‘BRS Tainá’ grapevine on different rootstocks under the conditions of the Sub-Middle São Francisco Valley. The main experimental factor consisted of eight rootstocks (IAC 313, IAC 572, IAC 766, 101-14 MgT, Paulsen 1103, Ramsey, SO4, and Teleki 5C), arranged in randomized blocks with four replicates. The experiment was conducted over four production cycles, from 2021 to 2023, in a commercial crop area in Petrolina, PE, Brazil. There were significant effects of rootstocks for the yield and number of bunches per plant, as well as berry length and firmness. ‘BRS Tainá’ achieved the highest yield (22.2 kg per plant) when grafted onto the Paulsen 1103 rootstock, which was superior to the yield on 101-14 MgT, IAC 313, and IAC 572 rootstocks. The highest number of bunches (88) was obtained with ‘BRS Tainá’ grafted on Paulsen 1103, while the lowest number (63) was obtained on IAC 572; both these rootstocks were not significantly different from the other rootstocks. For all scion–rootstock combinations, the mean values for soluble solid (SS) content, titratable acidity (TA), and the SS/TA ratio were similar to those previously described for ‘BRS Tainá’, meeting the commercialization standard. The results for the yield and number of bunches per plant indicate the suitability of grafting ‘BRS Tainá’ on Paulsen 1103 under the semi-arid tropical conditions of the São Francisco Valley.

Grapes are important sources of phenolic compounds, which have multiple beneficial effects on human health. Scientific advances in the field of genetics have allowed the production of seedless table grape varieties, which are highly demanded by consumers because of their nutritional value and their easy consumption. In this study, total phenolic content (TPC), radical scavenging activity (RSA) and total anthocyanin content (TAC), were determined in 65 seedless table grape varieties (41 experimental and 24 commercial varieties). Ultra-high performance liquid chromatography coupled to an ion-trap mass spectrometry detector (UHPLC-IT-MS/MS) was used to identify and quantify some phenolic acids, flavan-3-ols, flavonols and stilbenes in 14 experimental varieties. TPC ranged from 17 to 250 mg gallic acid equivalents/100 g fresh weight (FW), RSA ranged from 15 to 269 mg Trolox equivalents/100 g FW and TAC ranged from 0 to 168 mg cyanidin-3-glucoside/100 g FW. The RSA assay showed high correlation (R 2  = 0.90) between the TPC and the antioxidant activity of the 65 seedless table grapes analyzed. In the vast majority of the new experimental varieties analyzed, the TPC and TAC were similar to those of some common table grapes with seeds, indicating promising perspectives for their commercialization as potential sources of these bioactive compounds. In 6 grape varieties, high concentrations of catechin, procyanidin B2, epicatechin, quercetin 3-β- d -glucoside, 4-hydroxybenzoic acid, vanillic acid, caftaric acid and rutin were found, which would indicate that the regular intake of these varieties would be highly recommended.

cluster weight; berry weight; soluble solids; berry composition

The purpose of this research was to appreciate the impact of the synthetic cytokinin, well known as thidiazuron (TDZ) on seedless berry quality of cv. ‘Recel Uzümü’. Three concentration levels including 0, 5 and 10 mg/L were applied on the grapevines during different phenological stages of grapevine such as Time 1: beginning of berry stetting, Time 2: berries pepper corn size and Time 3: berries pea size. While TDZ application times had no impacts on cultivar characteristics, it was determined that the application doses of TDZ had major impacts on yield and quality components of cv. ‘Recel Uzümü’.Consequently, ascending TDZ doses increased berry and cluster size and led to decreases in total soluble solids content, total phenolic compound content, total anthocyanin content and p-value of grape juice regardless of TDZ application time. The most effective TDZ dose was 10 ppm for improving berry and cluster size in cv. ‘Recel Uzümü’.

Some plant growth regulators, including ethephon, can stimulate abscission of mature grape berries. The stimulation of grape berry abscission reduces fruit detachment force (FDF) and promotes the development of a dry stem scar, both of which could facilitate the production of high quality stemless fresh-cut table grapes. The objective of this research was to determine how two potential abscission treatments, 1445 and 2890 mg/L ethephon, affected FDF, pre-harvest abscission, fruit quality, and ethephon residue of Thompson Seedless and Crimson Seedless grapes. Both ethephon treatments strongly induced abscission of Thompson Seedless berries causing >90% pre-harvest abscission. Lower ethephon rates, a shorter post-harvest interval, or berry retention systems such as nets, would be needed to prevent excessive pre-harvest losses. The treatments also slightly affected Thompson Seedless berry skin color, with treated fruit being darker, less uniform in color, and with a more yellow hue than non-treated fruit. Ethephon residues on Thompson Seedless grapes treated with the lower concentration of ethephon were below legal limits at harvest. Ethephon treatments also promoted abscission of Crimson Seedless berries, but pre-harvest abscission was much lower (≅49%) in Crimson Seedless compared to Thompson Seedless. Treated fruits were slightly darker than non-treated fruits, but ethephon did not affect SSC, acidity, or firmness of Crimson Seedless, and ethephon residues were below legal limits.

One of the major objectives of table grape breeding is to produce seedless grapes of Vitis vinifera L. Of high importance among these objectives is the development of new cold-resistant seedless grapes for the colder regions of the world. Embryo rescue is an effective tool in breeding seedless grapes. Here, we report on nine cross-combinations between seedless cultivars and cold-resistant seedless cultivars or seeded hybrids. We carried out embryo rescue and molecular marker-assisted selection to create new cold-resistant seedless grape germplasm. We also examined the effects of different parents and the use of exogenous hormones on the success of embryo rescue as well as the optimal sampling time for a new seedless cultivar Qinxiu. The results show that a total of 473 new grape genotypes were obtained by embryo rescue using double-phase MM3 (modified ER) as the medium for embryo development and solid phase WPM as the medium for embryo germination and plantlet formation. We found the seedless cultivars Perlette, Qinhong No.2, Ruby Seedless and Qinhong No.10 were the most suitable female parents for embryo rescue, and the cold-resistant seedless cultivar Jupiter (a V. vinifera × V. labrusca hybrid) as the male parent. This was better than the seeded hybrid 0-1-5 (V. vinifera × V. amurensis). The best embryo development medium was MM3 with 500 mg/L CH, 1 mmol/L serine, 0.5 mg/L GA3, 1.0 mg/L IAA and 0.5 mg/L 6-BA. The best embryo germination and plantlet formation medium was WPM with 0.2 mg/L 6-BA and 0.1 mg/L IAA. The best sampling time for Qinxiu for embryo rescue was 42 days after flowering. We obtained a total of 440 hybrids by embryo rescue using the seedless molecular marker SCF27-2000.Key messageHybridization between grape seedless cultivars and cold-resistant cultivars and embryo rescue were performed. We obtained 473 new germplasms and performed marker assisted-selection using SCF27-2000. The embryo rescue system was optimized.

Conventional crossing of stenospermocarpic grapes for the obtainment of seedless cultivars presents some technical constraints causing embryo abortion in the early berry developmental stages. Embryo rescue technique partially overcomes these limitations, but the obtainment of viable plantlets relies on the optimization of several genetic and methodological issues. This work aimed to regenerate viable plants from immature ovules of stenospermocarpic table grape hybrids by applying a three-step in vitro culture protocol consisting of embryo development, embryo germination-rooting, and plantlet formation. The influence of parental genotypes (six “seedless × seedless” crosses), ovule sampling time (30, 40, 50 days after pollination (DAP)), and extent of embryo germination induction (4, 6, 8 weeks) was assessed on ovule fertilization, embryo development and germination, rooting, and plantlet formation to establish the best rescue time for each combination hybrid. Our optimized protocol included immature ovule isolation for 40 DAP and embryo germination induction for 8 weeks. As for genotypes, the most efficient embryo germination was recovered from hybrids of Thompson, Superior, and Regal cultivars, whereas the highest percentage of viable plants was derived from 50-DAP ovules of Luisa × Thompson progeny. Such an optimized protocol could be useful to maximize the efficiency of future breeding programs for grape seedlessness.

Background Grapevine ( Vitis vinifera L.) is the most important Mediterranean fruit crop, used to produce both wine and spirits as well as table grape and raisins. Wine and table grape cultivars represent two divergent germplasm pools with different origins and domestication history, as well as differential characteristics for berry size, cluster architecture and berry chemical profile, among others. ‘Sultanina’ plays a pivotal role in modern table grape breeding providing the main source of seedlessness. This cultivar is also one of the most planted for fresh consumption and raisins production. Given its importance, we sequenced it and implemented a novel strategy for the de novo assembly of its highly heterozygous genome. Results Our approach produced a draft genome of 466 Mb, recovering 82% of the genes present in the grapevine reference genome; in addition, we identified 240 novel genes. A large number of structural variants and SNPs were identified. Among them, 45 (21 SNPs and 24 INDELs) were experimentally confirmed in ‘Sultanina’ and six SNPs in other 23 table grape varieties. Transposable elements corresponded to ca. 80% of the repetitive sequences involved in structural variants and more than 2,000 genes were affected in their structure by these variants. Some of these genes are likely involved in embryo development, suggesting that they may contribute to seedlessness, a key trait for table grapes. Conclusions This work produced the first structural variants and SNPs catalog for grapevine, constituting a novel and very powerful tool for genomic studies in this key fruit crop, particularly useful to support marker assisted breeding in table grapes.