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Grapes are rich in primary and secondary metabolites. Among the secondary metabolites, polyphenolic compounds are the most abundant in grape berries. Besides their important impacts on grape and wine quality, this class of compounds has beneficial effects on human health. Due to their antioxidant activity, polyphenols and phenolic acids can act as anti-inflammatory and anticancerogenic agents, and can modulate the immune system. In grape berries, polyphenols and phenolic acids can be located in the pericarp and seeds, but distribution differs considerably among these tissues. Although some classes of polyphenols and phenolic acids are under strict genetic control, the final content is highly influenced by environmental factors, such as climate, soil, vineyard, and management. This review aims to present the main classes of polyphenolic compounds and phenolic acids in different berry tissues and grape varieties and special emphasis on their beneficial effect on human health.

Background: Grapevine breeding increasingly relies on molecular tools to introduce durable resistance to downy and powdery mildew. However, the reproducibility of simple sequence repeat (SSR) markers across platforms remains a challenge for marker-assisted selection (MAS). This study aimed to evaluate the performance of SSR markers associated with key resistance loci (Run1/Rpv1, Ren3/Ren9, Rpv3, Rpv10, Rpv12) using the Qsep100 system and to validate selected markers on the ABI platform. Methods: A panel of grapevine cultivars and breeding genotypes was analyzed for SSR markers linked to resistance loci. PCR amplicons were separated on the Qsep100 BioFragment Analyzer, and a subset of markers was cross-validated using ABI capillary electrophoresis. Results: Only a limited subset of markers displayed consistent performance across genotypes. Sc34-8 and Sc35-2 were most reliable for Run1/Rpv1, Indel-27 and Indel-20 for Ren3/Ren9, UDV737 for all Rpv3 sub-loci, GF-09-44 and GF-09-57 for Rpv10, and UDV340 and UDV343 for Rpv12. ABI validation of UDV737 and Indel-27 confirmed high concordance with Qsep100 results, with allele size differences typically ≤2 bp. Conclusions: The study identifies a core set of robust SSR markers suitable for routine MAS in grapevine breeding. Results demonstrate that the Qsep100 system is a reliable alternative to ABI for large-scale genotyping, supporting its broader implementation in resistance breeding programs.

The extraction of high-quality DNA is essential for molecular analyses in grapevine, yet differences among commonly used protocols remain underexplored. This study compared two cetyltrimethylammonium bromide (CTAB)-based methods, with and without polyvinylpyrrolidone (PVP), and three commercial kits (peqGOLD Plant DNA Mini Kit, Qiagen DNeasy Plant Mini Kit, and SPINeasy DNA Kit for Plant MP) using grapevine leaves and other tissues and further validated the CTAB protocol across 34 cultivars. DNA yield, purity, and integrity were assessed spectrophotometrically and by electrophoresis, while PCR suitability was confirmed for all methods. CTAB provided the highest yields and purity at low cost, with densitometry showing approximately 70–85% high-molecular-weight DNA (>20 kb). The Qiagen kit yielded reproducible results with moderate integrity (about 40–60% HMW fraction), making it suitable for high-throughput applications. The MP kit produced high concentrations but severe fragmentation (<10% HMW fraction) due to bead-beating, while the VWR kit performed worst in yield and purity. The addition of PVP improved DNA purity in polyphenol-rich tissues but reduced yield. All protocols generated DNA sufficient for PCR amplification. Overall, CTAB was robust and cost-effective across cultivars and tissues, Qiagen offered speed and reproducibility, and MP provided high concentration at the expense of integrity.

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.

Commercial sparkling wine production represents a relatively low but important part of the Croatian wine production, especially in the Zagreb county. This study presents the results of volatile aroma compounds profile and organic acid composition of commercial sparkling wine samples from three vine-growing regions in Zagreb county. In total, 174 volatile aroma compounds were identified, separated between their chemical classes (aldehydes, higher alcohols, volatile phenols, terpenes, C13-norisoprenoids, lactones, esters, fatty acids, sulfur compounds, other compounds, other alcohols). Higher alcohols such as phenylethyl and isoamyl alcohol as well as 2-methyl-1-butanol, and esters such as diethyl succinate, ethyl hydrogensuccinate, and ethyl lactate had the strongest impact on the volatile compounds profile of Zagreb county sparkling wine. The presence of diethyl glutarate and diethyl malonate, compounds whose concentrations are influenced by yeast autolysis or caused by chemical esterification during the ageing process, was also noted. The influence of every single volatile aroma compound was evaluated by discriminant analysis using forward stepwise model. The volatile profiles of traditional sparkling wines from Croatia were presented for the first time. It is hoped the results will contribute to better understanding the quality potential and to evaluate possible differences on the bases of detected aroma concentrations and multivariate analysis.

Research background. Anthocyanins, the most abundant pigments in red wine, play an important role in the visual aspect of wine sensory properties. However, due to their unstable nature, their ability to polymerise with tannins is important for colour stability. Their content varies with grapevine variety, growing conditions, viticultural and winemaking practices. Leaf removal, a common viticultural practice, enhances anthocyanin accumulation in red grapevines, and partial fruit zone leaf removal at different phenological stages can significantly influence the anthocyanin content of grapes and wine. This two-year study examined how two different times of fruit zone leaf removal at different phenological stages affect the initial anthocyanin content in wine and their stability during ageing in Merlot, Syrah and Cabernet Sauvignon wines grown in a Mediterranean climate. Experimental approach. Partial leaf removal was applied during flowering and during vérasion and compared with untreated control. The wines obtained from all treatments and varieties were bottled two months after the end of fermentation, and then stored and matured under the cellar conditions for one year. To determine the influence of different times of leaf removal on the concentration of anthocyanins and their stability in the wine, the wines were analysed immediately after bottling and again after 6 and 12 months of storage. For the determination of all phenolic compounds, high-performance liquid chromatography (HPLC) was used. Results and conclusions. Leaf removal treatments increased the concentration of anthocyanins in all three cultivars. The obtained results showed that malvidin-3-O-glucoside (Mal-3-Glc) was the most abundant individual anthocyanin, while the most unstable anthocyanin was petunidin-3-O-coumaroyl glucoside (Pet-3-Coum-Glc). Initial concentration of total anthocyanins in all wine samples was significantly affected by different conditions in the two years of study, but with a significant effect of the defoliation treatments. Anthocyanin concentration decreased during the ageing of the wine, and the degradation of anthocyanins ranged from 36 to 90 %. The stability of anthocyanins in wine was most influenced by ageing time, while year and treatment had no influence. The concentration of total phenolic acids increased during wine ageing, while the concentration of total flavonol glycosides (TFG) decreased in all wine samples except Merlot from 2016. Novelty and scientific contribution. The results of this study contribute to a better understanding of the stability of increased concentrations of anthocyanins in wines during ageing obtained by the practice of grapevine leaf removal in the vineyard.

The quality and sensory characteristics of wines are influenced by several factors, including grape variety, local climate, soil conditions, viticultural practices, and vintage. This study investigates the volatile organic compounds (VOCs) in Malvasija Dubrovačka wines, which include various chemical groups such as terpenes, esters, alcohols, acids, and C13-norisoprenoids. The aim was to investigate how vineyard location and vintage influence the VOC profiles of these wines in two consecutive vintages. Using gas chromatography–mass spectrometry, 54 individual VOCs were identified and quantified. The results showed remarkable differences in the composition of VOCs, especially C13-norisoprenoids, terpenes, and acids, between the two vintages and the studied locations. Principal component analysis showed a significant influence of vineyard location on the composition of Malvasija Dubrovačka wines, a result that was reinforced by conventional descriptive analysis (CDA) of sensory testing.

The biological characteristics of grapevine viruses, such as their transmission and host range, are important for the adoption of successful prophylaxis strategies. The aim of this study was to investigate the traits of two newly described grapevine viruses widely distributed in Croatia, grapevine badnavirus 1 (GBV-1) and grapevine virus G (GVG). The vine mealybug (Planoccocus ficus) proved to be a vector of GBV-1 and GVG capable of vine-to-vine transmission with overall experimental transmission rates of 61% and 14.6%, respectively. Transmission was also demonstrated by grafting, with an overall transmission rate of 53.8% for GBV-1 and 100% for GVG, as well as by green grafting using the T-budding technique. Symptoms of GBV-1 and GVG were not observed on the woody cylinders of the indicators LN 33, Kober 5BB, 110 Richter and cvs. Chardonnay and Cabernet Sauvignon. Seed transmission and mechanical transmission were not confirmed. Electron microscopy revealed accumulation of GBV-1 particles and viroplasms in the cytoplasm, but no alternations of the cell structure. Infection with GVG revealed the proliferation of tonoplast-associated vesicles inside phloem cells and cell wall thickening.

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.

A survey of recently discovered vitiviruses was performed on 113 Croatian autochthonous grapevine cultivars from the national collection “Jazbina” using one-step RT-PCR. The presence of grapevine virus H (GVH) was confirmed in nine (7.9%) cultivars and grapevine virus G in eight (7.1%), while the presence of grapevine viruses I and J were not detected. GVH was transmitted by the vine mealybug (Planococcus ficus) from a source plant to grapevine seedlings with a 10.5% transmission rate using a combination of 10 first and second instars per plant with 48 and 72 h of acquisition and inoculation access period, respectively. Transmission correlated with the presence of grapevine leafroll-associated virus 3 (GLRaV-3) in the GVH-source plant and recipient seedlings. No alternative GVH host was identified. A comparison of 356 nt fragments of the RdRP and CP coding regions showed nucleotide identity between the Croatian GVH isolates in the range of 95.5–99.2% and 97.5–99.4% and amino acid identity between 95.8 and 100% and between 98.3 and 100%, respectively. Comparison with foreign isolates revealed nucleotide sequence similarity in the RdRP and CP between 94 and 100% and between 97.7–100%, respectively. To the best of our knowledge, this is the first report of GVH in Croatia and the first identification of the vine mealybug as a vector of GVH.