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Main Conclusion: Supplying monochromatic blue LED light during the day, but not at night, promotes early coloration and improves anthocyanin accumulation in the skin of grape berries. Specific light spectra, such as blue light, are known to promote the biosynthesis and accumulation of anthocyanins in fruit skins. However, research is scarce on whether supplement of blue light during different periods of one day can differ in their effect. Here, we compared the consequences of supplying blue light during the day and night on the accumulation of anthocyanins in pigmented grapevine (Vitis vinifera) berries. Two treatments of supplemented monochromatic blue light were tested, with light emitting diodes (LED) disposed close to the fruit zone, irradiating between 8:00 and 18:00 (Dayblue) or between 20:00 and 6:00 (Nightblue). Under the Dayblue treatment, berry coloration was accelerated and total anthocyanins in berry skins increased faster than the control (CK) and also when compared to the Nightblue condition. In fact, total anthocyanin content was similar between CK and Nightblue. qRT-PCR analysis indicated that Dayblue slightly improved the relative expression of the anthocyanin-structural gene UFGT and its regulator MYBA1. Instead, the expression of the light-reception and -signaling related genes CRY, HY5, HYH, and COP1 rapidly increased under Dayblue. This study provides insights into the effect of supplementing monochromatic LED blue light during the different periods of one day, on anthocyanins accumulation in the berry skin., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Key Message: Wild and loss-of-function alleles of the 5 - O - glucosyltransferase gene responsible for synthesis of diglucoside anthocyanins in Vitis were characterized. The information aids marker development for tracking this gene in grape breeding. Anthocyanins in red grapes are present in two glycosylation states: monoglucoside (3-O-glucoside) and diglucoside (3, 5-di-O-glucoside). While monoglucoside anthocyanins are present in all pigmented grapes, diglucoside anthocyanins are rarely found in the cultivated grape species Vitis vinifera. Biochemically 3-O-glucoside anthocyanins can be converted into 3,5-di-O-glucoside anthocyanins by a 5-O-glucosyltransferase. In this study, we surveyed allelic variation of the 5-O-glucosyltransferase gene (5GT) in 70 V. vinifera ssp. vinifera cultivars, 52 V. vinifera ssp. sylvestris accessions, 23 Vitis hybrid grapes, and 22 accessions of seven other Vitis species. Eighteen 5GT alleles with apparent loss-of-function mutations, including seven premature stop codon mutations and six frameshift indel mutations, were discovered in V. vinifera, but not in the other Vitis species. A total of 36 5GT alleles without apparent loss-of-function mutations (W-type) were identified. These W-type alleles were predominantly present in wild Vitis species, although a few of them were also found in some V. vinifera accessions. We further evaluated some of these 5GT alleles in producing diglucoside anthocyanins by analyzing the content of diglucoside anthocyanins in a set of representative V. vinifera cultivars. Through haplotype network analysis we revealed that V. vinifera ssp. vinifera and its wild progenitor V. vinifera ssp. sylvestris shared many loss-of-function 5GT alleles and extensive divergence of the 5GT alleles was evident within V. vinifera. This work advances our understanding of the genetic diversity of 5GT and provides a molecular basis for future marker-assisted selection for improving this important wine quality trait.

Berry skin color OIV index, anthocyanin composition, and content of 78 grape cultivars were surveyed using a CIELAB system and high-performance liquid chromatography (HPLC)-mass spectrometry (MS) coupled with photodiode array detection. There were high correlations between L*, b*, and color, while a* was not a representative parameter. L* and b* values declined as berry skin color OIV became darker, and a* increased as berry skin color OIV became darker in pink and red grape cultivars only. The composition and content of anthocyanins varied widely among the cultivars. Total anthocyanins and types of anthocyanins were significantly correlated with color OIV parameters. Through multiple linear regression analysis, cyanidin derivatives had a positive effect on values of L* and b*. Delphinidin derivatives had positive effects on the value of a*. The CIELAB system gave good results for differentiation of grape berry skin color OIV.

Anthocyanin composition is responsible for the red colour of grape berries and wines, and contributes to their organoleptic quality. However, anthocyanin biosynthesis is under genetic, developmental and environmental regulation, making its targeted fine-tuning challenging. We constructed a mechanistic model to simulate the dynamics of anthocyanin composition throughout grape ripening in Vitis vinifera , employing a consensus anthocyanin biosynthesis pathway. The model was calibrated and validated using six datasets from eight cultivars and 37 growth conditions. Tuning the transformation and degradation parameters allowed us to accurately simulate the accumulation process of each individual anthocyanin under different environmental conditions. The model parameters were robust across environments for each genotype. The coefficients of determination (R 2) for the simulated versus observed values for the six datasets ranged from 0.92 to 0.99, while the relative root mean square errors (RRMSEs) were between 16.8 and 42.1 %. The leave-one-out cross-validation for three datasets showed R 2 values of 0.99, 0.96 and 0.91, and RRMSE values of 28.8, 32.9 and 26.4 %, respectively, suggesting a high prediction quality of the model. Model analysis showed that the anthocyanin profiles of diverse genotypes are relatively stable in response to parameter perturbations. Virtual experiments further suggested that targeted anthocyanin profiles may be reached by manipulating a minimum of three parameters, in a genotype-dependent manner. This model presents a promising methodology for characterizing the temporal progression of anthocyanin composition, while also offering a logical foundation for bioengineering endeavours focused on precisely adjusting the anthocyanin composition of grapes. [ABSTRACT FROM AUTHOR]

Red-fleshed grapes are important breeding resources, and study of the content and composition of phenolic compounds in red-fleshed grapes is lacking. In this study, the profiles of phenolic compounds in the whole berry, flesh, and peel of thirteen red-fleshed grape (Vitis) accessions were determined for two consecutive years. The content of total phenolic compounds ranged from 4.795 to 29.875 mg g−1 FW (fresh weight) in berry, from 1.960 to 12.593 mg g−1 FW in flesh, and from 17.067 to 60.182 mg g−1 FW in peel. As expected, anthocyanins were the main phenolic compounds, accounting for 90.4, 89.4, and 94.1% of the total phenolic compounds in berry, flesh, and peel, respectively. Flavanols accounted for 36.2% of the non-anthocyanin phenolic compounds in berry, 35.3% in flesh, and 38.3% in peel. In comparison, flavonols accounted for about 11.6, 5.7, and 15.8% of the non-anthocyanin phenolic compounds in berry, flesh, and peel, respectively. Hydroxycinnamic derivatives were the most abundant non-anthocyanins and accounted for 53.8, 56.1, and 44.3% of non-anthocyanin phenolic compounds in these three tissues. The content of phenolic compounds in peel was significantly higher than that in flesh and whole berry. A significant variation in the content of total and individual phenolic compounds was observed among different red-fleshed grapes, suggesting that genetic background was an important factor affecting the accumulation of these phenolic compounds. This work represents the most comprehensive characterization of phenolic compounds profiles in red-fleshed grapes. [ABSTRACT FROM AUTHOR]

Abstract: To explore wild genetic resources for improving fruit and processing quality of cultivated grape cultivars, the polyphenolic composition and content in the ripe berries of 147 grape accessions from 16 Vitis species for two consecutive years were characterised. A total of 48 polyphenolic compounds, including 28 anthocyanins, 6 flavonols, 6 flavanols, 6 hydroxycinnamic derivatives, and 2 hydroxybenzoic acids, were identified via HPLC-MS and quantified by HPLC-DAD. These wild grape species had unique presence of abundant di-glucoside derivatives of anthocyanins. In addition, anthocyanins in most wild species were predominantly nonacylated. The mean contents for anthocyanins, flavanols, flavonols, hydroxycinnamic derivatives, and hydroxybenzoic acids were 9.610, 0.769, 0.093, 0.441 and 0.027mgg−1 FW, respectively. They were about 2 to 10 folds higher than their respective counterparts in the most widely cultivated grape species Vitis vinifera. As expected, most of these groups of compounds were correlated negatively with berry weight, but positively with the content of total soluble solids. [Copyright &y& Elsevier]

Abstract: Polyphenolic profiles in the berry samples of 344 European grape (Vitis vinifera) cultivars were evaluated for two consecutive years. These cultivars represent a diverse collection of V. vinifera germplasm maintained at the USDA-Agricultural Research Service Vitis Clonal Repository in Davis of California, USA. A total of 36 polyphenolic compounds, including 16 anthocyanins, 6 flavonols, 6 flavanols, 6 hydroxycinnamic acids and 2 hydroxybenzoic acids, were identified via HPLC–MS and quantified by HPLC–DAD. The mean contents for anthocyanins, flavanols, flavonols, hydroxycinnamic acids and hydroxybenzoic acids were 0.946 (coloured cultivars), 0.147, 0.043, 0.195 and 0.016mgg−1 FW, respectively. On average, wine grapes had higher concentrations than had table grapes for all of these compounds except hydroxycinnamic acids. Berry colours affected the total contents of anthocyanins, but not others. Positive correlations (0.151–0.535) were found among these groups of compounds. As expected, these groups of compounds were all negatively correlated with berry weight. [Copyright &y& Elsevier]

Abstract: The composition and content of anthocyanins were surveyed by HPLC–MS for assessing genotypic variation in berry skin of 110 grape cultivars, including 3 species and 5 interspecific hybrids. Twenty-nine anthocyanins were identified. For total anthocyanin content, Vitis vinifera and hybrids of Vitis labrusca and V. vinifera were low, and in general, wild species and rootstock were higher than interspecific hybrids, and wine grapes were higher than table grapes in the same species. As regards the composition of anthocyanins, malvidin-derivatives were the most abundant anthocyanins in the majority of germplasms. All anthocyanins were monoglucoside derivatives in V. vinifera, but all the other Vitis germplasms had both mono- and di-glucoside derivatives. Moreover, peonidin-derivatives and malvidin 3-O-glucoside were, respectively, main anthocyanins in table and wine grapes of V. vinifera. Via principal component analysis, the distribution of the cultivars in a scatter plot depended upon their total anthocyanins content, mono- and di-glucoside derivatives. [Copyright &y& Elsevier]

Successful cross-breeding requires the investigation into the inheritance pattern of desirable traits. The present study recorded the segregation in coloration and analyzed anthocyanin concentration and composition in berry skin and flesh of the F1 interspecific populations ('Beifeng' × 'Yan-73') during the three successive growing seasons. All the progeny presented color in berry skin, whereas segregation was observed in berry flesh coloration with the ratio of 1:1. Meanwhile, attentions were paid to anthocyanin mono-and di-glucosides for the first time. Di-glucosides were only detected in the maternal parent 'Beifeng' and around a half number of the progeny in berry skin and colored flesh. On the other hand, mono-glucosides were detected in both parents and all the progeny in berry skin and with colored flesh. Concentrations of total and major anthocyanins in the progeny were continuously distributed and skewed towards the low concentration area. Transgressive inheritance was also noted, indicated by the exceptionally high anthocyanin concentrations observed amongst some of the progeny. Positive correlations were observed between traits except the slightly negative correlations between mono-and di-glucosides in both skin and flesh. These results are of both practical and scientific interests for further breeding efforts and researches on different coloration mechanisms in berry skin and flesh. [ABSTRACT FROM AUTHOR]