Targeted Metabolomic and Transcript Level Analysis Reveals Quality Characteristic of Chinese Wild Grapes (Vitis davidii Foex)

Dynamic changes in proanthocyanidin composition, biosynthesis, and histochemistry in spine grape (Vitis davidii Foëx) tissues during berry development

BACKGROUND

Spine grapes are widely cultivated in southern China because of their strong adaptability to hot and humid climates. As a wild species native to China, spine grape (Vitis davidii Foëx) was studied as a resource of proanthocyanidins (PAs). PA composition, biosynthesis, and histochemistry in different tissues (skins, seeds, and stems) during berry development were analyzed in this study.

RESULTS

The findings revealed that PA accumulation occurred in concurrence with flowering and was completed by veraison. High-performance liquid chromatographic results showed that the epicatechin type was the most dominant. The skins were more likely to accumulate PA polymers. Reverse transcription-quantitative polymerase chain reaction analysis revealed that the expression levels of structural genes (flavonoid-3'-hydroxylase, flavonoid-3'5'-hydroxylase, dihydroflavonol 4-reductase, leucoanthocyanidin reductase, and leucoanthocyanidin dioxygenase) were positively associated with PA dynamic changes. Histochemical results revealed that PAs in skins were mainly found in the hypodermis of the exocarp, PAs in seeds were mainly found in the middle layer of the outer integument of the testa, and PAs in stems were mainly found in the phloem.

CONCLUSION

This study provides a clear understanding of the spatial and temporal accumulation of PAs in spine grape, and forms a basis for the analysis of structural profiles and synthesis of PAs and their biological effects. © 2024 Society of Chemical Industry.

5-azaC treatment affected anthocyanins, sugars and organic acids and reduced DNA methylation in Merlot grape

DNA methylation plays a crucial role in regulating gene expression, thereby affecting the growth and development of organisms. The application of 5-azacytidine (5-azaC) serves as a potent regulator of DNA methylation levels by inhibiting DNA methyltransferase activity, which subsequently impacts organismal growth and development. In this study, we explored the effects of varying concentrations of 5-azaC on the growth and fruit quality attributes of Merlot grapes. Our findings indicate that treatment with 5-azaC accelerates fruit coloration in grape berries, particularly under conditions of suboptimal solar irradiance. Although 5-azaC treatments at various concentrations suppressed the accumulation of glucose and fructose, the accumulation of organic acids was more influenced by climatic factors than by 5-azaC exposure. Notably, high concentrations (200 μM) of 5-azaC significantly enhanced anthocyanin content, while subhigh concentrations (100 μM) had a contrasting effect. Genome-wide methylation profiling revealed that treatment with 5-azaC reduced CpG methylation levels, thereby affecting the transcriptional regulation of key genes involved in pertinent metabolic pathways. Expression levels of C4H, PAL, NAD-IDH, and SAI were markedly downregulated following treatment with 5-azaC. Collectively, our results demonstrate that 5-azaC modulates grape DNA methylation, stimulates grape growth and development, promotes anthocyanin accumulation, but also concurrently diminishes the levels of sugars and organic acids in mature grape fruits.

Metabolomics of Vitis davidii Foëx. grapes from southern China: Flavonoids and volatiles reveal the flavor profiles of five spine grape varieties

The spine grapes (Vitis davidii Foëx.) are wild grape species that grow in southern China, and can be used for table grapes, juicing and winemaking. To systematically investigate the flavor profiles of spine grapes, flavonoids and volatile compounds were detected in five spine grape varieties (Seputao, Ziqiu, Miputao, Tianputao and Baiputao) using HPLC-QqQ-MS/MS and GC-MS. The content of flavonoids highly depended on the variety, such as the total concentrations of anthocyanins (91.43-328.85 mg/kg FW) and flavonols (33.90 to 83.16 mg/kg FW). The volatile compounds with higher odor active value were selected to describe the aroma of spine grapes. Hexanal, (E)-2-hexenal and (E, Z)-2,6-nonadienal contributed to the higher herbaceous flavor to Baiputao and Ziqiu. β-Damascenone and (E)-2-nonenal gave Baiputao a flavor with more floral, fruity and earthy. Their characteristic flavor compounds were subsequently revealed using multivariate statistical analysis. The results helped producers to further develop and utilize the spine grapes.

The Metabolomic Profiling of the Flavonoid Compounds in Red Wine Grapes and the Impact of Training Systems in the Southern Subtropical Region of China

Flavonoids play an important role in forming wine grapes and wine quality characteristics. The flavonoids of three winter red wine grapes, Yeniang No. 2 (YN2), Marselan (Mar), and Guipu No. 6 (GP6), were analyzed by ultra-high-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QQQ-MS). Furthermore, the flavonoids in GP6 grapevines using two types of training systems, namely, trellis (T) and espaliers (E), were also compared in this study. Overall, 196 flavonoid metabolites, including 96 flavones, 38 flavonols, 19 flavanones, 18 polyphenols, 15 anthocyanins, 7 isoflavones, and 3 proanthocyanidins, were identified. The flavonoid profiles were remarkably different among these three grape varieties, while they did not change much in the GP6 managed on trellis and espaliers. Grape varieties with different genetic backgrounds have their own unique flavonoid profiles. Compared with Mar-T, isoflavones and flavonols presented higher contents in GP6-T and YN2-T, which mainly contain glycitein, genistin, calycosin, kaempferide, isotrifoliin, and ayanin. The anthocyanin content was significantly higher in YN2-T than in the other two varieties. YN2 and GP6-T present a more stable color, with significantly more acetylated diglucosides and methylated anthocyanins in YN2-T and GP6-T than in Mar-T. Notably, GP6 had more varied flavonoids and the better characteristics to its flavonoid profile out of these three varieties, due to it containing a higher number of anthocyanins, flavone, and flavonols and the greatest number of different flavonoid metabolites (DFMs), with higher contents than YN2 and Mar. Compared with the trellis training system, the espaliers training system increased the content of flavonoids detected in GP6 grape berries; however, the composition of flavonoids strictly depends on the grape variety.

Combined ultrasound and low temperature pretreatment improve the content of anthocyanins, phenols and volatile substance of Merlot red wine

Ultrasound combined with low temperature treatment is a new food processing technology. In this study, low temperature, three ultrasound power levels, and their combinations were adopted in the must before fermentation to study their effects on Merlot red wine. The results showed that ultrasound combined with low temperature pretreatment increased the total and monomer contents of anthocyanins and phenols, affected the color of the wine, and significantly increased its antioxidant capacity. In particular, 240 W of ultrasound combined with low temperature pretreatment reduced the bad odors (caprylic acid, benzaldehyde, and 1-ethanol content) and improved the flower and fruit aroma (1-octanol and phenethyl acetate), as well as the aftertaste, thus improving the quality of the wine. Ultrasound combined with low temperature pretreatment positively affected the quality of Merlot red wine.

Chromosome-scale genomics, metabolomics, and transcriptomics provide insight into the synthesis and regulation of phenols in Vitis adenoclada grapes

Vitis adenoclada is a wild grape unique to China. It exhibits well resistance to heat, humidity, fungal disease, drought, and soil infertility. Here, we report the high-quality, chromosome-level genome assembly of GH6 (V. adenoclada). The 498.27 Mb genome contained 221.78 Mb of transposable elements, 28,660 protein-coding genes, and 481.44 Mb of sequences associated with 19 chromosomes. GH6 shares a common ancestor with PN40024 (Vitis vinifera) from approximately 4.26-9.01 million years ago, whose divergence occurred later than Vitis rotundifolia and Vitis riparia. Widely-targeted metabolome and transcriptome analysis revealed that the profiles and metabolism of phenolic compounds in V. adenoclada varieties significantly were differed from other grape varieties. Specifically, V. adenoclada varieties were rich in phenolic acids and flavonols, whereas the flavan-3-ol and anthocyanin content was lower compared with other varieties that have V. vinifera consanguinity in this study. In addition, ferulic acid and stilbenes content were associated with higher expressions of COMT and STSs in V. adenoclada varieties. Furthermore, MYB2, MYB73-1, and MYB73-2 were presumably responsible for the high expression level of COMT in V. adenoclada berries. MYB12 (MYBF1) was positively correlated with PAL, CHS, FLS and UFGT.Meanwhile, MYB4 and MYBC2-L1 may inhibit the synthesis of flavan-3-ols and anthocyanins in two V. adenoclada varieties (YN2 and GH6). The publication of the V. adenoclada grape genome provides a molecular foundation for further revealing its flavor and quality characteristics, is also important for identifying favorable genes of the East Asian species for future breeding.

Effects of methyl jasmonate on the monoterpenes of Muscat Hamburg grapes and wine

BACKGROUND

The importance of monoterpenes in grape and wine aroma has compelled researchers to focus on developing methods to increase their abundance. Recent research has revealed that exogenous elicitors can increase the contents of these compounds. This study determined the effects of methyl jasmonate (MeJA) preharvest treatments on the monoterpene profiles of Muscat Hamburg grapes and wine.

RESULTS

A total of 27 monoterpenes were identified for Muscat Hamburg grapes and wine. The contents of most of the monoterpenes (free and glycosylated forms) in the grapes and wine increased in response to MeJA. An analysis of the expression of the genes in the terpenoid biosynthesis pathway indicated that the related biosynthetic pathways were activated by MeJA. The transcript levels of some genes were consistent with monoterpene production, including VviCSLinNer, VviGwbOciF, VviPNRLin, VviGT14 and VviUGT85A1L1. The developmental expression patterns of the VviPP2B1 and VviMYB24 transcription factor genes were positively correlated with monoterpene accumulation in ripening grapes.

CONCLUSIONS

Our results suggest that MeJA may be useful for improving the aroma quality of grapes and wines.

Anthocyanin and Phenolic Acids Contents Influence the Color Stability and Antioxidant Capacity of Wine Treated With Mannoprotein

Wine is consumed by humans worldwide, but the functional components are lost and the color changes during its production. Here, we studied the effects of mannoprotein (MP) addition (0, 0.1, and 0.3 g/L) upon crushing and storage. We measured anthocyanins, phenolic acids profiles, color characteristics, and antioxidant activities of wine. The results showed that the addition of MP before fermentation significantly increased the total phenolic content (TPC), total anthocyanin content, total tannin content (TTC), total flavonoid content, and total flavanol content in wine, whereas the addition of MP during storage had the opposite effect. The addition of MP before alcohol fermentation significantly increased the amount of individual anthocyanins and individual phenolic acids, maintained the color, and increased the antioxidant capacity of wine. In addition, the addition of 0.3 g/L MP during storage increased the content of individual phenolic acids and TPC of wine. However, the addition of 0.1 g/L MP during storage significantly reduced the TPC, TAC, TTC, and individual anthocyanin content (except for malvidin-3-glucoside and malvidin-3-acetly-glucoside); meanwhile, the treatment attenuated the color stability and antioxidant capacity of wine. The results demonstrated that the addition of MP before alcohol fermentation could increase the functional components and improve the color stability and antioxidant capacity of wine.

Effects of leaf removal on the accumulation of anthocyanins and the expression of anthocyanin biosynthetic genes in Cabernet Sauvignon (Vitis vinifera L.) grapes

BACKGROUND

Anthocyanins, a major flavonoid class, determine the color and quality of wine. Recent research revealed that basal leaf removal can increase the content of these compounds. This study determined the effects of basal leaf removal on the anthocyanin profiles of Cabernet Sauvignon grapes.

RESULTS

The effects of basal leaf removal on anthocyanin composition in Cabernet Sauvignon grapes were investigated over two growing seasons. Leaf removal at 5% veraison (VB6) and at 100% veraison (VC6) was compared with a control. Reducing sugar and total anthocyanin contents in the leaf removal group were significantly higher than in the control group at harvest for both vintages. Leaf removal increased the content of individual anthocyanins and significantly improved the malvidin-3-O-glucoside (Mv-3-glc), peonidin-3-O-glucoside (Pn-3-glc), and malvidin-3-O-(6-acetyl)-glucoside (Mv-3-acglc) content of the VB6 group. At harvest, VB6 treatment increased the transcript abundance of structural and regulator genes in the anthocyanin pathway, especially VvF3'5'H, VvLDOX, and VvDFR.

CONCLUSIONS

Our results suggest that leaf removal at 5% veraison may be useful for improving the anthocyanin content in grapes. © 2020 Society of Chemical Industry.

Transcriptomic and Metabolic Analyses Provide New Insights into the Effects of Exogenous Sucrose on Monoterpene Synthesis in "Muscat Hamburg" Grapes

Monoterpenes provide strong floral and fruit aromas to grapes and wines. In the present study, the effects of exogenous sucrose on the monoterpenes metabolites were studied at the metabolomic and transcriptomic levels in "Muscat Hamburg" grape berries. 6% sucrose aqueous solution was used as treatment, applied at the berry color change stage and 8 days after the first application. Transcriptomics analysis was carried out on berries collected at three phenological stages (berries with intermediate Brix values, E-L 36; berries not quite ripe, E-L 37; and berries harvest-ripe, E-L 38). Our results showed that the sucrose application induced the accumulation of monoterpenes at harvest, especially geraniol and geranic acid. The summary of the number of differentially expressed genes between the control and treatment was 3465, 977, and 2843 at E-L 36, E-L 37, and E-L 38, respectively. Weighted gene correlation network analysis was constructed based on the RNA-seq data, and the MElightyellow module was probably correlated with monoterpene metabolism, comprising 131 unigenes. Quantitative real-time polymerase chain expression analysis of five key differentially expressed genes in terpenoid pathways validated the RNA-seq-derived expression profiles (R² = 0.8143). Our findings provided new insights into the regulation of monoterpene biosynthesis in grape berries under exogenous sucrose.