Abscisic acid reduced methoxypyrazines concentration and its derived unpleasant odors in Cabernet Sauvignon grapes and wines.

BACKGROUND: The influences of abscisic acid (ABA) applications on precursors and gene expression in 3-alkyl-2-methoxypyrazines (MPs) biosynthetic pathway, MPs concentration and sensory evaluation of its derived peculiar odors in Cabernet Sauvignon grapes and wines were investigated. At the vineyard, ABA solution with 25, 100 and 400 mg L-1 (AT1, AT2 and AT3, respectively) and an aqueous solution (control) were sprayed three times from veraison to pre-harvest. RESULTS: Higher concentration ABA applications (AT2 and AT3) in grapes could significantly reduce MPs concentration and its derived peculiar odors in grapes and wines compared to a lower concentration ABA application (AT1) and control, with AT2 application having the strongest effect. The changes in MPs were mainly a result of the downregulated expression of VvOMTs genes at higher concentration ABA applications, independent of the levels of their potential precursors. CONCLUSION: The present study reveals that ABA application had the potential to decrease production of MPs in Cabernet Sauvignon grapes and wines, and this result provides reference values for the removal of unpleasant vegetable odors from Cabernet Sauvignon wines in production. © 2024 Society of Chemical Industry.

Enhancement of anthocyanin and chromatic profiles in 'Cabernet Sauvignon' (Vitis vinifera L.) by foliar nitrogen fertilizer during veraison.

BACKGROUND: The influence of foliar nitrogen fertilizer during veraison (FNFV) on anthocyanin accumulation and chromatic characteristics of 'Cabernet Sauvignon' grapes over two seasons was investigated. RESULTS: Urea and phenylalanine fertilizers (TU and TP, respectively) and a control were sprayed three times at veraison. In 2018, TU displayed a significant enhancement in total individual anthocyanin content and a* and Cab * profiles. In 2019, FNAV significantly improved the content of total non-acylated, acylated anthocyanin and total individual anthocyanin, and the profiles of L*, a* and Cab *, except a* in TU. The whole process from phenylalanine variation to anthocyanin accumulation in grape skins was analyzed. On the whole, after the first FNFV to harvest, the increase in phenylalanine metabolism, abscisic acid content, effects of PAL (Phenylalanine ammonia lyase), UFGT (UDP glucose-flavonoid 3-O-glucosyltransferase) and transcript concentrations of VvPAL and VvUFGT involved in anthocyanin biosynthesis were also strong evidence explaining the increased anthocyanin and chromatic profiles in 2019. CONCLUSION: Overall, FNFV for nitrogen-deficient grapevines could significantly improve grape color, especially in the 2019 veraison with a proper climate. © 2021 Society of Chemical Industry.

Using foliar nitrogen application during veraison to improve the flavor components of grape and wine.

Nitrogen is involved in the winemaking process from grapevine growth to wine fermentation, and its precise utilization in vineyards can regulate grape and wine quality. Foliar nitrogen application during veraison (FNAV) could prevent nitrogen deficiency in grape and must in nitrogen-deficient vineyards. Moreover, FNAV also could improve certain flavor components of grape and wine, but little attention has been paid to FNAV. Therefore, this paper mainly reviews the difficulties encountered in current applications of nitrogen in vineyards and wineries, and the advantages of FNAV over the addition of nitrogen in soil and wineries. And it discusses that FNAV can increase yeast-assimilable nitrogen and phenolics, and scarcely affect volatile components of grape (must and wine), and points out the existing problems including the core issue and then puts forward future research directions. This information may indicate future directions for research, and provide a reference for viticulturists and winemakers on the precise application of nitrogen on grapevine and must to further improve grape and wine quality in nitrogen-deficient vineyards. © 2020 Society of Chemical Industry.

Foliar Phenylalanine Application Promoted Antioxidant Activities in Cabernet Sauvignon by Regulating Phenolic Biosynthesis.

The effects of foliar phenylalanine application during veraison (FPV) on phenolic biosynthesis and correlation between phenolic compositions and antioxidant activities in Cabernet Sauvignon grown in field and greenhouse were investigated. Solutions with 69 and 138 mg N/vine phenylalanine (Pe1 and Pe2, respectively) and an aqueous solution without nitrogen (CK) were sprayed three times during veraison. FPV significantly improved antioxidant activities in grapes using the two culture methods. The most contributory phenolic compositions to antioxidant activities were anthocyanins and stilbenes following FPV compared with CK. Phenylalanine metabolism, abscisic acid content, and expression levels of VvPAL, VvCHS, VvF3H, VvUFGT, and VvSTS in the phenolic synthesis pathway were increased from the first FPV to harvest. Although Pe2 significantly increased total phenolic contents than Pe1, antioxidant parameters were not markedly affected by the phenylalanine dose. Our finding revealed that FPV was a useful fertilization method to enhance antioxidant activities in grapes in nitrogen-deficient vineyards.

Foliar nitrogen application from veraison to preharvest improved flavonoids, fatty acids and aliphatic volatiles composition in grapes and wines.

This study investigated the effects of foliar nitrogen application from veraison to preharvest (FNVH) on flavonoids, fatty acids and aliphatic volatiles in Cabernet Sauvignon grapes and wines. Solutions with 69 and 138 mg N/plant phenylalanine (P1 and P2, respectively), 69 and 138 mg N/plant urea (U1 and U2, respectively), as well as an aqueous solution without nitrogen (CK), were sprayed three times from veraison to preharvest. U1, P1 had the highest anthocyanins and acylated anthocyanins contents in grapes, respectively. U1 and P2 showed great potential to promote the accumulation of flavonols and flavanols in grapes and wines. U2 increased the contents of almost all free aliphatic volatiles in grapes, while it didn't affect the undesirable smell, and increased the concentrations of fruity esters in wines instead. The study showed FNVH was a useful fertilization way for improving contents of flavonoids and fruity aroma in grapes and wines in deficit-nitrogen vineyards.

Letting wine polyphenols functional: Estimation of wine polyphenols bioaccessibility under different drinking amount and drinking patterns.

Effects of drinking amount and patterns of wine on the digestive characteristics and bioaccessibility of wine polyphenols under in vitro gastrointestinal digestion were investigated. Wine polyphenols released well during mouth and stomach digestion, and the release rates in the "serum-available" fraction, "colon-available" fraction, and after the colon were much lower. Red wine showed a higher biological activity than white wine, but white wine had a better bioaccessibility than red wine, especially under binge drinking. The bioaccessibility of most polyphenols decreased as the drinking amount increased, indicating that drinking larger volumes of wine did not increase the bioaccessibility of polyphenols. Additionally, the relevant biological activities did not increase as the drinking amount increased. Drinking after a meal showed significantly better results than drinking before a meal in most of the tests. Hence, in order to let wine polyphenols play its functional for human health, there still need a moderate consumption amount of wine and drinking after meal is better.

Identification and expression analysis of ERECTA family genes in grape (Vitis vinifera L.).

BACKGROUND: ERECTA family (ERf) genes are found in many dicots and monocots, and play important roles in plant developmental processes and stress responses. However, there is little known on ERf genes in grape (Vitis vinifera L.). OBJECTIVES: The primary objective of this study was to identify the ERf genes in grape, and to analyze their expression profiles in different organs, during development, and in response to hormone treatments and abiotic/biotic stresses. METHODS: ERf protein sequences of dicots were aligned in the grape genome (V. vinifera cv. Pinot Noir, PN40024, 12X) with Blast server. The locus tags obtained were inputted in NCBI to retrieve corresponding nucleotide and protein accession numbers. The subcellular localization experiment was performed by the transient expression of VvERECTA-GFP and VvERL2-GFP in mesophyll protoplasts of Arabidopsis. The expression levels of ERf genes in grape leaves were detected by qRT-PCR after hormone treatments and abiotic/biotic stresses. RESULTS: We first identified the ERf genes in the grape genome, including VvERECTA and VvERL2. Their cDNA full-length sequences were obtained with the accession numbers MG601756 and MG601757. The result of subcellular localization indicated that the fusion proteins of VvERECTA and VvERL2 were localized in the plasma membrane. There were four conserved domains identified in VvERECTA and VvERL2, including a LRRNT-2, a LRR, a transmembrane and a protein kinase domain. The grape ERf genes expressed highly in young aboveground organs. As grape leaves or berries becoming mature, VvERECTA expressed in a declining trend. The transcript abundance of VvERL2 decreased during leaves development, but showed no significant differences during berries development. The hormone treatments of ABA, SA, MeJA and BR could induce the expression of VvERECTA and VvERL2. The treatments of heat, drought, downy and powdery mildew significantly increased the expression levels of the grape ERf genes. CONCLUSION: The grape ERECTA gene family might play crucial roles in response to abiotic and biotic stresses. We provide the first description of the grape ERf genes and the most comprehensive analysis of their expressions in different biological processes.