Metabolic and transcriptional changes associated with the use of Ascophyllum nodosum extracts as tools to improve the quality of wine grapes (Vitis vinifera cv. Sangiovese) and their tolerance to biotic stress

Exploring Seaweed and Glycine Betaine Biostimulants for Enhanced Phenolic Content, Antioxidant Properties, and Gene Expression of Vitis vinifera cv. "Touriga Franca" Berries

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum-ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run.

Ascophyllum nodosum Extract and Glycine Betaine Preharvest Application in Grapevine: Enhancement of Berry Quality, Phytochemical Content and Antioxidant Properties

The Douro Demarcated Region (DDR) has peculiar edaphoclimatic characteristics that provide a suitable terroir for premium wine production. As climate change effects continue to emerge, ensuring productivity and quality becomes increasingly important for viticulturists, as those directly determine their profits. Cultural approaches, such as the use of biostimulants, are actively being developed to mitigate abiotic stress. The main objective of this work was to assess the effect of foliar sprays of a seaweed (Ascophyllum nodosum)-based extract (ANE) and glycine betaine (GB) on grape berry quality, bioactive compounds, and antioxidant activity. A trial was installed in a commercial vineyard (cv. 'Touriga Franca') in the Douro Superior (Upper Douro) sub-region of the Douro Demarcated Region. In 2020 and 2021, three foliar sprayings were performed during the growing season, namely at pea size, bunch closure, and veraison. There was a positive effect of both biostimulants (ANE and GB) on the physiological and biochemical performance of cv. 'Touriga Franca' exposed to summer stress. In general, the GB 0.2% spraying was the most promising treatment for this grape cultivar, as it increased berry quality, the concentration of bioactive compounds (total phenolics, flavonoids, and ortho-diphenols), and the antioxidant activity. These results revealed the efficacy of biostimulant sprayings as a sustainable viticultural practice, improving berry quality under summer stress conditions.

Comparative metabolomic profiling of Arabidopsis thaliana roots and leaves reveals complex response mechanisms induced by a seaweed extract

Seaweed extracts are a prominent class of biostimulants that enhance plant health and tolerance to biotic and abiotic stresses due to their unique bioactive components. However, the mechanisms of action of biostimulants are still unknown. Here, we have used a metabolomic approach, a UHPLC-MS method, to uncover the mechanisms induced following application to Arabidopsis thaliana of a seaweed extract derived from Durvillaea potatorum and Ascophyllum nodosum. We have identified, following the application of the extract, key metabolites and systemic responses in roots and leaves across 3 timepoints (0, 3, 5 days). Significant alterations in metabolite accumulation or reduction were found for those belonging to broad groups of compounds such as lipids, amino acids, and phytohormones; and secondary metabolites such as phenylpropanoids, glucosinolates, and organic acids. Strong accumulations of TCA cycle and N-containing and defensive metabolites such as glucosinolates were also found revealing the enhancement of carbon and nitrogen metabolism and defence systems. Our study has demonstrated that application of seaweed extract dramatically altered the metabolomic profiles of Arabidopsis and revealed differences in roots and leaves that varied across the timepoints tested. We also show clear evidence of systemic responses that were initiated in the roots and resulted in metabolic alterations in the leaves. Collectively, our results suggest that this seaweed extract promotes plant growth and activates defence systems by altering various physiological processes at the individual metabolite level.

Biostimulants as an Alternative to Improve the Wine Quality from Vitis vinifera (cv. Tempranillo) in La Rioja

The application of biostimulants appears to be an environmentally friendly, innovative, and sustainable agronomical tool to mitigate the negative effects induced by adverse climatology in traditional grape-growing regions such as La Rioja (Spain). However, their mechanism of action in grapevines is still unclear. We evaluated how commercial substances (two from Ascophyllum nodosum extraction and one amino acids-based biostimulant) and the non-proteinogenic amino acid β-aminobutyric acid (BABA) affect the quality and quantity of musts and grapes in Vitis vinifera L. cv. Tempranillo from a semi-arid region of La Rioja during two seasons. We hypothesized an enhancement in organic metabolites in berries and leaves in response to these treatments, changing the organoleptic characteristics of the final products. The treatments altered the primary metabolites such as carbohydrates, organic acids (AcOrg), and free amino acids, first in the leaves as the effect of the foliar application and second in grapes and musts. As the main result, the biostimulant efficiency depended on the climatology and vineyard location to improve the final yield. Whereas biostimulant application enhanced the yield in 2018 (less dry year), it did not help production in 2019 (dry year). BABA was the most efficient biostimulant, enhancing plant production. Regarding yield quality, the biostimulant application improved the musts mainly by enhancing the fumaric acid content and by reducing carbohydrates, except in BABA-treated plants, where they were accumulated. These results corroborate biostimulants as an exciting approach in wine production, especially for improving wine quality.

The Role of Biostimulants as Alleviators of Biotic and Abiotic Stresses in Grapevine: A Review

The viticulture and wine industry contribute to the economy and reputation of many countries all over the world. With the predicted climate change, a negative impact on grapevine physiology, growth, production, and quality of berries is expected. On the other hand, the impact of these changes in phytopathogenic fungi development, survival rates, and host susceptibility is unpredictable. Grapevine fungal diseases control has been a great challenge to winegrowers worldwide. The use of chemicals in viticulture is high, which can result in the development of pathogen resistance, increasingly raising concerns regarding residues in wine and effects on human and environmental health. Promoting sustainable patterns of production is one of the overarching objectives and essential requirements for sustainable development. Alternative holistic approaches, such as those making use of biostimulants, are emerging in order to reduce the consequences of biotic and abiotic stresses in the grapevine, namely preventing grape fungal diseases, improving grapevine resistance to water stress, and increasing yield and berry quality.

Methyl Jasmonate Applications in Viticulture: A Tool to Increase the Content of Flavonoids and Stilbenes in Grapes and Wines

Recently, the interest in methyl jasmonate (MeJ) has increased in viticulture due to its effects on the synthesis of phenolic secondary metabolites in grapes, especially of anthocyanins, flavonols, and stilbenes derivatives, naturally occurring or synthesized, in berries in response to MeJ application to grapevines. These metabolites help to define sensory characteristics of wines by contributing to their color, flavor and mouthfeel properties, and to derive potential beneficial health effects due to their consumption. This review offers an overview of the importance of these phenolic compounds in grape and wine quality, in association with the MeJ supplementation to grapevines, and also considers their natural biosynthesis in grapes. On the other hand, this review describes the adaptation mechanisms induced after the grapevine elicitation. In addition, this report addresses the effects of MeJ over other aspects of Vitis immunity and its association with phenolic compounds and summarizes the recently published reports about the effects of exogenous MeJ applications to grapevines on grape and wine quality.

Influence of seaweed foliar application to Tempranillo grapevines on grape and wine phenolic compounds over two vintages

The study of seaweeds is increasing in viticulture due to their implications on plant protection and grape quality. This trial aimed to study the effects of foliar applications of an Ascophyllum nodosum extract at low (0.25%, v v-1) and high (0.50%, v v-1) dosages on grape and wine phenolic compounds in 2017 and 2018. In grapes, seaweed biostimulation increased the content of malvidin-3-glc, myricetin-3-glc and myricetin-3-gal in 2017 season. Moreover, both treatments improved the synthesis of trans-piceid and total stilbenes in both seasons. Sensory analysis revealed that 2017 wines had more color than the 2018 wines, which coincided with color intensity parameters. Therefore, seaweed applications to grapevines improved stilbenes content in grapes independently of the season and its effects on the rest of phenolic compounds in grapes and wines depended strongly of season factor.

Seaweeds in viticulture: a review focused on grape quality

Cell walls of seaweeds contain a wide number of organic and inorganic constituents, of which polysaccharides have important biological activity. Some researchers suggest that polysaccharides from seaweeds can behave as biotic elicitors in viticulture, triggering the synthesis of phenolic compounds in leaves and grape berries. The mechanism of action of seaweeds after a foliar application to grapevines is not fully understood but it is discussed in this review. An overview of the recent research focused on the effects of seaweeds foliar applications on grapevine productivity, on grape and wine quality is included as well as a short-term future perspective for the research in this field.

Effects on must and wine volatile composition after biostimulation with a brown alga to Tempranillo grapevines in two seasons

BACKGROUND

Seaweed application has been defined as a novel technique capable of improving the content of secondary metabolites in berries. There is limited available information about its effects on must and wine volatile composition. This field trial aimed to study the effects of biostimulation to Tempranillo grapevines through an Ascophyllum nodosum fertilizer applied at a low dosage (Ld) and high dosage (Hd) on must and wine volatile compounds over two seasons.

RESULTS

Ld treatment scarcely affected must and wine volatile compounds in both seasons. Hd foliar application increased the content in musts of several individual terpenoids, C13 norisoprenoids, esters, benzenoids, alcohols, carbonyl compounds and C6 compounds in 2018. Must yeast assimilable nitrogen conditioned the production of wine volatile compounds.

CONCLUSION

These results suggest that seaweeds applications can act as elicitors in Tempranillo, triggering the synthesis of several compounds by the plant in musts during a season with a high rainfall and relative humidity. © 2020 Society of Chemical Industry.

Grapevine Stimulation: A Multidisciplinary Approach to Investigate the Effects of Biostimulants and a Plant Defense Stimulator

The increasing use of plant defense stimulators (PDS) and biostimulants (BS) to make agriculture more sustainable has led to questions about their action on plants. A new PhysBioGen approach is proposed with complementary tools: PHYSiological (root weight); BIOchemical and BIOlogical (secondary metabolite quantification and Plasmopara viticola development) and expressions of 161 GENes involved in metabolic plant functions. The proposed approach investigated the effects of three phytostimulants on Vitis vinifera: one PDS (ASM) and one BS chelated (CH) and another enriched with seaweed (SW). Distinct responses were obtained between the PDS and the two BS. In particular, we observed the persistence of anti-mildew efficacy over time, correlated with differentiated expressions of defense genes (VvROMT, VvSAMT, VvPR8). As expected, the two BS displayed more similarities to each other than to the PDS (flavonols, anthocyanins, free salicylic acid). However, the two BS revealed differences in the modulation of genes involved in defense and primary metabolism and some genes were identified as potential markers of their action (VvWRKY1, VvLOX9, VvPOD, VvPDV1, VvXIP1, VVDnaJ). Our results highlight the common and the specific effects of the two BS and the PDS. These new tools could help in understanding the mode of action of phytostimulants in order to achieve better quality and production yield and/or as a way to limit chemical inputs in the vineyard.

Effects of Arthrospira platensis Extract on Physiology and Berry Traits in Vitis vinifera

Several advantages on physiology, productivity, and grape quality have been reported for grapevine treated with seaweed extracts, but little is known about the importance of cyanobacterial-based biostimulants in viticulture. The purpose of this pioneering work was to analyze the broad-spectrum effects of the Arthrospiraplatensis F&M-C256 extract on Vitis vinifera L. cv. Pinot Nero grown in pots in optimal conditions and under water stress. To evaluate the effects, major physiological parameters of the plants and the quali-quantitative parameters of grape were analyzed. According to the results obtained in this study, ameliorating effects in leaf gas exchanges induced by A. platensis F&M-C256 treatments were detected in both irrigation regimes. Above all, A. platensis F&M-C256 allowed keeping stomata open without negative consequences in water potential in treated vines under water-stress conditions. In terms of berry traits, A. platensis F&M-C256-treated vines presented higher berry weight in comparison with untreated vines in both water regimes and improved berry composition in treated vines subjected to drought. The results of the present study demonstrated an A. platensis-dependent physiological response in case of abiotic stress, which prominently affects grape traits at harvest.

Eco-Physiological Traits and Phenylpropanoid Profiling on Potted Vitis vinifera L. cv Pinot Noir Subjected to Ascophyllum nodosum Treatments under Post-Veraison Low Water Availability

In Mediterranean regions, extreme weather conditions during the growing season may alter grapevine physiology and metabolism, thus modifying the quality of wines. The objective of this study was to investigate the effects of Ascophyllum nodosum treatments on plant physiology and berry metabolism in Vitis vinifera exposed to water stress. The experiment was performed on potted vines subjected to two irrigation regimes (well-watered, WW, and water stressed, WS) both associated with A. nodosum treatments (SWE), compared with control plants (CTRL). Gas exchanges, chlorophyll fluorescence, and water relations were monitored on SWE and CTRL leaves, both in WW and WS vines at three times. Moreover, the quantification of secondary metabolites and their partitioning were performed in berry skins. Plants treated with A. nodosum extract showed higher photosynthesis and stomatal conductance than CTRL in both irrigation regimes and maintained a better plant hydraulic conductivity at the end of the sampling period. In addition, secondary metabolites in berry skins and their partitioning were significantly affected by the treatments in both irrigation regimes. Our results suggest that foliar application of A. nodosum extract may help the acclimation of grapevines to post-veraison water stress, likely improving plant physiological and biochemical performances under environmental constraints.

Seaweed foliar applications at two dosages to Tempranillo blanco (Vitis vinifera L.) grapevines in two seasons: Effects on grape and wine volatile composition

The effects of seaweed applications to grapevines on grape and wine volatile composition are currently unknown. The aim of this work was to study the influence of seaweed foliar applications (Ascophyllum nodosum) to a Tempranillo blanco vineyard on grape and wine volatile composition. A low (Ld) and a high dosage (Hd) of the seaweed fertilizer was applied in two consecutive seasons (2017-2018). The most abundant family of varietal volatile compounds in Tempranillo blanco grapes was C13 norisoprenoid. Hd treatment tended to increase the concentration of certain C6 compounds in grapes in both seasons, whereas Ld application tended to decrease 2-phenylethanol and 2-phenylethanal content in grapes with a season dependence. Season factor affected to the concentration of most of the volatile compounds in grapes due to the differences on rainfall, which affected to the weight of 100 berries and physico-chemical parameters. Yeast assimilable nitrogen (YAN) in musts could have affected the concentration of most of the wine volatile compounds. According to odor activity values (OAV), Tempranillo blanco wines were characterized as floral, fruity, banana, pear, among others aroma compounds.

Phenolic composition of Tempranillo Blanco (Vitis vinifera L.) grapes and wines after biostimulation via a foliar seaweed application

BACKGROUND

Seaweeds are defined as novel elicitors in many crops, allowing the synthesis of secondary metabolites to be triggered in different plant tissues. Currently, the phenolic composition of Tempranillo Blanco grapes and wines is unreported. The present study aimed to investigate the effects of an Ascophyllum nodosum seaweed extract applied to Tempranillo Blanco grapevines, at low (Ld) and high (Hd) dosages, on grape and wine phenolic compounds during two consecutive seasons (2017-2018).

RESULTS

The results obtained showed that catechin was the most abundant phenolic compound in Tempranillo Blanco grapes and wines. Season affected the weight of 100 berries and some enological parameters. Catechin and flavonols concentrations in grapes were increased after Hd application to grapevines, independently of season. The concentration of hydroxycinnamic and hydroxybenzoic acids in wines was affected by vintage, probably as a result of oxidation reactions, as well as pinking phenomena, whereas the stilbenes content in wines was conditioned by the affect of cryptogamic diseases in grapes.

CONCLUSION

Seaweeds might act as an elicitor of several phenolic compounds in grapes, enhancing the content of some phenolic compounds in wines. © 2019 Society of Chemical Industry.