Terroir 2020 banner
IVES 9 IVES Conference Series 9 Terpenoid profiles and biosynthetic gene expression pattern in Asti DOCG white muscat grapes at ripening as affected by different canopy management protocols

Terpenoid profiles and biosynthetic gene expression pattern in Asti DOCG white muscat grapes at ripening as affected by different canopy management protocols

Abstract

Aim: The main goal of this study was to find an efficient canopy management to limit the high temperature-related aroma losses of White Muscat grapes, and consequently to preserve the quality standards of Asti DOCG wines.

Methods and Results: Four different strategies have been tested in two vineyards of the Asti DOCG production area: pre-flowering leaf removal (m1), post-berry set leaf removal (m2), leaf removal at veraison (m3), and clusters thinning (m4). Control vines (m0) did not receive any thinning or defoliation. Grapes were collected at four time points: seven days before the commercial harvest, at the commercial harvest scheduled for “Asti spumante” wine, at the commercial harvest scheduled for “Moscato” wine and overripening. Free and glycosylated terpenoids content (GC-MS) as well as the expression of key genes involved in terpenoids biosynthesis and metabolism (RT-qPCR) were analysed separately in skin and pulp. The results revealed a peak of volatile accumulation, which occurred early and late throughout the sampling times. The treatments m3 and m4 were, in general, those more effective in enhancing the aroma profiles in both tissues analysed. Correspondingly, in these grapes, specific genes, such as VvDXS3 and VvGT14 resulted up-regulated. Other genes, such as VvHDR, showed different expression pattern resulting, in general, more expressed in pulp than skin, regardless the applied treatment.

Conclusions:

Based on these preliminary trials carried out in a specific production area of White Muscat, it seems that m3 and m4 treatments had a significant effect on the volatile’s accumulation in both grape skin and pulp. m1 treatment resulted to be the less effective in inducing changes in the aroma profile and the terpenoid biosynthetic pathway.

Significance and Impact of the Study: Moscato d’Asti DOCG is one of the most characteristic enological products of Piemonte (North-West Italy) wine grapes-growing area. It comes exclusively from White Muscat grapes which are exalted by the climatic and geographical conditions of the production area. Indeed, the interactions between vine and environment, limestone terrain and micro-climate typical of hilly zones leads to a characteristic fruity and sweety aroma. The characteristic aroma of Muscat wine is attributed to the presence of specific terpenoids, mainly linalool, nerol, geraniol, trans-piran linalool oxide and citronellol. The grapevine terpenoids pathway is strongly regulated by endogenous and environmental factors and among them, temperature and light exposure plays a crucial role. As recently observed, the content of these compounds is strongly decreasing due to the increasing temperatures. Higher temperature during the growing season is forcing growers to find ways to reliably control grape composition preserving the typical aroma of Asti DOCG wines. The present study could offer important information to address grower’s choice in term of canopy management that are better suited to the changing climate.

DOI:

Publication date: March 25, 2021

Issue: Terroir 2020

Type : Video

Authors

Margherita Modesti1*, Ron Shmulevitz, Stefano Brizzolara1, Daniele Eberle2, Guido Bezzo2, Pietro Tonutti1

1Life Sciences Institute, Scuola Superiore Sant’Anna, Piazza Martiri della Libertà 33, 50127 Pisa, Italy
2Consorzio per la Tutela dell’Asti DOCG. Piazza Roma 10, 14100 Asti, Italy

Contact the author

Keywords

Canopy management, Moscato d’Asti DOCG, terpenoid content and biosynthesis, climate change

Tags

IVES Conference Series | Terroir 2020

Citation

Related articles…

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)

Second pruning as a strategy to delay maturation in cv. ‘Touriga nacional’ in the Portuguese Douro region

The advance in maturation of wine grapes is an important climate change risk related effect that could affect warm regions like Portuguese Douro Wine Region. Indeed, the climate analysis over the past years registered a decrease in the precipitation, significant higher average temperatures, and a more frequent occurrence of extreme weather events, including heat waves. In these conditions the length from anthesis until maturation is shortened and the uncoupling of technical and phenolic maturity results in berries with higher sugar concentration (and lower acidity), but lower anthocyanins, tannins, and total phenolic concentration, which produce unbalanced wines.
In this work, an innovative strategy of crop forcing, based on forcing vine regrowth after a second pruning of green shoots, was tested, aimed at delaying ripening until the temperature becomes lower and, therefore, preventing acidity loss and increasing anthocyanin-to-sugar ratio. The experiments were conducted in 2019 and 2020 in a commercial vineyard of ‘Touriga Nacional’ located in the Douro Region. Crop forcing was conducted 15 (CF1) to 30 (CF2) days after fruit set. Vines pruned with conventional methods were used as control (CF0). Results confirmed that fruit ripening was shifted from the hot season (August/September), until a cooler period (October through early-November). At harvest, grapevine berries from CF1 and CF2 presented lower pH and higher acidity, than control, with no significant differences in colour intensity and phenolic levels composition. Sugar content was lower in CF2-treated vines in both seasons. However, in CF-treated vines the number and size of clusters were significantly lower (up to 88% reduction) than in control plants. A metabolomics analysis of mature berries from CF-treated vines and control is underway. Crop forcing was indeed effective in producing a more balance berry composition but severely reduced grapevine yield,

The modification of cultural practices in grapevine cv. Syrah, does it modify the characteristics of the musts?

The work shows the results of a year of experimentation (2020) in a Syrah variety vineyard in La Roda (Castilla-La Mancha, Spain). The trial approach was on a randomized block design with two factors: Irrigation (I) and Pruning (P).
Irrigation schedules were adjusted to apply amounts close to 1,500 m3/ha. With this provision, 2 different irrigation treatments were proposed: I1) Start of irrigation from pea-sized grape to post-harvest (providing at least 20 % of the total amount of irrigation water to be provided post-harvest); I2) Start of irrigation from pea-sized grape to harvest (usual irrigation practice in the study area). Pruning was proposed with two treatments, one at the end of January (P1), which is pruning on a conventional date; and P2) pruning carried out at the beginning of budding. In total, 4 repetitions were designed with 4 elementary plots, each one of them representing one of the proposed treatments (I1P1; I1P2; I2P1; I2P2). In total, 16 plots were worked on and each elementary plot consisted of 30 strains, distributed in 3 lines.
The productive response was evaluated with the yield results of the harvest harvested at 23 ºBrix. The qualitative response was measured in the musts through the indices of technological (acidity, pH and potassium) and phenolic maturity and aromatic compounds in free and glycosylated fractions. The treatments tested had, in general, an effect on the different variables analyzed.

Underpinning terroir with data: rethinking the zoning paradigm

Agriculture, natural resource management and the production and sale of products such as wine are increasingly data-driven activities. Thus, the use of remote and proximal crop and soil sensors to aid management decisions is becoming commonplace and ‘Agtech’ is proliferating commercially; mapping, underpinned by geographical information systems and complex methods of spatial analysis, is widely used. Likewise, the chemical and sensory analysis of wines draws on multivariate statistics; the efficient winery intake of grapes, subsequent production of wines and their delivery to markets relies on logistics; whilst the sales and marketing of wines is increasingly driven by artificial intelligence linked to the recorded purchasing behaviour of consumers. In brief, there is data everywhere!

Opinions will vary on whether these developments are a good thing. Those concerned with the ‘mystique’ of wine, or the historical aspects of terroir and its preservation, may find them confronting. In contrast, they offer an opportunity to those interested in the biophysical elements of terroir, and efforts aimed at better understanding how these impact on vineyard performance and the sensory attributes of resultant wines. At the previous Terroir Congress, we demonstrated the potential of analytical methods used at the within-vineyard scale in the development of Precision Viticulture, in contributing to a quantitative understanding of regional terroir. For this conference, we take this approach forward with examples from contrasting locations in both the northern and southern hemispheres. We show how, by focussing on the vineyards within winegrowing regions, as opposed to all of the land within those regions, we might move towards a more robust terroir zoning than one derived from a mixture of history, thematic mapping, heuristics and the whims of marketers. Aside from providing improved understanding by underpinning terroir with data, such methods should also promote improved management of the entire wine value chain.

Is wine terroir a valid concept under a changing climate?

The OIV[i] defines terroir as a concept referring to an area in which collective knowledge of the interactions between the physical and biological environment (soil, topography, climate, landscape characteristics and biodiversity features) and vitivinicultural practices develops, providing distinctive wine characteristics. Those are perceptible in the taste of wine, which drives consumer preference and, therefore, wine’s value in the marketplace. Geographical indications (GI) are recognized regulatory constructs formalizing and protecting the nexus between wine taste and the terroir generating it. Despite considering updates, GIs do not consider the nexus as a dynamic one and do not anticipate change, namely of climate. Being climate a fundamental feature of terroir, it strongly impacts wine characteristics, such as taste. According to IPCC[ii], many widespread, rapid and unprecedented changes of climate occurred, some being irreversible over hundreds to thousands of years. Climatic shifts and atmospheric-driven extreme events have been widely reported worldwide. Recent climatic trends are projected to strengthen in upcoming decades, whereas extremes are expected to increase in frequency and intensity, forcing wines away from GI definitions. Geographical shifts of viticultural suitability are projected, often moving into regions and countries different from current ones. Some authors propose adaptation in viticulture, winemaking and product innovation. We show evidence of climate changing wine characteristics in the Douro valley, home of 270-year-old Port GI. We discuss herein resist or adapt stances for when climate changes the nexus between terroir and wine characteristics. Using the MED-GOLD[iii] dashboard, a tool allowing for easy visual navigation of past and future climates, we demonstrate how policymakers can identify future moments, throughout the 21st century under different emission scenarios, when GI specifications will likely need updates (e.g., boundaries, varieties) to reduce climate-change impacts.