Berry phenolics of grapevine under challenging environments

Abstract

Plant phenolics have been for many years a theme of major scientific and applied interest. Grape berry phenolics contribute to organoleptic properties, color and protection against environmental challenges. Climate change has already caused significant warming in most grape-growing areas of the world, and the climatic conditions determine, to a large degree, the grape varieties that can be cultivated as well as wine quality. In particular, heat, drought and light/UV intensity severely affect phenolic metabolism and, thus, grape composition and development. In the variety Chardonnay, water stress increases the content of flavonols and decreases the expression of genes involved in biosynthesis of stilbene precursors. Also, polyphenolic profile is greatly dependent on genotype and environmental interactions. This review deals with the diversity and biosynthesis of phenolic compounds in the grape berry, from a general overview to a more detailed level, where the influence of environmental challenges on key phenolic metabolism pathways is approached. The full understanding of how and when specific phenolic compounds accumulate in the berry, and how the varietal grape berry metabolism responds to the environment is of utmost importance to adjust agricultural practices and thus, modify wine profile.

Figure 1

Flavonoid ring structure and numbering.

Figure 2

Schematic structure of a ripe grape berry and pattern phenolics biosynthesis distribution between several organs and tissues (indicated by arrows). ^a Anthocyanins are synthetized also in the inner flesh of the teinturier varieties [,–12].

Figure 3

Biosynthetic pathways of grape berry secondary compounds. Phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumaroyl:CoA-ligase (4CL), stilbene synthase (STS), chalcone synthase (CHS), chalcone isomerase (CHI), flavonoid 3′-hydroxylase (F3′H), flavonoid 3′,5′-hydroxylase (F3′5′H), flavanone-3-hydroxylase (F3H), flavonol synthase (FLS), dihydroflavonol reductase (DFR), leucoanthocyanidin reductase (LAR), anthocyanidin reductase (ANR), leucoanthocyanidin dioxygenase (LDOX), dihydroflavonol 4-reductase (DFR), flavonoid glucosyltransferase (UFGT), O-methyltransferase (OMT) (adapted from [3,43]).

Figure 4

HadCM3 modeled growing season average temperature anomalies for the Bordeaux region. The anomalies are referenced to the 1950–1999 base period from the HadCM3 model. Trend values are given as an average decadal change and the total change over the 2000–2049 50-year period. Note: this figure is adapted with permission from [56]. Copyright Springer, 2005.

Figure 5

Total phenolic grape berry profile of 21 Portuguese V. vinifera varieties grown in Estremadura Region (Instituto Nacional de Investigação Agrária, INIA, Dois-Portos, Portugal), collected at full mature state. Error bars denote the SD from the mean, n = 3. Inset: correlation between total phenolic content and antioxidant activity (Teixeira, A., Eiras-Dias, J. and Gerós, H.).