Grape Berry Secondary Metabolites and Their Modulation by Abiotic Factors in a Climate Change Scenario–A Review

Abstract

Temperature, water, solar radiation, and atmospheric CO2 concentration are the main abiotic factors that are changing in the course of global warming. These abiotic factors govern the synthesis and degradation of primary (sugars, amino acids, organic acids, etc.) and secondary (phenolic and volatile flavor compounds and their precursors) metabolites directly, via the regulation of their biosynthetic pathways, or indirectly, via their effects on vine physiology and phenology. Several hundred secondary metabolites have been identified in the grape berry. Their biosynthesis and degradation have been characterized and have been shown to occur during different developmental stages of the berry. The understanding of how the different abiotic factors modulate secondary metabolism and thus berry quality is of crucial importance for breeders and growers to develop plant material and viticultural practices to maintain high-quality fruit and wine production in the context of global warming. Here, we review the main secondary metabolites of the grape berry, their biosynthesis, and how their accumulation and degradation is influenced by abiotic factors. The first part of the review provides an update on structure, biosynthesis, and degradation of phenolic compounds (flavonoids and non-flavonoids) and major aroma compounds (terpenes, thiols, methoxypyrazines, and C13 norisoprenoids). The second part gives an update on the influence of abiotic factors, such as water availability, temperature, radiation, and CO2 concentration, on berry secondary metabolism. At the end of the paper, we raise some critical questions regarding intracluster berry heterogeneity and dilution effects and how the sampling strategy can impact the outcome of studies on the grapevine berry response to abiotic factors.

Managing Vineyard Topography and Seasonal Variability to Improve Grape Quality and Vineyard Sustainability

“…Although groups, SE and E, were in the same MU, the malic acid and anthocyanin concentrations in SE group of vineyards were lower than in E group likely because of the greater insolation of SE vineyards and the consequent greater number of daily hot hours. The lower concentration of anthocyanins also found in the SW group, particularly in 2012, was consistent with the high temperatures of the sites and the vintage; this finding complemented studies that observed lower anthocyanin concentration in cases of high temperature or high heat accumulation [12,35,37,38,[68][69][70]. The results for SW grouped vineyards were only partially in agreement with what was observed in the Douro Valley, where a negative effect of altitude and south-west aspect was observed on berry volume and yield, but not on skin total anthocyanin [43].…”

“…All the results of this study confirmed the huge influence of the thermal conditions on the accumulation trend of many grape metabolites determining grape and wine quality [28,29,35,70,[75][76][77] and, in particular, their negative impact on the anthocyanin biosynthesis as observed in pot experiments [34,35] and in field experiments [11,17,36]. Furthermore, it was also evidenced that not only the temperature itself, but also the vineyard topography together with the synergy between topo-climate and seasonal meteorological trends, plays an important role in affecting berry metabolism and grape ripening [7,17,28,69].…”

“…With the expected temperature increases associated with climate change, the occurrence of unfavourable years due to thermal excesses and prolonged periods of drought will be more and more frequent [48]. Particularly in temperate and warm climate this is not positive as some of the key berry parameters (acids, anthocyanins, and pH) can be impacted negatively in terms of quality output with increased temperatures [70].…”

Dietary Effects of Anthocyanins in Human Health: A Comprehensive Review

“…Phenolic compounds are secondary metabolites produced by plants to protect them against pathogens and predators, ultraviolet radiation, climate conditions, and acidified soils, acting also as attractants for pollinators, antifeedants, and phytoalexins [ 25 , 26 ]. They are also considered the main contributors to plants’ colour, nutritional, and sensory characteristics [ 27 ].…”

“…Their structure presents at least one benzene ring coupled to one or more hydroxyl groups and can range from simple phenolic, low molecular weight and single-aromatic molecules to highly polymerized compounds [ 28 ]. In order to facilitate their distinction, phenolics are classified into two major groups: (i) non-flavonoid compounds (phenolic acids, tannins, lignans, coumarins, stilbenes, and curcuminoids) and (ii) flavonoid compounds (anthocyanidins, flavan-3-ols, and their oligomeric structures, recognized as proanthocyanidins, flavanones, flavanonols, flavones, flavonols, and isoflavones) [ 7 , 25 , 26 ]. Their biosynthesis, which is shown in Figure 1 , comprises the shikimate, phenylpropanoid, and flavonoid pathways, and involves deamination, hydroxylation, and methylation reactions [ 25 ].…”