JOURNAL HIGHLIGHTS BY STEVE RANGER
Grapevines are highly susceptible to fungal diseases, which are usually controlled through the intensive use of chemical pesticides.
In cool and wet climates this can mean up to 12 treatments per season to keep vines healthy, and although this is effective, it also raises concerns around sustainability and soil quality.
In an attempt to reduce the amount of pesticide used, much effort has gone into developing disease-resistant grapevine cultivars in recent decades, with breeding programmes focusing on the production of hybrids that integrate resistance traits from wild American and Asian grapevine species. This has produced over 100 ‘PIWI’ cultivars (after the German pilzwiderstandsfähig, meaning ‘fungus-resistant’).
Now a team of researchers at the University of Naples Federico II has carried out a pilot, single-vintage investigation of the molecular and metabolic bases underlying the enological potential of selected Italian red PIWI grape cultivars, using Pinot Noir as a non-PIWI benchmark.
Despite their promise in terms of sustainability, there is still limited understanding of some of these PIWI grapes in terms of fermentation and ageing, or the metabolic composition of the berries, especially regarding skin and seed phenolics and glycosylated flavonoids. This information is needed to predict the behaviour of wines made from these grapes when they are in the cellar, the researchers said.
‘Without this knowledge, it is difficult to adapt vinification protocols or genetically choose the best clones to produce wines of reliable quality,’ said the paper, published in SCI’s Journal of the Science of Food and Agriculture.
At harvest, transcript levels of 15 genes involved in sugar/energy signalling (TOR3, SnRK1.1, SnRK1.2), flavonoid biosynthesis (LAR1, LAR2, ANR, DFR, LDOX, FLS4, FLS5) and flavonoid glycosylation (GAT1, UFGT, Va5GT, Vl3GT, UGT72), were quantified, together with technological maturity traits, skin and seed phenolic fractions, and skin flavonol profiles.
‘By integrating transcriptional and chemical data, this work provides a first cultivar-resolved framework to support future breeding- and winemaking-oriented investigations,’ the researchers said.
The researchers noted that several, but not all, PIWI cultivars combined moderate-to-high sugars with comparatively high acidity, frequent enrichment in skin anthocyanins and flavonol glycosides, and lower extractable skin tannins than Pinot Noir.
‘These results support a cultivar-resolved molecular and compositional framework for interpreting enological variability in Italian red PIWI grapes.
‘The data may guide breeding and cultivar-tailored winemaking strategies, while broader generalisation requires validation across additional genotypes, vintages and ripening stages,’ the paper said.
Gene expression and metabolic variability in fungus-resistant PIWI (‘Pilzwiderstandsfähig’) grape cultivars
Villano Clizia, Luciano Alessandra, Carputo Domenico, Frusciante Luigi, Forino Martino, Napolitano Felice, Smimmo Roberta, Gambuti Angelita, Aversano Riccardo
Journal of the Science of Food and Agriculture
doi.org/10.1002/jsfa.70645
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