Modifications in Chemical, Physical and Mechanical Properties of Nebbiolo (Vitis vinifera L.) Grape Berries Induced by Mixed Virus Infection

Abstract

Modifications in grape quality parameters induced by mixed infection with GFLV and GFkV, GLRaV-1 and GVA, and GLRaV-3 and GVA in three Nebbiolo clones were compared against healthy plants of the same clones in two experimental vineyards in Piemonte, northwest Italy. The aim of the study was to evaluate the effect of virus infection on the mechanical properties of the berry skin and the whole berry as assessed by texture analysis tests, and on the amount and quality of berry skin phenols. Differences were observed in grapevine vigour, yield and juice composition, depending on the viral status of the plants. The anthocyanin profile of the vines infected with GFV and GFkV and those infected with GLRaV-1 and GVA showed a lower percentage of the more stable tri-substituted malvidin-3-glucoside and a higher percentage of cyanidin and peonidin-3-glucosides. Texture analysis showed that the viruses may increase berry-skin thickness and reduce phenol extractability. These effects carry practical implications for wine quality.

Dissecting interplays between Vitis vinifera L. and grapevine virus B (GVB) under field conditions

“…For example, GLRaV‐3 induces a strong inhibition of carbohydrate and anthocyanin accumulation in berries (Alabi et al., ; Guidoni et al., ; Vega et al., ). Similarly, mixed infections of GFLV + GFkV and of GLRaV‐1 + GVA lead to a significant reduction in tri‐hydroxylated malvidin‐3‐glucoside forms and in phenol extractability in ‘Nebbiolo’ grapes, with a negative impact on the overall wine quality (Santini et al., ), whereas grapevine red blotch‐associated virus (GRBaV) inhibits ripening, reducing the accumulation of pigments and flavours (Blanco‐Ulate et al., ).…”

Probing into the Effects of Grapevine Leafroll-Associated Viruses on the Physiology, Fruit Quality and Gene Expression of Grapes

“…Similar to the situation with GLRaV-1, these studies reported highly variable findings, which can be difficult to interpret and confusing at times. For example, several studies reported that GLRaV-3 infection reduced berry weight [89,[94][95][96], while others claimed that infection with GLRaV-3 either had no effects or actually increased berry weight [88,[97][98][99][100][101]. Many factors may be attributable for the discrepancy between these studies, including differences in the cultivars and rootstocks used, the genetic variants of GLRaV-3 involved, co-infection with different viruses, age of the infected vines, climate, and methods of sampling.…”

“…No changes in either yield or the contents of soluble solids and phenolic compounds (anthocyanins and catechins) were observed [ 87 ]. In contrast, Santini et al, 2011 reported an increase in berry weight and titratable acidity but a reduction in yield in Nebbiolo vines co-infected with GLRaV-1 and GVA [ 88 ]. On the other hand, Guidoni et al, 2000 reported no change in yield, but documented decreased berry weight and titratable acidity level in vines co-infected with GLRaV-1 and GVA [ 89 ].…”

Vineyard Practice

“…GLRaV-1 and rugose wood viruses shift the relative proportion of phenolics from seeds and skins, but do not appear to affect grape anthocyanin or total phenolic contents (Tomažič et al, 2003). In contrast, the level of the more stable (oxidation-resistant) anthocyanins is reduced in Nebbiolo grapes, in association with joint infection with GFV and GFkV viruses (Santini et al, 2011).…”