Coming of age: do old vines actually produce berries with higher enological potential than young vines? A case study on the Riesling cultivar

Color is a key quality trait for grape berry and the producing wines. Berry color of red genotypes is mainly determined by the quantity and composition of anthocyanins accumulated in the skin and/or pulp. Both genetic and environmental factors could influence the quantity and composition of anthocyanins, while the underlying mechanisms are not fully clear. To explore the mechanisms underlying the diversity of anthocyanin accumulation in grape berry, we compared two grapevine genotypes showing distinct sensitivities to ABA-induced anthocyanin biosynthesis, where one genotype showed minor responses to exogenous ABA application while the other showed significant increase in anthocyanins after exogenous ABA application.

Dans une région comme la Toscane, zone dans laquelle sont produits certains des meilleurs vins italiens et du monde, la province d’Arezzo a actuellement une importance relativement marginale

The outer waxy layer of plant aerial structures, known as the cuticle, represents an important trait that can be targeted to increase plant tolerance against abiotic stresses exacerbated by environmental transition. The MIXTA transcription factor, member of the R2R3-MYB family, is known to affect conical shape of petal epidermal cells in Anthirrinum, cuticular thickness in tomato fruit and trichome formation and morphology in several crops. The aim of this study was to investigate the role of the grapevine MIXTA homologue by phenotypic and molecular characterization of overexpressing and knock-out grapevine lines.

Under-vine (UV) management has traditionally consisted of synthetic herbicide use to limit competition between weeds and grapevines. With growing global interest towards non-synthetic chemical use, this study aimed to capture the effects of alternative UV management at two commercial Shiraz vineyards in South Australia, where the sole management variables were UV management since 2016. In adjacent treatment blocks, cultivation (CU) was compared to spontaneous vegetation (SV) in McLaren Vale (MV), and herbicide was compared to SV in Eden Valley (EV). Soil water infiltration rates were slower and grapevine stem water potential was lower in CU compared to SV in MV, with the latter having a plant community dominated by soursob (Oxalis pes-caprae) during winter; while in EV, there was little separation between the treatments. Yields were affected at both sites, with SV being higher in MV and HE being higher in EV. In MV, the only effect on grape must was a lower 13C:12C isotope ratio in CU, indicating greater grapevine water stress. In the grape must at EV, SV had higher total soluble solids, total phenolics, anthocyanins, and yeast available nitrogen; and lower pH and titratable acidity. Pruning weights were not affected by the treatments in MV, while they were higher in HE at EV. Assessments revealed that the differing soil types at the two sites were likely the main determinants of the opposing production outcomes associated with UV management. In the silty loam soil of MV, the higher yields in SV were likely due to more plant-available water, as a potential result of the continuous soil bio-pores formed by winter UV vegetation. Conversely, in the loamy sand soils of EV with a lower cation exchange capacity, the lower yields and pruning weights in SV suggest the UV vegetation competed significantly with the grapevines for available water and nutrients.

A positive role of mannoproteins on wine stability and red wine mouth sensations has been widely described. Commercial mannoproteins are available and some yeast strains are offered with a higher formation of mannoproteins.