Characterizing the molecular basis of the differences in aromatic precursors found in commercial clones of Vitis vinifera cv. Tannat

Vegetative propagation of grapevines can generate spontaneous somatic variations, providing a valuable source for cultivar improvement. In this context, natural variation in the composition of phenolic compounds in grapevine berries and seeds stands as a pivotal factor in crafting wines with diverse oenological profiles from the same cultivar. To deepen on the understanding of the physiological and genetic mechanisms driving somatic variation in grape phenolics, here we characterized a somatic variant from Tempranillo Tinto, the clone VN21, that exhibits an intense reduced berry skin cuticle and increased extractability of phenolic compounds during wine fermentation.

Biomass accumulation in yeast has been studied in this work in terms of their role in fermentation processes. So, biotin is involved in many reactions and nitrogen metabolism disorders

Carmenère fruit during ripening of a Vertical shoot positioning, VSP, trained experimental vineyard with north-south row orientation.

Vineyards are highly variable and this variation is largely driven by environmental conditions and seasonal variation. For example, warm temperatures

Studying heat stress response of grapevine berries in the field often relies on weather conditions during the growing season. We constructed a mobile heating device, able to induce controlled heat stress on grapes in vineyards. The heater consisted of six 150 W infrared lamps mounted in a profile frame. Heating power of the lamps could be controlled individually by a control unit consisting of a single board computer and six temperature sensors to reach a pre-set temperature. The heat energy applied to individual berries within a cluster decreases by the squared distance to the heat source, enabling the establishment of temperature profiles within individual clusters. These profiles can be measured by infrared thermography once a steady state has been reached. Radiant flux density received by a berry depending on the distance was calculated based on a view factor and measured lamp surface temperature and resulted to 665 Wm-2 at 7cm. Infrared thermography of the fruit surface was in good agreement with measurements conducted with a thermocouple inserted at epidermis level. In combination with infrared thermography, the presented device offers possibilities for a wide range of applications like phenotyping for heat tolerance in the field to proceed in the understanding of the complex response of plants to heat stress. Sunburn necrosis symptoms were artificially induced with the aid of the device for cv. Bacchus and cv. Sylvaner in the 2020 and 2021 growing season. Threshold temperatures for sunburn induction (LT5030min) were derived from temperature data of single berries and visual sunburn assessment, applying logistic regression. A comparison of threshold temperatures for the occurrence of sunburn necrosis confirmed the higher susceptibility of cv. Bacchus. The lower susceptibility of cv. Sylvaner did not seem to be related to its phenolic composition, rendering a thermoprotective role of berry phenolic compounds unlikely.