ROUND TABLE #1 – Identity, typicality, traceability

Temperature variability inside a wine production area and its effect on vine phenology and grape ripening. An example from the Saint-Emilion-Pomerol

VAN LEEUWEN Cornelis, EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVV – DE RESSÉGUIER Laure, EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVV – PETITJEAN Théo. EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVV – LE ROUX Renan, UMR6554 LETG, CNRS – QUENOL Hervé. UMR6554 LETG, CNRS, France
Email contact: vanleeuwen[@]agro-bordeaux.fr

AIM: The aim of this study was to develop a method for fine-scale temperature zoning. The effect of temperature variability on vine phenology and grape composition was assessed in the production area of Saint-Emilion, Pomerol and their satellite appellations (Bordeaux, France).

METHODS: 90 temperature sensors were set up in 2012 inside the vine canopy over an area of 19,233 ha, including 12,200 ha of vineyards. Hourly temperatures were recorded from 2012-2018. Vine phenology and grape ripening were monitored on 60 plots, close to temperature sensors. Vine water and nitrogen status were assessed by measuring, respectively, δ¹³C and yeast available nitrogen on grape must.

RESULTS: A spatial model, based on temperatures recorded by the sensors and environmental co-variables derived from a digital elevation model, was developed to produce daily temperature maps over the study area. The effect of temperature on vine phenology was assessed. Significant variability was observed over the area for budbreak (19 days), flowering (9 days), véraison (13 days) and sugar ripeness (25 days). Sugar/acid ratio increased with higher temperatures and water deficit and decreased with higher vine nitrogen status.

CONCLUSIONS: A methodology was developed for fine scale temperature mapping inside a wine production area. The effect of temperature was assessed on vine development and grape ripening. This study shows that temperature variability is one of the major drivers of the terroir effect.

REFERENCES:
de RESSÉGUIER L., MARY S., LE ROUX R., PETITJEAN T., QUÉNOL H. and VAN LEEUWEN C., 2020. Temperature variability at local scale in the Bordeaux area. Relations with environmental factors and impact on vine phenology. Frontiers in Plant Science, 11, 515

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Fluorescence spectroscopy with XGBoost discriminant analysis for intraregional wine authentication

Ruchira RANAWEERA, Department of Wine Science, The University of Adelaide, Australia
Adam GILMORE, Horiba Instruments Inc., USA
Dimitra CAPONE, Susan BASTIAN, David JEFFERY – The Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, Australia
Email contact: ruchira.ranaweera01[@]adelaide.edu.au

AIM: This study aimed to use simultaneous measurements of absorbance, transmittance, and fluorescence excitation-emission matrix (A-TEEM) combined with chemometrics as a rapid method to authenticate wines from three vintages within a single geographical indication (GI) according to their subregional variations.

METHODS: The A-TEEM technique (Gilmore, Akaji, & Csatorday, 2017) has been applied to analyse experimental Shiraz wines (n = 186) from six subregions of Barossa Valley, South Australia, from 2018, 2019 and 2020 vintages. Absorbance spectra and EEM fingerprints of the wines were recorded and the data were fused for multivariate statistical modelling with extreme gradient boost discriminant analysis (XGBDA) as reported by Ranaweera, Gilmore, Capone, Bastian, and Jeffery (2021) to classify wine according to their subregions. The cross-validated (k =10, Venetian blinds) confusion matrix score probabilities of classes were used to assess the accuracy of the classification models. A similar procedure was also carried out to discriminate subregions for a single vintage year. Basic chemical parameters (alcohol %v/v, pH, titratable acidity, and volatile acidity) were modelled with the partial least squares regression (PLSR) using A-TEEM data and reference chemical data.

RESULTS: Results have shown an unprecedented 100% correct classification of wines according to subregion across the three vintages and 98% accuracy for subregion in a single vintage year. Other model performance parameters of confusion matrix, including sensitivity, specificity, precision, and F1 score, were also showing the highest values (1.0) for each of the subregions. PLSR modelling revealed that A-TEEM data can also be used for a rapid assessment of basic wine chemical parameters. Notably, the results confirmed a distinct resolution among subregions despite their relatively close proximity within a single GI, indicating the effect of terroir on intraregional variation.

CONCLUSIONS: The sensitivity of A-TEEM allied with multivariate statistical analysis of fluorescence data facilitated the accurate classification of Shiraz wines according to the subregion of origin and production year. As a robust analytical method, A-TEEM can help identify the drivers of regional expression of wine and can potentially be developed for use within the supply chain to guarantee the provenance indicated on the label and to provide an assurance of quality. Overall, A-TEEM with XGBDA modelling continues to be shown as an accurate wine authentication tool that could even be applied at a subregional level.

References:

Gilmore, A., Akaji, S., & Csatorday, K. (2017). Spectroscopic analysis of red wines with A-TEEM molecular fingerprinting. Readout, 2(49), 41-48. https://www.horiba.com/in/publications/readout/article/spectroscopic-analysis-of-red-wines-with-a-teem-molecular-fingerprinting-53035/.

Ranaweera, R. K. R., Gilmore, A. M., Capone, D. L., Bastian, S. E. P., & Jeffery, D. W. (2021). Authentication of the geographical origin of Australian Cabernet Sauvignon wines using spectrofluorometric and multi-element analyses with multivariate statistical modelling. Food Chemistry, 335, 127592. https://doi.org/https://doi.org/10.1016/j.foodchem.2020.127592

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Understanding the genetic determinism of phenological and quality traits in ‘Corvina’ grape variety for selection of improved genotypes

Diana BELLIN1, Martina MARINI1, Ron SHMULEVIZ1, Jessica VERVALLE2, Alice BARONI1, Riccardo MORA1, Tahir MUJTABA1, Laura COSTANTINI3, Martina ZERNERI1, Giada BOLOGNESI1, Giovanni Battista TORNIELLI1, Maria Stella GRANDO3, Annalisa POLVERARI1
1 Department of Biotechnology, University of Verona
2, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
3, Research and Innovation Centre, Fondazione Edmund Mach, San Michele all’Adige
Email contact: diana.bellin[@]univr.it

Downy and powdery mildew are major issues in grapevine cultivation, requiring many phytosanitary treatments to ensure yield and quality. Climatic changes are also challenging grape cultivation in several areas, leading to anticipation of phenological events and increasing impact of temperature on grape quality. Beside disease resistance, adaptation of varieties to changing climate is thus an additional breeding target, which includes the selection of late ripening varieties that may escape the warmer summer conditions, while preserving distinctive performance and wine quality. With the aim to increase our understanding of the genetic determinism for phenological and quality traits, we have crossed the autochthonous cv. Corvina, typical of the Verona province area, to previously identified divergent varieties. Segregating cross populations of Corvina x Solaris and Cabernet Sauvignon x Corvina including a high number of seedlings were developed, propagated and grown in field conditions for mapping of traits. High-density genetic maps based on SNPs obtained through hybridization to an Illumina Vitis18KSNP chip are produced. Field phenotyping includes the evaluation of the main phenological stages (budbreak, flowering, veraison and ripening) together with the assessment of some morphological and quality traits at harvest on all progenies with the final purpose of QTL mapping. Moreover, the introgression of resistance sources from cv Solaris is assessed in the relative cross. Response to Plasmopara viticola is investigated especially in selected resistant genotypes under field conditions or following inoculation of leaf discs and shows different degrees of resistance in some Corvina offsprings differing in the number of inherited Rpv loci. Based on resistance gene introgression as well as on phenotypic parameters, some selections are being propagated for a deeper characterization. New markers derived from the characterization of Corvina-crosses are expected to further assist future selections. Altogether, the described approaches will improve our understanding of the genetic control of phenology and berry quality traits, thus assisting breeding in this important local variety.06