Varietal differences in berry biometrics, skin structure, and wax biosynthesis of red grapevine varieties: A two-year study

Abstract

Climate change poses a major threat to vitiviniculture, particularly in Mediterranean regions, where increasing temperatures and drought events are reshaping berry development and composition. However, comparative information on varietal-specific responses under identical environmental conditions remains limited. Therefore, this two-year (2021 and 2022) field study aimed to identify morphological, histological, and biochemical traits associated with climate resilience across grapevine varieties. Twenty-seven red Vitis vinifera L. varieties grown in Northern Portugal were evaluated for berry biometrics (weight and dimensions), technological quality parameters (total soluble solids, pH, titratable acidity), cuticle thickness, epidermal and hypodermal structure, and cuticular wax accumulation. The expression of key genes involved in aliphatic wax biosynthesis, namely ERF045, CER10 and WSD1, was also evaluated on agronomically relevant varieties: ‘Cabernet Sauvignon’, ‘Tinto Cão’ and ‘Touriga Nacional’. The warmer and drier conditions observed in 2022 resulted in a widespread reduction in berry weight and size, with marked declines in some varieties, accompanied by increases in pH and higher cuticular wax content in several varieties, suggesting a coordinated stress response. Histological analyses revealed varietal-specific structural adjustments, with cuticle thickness generally decreasing in 2022. Gene expression analysis in ‘Cabernet Sauvignon’, ‘Tinto Cão’, and ‘Touriga Nacional’ demonstrated upregulation of the transcription factor ERF045, with varietal-specific modulation of the genes CER10 and WSD1, supporting enhanced wax-related protective responses in the berry skin.

By integrating berry morphology, tissue structure, and molecular regulation, this study identifies cuticular traits and wax biosynthetic pathways as potential markers of climate resilience. These findings contribute to evidence-based varietal selection and provide physiological targets for breeding strategies aimed at sustaining grape production under future climate scenarios.

Acknowledgements

The authors acknowledge the support provided by the project Vine&Wine Portugal reference C644866286-00000011, by the Portuguese Foundation for Science and Technology (FCT) through the individual grant number UI/BD/150730/2020 (https://doi.org/10.54499/UI/BD/150730/2020) of Miguel Baltazar under the Doctoral Program “Agricultural Production Chains—from fork to farm” (PD/00122/2012) and the Individual CEEC (https://doi.org/10.54499/2020.03997.CEECIND/CP1598/CT0001) of Márcia Carvalho; and through CITAB, UID/04033/2025 (https://doi.org/10.54499/UID/04033/2025) and Inov4Agro, LA/P/0126/2020 (https://doi.org/10.54499/10.54499/LA/P/0126/2020). The authors also thank the project STrengthS4WineChaiN-Scientific and Technological Synergies for Sustainable Development of the Wine Chain in the Northern Region, operation no. NORTE2030-FEDER-01786100, funded by the European Regional Development Fund (ERDF) through the Northern Regional Programme 2021-2027 (NORTE2030).