Grapevine varietal influence on leaf bacterial and fungal communities across phenological stages

Abstract

With the increasing frequency and intensity of extreme weather events, viticulture is expected to face progressively drier and warmer conditions, increasing the need for sustainable adaptation strategies such as the identification of resilient Vitis vinifera L. varieties. Grapevine leaves host complex microbial consortia composed of bacteria and fungi that interact with each other and the plant host, influencing stability and resilience to (a)biotic stresses. Understanding the structure of microbial communities is essential to elucidate varietal adaptation under climate change scenarios.

This study aimed to evaluate the dynamics of fungal and bacterial communities in leaves of six different grapevine varieties (‘Alicante Bouschet’, ‘Donzelinho Tinto’, ‘Malvasia Preta’, ‘Tinto Cão’, ‘Touriga Franca’ and ‘Touriga Nacional’) between veraison (BBCH 81) and harvest (BBCH 89) grown during the 2024 season in the Douro Demarcated Region-subregion Douro Superior. Leaves were sampled from a grapevine variety library located at Quinta do Ataíde of Symington Family Estates, in Vale da Vilariça, Northern Portugal. Metagenomic libraries (ITS and 16S) were prepared and sequenced using Illumina platform.

For the bacteria community, the phyla Actinomycetota and Pseudomonadota, as well as the genera Protofrankia and Paraburkholderia, were the most abundant across all varieties and phenological stages. At both phenological stages, the highest number of reads was detected in ‘Touriga Franca’ whereas the lowest was observed in ‘Alicante Bouschet’. The highest richness was also detected in ‘Touriga Franca’ and the lowest in ‘Tinto Cão’, both at veraison. The Shannon–Wiener diversity index revealed a significant decrease from veraison to harvest in ‘Donzelinho Tinto’ and ‘Touriga Franca’. As for fungal community, the phyla Ascomycota and Basidiomycota and the genera Alternaria and Filobasidium were the most abundant among all varieties and phenological stages. At harvest, ‘Donzelinho Tinto’ showed the highest number of reads, whereas the lowest was observed in ‘Tinto Cão’ at veraison. The highest richness was observed in ‘Touriga Nacional’, statistically higher than all varieties except ‘Touriga Franca’, while the lowest was observed in ‘Tinto Cão’, both at veraison. The Shannon–Wiener index revealed a significant increase from veraison to harvest in ‘Alicante Bouschet’ and a significant decrease in ‘Malvasia Preta’.

These results suggest that grapevine genotype influences leaf microbiome composition, with bacterial community showing stronger varietal differentiation than fungal community, potentially contributing to differential varietal resilience.

Acknowledgements

The authors acknowledge the Vine&Wine Portugal Project under reference C644866286-00000011 and FCT – Portuguese Foundation for Science and Technology, under the projects UID/04033/2025: Centre for the Research and Technology of Agro-Environmental and Biological Sciences (DOI: 10.54499/UID/04033/2025), and Inov4Agro, LA/P/0126/2020 (DOI: 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).