Influence of Environment and Rootstock On the Rhizosphere Bacterial Communities in Four Vineyards of the Douro Demarcated Region

The Douro Demarcated Region (DDR) is a worldwide acknowledged winemaking region. Climate change is threatening the sector, as climatic shifts are expected. This work analyzed environmental and genetic traits modulating the rhizobiome of four vineyards in the DDR, focusing on understanding the hierarchy of ecological conductors for these communities. These vineyards’ terroir was environmentally, genetically, and culturally characterized. Rhizosphere bacterial community composition was analyzed using 16S metabarcoding from soil samples collected between July 2022 and January 2024. Results support the hypothesis of an ecological profiling hierarchy. The soil physicochemical properties likely acted as a primary environmental modulator, determining the composition of the bacterial microbiome and contributing to the diversity and richness of the bacterial communities. The major drivers among the soil’s physiochemistry were organic/inorganic profile, mainly influenced by organic matter content and pH. Rootstock genotype appears to exert a secondary selection on the microbiome, focusing on the microorganisms’ functional traits. The 1103-P rootstock positively influenced the abundance of copiotrophic bacteria, compared to the R110, demonstrating that the first recruits a more versatile, exploratory, and expansionist microbiome, whilst the second focuses on attracting a highly specialized community, more focused on maximizing energy gathering and optimizing resource use. This work demonstrates that the microbial terroir is a result of multiple factors, promoting abiotic modulation and host-mediated selection, which establishes a very specific community for each scenario. The assessment of these holistic dynamics is fundamental to establishing a baseline for future precision viticulture strategies, namely bio-inoculants, to support and promote a better grapevine adaptation to climate change.