Soil Type Key to Biocontrol Agent Success in Vineyards

The agricultural sector has seen a significant shift toward reducing the use of synthetic chemicals, sparking extensive research into biological control agents as an alternative for combating crop diseases. These agents promise environmental benefits, yet their impact on beneficial microorganisms in the rhizosphere and native soil microbiota has not been widely explored.

In this vein, a research team has delved into the effects of two biocontrol agents, Trichoderma atroviride SC1 (Ta SC1) and Bacillus subtilis PTA-271 (Bs PTA-271), on the bacterial and fungal microbiota of grapevine rhizospheres, alongside their role in plant defense mechanisms. Employing advanced techniques such as amplicon sequencing and quantitative real-time polymerase chain reaction (qPCR), the study also quantified the presence of Ta SC1 and Bs PTA-271 in the rhizosphere using droplet digital PCR (ddPCR).

The findings revealed that fungal microbiota were significantly influenced by soil type, biocontrol treatment, and sampling time, whereas bacterial microbiota exhibited less variability in response to these factors. The survival and establishment of the biocontrol agents were contingent on soil type, suggesting that the soil's physicochemical properties play a crucial role in the success of these agents. Notably, treatments with Ta SC1 had a pronounced impact on fungal co-occurrence networks, leading to more complex and stable systems with increased positive correlations.

In terms of grapevine defenses, these varied based on soil type, proving more effective in sandy soils. This underscores the complexity of interactions between microorganisms in the rhizosphere and the necessity to consider multiple factors—such as soil type, sampling time, and biocontrol treatments—to fully understand the structure and dynamics of microbial communities.

This study, conducted by the BIOVITIS research group at the Institute of Grapevine and Wine Sciences (ICVV), in collaboration with Mendel University in Brno (Czech Republic), the University of Reims (France), and the Polytechnic University of Valencia, was published in the journal Phytobiomes under the title "Establishment of biocontrol agents and their impact on rhizosphere microbiome and induced grapevine defenses are highly soil-dependent."

The implications of these findings for vineyard management are significant. As the use of biocontrol agents becomes more prevalent, understanding their interactions with the rhizosphere microbiome can help optimize their effectiveness and minimize any unintended consequences. The study highlights the importance of soil type as a critical factor in the success of biocontrol agents, suggesting that vineyard managers may need to tailor their use of these agents based on specific soil conditions.

Moreover, the ability of Ta SC1 to enhance fungal network complexity and stability could offer new strategies for managing grapevine health. By fostering a more resilient microbial community, vineyards may be better equipped to withstand various stresses and diseases, leading to more sustainable and productive viticulture practices.

Future research should continue to explore the nuanced interactions between biocontrol agents and soil microbiota across different environmental conditions. Long-term studies could provide deeper insights into how these interactions evolve over multiple growing seasons and under varying climatic conditions. Additionally, investigating the mechanisms by which biocontrol agents influence microbial networks and plant defenses could lead to the development of more targeted and effective biocontrol strategies.

The integration of advanced molecular techniques, such as metagenomics and metabolomics, will be essential in uncovering the complex dynamics at play within the rhizosphere. By advancing our understanding of these interactions, we can better harness the potential of biocontrol agents to promote sustainable agriculture and improve crop resilience in the face of global challenges.

This pioneering study by the BIOVITIS research group and its collaborators offers valuable insights into the soil-dependent effects of biocontrol agents on vineyard microbiomes. The findings emphasize the need for a holistic approach to vineyard management that considers the intricate interplay between soil properties, microbial communities, and plant health. As the agricultural industry continues to seek sustainable alternatives to synthetic chemicals, such research will be crucial in guiding the effective and responsible use of biocontrol agents in viticulture and beyond.