Endophytic Pseudomonas as a novel source of Biological Control Agents: Mechanistic approach to study and improve strain performance against cereal fungal diseases

The global population is rapidly increasing, placing a growing dependence on food production. Their successful cultivation relies on various agricultural solutions and practices to ensure pest free farming and high-yield production. For decades, chemical pesticides have played a significant role in this success. Their excessive use over the years has raised environmental concerns, forcing regulatory authorities to implement measures to mitigate their impact. Nevertheless, farmers still face growing challenges as pests persist in the field and pathogens develop resistance to conventional solutions. As a result, there is a need for alternative products that align with new regulatory standards and market demands.
In response to these challenges, biological control agents, a subcategory of biological products, have emerged as promising alternatives due to their biodegradable nature and lower environmental impact. While some of those agents have been available for years, their adoption has been limited due to inconsistent performance and lower efficacy, particularly in cereals against fungal diseases. Existing biological solutions have shown greater effectiveness against fungal diseases in fruits and vegetables, highlighting a need for innovation in the cereal sector. Microbes from the genus Pseudomonas offer a promising alternative approach, as they differentiate enough in terms of protection mechanisms from the existing biocontrol products.
In this PhD study, we structured a research project to identify Pseudomonas strains with alternative mechanisms of action against cereal fungal diseases. We established a pipeline to isolate, screen and evaluate strains with potential as next-generation biological control agents. Additionally, we significantly focused on understanding the mechanisms underlying their biocontrol efficacy and the factors influencing their performance. We also explored the potential for optimizing their biocontrol properties through genetic modifications.
Our manuscripts illustrate a representative example of a promising biocontrol agent against a major fungal disease. They outline a systematic approach for identifying the primary mechanism of action of a Pseudomonas strain, which is linked to the production of a secondary metabolite. To achieve this, we investigated the individual contributions of various compounds produced by the strain, previously reported for their antifungal efficacy. Using loss-of-function mutants and a range of assays from in-vitro tests to plant experiments we demonstrated how a structured experimental process can accurately pinpoint the key compound responsible for biocontrol activity. This knowledge is essential for assessing a biological agent’s potential in real-world applications.
Furthermore, we explored a targeted genetic modification approach to enhance the production of an antifungal compound, shedding light on both the opportunities and challenges associated with strain optimization. Our findings and insights contribute to the successful development of new biological control agents that could offer true differentiation in the market and advance sustainable pest management in cereal crops.