Résumé
In 2019, a gathering of plant pathologists in Glasgow identified ten pivotal scientific questions within our field that remained unresolved for the years to come (Harris, Balint-Kurti et al. 2020). Among these inquiries, the impact of abiotic stresses on plant-microbe interactions, and the broader applicability of knowledge derived from simple interactions within ecological contexts, were highlighted. These questions underscore a significant gap in our understanding, particularly regarding how the environmental factors in which plants and microbes coexist influence their interactions. Concurrently, the concept of eco-immunity was introduced (Schulenburg et al., 2009), aiming to unravel the variations in immune responses, elucidating how both biotic and abiotic elements contribute to the variability in an organism's immunity (Nobori and Tsuda 2019).In France, we have introduced the concept of "agroecological immunity" within the technical and scientific network Bestim. This concept aims to unravel the influence of the agroecological context on disease management, with a central focus on enhancing plant immunity for a more effective but environmentally friendly control. In this context, the way plant-pant communications can protect their neighbors is included. The question is therefore : how agroecological practices such as varietal mixes, crop associations, the use of biostimulants, biological controls, plant resistance inducers can modify the immune system of cereals, thereby avoiding the need for fungicides. We will introduce and expound upon this concept, substantiating it with illustrative results.This presentation delves into the intricate interplay of five factors, either in isolation or combination, and their effects on the establishment of septoria (Zymoseptoria tritici) infection cycles in wheat seedlings. These factors have demonstrated individually significant impacts on the symptoms and levels of defense mechanisms in wheat. The studied factors encompass the partial resistance of the host variety, water stress experienced by seedlings during infection, two types of treatments—root biostimulants sown with the seeds to enhance host growth and plant defense inducers applied before inoculation to bolster host defenses. Additionally, we explore the effects of neighboring plant co-cultivation with the focal wheat variety that has also demonstrated effects on focal immunity and resistance (Pélissier et al., 2023).We have developed a model to delineate how plants manage trade-offs among these diverse factors. This model identifies conditions that are conducive to achieving a high defense level and efficient plant protection based on its immunity. For example, using neuronal network analysis we were able to highlight the impact of variety factor and the combination of water stress and biostimulation on the level of expression of plant defense. In our presentation, we will also elucidate the methodology for prioritizing the impact of these factors, underline their significance, and expound upon our model-building approach. This facilitates the applicability of our findings to other pathosystems.