Une approche en écologique microbienne pour décrypter les interactions PGPR-microbiote-plante

Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and crop resilience against biotic and abiotic stresses, offering a sustainable approach to agriculture. However, despite their commercialization, PGPR effectiveness remains inconsistent in field conditions. Beyond abiotic factors, their survival, proliferation, and bioactivity are shaped by interactions with native soil microbiota, an overlooked aspect that may explain variable field performance. While research on soil microbial ecology is expanding, no study has directly analyzed how contrasting microbiota influence PGPR growth, root colonization, and bioactivity. Current studies either focus on substrate sterilization effects (e.g., Torres et al., 2020, Appl. Soil Ecol.) or PGPR impacts on soil microbiota (e.g., Di Salvo et al., 2018, Appl. Soil Ecol.). This raises a key question: how do native microbial communities affect PGPR reliability? To address this, we conducted an experiment under gnotobiotic and non-gnotobiotic conditions, growing spring wheat on three agricultural soils inoculated with Bacillus velezensis strains. Results showed that PGPR significantly promoted plant growth in sterilized soils but that this effect diminished in the presence of native microbiota. We will discuss these findings, along with preliminary results from a broader study on wheat cultivation with 12 agricultural soils with diverse physico-chemical properties and management histories. Finally, we will present our methodological approach for deciphering PGPR-microbiota-plant interactions, aiming to improve PGPR application in real-world conditions.