Elevated ozone reshapes wheat root-associated microbiomes through coordinated plant responses and rhizosphere environmental filtering

ABSTRACT Elevated tropospheric ozone (O 3 ) threatens crop productivity, but how O 3 -induced changes in plant responses influence root-associated microbiomes remains unclear. We investigated the responses of microbial communities inhabiting the rhizosphere and root endosphere to elevated O 3 using four cultivars grown under ambient and 1.5-fold ambient O 3 in a field-based free-air O 3 -concentration enrichment (FACE) system. Plant traits, root-released organic carbon (ROC), rhizosphere properties, extracellular enzyme activities, and bacterial and fungal communities were jointly analyzed. Elevated O 3 reduced yield and root biomass, with cultivar-dependent changes in ROC. Elevated O 3 consistently increased rhizosphere pH and altered microbial resource allocation, increasing ecoenzymatic vector length by 4.1% and decreasing vector angle by 4.6%. Bacterial communities showed a stronger response than fungal taxonomic communities, particularly in the rhizosphere. However, variation partitioning indicated that soil properties, especially pH, rather than O 3 treatment alone, provided the strongest independent explanation for bacterial community variation. Fungal communities showed limited taxonomic turnover but exhibited shifts in predicted trophic guilds, including increased pathotroph- and saprotroph-associated groups and decreased symbiotroph-containing guilds under elevated O 3 . These results demonstrate that elevated O 3 reshapes the wheat root-associated microbiome through coordinated changes in plant performance, rhizosphere environmental filtering, and microbial functional strategies, highlighting the importance of plant-mediated processes in regulating belowground responses to atmospheric change. IMPORTANCE Elevated tropospheric O 3 is an increasing threat to crop production, but its effects on belowground microbial processes remain poorly understood. This study demonstrates that O 3 -induced root-associated microbiome changes are closely linked with altered plant carbon allocation and rhizosphere environmental conditions rather than O 3 exposure also. By integrating plant traits, soil properties, extracellular enzyme allocation, and microbial community analyses, we reveal a compartment-specific plant-soil-microbiome response to elevated O 3 . These findings improve our understanding of how atmospheric pollution may reshape crop-associated microbial functions and soil ecological processes under future climate change.