Microbial community dynamics responding to nutrient allocation associated with soybean cultivar 'Jake' ozone...

Tropospheric ozone (O₃), a major air pollutant, leads to significant global yield loss in soybean [Glycine max (L.) Merr.]. Soybean cultivar 'Jake' shows O₃ resilient traits in above-ground organs, but the root system remains sensitive to elevated O₃ (eO₃). Changing carbon (C) and nitrogen (N) resource composition during eO₃ stress suggests that eO₃ presumably alters belowground soil microbial communities and their driven nutrient transformation. Yet, the responses of belowground microbes to eO₃ and their feedback on nutrient cycling in 'Jake' are unknown. In this study, we holistically investigated soil microbial communities associated with C and N dynamics and bacterial-fungal inter-kingdom networks in the rhizosphere and bulk soil at different developmental stages of 'Jake' grown under sub-ambient O₃ [charcoal-filtered (CF) air, 12 h mean: 20 ppb] or eO₃ (12 h mean: 87 ppb). The results demonstrated eO₃ significantly decreased fungal diversity and complexity of microbial networks at different 'Jake' developmental stages, whereas bacterial diversity was more tolerant to eO₃ in both bulk soil and rhizosphere. In the bulk soil, no O₃-responsive microbial biomarkers were found to be associated with C and N content, implying eO₃ may stimulate niche-based processes during 'Jake' growth. In contrast, this study identified O₃-responsive microbial biomarkers that may contribute to the N acquisition (Chloroflexales) and C dynamics (Caldilineales, Thermomicrobiales, and Hypocreales) in the rhizosphere, which may support the O₃ resilience of the 'Jake' cultivar. However, further investigation is required to confirm their specific contributions by determining changes in microbial gene expression. Overall, these findings conduce to an expanding knowledge base that O₃ induces temporal and spatial changes in the effects of microbial and nutrient networks in the O₃-tolerant agriculture ecosystems.