Elevated ozone enhances the network stability of rhizospheric bacteria rather than fungi

The detrimental effects of elevated ozone (O3) on plants vary by species, and are closely related to soil microbial communities. Soil microbial communities vary in composition depending on the plant species. However, little is known about the effects of O3 on the soil microbiota associated with different plant genotypes in forests. Herein, we applied low O3 (24.7 ppb, charcoal-filtered air (CF-O3)), ambient O3 (58.3 ppb, A-O3), and elevated O3 (99.7 ppb, E-O3) to O3-tolerant and O3-sensitive poplar plants. We found that the compositions of rhizospheric bacterial communities were governed by O3 and poplar genotypes (Adonis, P < 0.05), while the compositions of fungal communities were driven by poplar genotype alone (R2 = 0.117, P < 0.05). Further analyses showed that O3 and poplar genotype had direct effects on both bacterial and fungal communities, and indirect effects on bacteria, via changing soil ammonia and nitrate nitrogen concentrations. Under E-O3 stress, the O3-tolerant poplar had more stable bacterial molecular ecological networks than the O3-sensitive poplar, while fungal communities were unaffected in both poplar genotypes. Our research combines the ecological stability of the soil microbiota with a deeper understanding of intraspecific O3-sensitive characteristics of poplars, thereby enhancing our knowledge regarding the global threat posed by elevated O3 to agroforestry-based climate change policy.