Phylogenetic Conservation of Microbial Responses to Elevated Ozone

Abstract Background: Global tropospheric ozone has doubled due to emissions from fossil fuel and biomass burning, and thus reduces plant primary productivity and crop yields. In contrast, little is known about how elevated tropospheric ozone affects soil microbial communities in the cropland ecosystem and whether such effects are sensitive to nitrogen (N) supply. Here, we examined the responses of bacterial and fungal communities in maize soils to elevated ozone (+60 ppb ozone) across different levels of N fertilization (+60, +120, and +240 kg N ha -1 yr -1 ). Results: Proteobacteria , Actinobacteria , Bacteroidetes , Chloroflexi , Elusimicrobia , and Planctomycetes were altered by N fertilization or elevated ozone ( P < 0.05). No interactive effects between N fertilization and elevated ozone were observed for bacterial and fungal communities ( P > 0.1). While bacterial responses to N fertilization were phylogenetically conserved, bacterial and fungal responses to elevated ozone were phylogenetically conserved, showing universal homogeneous selection (homogeneous environmental conditions leading to more similar community structures). The ozone-responsive phyla were generally correlated ( P < 0.05) with plant biomass, plant carbon (C) uptake, and soil dissolved organic C. Conclusions: Our study highlighted that microbial response to elevated ozone displayed a phylogenetic clustering pattern, suggesting that response strategies to elevated ozone stress may be a phylogenetically conserved ecological trait.