Exploring the Effects of Biological Nitrification Inhibition on the Rhizosphere Microbiome of a BNI-enabled Winter Wheat

Biological Nitrification Inhibitors (BNIs) are compounds naturally produced by plants to block the nitrification process in the soils. BNIs have been proposed as a potentially safe and effective strategy to increase the nitrogen use efficiency of crops while mitigating the environmental damage derived from overfertilization, namely nitrous oxide emissions and nitrate leaching. 

In this study, we investigate the influence of a BNI-enabled winter wheat line on the rhizosphere microbiome compared to its isogenic non-BNI counterpart. We conducted a longitudinal field trial during which rhizosphere samples were collected at different timepoints throughout the vegetative growth phase of the crops, to capture potential shifts in the BNI production, as well as changes in the climatic conditions and the temporal dynamics of the microbial community. Given that ammonia oxidation represents the first and often rate-limiting step of nitrification, we focused on ammonia-oxidizing microorganisms by quantifying the abundance and transcriptional activity of the amoA gene using qPCR and RT-qPCR, to assess the impact of the BNI-wheat on nitrifying microorganisms. To evaluate broader microbial responses and ensure no adverse effects on non-nitrifying key microbial groups, we also characterized the overall microbial community with amplicon sequencing, using specific marker genes to target the prokaryotic, total fungal, arbuscular mycorrhizal and protist communities. This work aims to evaluate the efficacy and safety of a BNI-enabled wheat under similar conditions to a modern intensified agricultural setting.