Identification of regulatory genes to reduce N2O production

Siciliano, S. D. 2014. Identification of regulatory genes to reduce N2O production. Can. J. Plant Sci. 94: 1033–1036. The production of nitrous oxide occurs predominantly by microbial activity. This microbial activity can be broadly sub-divided into denitrification, the sequential reduction of nitrate to nitrous oxide or dinitrogen gas, or into nitrification, the sequential oxidation of ammonia to nitrite. The consumption of nitrous oxide occurs by microbial activity as well, but only by a single pathway, i.e., the activity of nitrous oxide reductase (nos). The purpose of this investigation was to determine the dominant producer of nitrous oxide in our agricultural ecosystems, and then explore how these producers interacted with other biological and edaphic factors to regulate overall nitrous oxide production. Finally, we also investigated what controlled nitrous oxide consumption in these agricultural ecosystems. Much to our surprise, the dominant production of nitrous oxide in these upland agricultural soils occurred by nitrification, likely the nitrification-denitrification pathway. In addition, a root exudate, formate, was a large driver of nitrous oxide release via its interaction with the fungal biomass under micro-aerophilic conditions. Despite these unusual sources of production, what became apparent was that the net flux of nitrous oxide in an agricultural soil was linked to denitrifier consumption of nitrous oxide. In conclusion, this project found that there was a wide variety of non-bacterial denitrifier producers of nitrous oxide in an agricultural soil and that they interact not only between themselves but with the plant community. However, the net production of nitrous oxide in agricultural fields was still tightly linked to bacterial denitrification, but through the consumption of nitrous oxide by bacterial denitrifiers.