Expression of nitrous oxide reductase from Pseudomonas stutzeri in transgenic tobacco roots using the root‐specific rolD promoter from Agrobacterium rhizogenes

Abstract The nitrous oxide (N 2 O) reduction pathway from a soil bacterium, Pseudomonas stutzeri , was engineered in plants to reduce N 2 O emissions. As a proof of principle, transgenic plants expressing nitrous oxide reductase (N 2 OR) from P. stutzeri , encoded by the nosZ gene, and other transgenic plants expressing N 2 OR along with the more complete operon from P. stutzeri , encoded by nosFLZDY , were generated. Gene constructs were engineered under the control of a root‐specific promoter and with a secretion signal peptide. Expression and rhizosecretion of the transgene protein were achieved, and N 2 OR from transgenic Nicotiana tabacum proved functional using the methyl viologen assay. Transgenic plant line 1.10 showed the highest specific activity of 16.7 µmol N 2 O reduced min −1 g −1 root protein. Another event, plant line 1.9, also demonstrated high specific activity of N 2 OR, 13.2 µmol N 2 O reduced min −1 g −1 root protein. The availability now of these transgenic seed stocks may enable canopy studies in field test plots to monitor whole rhizosphere N flux. By incorporating one bacterial gene into genetically modified organism (GMO) crops (e.g., cotton, corn, and soybean) in this way, it may be possible to reduce the atmospheric concentration of N 2 O that has continued to increase linearly (about 0.26% year −1 ) over the past half‐century.