, Volume 21, Issue 3, pp 593-603
Date: 22 Sep 2011

Expression of the nos operon proteins from Pseudomonas stutzeri in transgenic plants to assemble nitrous oxide reductase

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Nitrous oxide (N2O) is a stable greenhouse gas that plays a significant role in the destruction of the ozone layer. Soils are a significant source of atmospheric N2O. It is important to explore some innovative and effective biology-based strategies for N2O mitigation. The enzyme nitrous oxide reductase (N2OR), naturally found in soil bacteria, is responsible for catalysing the final step of the denitrification pathway, conversion of N2O to dintrogen gas (N2). To transfer this catalytic pathway from soil into plants and amplify the abundance of this essential mechanism (to reduce global warming), a mega-cassette of five coding sequences was assembled to produce transgenic plants heterologously expressing the bacterial nos operon in plant leaves. Both the single-gene transformants (nosZ) and the multi-gene transformants (nosFLZDY) produced active recombinant N2OR. Enzymatic activity was detected using the methyl viologen-linked enzyme assay, showing that extracts from both types of transgenic plants exhibited N2O-reducing activity. Remarkably, the single-gene strategy produced higher reductase capability than the whole-operon approach. The data indicate that bacterial N2OR expressed in plants could convert N2O into inert N2 without involvement of other Nos proteins. Silencing by homologous signal sequences, or cryptic intracellular targeting are possible explanations for the low activities obtained. Expressing N2OR from Pseudomonas stutzeri in single-gene transgenic plants indicated that such ag-biotech solutions to climate change have the potential to be easily incorporated into existing genetically modified organism seed germplasm.