Absence of the nitrous oxide reductase gene cluster in commercial alfalfa inoculants is probably due to the extensive loss of genes during rhizobial domestication
As other legume crops, alfalfa cultivation increases the emission of the greenhouse gas nitrous oxide (N2O). Since legumesymbiotic nitrogen-fixing bacteria play a crucial role in this emission, it is important to understand the possible impacts of rhizobial domestication on the evolution of denitrification genes. In comparison with the genomes of non-commercial strains, those of commercial alfalfa inoculants exhibit low total genome size, low number of ORFs and high numbers of both frameshifted genes and pseudogenes, suggesting a dramatic loss of genes during bacterial domestication. Genomic analysis focused on denitrification genes revealed that commercial strains have perfectly conserved the nitrate (NAP), nitrite (NIR) and nitric (NOR) reductase clusters related to the production of N2O from nitrate but completely lost the nitrous oxide (NOS) reductase cluster (nosRZDFYLX genes) associated with the reduction of N2O to gas nitrogen. Based on these results, we propose future screenings for alfalfa-nodulating isolates containing both nitrogen fixation and N2O reductase genes for environmental sustainability of alfalfa production.
| Main Authors: | , , , , |
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| Format: | info:ar-repo/semantics/artículo biblioteca |
| Language: | eng |
| Published: |
Springer
2018-08
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| Subjects: | Óxido Nitroso, Medicago sativa, Fijación del Nitrógeno, Muestreo cluster, Genes, Rhizobium, Nitrous Oxide, Nitrogen Fixation, Cluster Sampling, Inoculantes comerciales, |
| Online Access: | https://link.springer.com/article/10.1007/s00248-018-1145-9 http://hdl.handle.net/20.500.12123/3399 https://doi.org/10.1007/s00248-018-1145-9 |
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| Summary: | As other legume crops, alfalfa cultivation increases the emission of the greenhouse gas nitrous oxide (N2O). Since legumesymbiotic
nitrogen-fixing bacteria play a crucial role in this emission, it is important to understand the possible impacts of
rhizobial domestication on the evolution of denitrification genes. In comparison with the genomes of non-commercial strains,
those of commercial alfalfa inoculants exhibit low total genome size, low number of ORFs and high numbers of both
frameshifted genes and pseudogenes, suggesting a dramatic loss of genes during bacterial domestication. Genomic analysis
focused on denitrification genes revealed that commercial strains have perfectly conserved the nitrate (NAP), nitrite (NIR) and
nitric (NOR) reductase clusters related to the production of N2O from nitrate but completely lost the nitrous oxide (NOS)
reductase cluster (nosRZDFYLX genes) associated with the reduction of N2O to gas nitrogen. Based on these results, we propose
future screenings for alfalfa-nodulating isolates containing both nitrogen fixation and N2O reductase genes for environmental
sustainability of alfalfa production. |
|---|