Absence of the nitrous oxide reductase gene cluster in commercial alfalfa inoculants is probably due to the extensive loss of genes during rhizobial domestication

Authors
Brambilla, Silvina Maricel; Frare, Romina Alejandra; Soto, Gabriela Cinthia; Jozefkowicz, Cintia; Ayub, Nicolás Daniel
Publication Year
2018
Language
English
Format
article
Status
Published version
Description
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.
Instituto de Genética
Fil: Brambilla, Silvina Maricel. INTA. Instituto de Genética "Ewald A. Favret"; Argentina
Fil: Frare, Romina Alejandra. INTA. Instituto de Genética "Ewald A. Favret"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Soto, Gabriela Cinthia. INTA. Instituto de Genética "Ewald A. Favret"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Jozefkowicz, Cintia. INTA. Instituto de Genética "Ewald A. Favret"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Ayub, Nicolás Daniel. INTA. Instituto de Genética "Ewald A. Favret"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Source
Microbial Ecology 76 (2): 299–302 (August 2018)
Subject
Óxido Nitroso
Medicago sativa
Fijación del Nitrógeno
Muestreo cluster
Genes
Rhizobium
Nitrous Oxide
Nitrogen Fixation
Cluster Sampling
Inoculantes comerciales
Access level
Restricted access
License
Repository
INTA Digital (INTA)
Institution
Instituto Nacional de Tecnología Agropecuaria
OAI Identifier
oai:localhost:20.500.12123/3399