Oxygen as a key developmental regulator of Rhizobium meliloti N2-fixation gene expression within the alfalfa root nodule

The symbiotic pattern of expression of Rhizobium meliloti N2-fixation genes is tightly coupled with the histological organization of the alfalfa root nodule and thus is under developmental control. N2-fixation gene expression is induced very sharply at a particular zone of the nodule called interzon...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1995-04, Vol.92 (9), p.3759-3763
Main Authors: Soupene, E. (Institut National de la Recherche Agronomique, Castanet Tolosan, France.), Foussard, M, Boistard, P, Truchet, G, Batut, J
Format: Article
Language:English
Subjects:
ADN RECOMBINADO
ADN RECOMBINE
Aerobiosis
Alfalfa
Bacteroids
BETA GALACTOSIDASA
BETA GALACTOSIDASE
Botany
Cellular Biology
Electrophysiology
EXPRESION GENICA
EXPRESSION DES GENES
FIJACION DEL NITROGENO
FIXATION DE L'AZOTE
Flowers & plants
GENE
Gene expression
Gene expression regulation
Gene Expression Regulation, Bacterial
GENES
Genes, Bacterial
Genetic mutation
GENETICA
Genetics
GENETIQUE
Infections
Life Sciences
MEDICAGO SATIVA
Medicago sativa - microbiology
Microelectrodes
Molecular biology
Nitrogen Fixation - genetics
NODOSITE RACINAIRE
Nodules
NUDOSIDADES RADICULARES
OXIGENO
Oxygen
Oxygen - metabolism
OXYGENE
Plant Roots
Plasmids
Point Mutation
Restriction Mapping
RHIZOBIUM MELILOTI
Sinorhizobium meliloti - genetics
Sinorhizobium meliloti - physiology
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Summary:The symbiotic pattern of expression of Rhizobium meliloti N2-fixation genes is tightly coupled with the histological organization of the alfalfa root nodule and thus is under developmental control. N2-fixation gene expression is induced very sharply at a particular zone of the nodule called interzone II-III that precedes the zone where N2 fixation takes place. We show here that this coupling can be disrupted, thereby resulting in ectopic expression of N2-fixation genes in the prefixing zone II of the nodule. Uncoupling was obtained either by using a R. meliloti strain in which a mutation rendered N2-fixation gene expression constitutive with respect to oxygen in free-living bacterial cultures or by placing nodules induced by a wild-type R. meliloti strain in a microoxic environment. These results implicate oxygen as a key determinant of the symbiotic pattern of N2-fixation gene expression
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.92.9.3759