title: Photosynthetic Bradyrhizobium Sp. strain ORS285 synthesizes 2-O-methylfucosylated lipochitooligosaccharides for nod gene-dependent interaction with Aeschynomene plants.
abstract: Bradyrhizobium sp. strain ORS285 is a photosynthetic bacterium that forms nitrogen-fixing nodules on the roots and stems of tropical aquatic legumes of the Aeschynomene genus. The symbiotic interaction of Bradyrhizobium sp. strain ORS285 with certain Aeschynomene spp. depends on the presence of nodulation (nod) genes whereas the interaction with other species is nod gene independent. To study the nod gene-dependent molecular dialogue between Bradyrhizobium sp. strain ORS285 and Aeschynomene spp., we used a nodB-lacZ reporter strain to monitor the nod gene expression with various flavonoids. The flavanones liquiritigenin and naringenin were found to be the strongest inducers of nod gene expression. Chemical analysis of the culture supernatant of cells grown in the presence of naringenin showed that the major Nod factor produced by Bradyrhizobium sp. strain ORS285 is a modified chitin pentasaccharide molecule with a terminal N-C(18:1)-glucosamine and with a 2-O-methyl fucose linked to C-6 of the reducing glucosamine. In this respect, the Bradyrhizobium sp. strain ORS285 Nod factor is the same as the major Nod factor produced by the nonphotosynthetic Bradyrhizobium japonicum USDA110 that nodulates the roots of soybean. This suggests a classic nod gene-dependent molecular dialogue between Bradyrhizobium sp. strain ORS285 and certain Aeschynomene spp. This is supported by the fact that B. japonicum USDA110 is able to form N(2)-fixing nodules on both the roots and stems of Aeschynomene afraspera.
authors.affiliation: Laboratoire des Symbioses Tropicales et Mediterraneennes, UMR IRD, Montpellier, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Renier
authors.forename: Fabienne
authors.initials: F
authors.lastname: Maillet
authors.forename: Joel
authors.initials: J
authors.lastname: Fardoux
authors.forename: Verena
authors.initials: V
authors.lastname: Poinsot
authors.forename: Eric
authors.initials: E
authors.lastname: Giraud
authors.forename: Nico
authors.initials: N
authors.lastname: Nouwen
mesh_terms: D000581:Amidohydrolases / Q000187:drug effects / Q000235:genetics*; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics*; D020369:Bradyrhizobium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D007887:Fabaceae / Q000382:microbiology* / Q000502:physiology; D044950:Flavanones / Q000737:chemistry / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D005643:Fucose / Q000031:analogs & derivatives / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D017930:Genes, Reporter; D008070:Lipopolysaccharides / Q000737:chemistry*; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism; D010788:Photosynthesis; D018517:Plant Roots / Q000382:microbiology / Q000502:physiology; D018547:Plant Stems / Q000382:microbiology / Q000502:physiology; D053204:Root Nodules, Plant; D015398:Signal Transduction; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D044950:Flavanones; D005419:Flavonoids; D008070:Lipopolysaccharides; C073606:nodB protein, Bacteria; D005643:Fucose; C076754:2-O-methylfucose; D009591:Nitrogenase; D000581:Amidohydrolases; C005273:naringenin; C083152:liquiritigenin