Renier A. auteur aut IRD Maillet F. auteur aut IRD Fardoux Joël auteur aut IRD Poinsot V. auteur aut IRD Giraud Eric auteur aut IRD Nouwen Nico auteur aut IRD text journalArticle eng text/pdf born digital access 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. specialized 084 020 24 12 1440-1447 2011 0894-0282 https://www.documentation.ird.fr/hor/fdi:010054194 10.1094/mpmi-05-11-0104 0894-0282 [F B010054194] https://www.documentation.ird.fr/hor/fdi:010054194 https://www.documentation.ird.fr/intranet/publi/2011/12/010054194.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2012-01-10 2024-04-29 fdi:010054194 fre