title: The nodC, nodG, and glgX genes of Rhizobium tropici strain PRF 81.
abstract: Rhizobium tropici is a diazotrophic microsymbiont of common bean (Phaseolus vulgaris L.) that encompasses important but still poorly studied tropical strains, and a recent significant contribution to the knowledge of the species was the publication of a genomic draft of strain PRF 81, which revealed several novel genes [Pinto et al. Funct Int Gen 9:263-270, 2009]. In this study, we investigated the transcription of nodC, nodG, and glgX genes, located in the nod operon of PRF 81 strain, by reverse-transcription quantitative PCR. All three genes showed low levels of transcription when the cells were grown until exponential growth phase in the presence of common-bean-seed exudates or of the root nod-gene inducer naringenin. However, when cells at the exponential phase of growth were incubated with seed exudates, transcription occurred after only 5 min, and nodC, nodG, and glgX were transcribed 121.97-, 14.86-, and 50.29-fold more than the control, respectively, followed by a rapid decrease in gene transcription. Much lower levels of transcription were observed in the presence of naringenin; furthermore, maximum transcription required 8 h of incubation for all three genes. In light of these results, the mechanisms of induction of the nodulation genes by flavonoids are discussed.
authors.affiliation: Embrapa Soja, Cx. Postal 231, CEP 86001-970, Londrina, Paraná, Brazil. lu_ruano@hotmail.com
authors.forename: Luciana Ruano
authors.initials: LR
authors.lastname: Oliveira
authors.forename: Francismar Corrêa
authors.initials: FC
authors.lastname: Marcelino
authors.forename: Fernando Gomes
authors.initials: FG
authors.lastname: Barcellos
authors.forename: Elisete Pains
authors.initials: EP
authors.lastname: Rodrigues
authors.forename: Manuel
authors.initials: M
authors.lastname: Megías
authors.forename: Mariangela
authors.initials: M
authors.lastname: Hungria
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D044950:Flavanones / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics*; D053147:Plant Exudates / Q000494:pharmacology; D042162:Rhizobium tropici / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D001426:Bacterial Proteins; D044950:Flavanones; D053147:Plant Exudates; C005273:naringenin