title: Evidence of autoinducer-dependent and -independent heterogeneous gene expression in Sinorhizobium fredii NGR234.
abstract: Populations of genetically identical Sinorhizobium fredii NGR234 cells differ significantly in their expression profiles of autoinducer (AI)-dependent and AI-independent genes. Promoter fusions of the NGR234 AI synthase genes traI and ngrI showed high levels of phenotypic heterogeneity during growth in TY medium on a single-cell level. However, adding very high concentrations of N-(3-oxooctanoyl-)-l-homoserine lactone resulted in a more homogeneous expression profile. Similarly, the lack of internally synthesized AIs in the background of the NGR234-ΔtraI or the NGR234-ΔngrI mutant resulted in a highly homogenous expression of the corresponding promoter fusions in the population. Expression studies with reporter fusions of the promoter regions of the quorum-quenching genes dlhR and qsdR1 and the type IV pilus gene cluster located on pNGR234b suggested that factors other than AI molecules affect NGR234 phenotypic heterogeneity. Further studies with root exudates and developing Arabidopsis thaliana seedlings provide the first evidence that plant root exudates have strong effects on the heterogeneity of AI synthase and quorum-quenching genes in NGR234. Therefore, plant-released octopine appears to play a key role in modulation of heterogeneous gene expression.
authors.affiliation: Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Hamburg, Germany.
authors.forename: Jessica
authors.initials: J
authors.lastname: Grote
authors.affiliation: Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Hamburg, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Krysciak
authors.affiliation: Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Hamburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Schorn
authors.affiliation: Entwicklungsbiologie und Physiologie der Pflanzen, Universität Kiel, Kiel, Germany.
authors.forename: Renate I
authors.initials: RI
authors.lastname: Dahlke
authors.affiliation: Entwicklungsbiologie und Physiologie der Pflanzen, Universität Kiel, Kiel, Germany.
authors.forename: Liina
authors.initials: L
authors.lastname: Soonvald
authors.affiliation: Zentrum Mathematik, Technische Universität München, Munich, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Müller
authors.affiliation: Institut für Biomathematik und Biometrie, Helmholtz Zentrum München, Munich, Germany.
authors.forename: Burkhard A
authors.identifier: http://orcid.org/0000-0001-5848-7227
authors.initials: BA
authors.lastname: Hense
authors.affiliation: Institut für Biomathematik und Biometrie, Helmholtz Zentrum München, Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwarzfischer
authors.affiliation: Entwicklungsbiologie und Physiologie der Pflanzen, Universität Kiel, Kiel, Germany.
authors.forename: Margret
authors.initials: M
authors.lastname: Sauter
authors.affiliation: Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Hamburg, Germany.
authors.forename: Christel
authors.initials: C
authors.lastname: Schmeisser
authors.affiliation: Biozentrum Klein Flottbek, Abteilung für Mikrobiologie und Biotechnologie, Universität Hamburg, Hamburg, Germany wolfgang.streit@uni-hamburg.de.
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Streit
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D017360:Arabidopsis / Q000382:microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D010936:Plant Extracts / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D042181:Sinorhizobium fredii / Q000187:drug effects* / Q000235:genetics*
chemical_list: D054742:Acyl-Butyrolactones; D010936:Plant Extracts