title: The Sinorhizobium fredii HH103 MucR1 Global Regulator Is Connected With the nod Regulon and Is Required for Efficient Symbiosis With Lotus burttii and Glycine max cv. Williams.
abstract: Sinorhizobium fredii HH103 is a rhizobial strain showing a broad host range of nodulation. In addition to the induction of bacterial nodulation genes, transition from a free-living to a symbiotic state requires complex genetic expression changes with the participation of global regulators. We have analyzed the role of the zinc-finger transcriptional regulator MucR1 from S. fredii HH103 under both free-living conditions and symbiosis with two HH103 host plants, Glycine max and Lotus burttii. Inactivation of HH103 mucR1 led to a severe decrease in exopolysaccharide (EPS) biosynthesis but enhanced production of external cyclic glucans (CG). This mutant also showed increased cell aggregation capacity as well as a drastic reduction in nitrogen-fixation capacity with G. max and L. burttii. However, in these two legumes, the number of nodules induced by the mucR1 mutant was significantly increased and decreased, respectively, with respect to the wild-type strain, indicating that MucR1 can differently affect nodulation depending on the host plant. RNA-Seq analysis carried out in the absence and the presence of flavonoids showed that MucR1 controls the expression of hundreds of genes (including some related to EPS production and CG transport), some of them being related to the nod regulon.
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Acosta-Jurado
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Alias-Villegas
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Navarro-Gómez
authors.affiliation: 2 Technische Universität Dresden, Institut für Genetik, Helmholtzstrasse 10, 01062 Dresden, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Zehner
authors.affiliation: 3 Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla.
authors.forename: Piedad Del Socorro
authors.initials: PD
authors.lastname: Murdoch
authors.affiliation: 4 Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Calle Profesor García González 1, C. P. 41012, Sevilla, Spain, and.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Rodríguez-Carvajal
authors.affiliation: 5 Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Soto
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: Francisco-Javier
authors.initials: FJ
authors.lastname: Ollero
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: José E
authors.initials: JE
authors.lastname: Ruiz-Sainz
authors.affiliation: 2 Technische Universität Dresden, Institut für Genetik, Helmholtzstrasse 10, 01062 Dresden, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Göttfert
authors.affiliation: 1 Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, C.P. 41012, Sevilla, Spain.
authors.forename: José-María
authors.initials: JM
authors.lastname: Vinardell
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005419:Flavonoids / Q000378:metabolism; D000070116:Lotus / Q000382:microbiology*; D009586:Nitrogen Fixation; D055170:Plant Root Nodulation; D018085:Regulon / Q000235:genetics*; D017423:Sequence Analysis, RNA; D042181:Sinorhizobium fredii / Q000235:genetics / Q000502:physiology*; D013025:Glycine max / Q000382:microbiology*; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D005419:Flavonoids