Sinorhizobium fredii HH103 cgs Mutants Are Unable to Nodulate Determinate- and Indeterminate Nodule-Forming Legumes and Overproduce an Altered EPS

• Published in: Molecular plant-microbe interactions Vol. 22; no. 5; pp. 575 - 588
• Main Authors: Crespo-Rivas, Juan C, Margaret, Isabel, Hidalgo, Angeles, Buendia-Claveria, Ana M, Ollero, Francisco J, Lopez-Baena, Francisco J, Socorro Murdoch, Piedad del, Rodriguez-Carvajal, Miguel A, Soria-Diaz, M. Eugenia, Reguera, Maria, Lloret, Javier, Sumpton, David P, Mosely, Jackie A, Thomas-Oates, Jane E, Brussel, Anton A.N. van, Gil-Serrano, Antonio
• Format: Journal Article
• Language: English
• Published: St. Paul, MN APS Press 01.05.2009; The American Phytopathological Society
• Subjects: Bacterial plant pathogens; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; beta-glucans; beta-Glucans - analysis; beta-Glucans - metabolism; Biological and medical sciences; cowpeas; DNA, Plant - chemistry; DNA, Plant - genetics; Flavonoids - pharmacology; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Regulation, Bacterial - drug effects; genes; Genetic Complementation Test; glucose; Glycine max; Glycine max - growth & development; Glycine max - microbiology; Glycyrrhiza uralensis; Glycyrrhiza uralensis - growth & development; Glycyrrhiza uralensis - microbiology; Host-Pathogen Interactions; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; messenger RNA; microbial genetics; Molecular Sequence Data; Mutation; nitrogen fixation; nitrogen-fixing bacteria; nodulation; nucleotide sequences; Phytopathology. Animal pests. Plant and forest protection; polysaccharides; Polysaccharides, Bacterial - analysis; Polysaccharides, Bacterial - metabolism; Reverse Transcriptase Polymerase Chain Reaction; root nodules; Root Nodules, Plant - growth & development; Root Nodules, Plant - microbiology; Sequence Analysis, DNA; Sinorhizobium fredii; Sinorhizobium fredii - genetics; Sinorhizobium fredii - metabolism; Sinorhizobium fredii - physiology; Sodium Chloride - pharmacology; soybeans; species differences; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; transcription (genetics); Vigna unguiculata; Sinorhizobium; Bacteria; Plant; Rhizobiaceae; Mutation; Microbiology
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-22-5-0575

Sinorhizobium fredii HH103 produces cyclic β glucans (CG) composed of 18 to 24 glucose residues without or with 1-phosphoglycerol as the only substituent. The S. fredii HH103-Rif(r) cgs gene (formerly known as ndvB) was sequenced and mutated with the lacZ-gentamicin resistance cassette. Mutant SVQ562 did not produce CG, was immobile, and grew more slowly in the hypoosmotic GYM medium, but its survival in distilled water was equal to that of HH103-Rif(r). Lipopolysaccharides and K-antigen polysaccharides produced by SVQ562 were not apparently altered. SVQ562 overproduced exopolysaccharides (EPS) and its exoA gene was transcribed at higher levels than in HH103-Rif(r). In GYM medium, the EPS produced by SVQ562 was of higher molecular weight and carried higher levels of substituents than that produced by HH103-Rif(r). The expression of the SVQ562 cgslacZ fusion was influenced by the pH and the osmolarity of the growth medium. The S. fredii cgs mutants SVQ561 (carrying cgs omega) and SVQ562 only formed pseudonodules on Glycine max (determinate nodules) and on Glycyrrhiza uralensis (indeterminate nodules). Although nodulation factors were detected in SVQ561 cultures, none of the cgs mutants induced any macroscopic response in Vigna unguiculata roots. Thus, the nodulation process induced by S. fredii cgs mutants is aborted at earlier stages in V. unguiculata than in Glycine max.