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1.
Int J Mol Sci ; 17(5)2016 May 18.
Article in English | MEDLINE | ID: mdl-27213334

ABSTRACT

Sinorhizobium (Ensifer) fredii (S. fredii) is a rhizobial species exhibiting a remarkably broad nodulation host-range. Thus, S. fredii is able to effectively nodulate dozens of different legumes, including plants forming determinate nodules, such as the important crops soybean and cowpea, and plants forming indeterminate nodules, such as Glycyrrhiza uralensis and pigeon-pea. This capacity of adaptation to different symbioses makes the study of the molecular signals produced by S. fredii strains of increasing interest since it allows the analysis of their symbiotic role in different types of nodule. In this review, we analyze in depth different S. fredii molecules that act as signals in symbiosis, including nodulation factors, different surface polysaccharides (exopolysaccharides, lipopolysaccharides, cyclic glucans, and K-antigen capsular polysaccharides), and effectors delivered to the interior of the host cells through a symbiotic type 3 secretion system.


Subject(s)
Bacterial Proteins/metabolism , Glycine max/microbiology , Sinorhizobium fredii/physiology , Bacterial Proteins/chemistry , Molecular Structure , Plant Root Nodulation , Polysaccharides, Bacterial/metabolism , Sinorhizobium fredii/metabolism , Symbiosis , Type III Secretion Systems
2.
Mol Plant Microbe Interact ; 22(5): 575-88, 2009 May.
Article in English | MEDLINE | ID: mdl-19348575

ABSTRACT

Sinorhizobium fredii HH103 produces cyclic beta glucans (CG) composed of 18 to 24 glucose residues without or with 1-phosphoglycerol as the only substituent. The S. fredii HH103-Rifr 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-Rifr. 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-Rifr. In GYM medium, the EPS produced by SVQ562 was of higher molecular weight and carried higher levels of substituents than that produced by HH103-Rifr. The expression of the SVQ562 cgsColon, two colonslacZ 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.


Subject(s)
Bacterial Proteins/genetics , Mutation , Polysaccharides, Bacterial/metabolism , Root Nodules, Plant/growth & development , Sinorhizobium fredii/genetics , Bacterial Proteins/metabolism , DNA, Plant/chemistry , DNA, Plant/genetics , Flavonoids/pharmacology , Gene Expression Regulation, Bacterial/drug effects , Genetic Complementation Test , Glycyrrhiza uralensis/growth & development , Glycyrrhiza uralensis/microbiology , Host-Pathogen Interactions , Hydrogen-Ion Concentration , Magnetic Resonance Spectroscopy , Molecular Sequence Data , Polysaccharides, Bacterial/analysis , Reverse Transcriptase Polymerase Chain Reaction , Root Nodules, Plant/microbiology , Sequence Analysis, DNA , Sinorhizobium fredii/metabolism , Sinorhizobium fredii/physiology , Sodium Chloride/pharmacology , Glycine max/growth & development , Glycine max/microbiology , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , beta-Glucans/analysis , beta-Glucans/metabolism
3.
Int Microbiol ; 10(3): 169-76, 2007 Sep.
Article in English | MEDLINE | ID: mdl-18075998

ABSTRACT

Transposon Tn5-Mob mutagenesis allowed the selection of a Sinorhizobium fredii HH103 mutant derivative (SVQ 292) that requires the presence of uracil to grow in minimal media. The mutated gene, pyrF, codes for an orotidine-5 - monophosphate decarboxylase (EC 4.1.1.23). Mutant SVQ 292 and its parental prototrophic mutant HH103 showed similar Nod-factor and lipopolysaccharide profiles. The symbiotic properties of mutant SVQ 292 were severely impaired with all legumes tested. Mutant SVQ 292 formed small ineffective nodules on Cajanus cajan and abnormal nodules (pseudonodules) unable to fix nitrogen on Glycine max (soybean), Macroptitlium atropurpureum, Indigofera tinctoria, and Desmodium canadense. It also did not induce any macroscopic response in Macrotyloma axillare roots. The symbiotic capacity of SVQ 292 with soybean was not enhanced by the addition of uracil to the plant nutritive solution.


Subject(s)
Gene Expression Regulation, Bacterial , Glycine max/microbiology , Mutation , Orotidine-5'-Phosphate Decarboxylase/genetics , Sinorhizobium fredii/growth & development , Symbiosis , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Fabaceae/microbiology , Orotidine-5'-Phosphate Decarboxylase/chemistry , Orotidine-5'-Phosphate Decarboxylase/metabolism , Sequence Alignment , Sinorhizobium fredii/enzymology , Sinorhizobium fredii/genetics , Symbiosis/genetics , Uracil/metabolism
4.
Int. microbiol ; 10(3): 169-176, sept. 2007. tab, ilus
Article in En | IBECS | ID: ibc-056708

ABSTRACT

Transposon Tn5-Mob mutagenesis allowed the selection of a Sinorhizobium fredii HH103 mutant derivative (SVQ 292) that requires the presence of uracil to grow in minimal media. The mutated gene, pyrF, codes for an orotidine-5 - monophosphate decarboxylase (EC 4.1.1.23). Mutant SVQ 292 and its parental prototrophic mutant HH103 showed similar Nod-factor and lipopolysaccharide profiles. The symbiotic properties of mutant SVQ 292 were severely impaired with all legumes tested. Mutant SVQ 292 formed small ineffective nodules on Cajanus cajan and abnormal nodules (pseudonodules) unable to fix nitrogen on Glycine max (soybean), Macroptitlium atropurpureum, Indigofera tinctoria, and Desmodium canadense. It also did not induce any macroscopic response in Macrotyloma axillare roots. The symbiotic capacity of SVQ 292 with soybean was not enhanced by the addition of uracil to the plant nutritive solution (AU)


No disponible


Subject(s)
Sinorhizobium fredii/genetics , Fabaceae/genetics , Mutation , Symbiosis/genetics , Oligosaccharides/genetics , Mutation/genetics
5.
Mol Plant Microbe Interact ; 19(1): 43-52, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16404952

ABSTRACT

The Sinorhizobium fredii HH103 rkp-1 region, which is involved in capsular polysaccharides (KPS) production, was isolated and sequenced. The organization of the S. fredii genes identified, rkpUAGHIJ and kpsF3, was identical to that described for S. meliloti 1021 but different from that of S. meliloti AK631. The long rkpA gene (7.5 kb) of S. fredii HH103 and S. meliloti 1021 appears as a fusion of six clustered AK631 genes, rkpABCDEF. S. fredii HH103-Rif(r) mutants affected in rkpH or rkpG were constructed. An exoA mutant unable to produce exopolysaccharide (EPS) and a double mutant exoA rkpH also were obtained. Glycine max (soybean) and Cajanus cajan (pigeon pea) plants inoculated with the rkpH, rkpG, and rkpH exoA derivatives of S. fredii HH103 showed reduced nodulation and severe symptoms of nitrogen starvation. The symbiotic capacity of the exoA mutant was not significantly altered. All these results indicate that KPS, but not EPS, is of crucial importance for the symbiotic capacity of S. fredii HH103-Rif(r). S. meliloti strains that produce only EPS or KPS are still effective with alfalfa. In S. fredii HH103, however, EPS and KPS are not equivalent, because mutants in rkp genes are symbiotically impaired regardless of whether or not EPS is produced.


Subject(s)
Cajanus/microbiology , Glycine max/microbiology , Mutation/genetics , Polysaccharides, Bacterial/metabolism , Sinorhizobium fredii/genetics , Sinorhizobium fredii/physiology , Genes, Bacterial , Molecular Sequence Data , Nuclear Magnetic Resonance, Biomolecular , Polysaccharides, Bacterial/analysis , Polysaccharides, Bacterial/biosynthesis , Sinorhizobium fredii/classification , Glycine max/cytology
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