Sinorhizobium fredii HH103 cgs mutants are unable to nodulate determinate- and indeterminate nodule-forming legumes and overproduce an altered EPS.
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.
Departamento de Microbiología, Facultad de Biología, Unviersidad de Sevilla, Sevilla, Spain.
Juan C
JC
Crespo-Rivas
Isabel
I
Margaret
Angeles
A
Hidalgo
Ana M
AM
Buendía-Clavería
Francisco J
FJ
Ollero
Francisco J
FJ
López-Baena
Piedad
P
del Socorro Murdoch
Miguel A
MA
Rodríguez-Carvajal
M Eugenia
ME
Soria-Díaz
María
M
Reguera
Javier
J
Lloret
David P
DP
Sumpton
Jackie A
JA
Mosely
Jane E
JE
Thomas-Oates
Anton A N
AA
van Brussel
Antonio
A
Gil-Serrano
Jose M
JM
Vinardell
Jose E
JE
Ruiz-Sainz
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D005419:Flavonoids / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005816:Genetic Complementation Test; D029882:Glycyrrhiza uralensis / Q000254:growth & development / Q000382:microbiology; D054884:Host-Pathogen Interactions; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009154:Mutation; D011135:Polysaccharides, Bacterial / Q000032:analysis / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053204:Root Nodules, Plant / Q000254:growth & development* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D042181:Sinorhizobium fredii / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013025:Glycine max / Q000254:growth & development / Q000382:microbiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D047071:beta-Glucans / Q000032:analysis / Q000378:metabolism
D001426:Bacterial Proteins; D018744:DNA, Plant; C083492:EPSI polysaccharide; D005419:Flavonoids; D011135:Polysaccharides, Bacterial; D047071:beta-Glucans; D012965:Sodium Chloride