Document Detail

Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899.
MedLine Citation:
PMID:  18312393     Owner:  NLM     Status:  MEDLINE    
Three transposon mutants of Rhizobium tropici CIAT899 affected in lipopolysaccharide (LPS) biosynthesis were characterized and their maize rhizosphere and endophytic root colonization abilities were evaluated. The disrupted genes coded for the following putative products: the ATPase component of an O antigen ABC-2 type transporter (wzt), a nucleotide-sugar dehydratase (lpsbeta2) and a bifunctional enzyme producing GDP-mannose (noeJ). Electrophoretic analysis of affinity purified LPS showed that all mutants lacked the smooth LPS bands indicating an O antigen minus phenotype. In the noeJ mutant, the rough LPS band migrated faster than the parental band, suggesting a truncated LPS core. When inoculated individually, the wzt and noeJ mutants colonize the rhizosphere and root to a lower extent than the parental strain while no differences were observed between the lpsbeta2 mutant and the parental strain. All mutants were impaired in competitive rhizosphere and root colonization. Pleiotropic effects of the mutations on known colonization traits such as motility and growth rate were observed, but they were not sufficient to explain the colonization behaviours. It was found that the LPS mutants were sensitive to the maize antimicrobial 6-methoxy-2-benzoxazolinone (MBOA). Only the combined effects of altered growth rate and susceptibility to maize antimicrobials could account for all the observed colonization phenotypes. The results suggest an involvement of the LPS in protecting R. tropici against maize defence response during rhizosphere and root colonization.
Ernesto Ormeño-Orrillo; Monica Rosenblueth; Ellen Luyten; Jos Vanderleyden; Esperanza Martínez-Romero
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-02-27
Journal Detail:
Title:  Environmental microbiology     Volume:  10     ISSN:  1462-2920     ISO Abbreviation:  Environ. Microbiol.     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-04-09     Completed Date:  2008-05-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100883692     Medline TA:  Environ Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1271-84     Citation Subset:  IM    
Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, Mexico.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/DQ311659;  DQ311660;  DQ311661
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MeSH Terms
Anti-Bacterial Agents / pharmacology
Bacterial Proteins / genetics*
Lipopolysaccharides / biosynthesis*,  chemistry,  isolation & purification
Microbial Sensitivity Tests
Molecular Sequence Data
Phaseolus / microbiology
Plant Roots / microbiology*
Rhizobium tropici / drug effects,  genetics*,  growth & development*,  metabolism
Sequence Analysis, DNA
Soil Microbiology*
Zea mays / microbiology*
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Bacterial Proteins; 0/Lipopolysaccharides

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