Rhizobium phaseoli symbiotic mutants with transposon Tn5 insertions

Noel, K. Dale; Sanchez, Amanda D.; Fernández, Leonor; Leemans, J.; Cevallos, Miguel A.

doi:10.1128/jb.158.1.148-155.1984

Cited by 260 publications

(54 citation statements)

References 34 publications

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“…This strain was referred as the parental strain in this study. R. tropici were routinely grown in the complex PY medium at 30°C (Noel et al, 1984). YEM (Vincent, 1970) and the MM described by Kingsley and Bohlool (1992) using 10 mM ammonium nitrate as nitrogen source were used for some tests.…”

Section: Methodsmentioning

confidence: 99%

Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899

Ormeño‐Orrillo

Rosenblueth

Luyten

et al. 2008

Environmental Microbiology

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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.

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Section: Methodsmentioning

confidence: 99%

Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899

Ormeño‐Orrillo

Rosenblueth

Luyten

et al. 2008

Environmental Microbiology

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“…Strains from the Department of Bacteriology strain collection (DBSC), University of Wisconsin‐Madison were grown in Difco nutrient broth (Becton Dickinson). The control strains included: Aureobasidium pullulans; Bacillus cereus UW85; Bacillus megaterium 7A1 (Bacillus Genetic Stock Center, Ohio State University); Erwinia herbicola 005; Escherichia coli 8009 (DBSC); Leptospirillum ferrooxidans; Methanobacterium formicicum (medium II; Kim et al ., 1996); Methylosinus trichosporium; Pseudomonas fluorescens 2‐79; Rhizobium etli CE3 (Noel et al ., 1984); Rhodobacter sphaeroides 9502 (DBSC); Rhodospirillum rubrum 9405 (DBSC); Salmonella typhimurium LT2 (Lilleengen, 1948); Staphylococcus aureus 3001 (DBSC); Sulfolobus shibatae; Sulfolobus solfataricus; Thermococcus litoralis; Thiobacillus ferrooxidans; Vibrio cholerae F115A (DBSC); and Yersinia enterocolitica WA.…”

Section: Methodsmentioning

confidence: 99%

Crenarchaeota colonize terrestrial plant roots

Simon

Dodsworth

Goodman

2000

Environmental Microbiology

108

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Microorganisms that colonize plant roots are recruited from, and in turn contribute substantially to, the vast and virtually uncharacterized phylogenetic diversity of soil microbiota. The diverse, but poorly understood, microorganisms that colonize plant roots mediate mineral transformations and nutrient cycles that are central to biosphere functioning. Here, we report the results of epifluorescence microscopy and culture-independent recovery of small subunit (SSU) ribosomal RNA (rRNA) gene sequences showing that members of a previously reported clade of soil Crenarchaeota colonize both young and senescent plant roots at an unexpectedly high frequency, and are particularly abundant on the latter. Our results indicate that non-thermophilic members of the Archaea inhabit an important terrestrial niche on earth and direct attention to the need for studies that will determine their possible roles in mediating root biology.

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“…coli strains were grown at 37∞C in Luria-Bertani medium. Rhizobium strains were grown at 30∞C in PY medium supplied with 1 mM CaCl 2 (Noel et al, 1984). When needed, antibiotics were added at the following concentrations (in mg ml -1 ): nalidixic acid, 20; gentamicin, 30; chloramphenicol, 30; and kanamycin, 30. Bacterial mating pRK7813, pBBMCS53, pHER, pTLF, pDO and pDOP derivatives were introduced into Rhizobium using E. coli S17-1 as a donor strain (Simon et al, 1983).…”

Section: Bacterial Strains and Growth Conditionsmentioning

confidence: 99%

Two discrete elements are required for the replication of a repABC plasmid: an antisense RNA and a stem–loop structure

Venkova-Canova

Soberón

Ramírez-Romero

et al. 2004

Molecular Microbiology

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SummaryThe repABC replicons contain an operon encoding the initiator protein (RepC) and partitioning proteins (RepA and RepB). The latter two proteins negatively regulate the transcription of the operon. In this article we have identified two novel regulatory elements, located within the conserved repB-repC intergenic sequence, which negatively modulate the expression of repC , in plasmid p42d of Rhizobium etli . One of them is a small antisense RNA and the other is a stem-loop structure in the repABC mRNA that occludes the Shine-Dalgarno sequence of repC. According to in vivo and in vitro analyses, the small antisense RNA (57-59 nt) resembles canonical negative regulators of replication because: (i) it is transcribed from a strong constitutive promoter (P2), (ii) the transcript overlaps untranslated region upstream of the RepC coding sequences, (iii) the RNA forms one secondary structure acting as a rho -independent terminator, (iv) the antisense RNA is a strong transincompatibility factor and (v) its presence reduces the level of repC expression. Surprisingly, both of these seemingly negative regulators are required for efficient plasmid replication.

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Rhizobium phaseoli symbiotic mutants with transposon Tn5 insertions

Cited by 260 publications

References 34 publications

Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899

Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899

Crenarchaeota colonize terrestrial plant roots

Two discrete elements are required for the replication of a repABC plasmid: an antisense RNA and a stem–loop structure

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