A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

Journal Article · Thu Feb 01 00:00:00 EST 1990 · Journal of Bacteriology; (USA)

OSTI ID:7014714

Nadler, K D; Chen, Jing-Wen; John, T R ^[1]; Johnston, A W.B. ^[2]

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1. Michigan State Univ., East Lansing (USA)
2. The John Innes Institute, Norwich (England)

Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of {sup 55}Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. The authors mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbiotically.

• OSTI ID: 7014714
• Journal Information: Journal of Bacteriology; (USA), Vol. 172:2; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
IRON
BIOLOGICAL EFFECTS
RHIZOBIUM
NITROGEN FIXATION
CYTOCHROMES
GENETIC MAPPING
IRON 55
MUTAGENESIS
MUTANTS
NITROSO COMPOUNDS
PHENOTYPE
RECOMBINANT DNA
UPTAKE
BACTERIA
BETA DECAY RADIOISOTOPES
DNA
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IRON ISOTOPES
ISOTOPES
MAPPING
METALS
MICROORGANISMS
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
RADIOISOTOPES
TRANSITION ELEMENTS
YEARS LIVING RADIOISOTOPES
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