title: Assignment of biological functions to specific plasmids in a local isolate of Rhizobium cicer.
abstract: The genetic basis of symbiosis, mucoid structure and melanin biosynthesis in a local isolate of Rhizobium cicer was investigated. The strain was a very effective symbiont and produced substantial amounts of exopolysaccharides and melanin. It harbored three high-molar-mass plasmids of 55, 80 and 130 kb, respectively. Thirty-one melanin production-negative (Mep-) derivatives were obtained through plasmid curing. The plasmid patterns of cured derivatives indicated that the loss of 55 and/or 80 kb plasmids was sufficient for obtaining Mep- phenotype. The specific involvement of 55-kb plasmid in melanin production was confirmed upon re-introduction of this plasmid into one of the Mep- derivatives. Further investigation also indicated that the 130-kb plasmid might be necessary for both mucoidal appearance and symbiotic functions.
authors.affiliation: Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
authors.forename: E E
authors.initials: EE
authors.lastname: Yildiz
authors.forename: G
authors.initials: G
authors.lastname: Ozcengiz
authors.forename: B
authors.initials: B
authors.lastname: Içgen
authors.forename: N G
authors.initials: NG
authors.lastname: Alaeddinoğlu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004586:Electrophoresis; D008543:Melanins / Q000096:biosynthesis; D010641:Phenotype; D010957:Plasmids / Q000302:isolation & purification / Q000502:physiology*; D012231:Rhizobium / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012639:Seeds; D013559:Symbiosis
chemical_list: D000900:Anti-Bacterial Agents; D008543:Melanins