Characterization of extrachromosomal replicons present in the extended host range Rhizobium sp. LPU83.
In several rhizobia, bacteria that inhabit the soil in free-living conditions and associate in symbiosis with the root of legumes as nitrogen-fixing organisms, plasmid DNA can constitute a high percentage of the genome. We have characterized acid-tolerant isolates of rhizobia-here represented by the strain Rhizobium sp. LPU83-that have an extended nodulation-host range including alfalfa, the common bean, and Leucena leucocephala. In this study we analyzed the plasmids of R. sp. LPU83 in order to characterize their role in the evolution of Medicago symbionts and their involvement in symbiotic behavior. The pLPU83a plasmid was found to be transmissible with no associated phenotypic traits. The symbiotic plasmid pLPU83b could be transferred at very low frequencies under laboratory conditions only when pLPU83a was present; could restore nodulation to a strain cured of its symbiotic plasmid, S. meliloti A818; but could not restore the full nitrogen fixation associated with alfalfa.
Torres Tejerizo
Gonzalo
G
IBBM - Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, La Plata, Argentina.
Del Papa
María Florencia
MF
de los Angeles Giusti
María
M
Draghi
Walter
W
Lozano
Mauricio
M
Lagares
Antonio
A
Pistorio
Mariano
M
D003227:Conjugation, Genetic / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D007887:Fabaceae / Q000235:genetics / Q000382:microbiology*; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009586:Nitrogen Fixation / Q000235:genetics / Q000502:physiology; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D012093:Replicon / Q000235:genetics* / Q000502:physiology; D012231:Rhizobium / Q000235:genetics* / Q000502:physiology; D013559:Symbiosis / Q000235:genetics
D018744:DNA, Plant