title: Genetic diversity of bradyrhizobial populations from diverse geographic origins that nodulate Lupinus spp. and Ornithopus spp.
abstract: The genetic diversity of 45 bradyrhizobial isolates that nodulate several Lupinus and Ornithopus species in different geographic locations was investigated by 16S rDNA PCR-RFLP and sequence analysis, 16S-23S rDNA intergenic spacer (IGS) PCR-RFLP analysis, and ERIC-PCR genomic fingerprinting. Reference strains of Bradyrhizobium japonicum, B. liaoningense and B. elkanii and some Canarian isolates from endemic woody legumes in the tribe Genisteae were also included. The 16S rDNA-RFLP analysis resolved 9 genotypes of lupin isolates, a group of fourteen isolates presented restriction-genotypes identical or very similar to B. japonicum, while another two main groups of isolates (69%) presented genotypes that clearly separated them from the reference species of soybean. 16S rDNA sequencing of representative strains largely agreed with restriction analysis, except for a group of six isolates, and showed that all the lupin isolates are relatives of B. japonicum, but different lineages were observed. The 16S-23S IGS-RFLP analysis showed a high resolution level, resolving 19 distinct genotypes among 30 strains analysed, and so demonstrating the heterogeneity of the 16S-RFLP groups. ERIC-PCR fingerprint analysis showed an enormous genetic diversity producing a different pattern for each but two of the isolates. Phylogeny of nodC gene was independent from the 16S rRNA phylogeny, and showed a tight relationship in the symbiotic region of the lupin isolates with isolates from Canarian genistoid woody legumes, and in concordance, cross-nodulation was found. We conclude that Lupinus is a promiscuous host legume that is nodulated by rhizobia with very different chromosomal genotypes, which could even belong to several species of Bradyrhizobium. No correlation among genomic background, original host plant and geographic location was found, so, different chromosomal genotypes could be detected at a single site and in a same plant species, on the contrary, an identical genotype was detected in very different geographical locations and plants.
authors.affiliation: Departamento de Microbiologia y Biología Celular, Universidad de La Laguna, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Jarabo-Lorenzo
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pérez-Galdona
authors.forename: Javier
authors.initials: J
authors.lastname: Donate-Correa
authors.forename: Raúl
authors.initials: R
authors.lastname: Rivas
authors.forename: Encarna
authors.initials: E
authors.lastname: Velázquez
authors.forename: Mariano
authors.initials: M
authors.lastname: Hernández
authors.forename: Francisco
authors.initials: F
authors.lastname: Temprano
authors.forename: Eustoquio
authors.initials: E
authors.lastname: Martínez-Molina
authors.forename: Tomás
authors.initials: T
authors.lastname: Ruiz-Argüeso
authors.forename: Milagros
authors.initials: M
authors.lastname: León-Barrios
mesh_terms: D001426:Bacterial Proteins; D020369:Bradyrhizobium / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D021903:DNA, Ribosomal Spacer / Q000032:analysis*; D004463:Ecology; D007887:Fabaceae / Q000382:microbiology*; D014644:Genetic Variation; D005838:Genotype; D031297:Lupinus / Q000382:microbiology*; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D017351:N-Acetylglucosaminyltransferases; C060771:NodC protein, Rhizobiales