title: Population structure of root nodulating Rhizobium leguminosarum in Vicia cracca populations at local to regional geographic scales.
abstract: The genetic diversity and population structure of about 350 Rhizobium leguminosarum biovar viciae isolates from Vicia cracca were analysed. A hierarchical sampling design was used covering three regions, one region in Belgium and two in France, in which multiple local V. cracca populations were sampled. Rhizobium isolates were genotyped using RAPD and by sequencing two chromosomal housekeeping genes (glnII and recA) and one plasmid-borne gene (nodC). Twenty-six nodC types and sixty-seven chromosomal types were identified, many of which appeared to be regional or local endemics. We found strong genetic differentiation both among V. cracca populations that are separated by only a few kilometres, and among regions that are 50 to 350km apart. Despite significant plasmid exchange, chromosomal and nod types were similarly structured among host populations and regions. We found two lineages of which one prevailed in the Belgian region while the other dominated the French regions. Although a significant correlation between genetic differentiation and geographic distance was found, it is deemed more likely that the observed biogeographic patterns are rather due to coevolutionary interactions and environmental pressures. Furthermore, the impact of recombination on the chromosomal differentiation was found to be considerable.
authors.affiliation: Plant Conservation and Population Biology, Biology Department, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium; Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium. Electronic address: jannick.vancauwenberghe@bio.kuleuven.be.
authors.forename: Jannick
authors.initials: J
authors.lastname: Van Cauwenberghe
authors.affiliation: Plant Conservation and Population Biology, Biology Department, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium; Botanic Garden Meise, Domein van Bouchout, B-1860 Meise, Belgium.
authors.forename: Brecht
authors.initials: B
authors.lastname: Verstraete
authors.affiliation: Plant Conservation and Population Biology, Biology Department, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Benny
authors.initials: B
authors.lastname: Lemaire
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Cluster for Bioengineering Technology (CBeT), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Michiels
authors.affiliation: Plant Conservation and Population Biology, Biology Department, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Honnay
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004463:Ecology; D005828:Genetics, Population; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D010802:Phylogeny; D016961:Rhizobium leguminosarum / Q000145:classification* / Q000235:genetics*; D053204:Root Nodules, Plant / Q000382:microbiology*; D031306:Vicia / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D017351:N-Acetylglucosaminyltransferases
keywords: Genetic differentiation; Hierarchical sampling; Population genetic structure; Recombination; Rhizobium leguminosarum biovar viciae; Vicia cracca