Affiliation:
1. Department of Integrative Biology, University of California, Berkeley, California 94720
Abstract
ABSTRACT
Bacteria often infect their hosts from environmental sources, but little is known about how environmental and host-infecting populations are related. Here, phylogenetic clustering and diversity were investigated in a natural community of rhizobial bacteria from the genus
Bradyrhizobium
. These bacteria live in the soil and also form beneficial root nodule symbioses with legumes, including those in the genus
Lotus
. Two hundred eighty pure cultures of
Bradyrhizobium
bacteria were isolated and genotyped from wild hosts, including
Lotus angustissimus
,
Lotus heermannii
,
Lotus micranthus
, and
Lotus strigosus
. Bacteria were cultured directly from symbiotic nodules and from two microenvironments on the soil-root interface: root tips and mature (old) root surfaces. Bayesian phylogenies of
Bradyrhizobium
isolates were reconstructed using the internal transcribed spacer (ITS), and the structure of phylogenetic relatedness among bacteria was examined by host species and microenvironment. Inoculation assays were performed to confirm the nodulation status of a subset of isolates. Most recovered rhizobial genotypes were unique and found only in root surface communities, where little bacterial population genetic structure was detected among hosts. Conversely, most nodule isolates could be classified into several related, hyper-abundant genotypes that were phylogenetically clustered within host species. This pattern suggests that host infection provides ample rewards to symbiotic bacteria but that host specificity can strongly structure only a small subset of the rhizobial community.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference74 articles.
1. Akaike, H. 1973. Information theory and an extension of the maximum likelihood principle, p. 267-281. In B. N. Petrov and F. Csaki (ed.), Second international symposium on information theory. Akademiai Kiado, Budapest, Hungary.
2. Gapped BLAST and PSI-BLAST: a new generation of protein database search programs
3. Bennett, A. F., and R. E. Lenski. 1993. Evolutionary adaptation to temperature. II. Thermal niches of experimental lines of Escherichia coli. Evolution47:1-12.
4. Brockwell, J., R. J. Roughley, and D. F. Herridge. 1987. Population dynamics of Rhizobium japonicum strains used to inoculate three successive crops of soybeans. Aust. J. Agric. Res.38:61-74.
5. Keys to Symbiotic Harmony
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