Affiliations: Department of Biological Sciences and Biotechnology,
Tsinghua University, Beijing 100084, China | Department of Microbiology, Peking University Health
Science Center, Beijing 100083, China
Abstract: Previous research reveals that the genome structures of rhizobial
type strains and reference strains can reflect their phylogenetic
relationships. In order to further explore the potential application of genome
structure as a phylogenetic marker in rhizobial natural taxonomy, this study
analyzed the genome structures of 29 unclassified nodule bacteria isolated from
the root nodules of leguminous trees, Robinia sp., Dalbergia spp., and A lbizia
spp. and 7 rhizobial reference strains by I-CeuI cleavage, then clustered these
bacteria phylogenetically based on their genome structures and compared these
clusters with those based on numerical taxonomy and 16S rDNA PCR-RFLP. Eleven
phylogenetic clusters were obtained. The clusters were in large part consistent
with those based on numerical taxonomy and 16S rDNA PCR-RFLP. Also there are
inconsistent clusters based on the above three methods. But results are
completely consistent with 16S rRNA clusters. This suggested that the genome
structure clustering method can be used to fastly identify root nodule isolates
and detect their phylogenetic relationships. The credibility and repeatability
of the results, together with the simplicity and possibility to analyze a large
number of strains in a short time of the method, indicates the broad potential
application of genome structure as phylogenetic marker to categorize rhizobial
isolates and should in the future facilitate biodiversity studies.
Keywords: rhizobia, genome structure, phylogenetic analysis, pulsed field gel electrophoresis, I-CeuI
