Diverse rhizobia that nodulate two species of Kummerowia in China

Abstract

A total of 63 bacterial strains were isolated from root nodules of Kummerowia striata and K. stipulacea grown in different geographic regions of China. These bacteria could be divided into fast-growing (FG) rhizobia and slow-growing (SG) rhizobia according to their growth rate. Genetic diversity and taxonomic relationships among these rhizobia were revealed by PCR-based 16 S rDNA RFLP and sequencing, 16 S-IGS RFLP, SDS-PAGE of whole cell soluble proteins, BOX-PCR and symbiotic gene (nifH/nodC) analyses. The symbiotic FG strains were mainly isolated from temperate regions and they were identified as four genomic species in Rhizobium and Sinorhizobium meliloti based on the consensus of grouping results. The SG strains were classified as five genomic species within Bradyrhizobium and they were mainly isolated fron the subtropic and tropical regions. The phylogenetic analyses of nifH and nodC genes showed relationships similar to that of 16 S rDNA but the symbiotic genes of Bradyrhizobium strains isolated from Kummerowia were distinct from those isolated from Arachis and soybean. These results offered evidence for rhizobial biogeography and demonstrated that the Kummerowia-nodulating ability might have evolved independently in different regions in association with distinctive genomic species of rhizobia.

Rhizobium mesosinicum sp. nov., isolated from root nodules of three different legumes

“…The microsymbionts associated with Dalbergia species in Chinese soils have not been studied. In this study, a group of Dalbergia rhizobia are reported that showed close phylogenetic relationships with some strains isolated from Albizia (Wang et al, 2006) and Kummerowia (Lin et al, 2007), also grown in subtropical regions. Based upon a comparative study with multiple analyses, these strains were classified into a single group distinct from defined Rhizobium species.…”

“…Kummerowia species are leguminous plants of medicinal value that originate from East Asia, and some of them have been introduced to other areas. Our previous data indicated that Kummerowia species were non-selective hosts for rhizobia and that they might nodulate with various bacteria in different regions (Lin et al, 2007(Lin et al, , 2008. Rosewoods (species of Dalbergia L.), belonging to the subfamily Papilionoideae of the Leguminosae, are slowgrowing ornamental trees, some of which have medicinal value (Ito et al, 2003), and are usually used as hard timber in furniture production.…”

Novel associations between rhizobial populations and legume species within the genera Lathyrus and O xytropis grown in the temperate region of China

“…They also hypothesized that the environment selects is, in part, responsible for spatial variation in microbial diversity. Some previous studies have demonstrated that biogeographic patterns also exist in rhizobia, the symbiotic bacteria [22,26,27] . The data in the present study and in the previous studies showed that the geological distribution of nodule occupant bacteria or symbiotic bacteria in root and/or stem nodules were not only determined by the environment, but also related to the geography of their corresponding host plants.…”

Rhizobium tibeticum sp. nov., a symbiotic bacterium isolated from Trigonella archiducis-nicolai (Sirj.) Vassilcz.

“…S3), which was consistent with the phylogenetic relationships estimated from 16S rRNA gene sequences. Since the similarity of protein patterns among strains within a rhizobial species is always greater than 80 % (Gu et al, 2007;Lin et al, 2007;Liu et al, 2007;Yan et al, 2007), the results of this analysis also imply that the two Tibetan strains represent a species that is distinct from the Rhizobium species represented by the reference strains.…”