Divergent Nod-containing Bradyrhizobium sp. DOA9 with a megaplasmid and its host range

Kamonluck Teamtisong, Pongpan Songwattana, Rujirek Noisangiam, Pongdet Piromyou, Nantakorn Boonkerd, Panlada Tittabutr, Kiwamu Minamisawa, Achara Nantagij, Shin Okazaki, Mikiko Abe, Toshiki Uchiumi, Neung Teaumroong

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)


    Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root nodules of the legume Aeschynomene americana, is a divergent nod-containing strain. It exhibits a broad host range, being able to colonize and efficiently nodulate the roots of most plants from the Dalbergioid, Millettioid, and Robinioid tribes (7 species of Papilionoideae). In all cases, nodulation was determinate. The morphology and size of DOA9 bacteroids isolated from the nodules of various species of Papilionoideae were indistinguishable from the free-living form. However, they were spherical in Arachis hypogaea nodules. GusA-tagged DOA9 also colonized rice roots as endophytes. Since broad-host-range legume symbionts often carry multiple replicons in their genome, we analyzed the replicons for symbiosis genes by electrophoresis. DOA9 carried two replicons, a chromosome (cDOA9) and single megaplasmid (pDOA9) larger than 352 kb. The genes for nodulation (nodA, B, C) and nitrogen fixation (nifH) were localized on the megaplasmid. Southern blot hybridization revealed two copies of nodA on the megaplasmid, single copies of nodB and C on the megaplasmid, and one copy each of nifH on the chromosome and megaplasmid. These results suggested that Bradyrhizobium sp. DOA9 may have the unusual combination of a broad host range, bacteroid differentiation, and symbiosis-mediating replicons.

    Original languageEnglish
    Pages (from-to)370-376
    Number of pages7
    JournalMicrobes and environments
    Issue number4
    Publication statusPublished - 2014 Dec 19


    • Aeschynomene americana
    • Bradyrhizobium
    • Broad host range
    • Megaplasmid

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Soil Science
    • Plant Science


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