Identification of mesorhizobium loti genes relevant to symbiosis by using signature-tagged mutants

Naoganchaolu Borjigin, Keisuke Furukawa, Yoshikazu Shimoda, Satoshi Tabata, Shusei Sato, Shima Eda, Kiwamu Minamisawa, Hisayuki Mitsui

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)


    Signature-tagged mutagenesis was applied to Mesorhizobium loti, a nitrogen-fixing root-nodule symbiont of the leguminous plant Lotus japonicus. We arranged 1,887 non-redundant mutant strains of M. loti into 75 sets, each consisting of 24 to 26 strains with a different tag in each strain. These sets were each inoculated en masse onto L. japonicus plants. Comparative analysis of total DNA extracted from inoculants and resulting nodules based on quantitative PCR led to the selection of 69 strains as being reduced in relative abundance during nodulation. Plant assays conducted with individual strains confirmed that 3 were defective in nodulation (Nod-) and that 10 were Nod+but defective in nitrogen fixation (Fix-); in each case, the symbiosis deficiency could be attributed to the transposon insertion carried by that strain. Although the remaining 56 strains were Fix+, 33 of them showed significantly reduced competitiveness during nodulation. Among the mutants we identified are known genes that are diverse in predicted function as well as some genes of unknown function, which demonstrates the validity of this screening procedure for functional genomics in rhizobia.

    Original languageEnglish
    Pages (from-to)165-171
    Number of pages7
    JournalMicrobes and environments
    Issue number2
    Publication statusPublished - 2011


    • Competitiveness
    • Mesorhizobium loti
    • Root nodule
    • Signature-tagged mutagenesis
    • Symbiosis

    ASJC Scopus subject areas

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


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