Soil microbial community coalescence and fertilization interact to drive the functioning of the legume–rhizobium symbiosis

Josep Ramoneda*, Johannes Le Roux, Stefanie Stadelmann, Emmanuel Frossard, Beat Frey, Hannes Andres Gamper

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)
    5 Downloads (Pure)


    1. Soil microbial community coalescence, where entire microbial communities mix and interact under new conditions, is a widespread phenomenon whose applicability for targeted root microbiome assembly has not been studied. Whether soil mixing can lead to predictable outcomes for community assembly and functioning of specific functional groups, for example, N2-fixing rhizobia, remains unknown.

    2. Using a legume shrub adapted to nutrient-poor soils, we tested the effects of community coalescence on plant nutrition and growth, and its influence on the rhizobial root nodule symbiosis. We grew seedlings of rooibos [Aspalathus linearis (Burm.f.) Dahlg.] in individual rhizosphere soils collected from cultivated and wild rooibos plants and their mixtures, and included a fertilization treatment. Portions of the taxonomic gyrB and the symbiotic nodA gene makers were sequenced to characterize rhizobial communities present in rooibos root nodules under the different soil conditions.

    3. Overall, community coalescence by soil mixing had positive effects on plant nutrition and growth, and interacted with fertilizer addition to concurrently change rhizobial taxonomic evenness and promote higher relative N2 fixation. We identified particular rhizobia preferentially associated with rooibos plants that showed higher N fractions from N2 fixation, raised in mixed fertilized soils.

    4. These findings indicate that soil bacterial community coalescence and fertilization can have synergistic effects on plant performance, while promoting the assembly of alternative symbiotic rhizobial communities that provide improved nutritional benefits to host plants.

    5. Synthesis and applications. The combination of soil mixing and fertilizer addition may be an important, but hitherto overlooked measure to improve the functioning of rhizobium symbioses in legume crops. Microbial community coalescence should gain recognition as a potentially effective mechanism to improve the functioning of plant microbiomes.

    Original languageEnglish
    Pages (from-to)2590-2602
    Number of pages13
    JournalJournal of Applied Ecology
    Issue number11
    Early online date30 Aug 2021
    Publication statusPublished - Nov 2021

    Bibliographical note

    Copyright the Author(s) 2021. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


    • biological nitrogen fixation
    • community coalescence
    • microbial community assembly
    • plant microbiomes
    • rhizobia
    • rooibos
    • soil mixing
    • symbiosis


    Dive into the research topics of 'Soil microbial community coalescence and fertilization interact to drive the functioning of the legume–rhizobium symbiosis'. Together they form a unique fingerprint.

    Cite this