Geographical patterns of root nodule bacterial diversity in cultivated and wild populations of a woody legume crop

Josep Ramoneda*, Jaco Le Roux, Emmanuel Frossard, Beat Frey, Hannes Andres Gamper

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    5 Citations (Scopus)
    7 Downloads (Pure)


    There is interest in understanding how cultivation, plant genotype, climate and soil conditions influence the biogeography of root nodule bacterial communities of legumes. For crops from regions with relict wild populations, this is of even greater interest because the effects of cultivation on symbiont communities can be revealed, which is of particular interest for bacteria such as rhizobia. Here, we determined the structure of root nodule bacterial communities of rooibos (Aspalathus linearis), a leguminous shrub endemic to South Africa. We related the community dissimilarities of the root nodule bacteria of 18 paired cultivated and wild rooibos populations to pairwise geographical distances, plant ecophysiological characteristics and soil physicochemical parameters. Using next-generation sequencing data, we identified region-, cultivation- and farm-specific operational taxonomic units for four distinct classes of root nodule bacterial communities, dominated by members of the genus Mesorhizobium. We found that while bacterial richness was locally increased by organic cultivation, strong biogeographical differentiation in the bacterial communities of wild rooibos disappeared with cultivation of one single cultivar across its entire cultivation range. This implies that expanding rooibos farming has the potential to endanger wild rooibos populations through the homogenisation of root nodule bacterial diversity.

    Original languageEnglish
    Article numberfiaa145
    Pages (from-to)1-13
    Number of pages13
    JournalFEMS Microbiology Ecology
    Issue number10
    Early online date21 Jul 2020
    Publication statusPublished - Oct 2020

    Bibliographical note

    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.


    • rhizobia
    • rooibos
    • microbial biogeography
    • Mesorhizobium
    • distance-decay relationship
    • crop wild relatives


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