Plant monocultures produce more antagonistic soil Streptomyces communities than high-diversity plant communities

Matthew G. Bakker, Lindsey Otto-Hanson, A. J. Lange, James M. Bradeen, Linda L. Kinkel

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54 Scopus citations


Plant-soil feedbacks are important to productivity and plant community dynamics in both natural and managed ecosystems. Among soil bacteria, the Streptomyces possess particularly strong antagonistic activities and inhibit diverse plant pathogens, offering a clear pathway to involvement in plant-soil feedbacks. We hypothesized that feedback effects and the ability of individual host plant species to foster antagonistic Streptomyces populations may be modified by the richness of the surrounding plant community. To test this, we collected soil associated with four different plant species (two C4 grasses: Andropogon gerardii, Schizachyrium scoparium; and two legumes: Lespedeza capitata, Lupinus perennis), grown in communities that spanned a gradient of plant species richness (1, 4, 8, 16, or 32 species). For each of these soils, we characterized the potential of soil Streptomyces to antagonize plant pathogens, using an invitro plate assay with indicator strains to reveal inhibition. We cultivated each plant species in each conditioned soil to assess feedback effects on subsequent plant growth performance. Surrounding plant richness modified the impacts of particular plant species on Streptomyces antagonistic activity; A.gerardii supported a higher proportion of antagonistic Streptomyces when grown in monoculture than when grown in 32-spp plant communities, and L.capitata supported more strongly antagonistic Streptomyces when grown in 4- or 32-spp plant communities than in 8-spp plant communities. Similarly, the feedback effects of particular plant species sometimes varied with surrounding plant richness; aboveground biomass production varied with plant species richness for A.gerardii in L.perennis-trained soil, for L.capitata in A.gerardii-trained soil, and for L.perennis in L.capitata-trained soil. Streptomyces antagonist density increased with overall Streptomyces density under low but not under high plant richness, suggesting that plant diversity modifies selection for antagonistic phenotypes among soil Streptomyces. This work highlights the complexity of feedback dynamics among plant species, and of plant-microbiome interactions in soil.

Original languageEnglish (US)
Pages (from-to)304-312
Number of pages9
JournalSoil Biology and Biochemistry
StatePublished - Oct 2013

Bibliographical note

Funding Information:
We thank D. Tilman and the Cedar Creek Ecosystem Science Reserve for permission to collect soil samples from an on-going experiment. MGB received support from the National Science Foundation (Graduate Research Fellowship). Research funding was provided by the National Science Foundation Long-Term Ecological Research Network Grant 0620652 and the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service , through the Microbial Observatories program (2006-04464).


  • Antagonism
  • Antibiosis
  • Diversity
  • Plant soil feedbacks
  • Resource diversity
  • Streptomy c es


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