Abstract
The leaves of fescue grasses are protected from herbivores by the production of loline alkaloids by the mutualist fungal endophytes Neotyphodium sp. or Epichloë sp. Most bacteria that reside on the leaf surface of such grasses can consume these defensive chemicals. Loline-consuming bacteria are rare on the leaves of other plant species. Several bacterial species including Burkholderia ambifaria recovered from tall fescue could use N-formyl loline as a sole carbon and nitrogen source in culture and achieved population sizes that were about eightfold higher when inoculated onto plants harboring loline-producing fungal endophytes than on plants lacking such endophytes or which were colonized by fungal variants incapable of loline production. In contrast, mutants of B. ambifaria and other bacterial species incapable of loline catabolism achieved similarly low population sizes on tall fescue colonized by loline-producing Neotyphodium sp. and on plants lacking this endophytic fungus. Lolines that are released onto the surface of plants benefiting from a fungal mutualism thus appear to be a major resource that can be exploited by epiphytic bacteria, thereby driving the establishment of a characteristic bacterial community on such plants.
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Acknowledgements
This work was funded in part by National Science Foundation Postdoctoral Fellowship 0610319 to ER. We are grateful to Dr Ellen Beaulieu for her help with mass spectrometry and other chemical analyses. We also thank Lena Tran for her assistance in generating transposon mutants and in other aspects of the study and Sara Sirvanchai for helpful comments on the manuscript. We are also grateful to Chris Schardl for supplying seeds of Meadow Fescue infected with loline-deficient strains of Epichloë.
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Roberts, E., Lindow, S. Loline alkaloid production by fungal endophytes of Fescue species select for particular epiphytic bacterial microflora. ISME J 8, 359–368 (2014). https://doi.org/10.1038/ismej.2013.170
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DOI: https://doi.org/10.1038/ismej.2013.170
