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Front. Microbiol. | doi: 10.3389/fmicb.2018.00857

Rhizosphere protists change metabolite profiles in Zea mays

 Anke Kuppardt1*, Thomas Fester1, Claus Härtig1 and  Antonis Chatzinotas1, 2
  • 1Environmental Microbiology, Helmholtz-Zentrum für Umweltforschung (UFZ), Germany
  • 2German Center for Integrative Biodiversity Research, Germany

Plant growth and productivity depend on the interactions of the plant with the associated rhizosphere microbes. Rhizosphere protists play a significant role in this respect: considerable efforts have been made in the past to reveal the impact of protist-bacteria interactions on the remobilization of essential nutrients for plant uptake, or the grazing induced changes on plant-growth promoting bacteria and the root-architecture. However, the metabolic responses of plants to the presence of protists or to protist-bacteria interactions in the rhizosphere have not yet been analyzed. Here we studied in controlled laboratory experiments the impact of bacterivorous protists in the rhizosphere on maize plant growth parameters and the bacterial community composition. Beyond that we investigated the induction of plant biochemical responses by separately analyzing above- and below-ground metabolite profiles of maize plants incubated either with a soil bacterial inoculum or with a mixture of soil bacteria and bacterivorous protists. Significantly distinct leaf and root metabolite profiles were obtained from plants which grew in the presence of protists. These profiles showed decreased levels of a considerable number of metabolites typical for the plant stress reaction, such as polyols, a number of carbohydrates and metabolites connected to phenolic metabolism. We assume that this decrease in plant stress is connected to the grazing induced shifts in rhizosphere bacterial communities as shown by distinct T-RFLP community profiles. Protist grazing had a clear effect on the overall bacterial community composition, richness and evenness in our microcosms. Given the competition of plant resource allocation to either defense or growth, we propose that a reduction in plant stress levels caused directly or indirectly by protists may be an additional reason for corresponding positive effects on plant growth.

Keywords: predator-prey interactions, trophic interactions, Metabolites, microcosms, Rhizosphere microorganisms

Received: 15 Feb 2018; Accepted: 13 Apr 2018.

Edited by:

Sergio Rasmann, University of Neuchâtel, Switzerland

Reviewed by:

Elvira S. De Lange, University of California, Davis, United States
Lingfei Hu, Universität Bern, Switzerland  

Copyright: © 2018 Kuppardt, Fester, Härtig and Chatzinotas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Anke Kuppardt, Helmholtz-Zentrum für Umweltforschung (UFZ), Environmental Microbiology, Permoser Straße 15, Leipzig, 04318, Germany, anke.kuppardt@ufz.de