Spatio-temporal dynamics of bacterial communities associated with two plant species differing in organic acid secretion: A one-year microcosm study on lupin and wheat |
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Authors: | Laure Weisskopf Renée-Claire Le Bayon Florian Kohler Valérie Page Maryline Jossi Jean-Michel Gobat Enrico Martinoia Michel Aragno |
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Affiliation: | 1. Institute of Biology, University of Neuchâtel, Emile-Argand 11, CP 158, CH-2009 Neuchâtel, Switzerland;2. Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland;3. Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland;4. Postech-UZH Global Research Laboratory, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea |
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Abstract: | Plants are generally assumed to influence the surrounding soil microflora through rhizodeposition. However, the role of rhizodeposits, and especially organic acids, in structuring the bacterial communities is still poorly understood. In this study, we asked the question whether plants differing in organic acid secretion have a different impact on the soil bacterial communities, and if this is the case, to which extent this impact is due to different organic acid concentrations in the rhizosphere. To investigate this question, we compared white lupin and wheat. The former is a high organic acid-secreting species, while the latter secretes only low amounts of carboxylates. We grew the plants in large microcosms including root-free control compartments for one year (replanted every second month) and analyzed the spatio-temporal changes in soil ATP concentrations, as well as in diversity and structure of bacterial communities (using DNA- and RNA-based DGGE) along a root-soil gradient after two, six and twelve month's cultivation. Our results showed: i) that white lupin and wheat differed in their impact on soil ATP concentrations and on the structure of root bacterial communities; ii) that cultivation time was a key factor in explaining the observed differences in all the parameters studied; and iii) that the amounts of organic acids accounted for a significant proportion (15%) of the variability within root active communities. These results indicate that plants influence their associated bacterial communities in a species-specific way and that for communities living in the direct vicinity of roots (rhizoplane-endorhizosphere), a significant part of this influence can be attributed to root-secreted organic acids. |
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