Autor:innen:
Debjyoti Ghosh | Molecular Systems Biology, Helmholtz Centre for Environmental Research GmbH | Germany
Yijie Shi | Christian-Albrechts Universität zu Kiel, Institut für Pflanzenernährung und Bodenkunde | Germany
Tobias Stürzebecher | Biogeochemistry of Agroecosystems, Georg-August-University Göttingen, Göttingen, Germany | Germany
Henrik Füllgrabe | Biogeochemistry of Agroecosystems, Georg-August-University Göttingen, Göttingen, Germany | Germany
Katja Holzhauser | Institute of Crop Science and Plant Breeding, Agronomy and Crop Science, Christian-Albrechts-University Kiel | Germany
Dr. Iris Zimmermann | Christian-Albrechts Universität zu Kiel, Institut für Pflanzenernährung und Bodenkunde | Germany
Prof. Dr. Michaela A. Dippold | Geo-Biosphere Interactions, Department of Geosciences, University of Tübingen | Germany
Prof. Dr. Sandra Spielvogel | Christian-Albrechts Universität zu Kiel, Institut für Pflanzenernährung und Bodenkunde | Germany
Dr. Jochen A. Müller | Karlsruhe Institute of Technology - KIT, Eggenstein-Leopoldshafen, Germany | Germany
Dr. Nico Jehmlich | Molecular Systems Biology, Helmholtz Centre for Environmental Research GmbH | Germany
Climate change has a major impact on soil ecosystems. The use of cover crops to re-root cash crops is one method to address deficiencies in topsoil nutrient and water availability. Maize and cover crop root channels may interact favorably or unfavorably, respectively. However, the role of microorganisms in nutrient mobilization in the soil and rhizosphere in such situations is not well understood.
The cultivation of winter cover crops (Trifolium pratense, Trifolium repens, Festuca arundinacea, Lolium perenne, Raphanus sativus var. oleiformis, Brassica napus) in monocultures and mixtures was followed by the growth of maize in summer at a Luvisol field site in Northern Germany. At various stages of maize growth – germination, leaf development, and flowering, samples from the root channels of maize roots in bulk soil and root channels of maize roots in reused crop channels were collected. These samples were analyzed using 16S amplicon DNA sequencing and metaproteomics. Metaproteomics provides in-depth functional information regarding the contribution of bacteria to various element cycles (C, N, and P).
Proteobacteria, Planctomycetota, Acidobacteriota, and Actinomycetota were the major bacterial phyla inhabiting the maize rhizospheres, according to the 16S amplicon sequencing results. The release of N and P from organic matter was carried out by the taxa Bacteroidota and Firmicutes. In plots where the oil radish (Raphanus sativus var. oleiformis) is the cover crop, the relative proportions of Proteobacteria, Planctomycetota, Acidobacteriota, and Actinobacteriota were higher compared to plots with mixtures. Since maize rhizosphere re-rooting with cover crops induced variability among KEGG pathways, this provides a lead in the C, N, and P cycles essential for maize growth. Phyla like Actinobacteriota, Proteobacteria, Planctomycetota, Bacteroidota, Firmicutes, and Verrucomicrobiota had higher protein abundances in mixture plots than monoculture plots. Fescue (Festuca arundinacea) plots showed a relatively lower protein abundance, which may indicate that they partially inhibit microbial activity. With the aid of these observations, we could choose a cover crop that would work best when planted alongside maize during re-rooting to maximize microbial activity, replenish the resources needed for growth in distant niches, and increase crop production in the future.
Keywords: 16S amplicon sequencing, metaproteomics, rhizosphere, soil, roots, cash crops, cover crops