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INPLAMINT - Increasing agricultural nutrient-use efficiency by optimizing plant-soil-microorganism interactions

Subproject B

Dr. Julien Roy and Prof. Matthias Rillig

Freie Universität Berlin

Arbuscular mycorrhizal (AM) fungi are a widespread group of plant symbionts, with high potential for increasing nutrient use efficiency by plants while reducing the amount of fertilizers, and for crop disease management. These are root-colonizing fungi (Fig. 1), which are also very commonly found in many agriculturally important plants.

Arbuscular mycorrhizal fungi inside the root of a host plantFig. 1 Arbuscular mycorrhizal fungi (stained blue) inside the root of a host plant. The linear structures are the hyphae, and also visible are the arbuscules, which represent the symbiotic interface for nutrient/ carbon exchange between fungus and host root cell.

Main project aims

We study communities of AM fungi, which we decode using Illumina sequencing of AM fungal 28S rDNA large subunit (LSU) sequences. We focus on understanding temporal dynamics in successional timescales (52 years), using a chronosequence of recultivation. We also examine the effects of cover crops and work on various long-term field experiments in Germany, testing for links between AM fungal communities and stoichiometry.

Findings

We sampled soil along a 52-year chronosequence of field recultivation after open-cast mining to better understand the dynamic of AM fungal community succession under human-influenced field management.

Illumina sequencing provides a powerful way of estimating the diversity of AM fungal community in the field. LSU sequences provides a marker-gene with good resolution to discriminate taxa with a positive or negative correlation to soil quality. Our data (Roy et al. 2017) reveal a quick and strong recovery of AM fungal richness after a few years of recultivation, but also a rapid decline following years of conventional agriculture. The community structure was strongly correlated to mineral nitrogen and phosphorus, richness peaking at high N:P ratio. Further analyses showed that N and P affect community composition at different phylogenetic resolutions, with P affecting the distribution of deeply diverging clades.

This work shows the deleterious effect of conventional agricultural practices on AM fungal species richness developing over time. Nonetheless, the highly dynamic nature of AM fungal communities suggests strategies for site-level management for which considering N:P stoichiometry is crucial.

In additional work (Lehmann et al. 2017), we conducted a comprehensive meta-analysis to examine the effects of soil biota (and their interactions) on soil aggregation, a key ecosystem contribution of AM fungi, also in agricultural systems.

Additionally, we explored what a mycorrhizal technology of the future in the context of sustainable agriculture could look like (Rillig et al. 2016), and we explored the potential consequences of soil biodiversity, including mycorrhiza, on food production, taking into the account the agrifood chain as a whole (Rillig et al. 2018).

Publications

Lehmann A, Zheng W, Rillig MC. 2017. Soil biota contributions to soil aggregation. Nature Ecology & Evolution 1: 1828-1835.

Rillig MC, Lehmann A, Lehmann J, Camenzind T, Rauh C. 2018. Soil biodiversity effects from field to fork. Trends in Plant Science ; doi: 10.1016/j.tplants.2017.10.003

Rillig MC, Sosa-Hernandez MA, Roy J, Aguilar-Trigueros CA, Valyi K, Lehmann A. 2016. Towards an integrated mycorrhizal technology: harnessing mycorrhizae for sustainable intensification in agriculture. Frontiers in Plant Science 7: 1625. doi: 10.3389/fpls.2016.01625.

Roy J, Reichel R, Brüggemann N, Hempel S, Rillig MC. 2017. Succession of arbuscular mycorrhizal fungi along a 52-year agricultural recultivation chronosequence. FEMS Microbiology Ecology 93: fix102


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