FTICR-mass spectrometry reveals shifts in plant-microorganism interactions over time

A plethora of experimental studies manipulating plant diversity have shown a positive effect of biodiversity on ecosystem functions (aboveground biomass, microbial biomass etc.), which strengthens over time. Tightening of the interactions between plant and soil microorganisms over time is considered to be one of the mechanisms responsible for the observed strengthening of the biodiversity-ecosystem functioning (BEF) relationship. Belowground plant-microorganism interactions occur via the exchange of molecules present in the dissolved organic matter (DOM). Hence, an untargeted ultrahigh resolution mass spectrometric analysis of DOM provides an opportunity to understand the mechanisms of interaction between plants and microorganisms in soil. To investigate if and how plants-soil interactions changed over time, we took advantage of the highly replicated DBEF experiment of the Jena Experiment (JE) (Roscher et al., 2004, Vogel et al., 2019). In this experiment, the duration of plant-soil interactions (“history”) and the respective effects of plant diversity on ecosystem functioning were manipulated. Here, we analyzed the water extractable organic matter fraction of topsoil (WEOM; analogous to DOM in this study) using online nano solid phase extraction FTICR-mass spectrometry. While the molecular composition of the WEOM was not impacted by soil history, plant diversity effect differs among the soil history treatments. Specifically, plant diversity had a significant impact on the molecular composition of WEOM in treatments with plant and soils history. In addition, the molecular composition of WEOM in this treatment held a large number of molecular formulae that significantly correlated with plant diversity. This suggests that the strengthening of the biodiversity-ecosystem functioning over time is reflected in the WEOM molecular composition. Thus, the molecular composition of WEOM potentially provides insight into the mechanism underlying the strengthening of biodiversity-ecosystem functioning.

 

 

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Vogel, A., Ebeling, A., Gleixner, G., Roscher, C., Scheu, S., Ciobanu, M., ... & Eisenhauer, N. (2019). A new experimental approach to test why biodiversity effects strengthen as ecosystems age. In Advances in ecological research (Vol. 61, pp. 221-264). Academic Press.