Protists communities are dynamic and more complex in the rhizosphere

Our new study on the succession of protists in the rhizosphere of switchgrass is now published. This work is part of a multi-institutional collaboration in which my team was in charge of studying soil microfauna – protists, which are microbes too!

The study shows that protists’ community diversity and composition change as the switchgrass plants go through different phenological stages, from early vegetative growth to senescence. The plants were grown in two marginal soil sites managed by the Noble Research Institute. Hence, the study is the result of a field experiment beautifully managed by the Noble scientists. Part of the analysis of protist community dynamics included the reconstruction of co-occurrence networks whose similarity thresholds were not arbitrary by calculated using Random Matrix Theory-based approaches. The results of these analyses show that the networks of protists in the rhizosphere are more complex and dynamic than those of the bulk soil, which remain unchanged from beginning to end of the study (for the most part). We also used iCAMP to analyze the mechanisms that control protist community assembly. We show that dispersal limitation is the mechanism controlling protist assembly in the bulk soil, while homogeneous selection is the mechanism that regulates the assembly of protists in the rhizosphere.

Protists are a type of microbe, and are slowly being recognized as key elements of the soil and rhizosphere microbiome. In this study, protist communities near plant roots were found to respond to the different developmental stages of switchgrass. (Credit: Javier A. Ceja Navarro)