PNNL

Abstract

Most of Earth’s trees rely on critical soil nutrients that ectomycorrhizal fungi (EcMF) liberate and provide, and all of Earth’s land plants associate with bacteria that help them survive in nature. Yet our understanding of how EcMF modify soil bacterial communities, soil food webs, and root chemistry requires direct experimental evidence to comprehend the cascading effects that EcMF may generate in the belowground plant microbiome. To this end, we grew Pinus muricata plants in soils that were either inoculated with EcMF and native forest bacterial communities or only native bacterial communities. We then profiled the soil bacterial communities, applied metabolomics and lipidomics, and linked omics datasets to understand how the presence of EcMF modifies belowground biogeochemistry and bacterial taxa-function relationships. Our analyses revealed that EcMF have strong cascading effects on bacterial-taxa relationships and soil food webs. Specifically, we demonstrate that the presence of EcMF (1) enriches soil bacteria known to benefit plant growth in nature, (2) alters the quantity and composition of soil food webs, and (3) reprograms plant root chemistry toward pathogen suppression and enzymatic conservation. Our work therefore uses a multi-omic approach to highlight mechanisms that are involved in widespread interactions among bacteria, EcMF, and a common host plant.