Transcriptomic response of wetland microbes to root influence

Summary: Wetlands are hotspots for carbon and nutrient cycling. The important role of plant-microbe interactions in driving wetland biogeochemistry is widely acknowledged, prompting research into their molecular biological basis for a deeper understanding of these processes. We analyzed transcriptomic responses of soil microbes to root exudates in coastal wetland soils using 13CO2 pulse labeling. Metatranscriptomics revealed 388 upregulated and 11 downregulated genes in response to root exudates. The Wood-Ljungdahl pathway and dissimilatory sulfate reduction/oxidation were the most active microbial pathways independent of root influence, whereas pathways with the strongest upregulation in response to root influence were related to infection, stress response, and motility. We demonstrate shifts within the active community toward higher relative abundances of Betaproteobacteria, Campylobacterota, Kiritimatiellota, Lentisphaerota, and Verrucomicrobiota in response to exudates. Overall, this study improves our mechanistic understanding of wetland plant-soil microbe interactions by revealing the phylogenetic and transcriptional response of soil microorganisms to root influence and exudate input.