Biochar Rewires Root Exudates and the Rhizosphere Microbiome and Its Functionality

Abstract

Biochar amendment is beneficial to the soil-plant system; yet the underlying mechanism is not fully understood. Integrating microfluidics and multi-omics and using wheat as a model plant, we found biochar induces differential root exudates, especially complex molecules like secondary metabolites and signaling cues, and rewires the rhizosphere microbiome, evoking a plant-beneficial rhizosphere microbiome centered by diverse plant growth promoting rhizobacteria (PGPR) known to participate in nitrogen cycling, organic matter turnover, nutrient acquisition, phytohormone metabolism, and stress resistance. Network analysis and machine learning identified high co-occurrence between specific root exudates and PGPR. qPCR, 16S rRNA gene sequencing, and untargeted soil metabolomics suggested the restructured rhizosphere microbiome may have shifted nitrogen and methane metabolism leading to reduced potential of N2O and methane emissions, and may participate in the metabolism of signaling cues and redox reactions. This study provides new insights into biochars profound impact on the soil-plant system and highlights the potential of engineering the rhizosphere through reshaping root-microbe interactions.