Reference Data

This review synthesizes current knowledge on how root secondary metabolites, beyond their established roles in plant defense and symbiosis, act as critical regulators of nitrous oxide (N₂O) emissions in the rhizosphere. While the rhizosphere has long been recognized as a hotspot of N₂O production, most studies have emphasized primary metabolites or bulk soil nutrient dynamics, leaving the regulatory potential of root-derived secondary metabolites largely underexplored. By integrating evidence from plant physiology, soil microbiology, and biogeochemistry, we delineate two mechanistic pathways through which root secondary metabolites influence soil N₂O dynamics: (1) direct modulation of the abundance and activity of key N-cycling microorganisms, and (2) indirect mediation of complex inter- and intra-kingdom microbial interactions. This dual framework provides a novel conceptual perspective for understanding metabolite–microbiome–N₂O linkages. We further highlight how metabolite diversity, chemotaxis, and trophic interactions collectively shape rhizosphere community assembly and nitrogen transformations, emphasizing the need for integrated multi-omics approaches and experimental validation. Given the urgent global challenge of mitigating agricultural N₂O emissions, which contribute disproportionately to climate change and ozone depletion, elucidating the role of root secondary metabolites opens new opportunities for sustainable land management and climate-smart agriculture.