Nitrogen starvation induces arbuscular mycorrhizal fungi to optimize resource allocation in sugarcane roots via suppression of basal metabolism

The interplay between nutrient availability and arbuscular mycorrhizal fungi (AMF) symbiosis during plant growth exhibits intricate complexity. In this study, we employ integrated physiological, transcriptomic, proteomic, and metabolomic analyses to investigate how sugarcane differentially adapts to nitrogen (N) fertilization and AMF colonization. Under nitrogen stress conditions, AMF colonization significantly enhances sugarcane growth, increasing plant height, stem diameter, and biomass while stimulating root exudation and rhizospheric nutrient mobilization-particularly available N, phosphorus (P), and potassium (K). Multi-omics analyses reveal that AMF induces nitrogen-dependent metabolic reprogramming in sugarcane roots, activating pathways such as carbohydrate and lipid metabolic pathways while suppressing butanoate and ascorbate metabolism. Weighted gene co-expression network analysis (WGCNA) identifies key root modules strongly correlated with soil N, P, and K availability, indicating AMF-mediated coordination of nutrient acquisition strategies. Field trials demonstrate that AMF boost sugarcane yield under nitrogen stress by enhancing root elongation and carbon partitioning for sucrose accumulation. Temporal integration of transcriptomic and metabolomic data highlights flavonoid biosynthesis as a persistently activated pathway across growth stages, potentially facilitating AMF symbiosis and stress resilience. Our findings elucidate how sugarcane optimizes AMF-mediated nutrient acquisition under nitrogen stress through root transcriptional and metabolic adjustments, providing insights for sustainable crop nutrient management.