Multi‐Omics Analysis Deciphers Nitrogen‐Phosphate Balance to Maintain Metabolic Homoeostasis and Promote Plant Growth in Rapeseed

Nitrogen (N) and phosphate (P) are essential macronutrients, yet their combined regulatory dynamics in rapeseed (Brassica napus) remain elusive. This study integrated transcriptomics, metabolomics, lipidomics and physiological phenotyping to dissect responses to N-P co-deficiency (-N-P), single deficiencies (-P, -N) and sufficiency (+N+P). Under -N-P, rapeseed exhibited severe growth inhibition (44.8% reduction in shoot biomass) and prioritised nutrient acquisition via transcriptional upregulation of root NRTs/AMTs (N uptake) and PHTs/PAPs (P scavenging) genes, sustaining higher N/P utilisation efficiency by root plasticity than single deficiencies. Photosynthesis was suppressed during deficiencies, with starch accumulation and TCA cycle perturbation indicating energy and carbon repartitioning. N-P imbalance (-P or -N) induced more severe carbon-metabolic dysregulation than dual deficiency. Crucially, lipid remodelling emerged as a central adaptive strategy: -P triggered phospholipid-to-galactolipid/sulfolipid conversion to conserve P, while -N diverted carbon toward signalling/storage lipids. -N-P attenuated these shifts but induced unique lipid species adjustments to maintain membrane stability. We propose an 'N-P Tumbler' model wherein balanced N-P supply stabilises metabolic homoeostasis and optimises carbon allocation. Our work uncovers transcriptionally orchestrated lipid metabolic trade-offs as key to N-P interplay, providing a framework for breeding nutrient-efficient crops and precision fertilisation strategies for sustainable agriculture.