Tissue-specific phosphorus stress adaptation in Brassica rapa: WGCNA reveals root hormonal triad and leaf lipid remodeling as key tolerance mechanisms

• Tolerant Brassica rapa uniquely combines leaf galactolipid remodeling with root ABAauxin-JA crosstalk for P-stress adaptation. • WGCNA reveals temporal decoupling: early lipid recycling precedes systemic hormonalresponses via specialized PAH1 hubs. • Brassica employs polyploid-paralog plasticity and non-canonical PHR1 pathways,suggesting novel PUE improvement targets. Phosphorus (P) deficiency severely limits global crop productivity, yet the tissue-specific adaptation mechanisms in Brassica rapa, a key leafy vegetable, remain poorly characterized. Using transcriptomic and WGCNA, we dissected leaf and root responses to P-stress in tolerant (TL) and sensitive (SL) genotypes across early (2-day) and late (2-week) phases. In leaves, TL exhibited coordinated membrane lipid remodeling, with strong induction of galactolipid synthases (MGD2/3, and uncharacterized DGD) and suppression of phospholipid degradation, coupled with phased downregulation of photosynthetic genes. Roots deployed a novel hormonal triad—ABA activation, auxin homeostasis, and jasmonate suppression—to enhance PHT1;4-mediated P uptake. WGCNA revealed paralog specialization in lipid metabolism (PAH1 hubs) and temporal decoupling of acute lipid recycling from systemic hormonal responses. Crucially, TL’s hierarchical regulation optimized PUE without growth penalties, unlike SL’s dysregulated signaling. Our work uncovers Brassica-specific innovations in P adaptation, including polyploid-paralog plasticity and hormonal crosstalk beyond canonical PHR1 pathways, providing strategic targets for improving crop resilience.