Zinc-mediated alleviation of cadmium stress in potato via suppressing StZIP5 induced Cd uptake and enhancing StPCR9 induced Cd efflux

Cadmium (Cd) soil contamination severely threatens potato production and food safety by accumulating in edible tubers. This study systematically integrated physiology, transcriptomics, and gene validation to elucidate the organ-specific mechanisms by which exogenous zinc (Zn) alleviates Cd toxicity and explores its field potential. Physiological assays demonstrated 50 μM ZnSO₄ supplementation under 100 μM CdCl₂ stress increased biomass over twofold while reducing root and leaf Cd by 57.6 % and 15.4 %, respectively. Transcriptomics revealed organ-specific regulation of Zn in alleviating Cd stress. In roots, Zn downregulated StZIP3/4/5 ( ZIPs family) and upregulated StPCR2/8/9 ( PCRs family), suppressing Cd uptake and enhancing efflux, respectively. Zn concurrently regulated antioxidant defense (SOD and POD decreased 22.2–23.9 %), osmoregulation (PRO reduced 42.8 %), and alleviated membrane damage (MDA decreased 25.2 %). Simultaneously, Zn mitigates metabolic overload by blocking the hyperactivation of phenylpropanoid metabolism in roots and glutathione-based detoxification in leaves. Functional analyses demonstrated that plasma membrane-localized StPCR9 facilitates Cd and Zn efflux in potato. Its overexpression increased biomass by approximately 2-fold under Cd stress while reducing Cd accumulation in organs. Conversely, StZIP5 overexpression decreased biomass by 15.0–20.5 % and increased Cd accumulation. Critically, field application (37.5 and 75.0 kg·hm −2 ZnSO 4 ) reduced tuber Cd by 64.2–66.3 % (primarily via about 60.0 % reduction in stem-to-tuber translocation), significantly lowering dietary Cd risk, while concurrently enhancing tuber Zn (>3 μg·g⁻¹ FW) for improved nutritional quality. This integrated approach elucidates the coordinated organ-specific defense of Zn and provides a field-validated strategy for safer potato production in Cd-contaminated soils. • First mechanistic dissection of Zn-Cd antagonism in potato. • Discovery of StPCR9 mediating Cd/Zn efflux from roots. • Field application reduces tuber Cd by 64–66 % in polluted soils. • Dual benefit: Cd mitigation and Zn biofortification in tubers. • Provides a cost-effective strategy for safe potato production.