From fruiting failure to success: Soil amendment strategy rescues Morchella sextelata cultivation in cadmium-contaminated soils

Cadmium (Cd) contamination poses a serious threat to soil microbial function and the safe cultivation of edible fungi, yet ecological remediation strategies targeting heterotrophic fungi remain poorly studied. In this study, a pot experiment was conducted using Morchella sextelata as the research organism, applying five treatments involving 2 mg/kg Cd, organic fertilizer, and Fe 2+ spraying to evaluate ecological responses. Only the T1 (organic fertilizer) and T2 (organic fertilizer + Fe 2+ ) treatments successfully induced fruiting under high Cd stress, underscoring the critical role of energy supply in fungal development. Soil analyses showed that both T1 and T2 enhanced nutrient availability and enzymatic activity. Notably, under unchanged Cd speciation, T2 significantly reduced Cd accumulation in fungal caps and stipes by 27.4% and 36.9%, respectively, suggesting that Fe 2+ effectively suppressed Cd translocation into fungal tissues. Metagenomic profiling revealed that Morchella abundance was positively correlated with SOC and SDHA, and negatively with Cd. Mantel tests and correlation heatmaps identified CEC, UE, and S-AKP as key drivers of fungal community shifts. Co-occurrence network analysis demonstrated higher network density and modularity in T2, indicating greater community stability. Functional annotation revealed that Cd-stressed groups (D1/D2) exhibited “carbon overflow” via enriched glycolysis and fermentation, while T2 enhanced nitrogen cycling and oxidative metabolism, maintaining a moderate and stable energy state. This study highlights the heightened sensitivity of heterotrophic fungi to nutrient and environmental buffering under Cd stress. We propose a dual strategy of “nutritional support and translocation blockage” to promote fungus-compatible ecological remediation of contaminated soils. • Cd stress fully blocked fruiting of M. sextelata , underscoring its high ecological sensitivity. • Organic fertilizer restored fruiting, while Fe 2+ addition further reduced Cd accumulation. • Combined amendment improved SOC, CEC, and enzyme activities, stabilizing soil buffering. • Metagenomics showed Cd stress drove “carbon overflow,” while amendments restored C–N balance. • A “nutritional support + translocation blockage” model is proposed for fungus-compatible remediation.